Patent ID: 8653921

Claim:
A switching electromagnet, comprising: a field winding located on a coil form; a first pole piece forming a part of a magnet return path; a pole core and an axially movable magnetic piston inside said coil form, said magnetic piston being mounted in a guide of said pole core for movement of said magnetic piston; an aperture opening in said first pole piece for said magnetic piston on a region thereof opposite said pole core; a flange part on said first pole piece at least partially extending over said coil form; a bushing part of said first pole piece extending axially from said flange part and forming a hollow cylinder extending over a longitudinal section of said magnetic piston inside said coil form; a parasitic air gap between an inner wall of said hollow cylinder and a circumference of said magnetic piston; and a guide sleeve coaxial to said hollow cylinder of said first pole piece, mounting said magnetic piston with a sliding fit and having a tight tolerance such that said magnetic piston does not contact said hollow cylinder when said parasitic air gap has a width less than 0.1 mm.