Linear motor or alternator plunger configuration using variable magnetic properties for center row and outer rows of magnets

Claim 1

A linear electromagnetic reciprocating machine, comprising: a stator having end portions forming axially spaced-apart pole pieces, said stator further including a coil cavity; a coil mounted in said coil cavity; a plunger arranged for reciprocation with respect to said stator, wherein said plunger includes two outer portions spaced axially apart with a central portion axially adjacent to and between said two outer portions; wherein said two outer portions are of equal axial length and the central portion is axially longer than either of said outer portions, and such that adjacent ends of the outer and central portions define interface zones between said portions, said interface zones between said portions being substantially within a region defined by said stator pole pieces for most operating axial positions of said plunger; wherein said end portions are of equal magnetic strength to each other and wherein said central portion has a higher magnetic strength than said end portions; and flux return means associated with said stator for completing a magnetic circuit.