EXTERNAL MAGNET FLYWHEEL MOUNTING

摘要

A flywheel assembly for a small internal combustion engine including a permanent magnet structure secured to the flywheel near the outer periphery thereof and for cooperating with the ignition stator to induce spark creating voltages therein. The permanent magnet structure includes two pole shoes and a permanent magnet captured between shoulder portions of the pole shoes. A non-magnetic spacer plate includes two protuberances and is inserted between the flywheel and the magnet group consisting of the pole shoes and the permanent magnet. The protuberances cooperate with outer peripheral surfaces of the pole shoes. The magnet group is held accurately and rigidly in position by axially compressing a pair of rivets which pass through the flywheel, the plate and the magnet group, whereby the rivets are radially expanded to tightly fill the respective apertures through which they pass. The protuberances on the plate prevent the pole shoes from pivoting when the pole shoe outer surfaces are machined. The magnets are prevented from radial movement with respect to the axis of the flywheel by the recess portions of the pole shoes.