Overspeed/overheat circuit with a latch for capacitive ignition systems

摘要

A circuit protecting against overspeed and overheating in a two-cycle engine having a capacitive discharge ignition system which includes a charging coil in which voltage is induced when a magnet in the flywheel of the engine passes the coil. A rectifier bridge is connected to the coil and a capacitor connected to the bridge. An ignition coil and spark plug are associated with each cylinder of the engine. An electronic switch is associated with each ignition coil and has a trigger which responds to an applied trigger voltage to conduct and discharge the capacitor through the ignition coil. A trigger coil applies a trigger voltage to the triggers. The protective circuit includes a control responsive to engine speed. The control triggers one of the electronic switches to conduct and discharge the capacitor in response to a predetermined response speed. A circuit responsive to operation of an engine temperature responsive switch reduces the predetermined response speed of the control to a lower response speed. The lower response speed is maintained effective even if the engine temperature subsequently falls below the maximum engine temperature. The circuit requires reduction of the engine speed to a speed below the lower response speed in order to restore the response speed of the speed responsive control to the predetermined speed.