Abstract:
A control circuit for an ignition system having a magnet generator provides an abrupt adjustment of the ignition time point toward an advanced ignition when a predetermined upper speed range of an engine is reached. The control circuit includes a frequency dependent R-C member coupled to a control switching transistor activated at a preset voltage level to trigger an ignition switching power transistor. The R-C member is preadjusted so as to be charged to the preset voltage level at the time point of the transition from a lower to the upper speed range.
Abstract:
A control circuit operates with a small toroidal transformer, having a ferrite core, to produce high voltage pulses efficiently. The circuit applies a magnetizing force to the transformer core that is in excess of the force required to produce maximum magnetization of the core. The initial magnetizing force is opposed by current flow in the secondary winding. As the secondary current flow approaches zero, it no longer can act to demagnetize the core and the primary can generate a rapid change in magnetic strength resulting in a high voltage in the secondary winding. The rate of change of current in the primary circuit is limited by a small inductor in series with the primary winding of the transformer. The charging circuit is interrupted simultaneously with discharge of a capacitor through the transformer primary. The core is insulated for high voltage and carries a secondary winding of about 300 turns extending over about 300 degrees of the circumference and a primary winding of about three to five turns. The unit occupies only about one cubic inch of space and weighs less than two ounces. It is capable of delivering more than 10,000 volts to a discharge element in a gaseous medium that results, subsequent to breakdown, with a current of as much as one-half ampere for a period of about 0.05 microseconds.
Abstract:
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 recessed portions of the pole shoes.
Abstract:
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.
Abstract:
An exciter coil and pulser coil induce voltages in phase reversal to each other by the rotation of an internal combustion engine are provided. A first condenser and second condenser are charged with the negative and positive induced voltage of the exciter coil respectively. A second switching element conductive by the discharged voltage of the second condenser discharged through a first switching element conductive when the induced voltage of the pulser coil reaches a set level is connected in series with a circuit connecting the ignition coil and first condenser. A circuit controlling the switching time of the first switching element is operated so as to retard the operation of the second switching element in the low speed operation range of the engine and to advance the same in the high speed operation range. This circuit includes a further switching element operating in response to the voltage inducing state of the pulser coil.
Abstract:
The capacitor discharge ignition system has a capacitor connected to and charged by a charging coil through a diode. The primary of an ignition transformer is connected to the capacitor and a trigger device controls discharge of the capacitor to ground through said primary coil. The anode of a second diode is connected between the charging coil and the first diode and a shutdown switch is connected in series between the cathode of the second diode and ground.
Abstract:
A magnet rotating synchronously with an internal combustion engine magnetically couples periodically with a stator having primary and secondary windings to induce a voltage in the primary winding. A switching transistor is connected across the primary winding terminals. A voltage divider circuit is connected between one primary winding terminal and the transistor base for supplying base-emitter current when the primary voltage reaches a predetermined level, thereby turning the transistor switch on. The anode and gate of a programmable unijunction transistor (PUT) are connected to points in the divider to sense increasing base current and a corresponding increasing PUT anode-to-gate voltage. At a specific anode-gate voltage, the PUT conducts to short circuit the transistor switch base current, and turn the switch off. This causes the magnetic field in the stator to collapse and induce a high voltage in the secondary winding to fire the engine spark plug.
Abstract:
An electronic ignition system of the capacitor-discharge type for an internal combustion engine includes a magneto generator having substantially a single generating coil with no center tap, and includes a change-over circuit which changes over the supply of power generated from the generating coil from the capacitor to an auxiliary unit when the capacitor is charged to a given voltage by the half-waves of one polarity of the alternating electromotive force generated in the generating coil. The opposite-polarity half-waves of the alternating electromotive force are supplied to the auxiliary unit even while the capacitor is being charged.
Abstract:
An inexpensive or economical ignition device which is capable of advancing the ignition timing in proportion to an increase in the engine speed when it stays within a preset range and obtaining constant minimum and maximum ignition angle characteristics when the engine speed is below and above the preset range, respectively, so that the ignition device may be operate in conformity with the output characteristic of an engine. A driving power source for the controller of the ignition device can be provided independently of the pulser coil, thereby to greatly stabilize the ignition characteristic in the low engine speed region.
Abstract:
An improved trigger circuit for a magneto-type ignition system is described. The trigger circuit includes a first generating coil for supplying current flow to a primary winding of the ignition coil, a transistor for controlling the current flow through the primary winding, a capacitor, a thyristor for cooperating with the capacitor to render the transistor non-conductive, and a second generating coil for supplying the power required to charge the capacitor and to control the conduction of both the transistor and thyristor, such that the capacitor is charged and the transistor is rendered conductive by one half wave output from the second generating coil and the thyristor is rendered conductive by the other half wave output from the second generating coil. The conduction of the thyristor is operative to discharge the capacitor and render the transistor non-conductive, whereby the current flow from the first generating coil is directed through the primary winding of the ignition coil to induce a sparking potential in the secondary winding of the ignition coil.