Bistable em relay with high coercivity magnetised pellet - has winding on central branch of W=shaped yoke which acts on moving contact through rare earth magnet

摘要

The W-shaped yoke (1) with a central branch (2) against which is wound an exciting coil (10). This branch is terminated by a pole-piece (20) on which is fixed a magnetised pellet (3) having a very high coercivity. The top face has one polarity, the bottom fixed face the opposite polarity. A preferred form for the magnetised pellet is grains of rare earth complexes agglomovated by synthetic resin. A paddle (4) having two contacting blocks (6,7) is pivoted on an outer branch of the yoke (1a). The relay has fixed contacts (9) formed from two screw heads whose relative position may be adjusted. When the relay is disengaged the paddle is maintained against the contact at rest (8) by the permanent magent (5). When cement flows in the coil in the sense which adds EM flux to that of the pellet the paddle is attracted to and held at the working contact. When cement flows in the opposite sense the attraction of the pellet is cancelled and the paddle returns to the at rest. A push button allows the paddle position to be adjusted manually.