Mcculloch Corporation

Robert V Jackson

Harold F Anderson, Deceased

A magnetic structure for use in a chain saw or edge trimmer ignition system or the like where the ignition system includes a flywheel having a plurality of cooling fins disposed around the peripheral portion thereof and at least one magnetic structure embedded in the periphery, a magnetically permeable core disposed adjacent the flywheel, a coil wound on the core and connected to an ignition circuit so that a voltage waveform is induced in the coil and applied to the circuit each time the magnetic structure passes the coil, the magnetic structure including (a) a magnet having first and second end faces and (b) first and second pole pieces which respectively engage the end faces, the pole pieces being asymmetrical in a plane perpendicular to the plane of the flywheel to thereby effect concentration of the flux produced by the magnet and coupled to the core by the pole pieces to thereby permit a reduction in size of the magnet without substantially lessening the energy in the voltage waveform applied to the ignition circuit and an increase in the size of those cooling fins disposed adjacent the reduced size magnet. The pole pieces may also be asymmetrical in the plane of the rotor.

Magnetic structure for use in a chain saw or edge trimmer ignition

An electrical energy storage and transforming device and associated pulse-forming systems suitable for receiving, storing, and transforming an electrical charge to produce electrical output pulses, for example, ignition pulses for a spark-ignition internal combustion engine, includes a current sheet inductor network defined by at least two conductive current sheet inductors separated by and insulated from one another by a dielectric material to provide coupled current sheet inductors having resistive, capacitive, and inductive characteristics. When electrical energy is applied to the current sheet inductor network, and electrical charge is stored and retained as an electrostatic field between the conductive current sheets until an output pulse is desired, at which time the conductive strips of the inductively coupled current sheet inductors are substantially shunted to rapidly discharge the previously charged energy. Electron flow in each sheet during discharge reinforces to provide a consequent magnetic field. An output inductor in magnetic proximity to the so-produced magnetic field provides the desired electrical output pulse. The conductive sheets can be configured so as to have resistive, capacitive, and inductive reactance, and relative ratios thereof, that are largely independently controlled to provide selected magnetic field, transient, and pulse-forming characteristics for a desired application.

Current-sheet inductor network and pulse-forming systems

The several embodiments of the self-generating breakerless ignition system disclosed herein are each comprised of a rotor structure with a permanent magnet which induces voltages in a plurality of windings, three cascaded semi-conductor switching elements to control the current in the windings, a trigger signal which is provided by one of the windings and which activates the switching elements at a predetermined time, and means which simultaneously supply positive and negative biasing to the switching elements to enhance the switching procedure.

Self generating ignition system

A capacitor discharge ignition system employing in-phase trigger, charge and shut-off coils, in a circuit which provides force commutation of the electronic switch and which provides compensation for variations in temperature, inhibition of extraneous triggering of the electronic switch and selective system shut-off. Extraneous triggering may be inhibited by the biasing of the electronic switch as a function of the polarity of the waveforms as well as by the damping of the transient which occurs at the end of the charge of the ignition capacitor. Shut-off is achieved by the shorting of the trigger coil which loads the charge coil to protect the ignition capacitor. Additional protection is provided by the selective shorting of the shut-off coil. Gate protection for the electronic switch is provided by the clamping of the cathode to gate potential.

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Los Angeles, CA, United States of America

Robert V Jackson