Magnetic mounting for electric starter motor - uses section of motor casing forced into dove-tail shaped hole in outer surface of magnet

摘要

The process for attaching magnetic poles into a motor casing is partic. suitable for constructing starter motors. The pole pieces (3) on which a winding (2) is formed has a concave surface facing the rotor of the motor, and a smaller convex surface fitting against the casing (1) of the motor. The convex surface has a dovetail shaped hole cut in it, the hole (4a) becoming wider as it cuts deeper into the pole piece. With the pole piece in situ inside the casing, a small part of the casing material is pushed through so that it touches the bottom of the dovetail hole. The projection is then further enlarged using a suitable tool so that it extends across the full width of the base of the hole, securing the pole piece to the casing. The technique does not require the accurate alignment which is necessary for rivetting or screw fitting.