Rotor controlled automatic spark advance

摘要

Disclosed herein is an ignition system comprising a coil mounted on a core having first and second spaced legs, together with a rotor mounted for rotation, under normal operating conditions, in one direction relative to the core such that any point on the periphery of the rotor passes the first leg prior to the second leg. The rotor includes a magnet having arcuately spaced first and second poles and first and second pole shoes extending respectively from the first and second poles. In addition, the first pole shoe extends in spaced relation from the second pole shoe in the direction of normal rotor rotation and has an arcuate length which is greater than the spacing of the first and second legs, and is effective, incident to travel of the first pole shoe past the first and second legs, to cause initial flow of flux of one direction into the coil core so as to generate in the coil a first current pulse of one polarity and thereafter to cause outflow of the flux from the coil core so as to generate in the coil a second pulse of the opposite polarity prior to approach of the second pole shoe to the first leg.