JPS5720558A - Noncontact igniter - Google Patents

Abstract

PURPOSE:To prevent kickback, by providing a protrusion on the peripheral part of a rotor which corresponds to the maximum width of spark advancement and by providing steps in appropriate positions on the protrusion to detect the position of ignition to place the position of ignition for starting behind that for idling. CONSTITUTION:A protrusion 1A is provided on the peripheral part of a magnetic- substance-made rotor 1 which corresponds to the width theta of spark advancement. Two steps, which are parallel with the tangents on the protrusion 1A, is provided at the rear end of the protrusion. When the rotor 1 is rotated counterclockwise depending on the rotation of a crankshaft, the quantity of magnetic flux of cores 4a, 4b of a pulser 2 is made large at the front end of the protrusion 1A and made slightly small at the steps and made smaller at the rear end. The output of a coil 5 has positive and negative wave shapes at the front and the rear ends with an interval of theta and has the same wave shape at the rear end and in the position by theta1 ahead of the rear end. According to this constitution, the position of ignition is changed stepwise at the low speed of the crankshaft to prevent kickback.