Patent ID: 8550221

Claim:
A spring comprising: a first part and a second part moveable relative to each other along a longitudinal axis, at least one gap being defined between the first part and the second part, the first part including permanent magnets of a hard magnetic material, the second part including a soft magnetic material, the second part having at least two teeth of soft magnetic material which each have a surface facing an adjacent surface of one of the permanent magnets when the first part is in an aligned position relative to the second part, the at least one gap being defined between the at least two teeth and the corresponding permanent magnets, wherein, when the first part moves from the aligned position relative to the second part along the longitudinal axis, the total area of the facing surfaces of the teeth and of the permanent magnets varies such that the magnetic permeability of the second part in response to a magnetic field of the permanent magnets varies along the longitudinal axis.