Patent ID: 8006952
Filing Date: 2011-08-30
Classification: F16K,H01F,H02K

Abstract:
1. An actuator comprising a thrust member moveable between two end of travel positions, an annular rotor having magnetic poles, an annular magnetisable stator having at least one winding and poles with which the rotor poles are aligned in each of a plurality of rotational positions of the rotor relative to the stator, in which the rotor poles remain attracted to a set of stator poles until a current is caused to flow in the at least one winding, which alters the magnetic field acting between the rotor and stator poles sufficiently to cause the former to be repelled from the stator poles with which they are currently aligned and to be attracted to and aligned with another set of stator poles, and a drive connection between the rotor and the thrust member which is adapted to convert rotational movement of the rotor into linear movement of the thrust member, wherein the actuator is arranged so as to define a flowpath through it, which extends through the rotor and stator.