Electromagnet, particularly a proportional magnet for operating a hydraulic valve

An electromagnet for operating a hydraulic valve which hydraulic valve is installed within a hydraulic system of a device for varying valve timing in an internal combustion engine, said electromagnet comprising:

• at least one coil winding carried by a hollow cylindrical coil spool, which coil spool is circumferentially surrounded by a hollow cylindrical magnet housing and a pole shoe is mounted adjacent each end of the coil spool, said electromagnet further comprising an axially moveable cylindrical armature which is disposed in a hollow cylinder of the coil spool which hollow cylinder defines a reception for an armature, said armature being mounted in low friction rotary, longitudinally moveable axial guides, and electromagnetically produced axial movements of the armature are transmitted to a hydraulic valve piston against a force of a spring via a push rod which is connected to the armature to form an axial extension thereof, wherein the rotary, longitudinally moveable axial guides of the armature comprise at least one bushing-less linear ball cage having a number of circumferentially spaced balls, said cage also serving as an anti-stick means of the armature, an outer peripheral surface of the armature and/or an outer peripheral surface of the push rod defines an inner running track for the balls, and an inner peripheral surface of the pole shoes or an inner peripheral surface of a pressure pipe lining the reception of the armature define an outer running track for the balls.