Electromagnetic actuator comprising at least two distinct magnetic circuits

摘要

An electromagnetic actuator comprises two armatures which are relatively movable to define a stroke and which form a main magnetic circuit the reluctance of which is variable between the ends of the stroke. A secondary magnetic circuit is formed between the armatures and its reluctance is also variable between the ends of the stroke, the variation being different to that of the first circuit to allow the relationship between the force of the actuator and the stroke position to be trailored to suit different requirements.