Abstract: An engine-generator starting apparatus a three-phase winding equipped with a generating unit that rotates relative to rotation of a crankshaft of an engine, and an electronic control unit that controls supply of electric current the three-phase winding to rotate the crankshaft and start the engine. In the apparatus, the electronic control unit controls to supply first current to the three-phase winding to make the engine crankshaft of rotate reverse, the first current is of a level for stopping the piston connected to the crankshaft at a position in a compression stroke. Then it controls to supply second current (that is greater than the first current) to the three-phase winding to make the crankshaft of the engine rotate forward when a predetermined time period has elapsed, and control to ignite fuel supplied to the engine after the second current is supplied to the three-phase winding.

Abstract: Systems and methods for operating an internal combustion engine that may be automatically stopped and started are described. In one example, an engine is rotated in a reverse direction after an engine stop so that a belt integrated starter/generator may rotate the engine in a forward direction and utilize the inertia of the engine to rotate trough top-dead-center compression stroke, thereby starting the engine.

Abstract: A control device sets reverse rotation period as a cranking prohibition period, and when a start request of an engine is generated during reverse rotation period, cranking is started by driving either or both of the first starter and the second starter when it is detected that a crankshaft is shifted from reverse rotation to forward rotation based on an information of a rotation angle sensor. As a result, the delay from generation of the start request of the engine until cranking is started can be reduced, so that the starting time of the engine can be shortened.

Abstract: A control device sets reverse rotation period as a cranking prohibition period, and when a start request of an engine is generated during reverse rotation period, cranking is started by driving either or both of the first starter and the second starter when it is detected that a crankshaft is shifted from reverse rotation to forward rotation based on an information of a rotation angle sensor. As a result, the delay from generation of the start request of the engine until cranking is started can be reduced, so that the starting time of the engine can be shortened.

Abstract: A DC electric motor control device has a motor driving circuit that is constructed by a plurality of switching elements, a controller that operates the motor driving circuit to control a normal rotation or a reverse rotation of a DC electric motor, and an abnormality determination part that determines whether an abnormality is generated while the controller controls the DC electric motor. The controller previously performs reverse rotation control of the DC electric motor for a predetermined time using the motor driving circuit when performing normal rotation control of the DC electric motor, and the controller performs the normal rotation control only when the abnormality determination part determines that the abnormality is not generated during the reverse rotation control.

Abstract: An ignition control device and corresponding method are provided for suppressing reverse rotation of the engine during startup process of a light duty gasoline engine, the ignition control device includes: a charge coil, a transformer, an electric-spark-generating control circuit, a trigger coil, a position sensing circuit, and a micro-controller. The position sensing circuit is used to shape the positive signal and negative signal of the second alternating current signal induced by the trigger coil while the fly wheel rotates respectively to generate a first position signal and a second position signal. According to the first position signal and the second position signal, it is determined by the micro-controller whether the engine is in the state of reverse rotation, and if YES, output of the ignition signal is stopped to make engine halt due to absence of reverse power.

Abstract: A reverse rotation preventive device wherein an engine can be restarted without once stopping the vehicle even in the case where a reverse rotation preventive function is operated in response to momentary locking of a rear wheel. A plurality of reluctors are arranged at regular intervals, exclusive of a toothless part at one location with a crank pulse rotor rotated synchronously with a crankshaft of the engine, and a first and second pulse generators each of which outputs a pulse signal corresponding to the interval of the reluctors. Reverse rotation preventive means inhibits ignition of a spark plug by operating the reverse rotation preventive function when the interpulse time of the pulse signal exceeds a predetermined time and cancels the inhibition of the ignition when it is detected that a crankshaft is in normal rotation after the ignition is inhibited by the operation of the reverse rotation preventive function.

Abstract: A control apparatus for an internal combustion engine, includes: a crankshaft; a crank angle detection unit; a generator; and a control unit to which alternating voltage signals are input, that ascertains ignition timings based on crank signals, performs ignition control so as to spark the internal combustion engine at the ignition timings, performs polarity determination processing in which the control unit determines a polarity of the alternating voltage signal each predetermined cycle and determines a current polarity determination result, and performs reverse rotation detection processing in which the control unit obtains the current polarity determination result each time the crank signal is detected so that the control unit ascertains a polarity cycle of the alternating voltage signals and in which the control unit determines that the crankshaft is in reverse rotation and stops the ignition control.

Abstract: A control apparatus for an internal combustion engine, includes: a crankshaft; a crank angle detection unit; a generator; and a control unit to which alternating voltage signals are input, that ascertains ignition timings based on crank signals, performs ignition control so as to spark the internal combustion engine at the ignition timings, performs polarity determination processing in which the control unit determines a polarity of the alternating voltage signal each predetermined cycle and determines a current polarity determination result, and performs reverse rotation detection processing in which the control unit obtains the current polarity determination result each time the crank signal is detected so that the control unit ascertains a polarity cycle of the alternating voltage signals and in which the control unit determines that the crankshaft is in reverse rotation and stops the ignition control.

Abstract: A control apparatus for an internal combustion engine, includes: a crankshaft; a crank angle detection unit; a generator; and a control unit to which alternating voltage signals are input, that ascertains ignition timings based on crank signals, performs ignition control so as to spark the internal combustion engine at the ignition timings, performs polarity determination processing in which the control unit determines a polarity of the alternating voltage signal each predetermined cycle and determines a current polarity determination result, and performs reverse rotation detection processing in which the control unit obtains the current polarity determination result each time the crank signal is detected so that the control unit ascertains a polarity cycle of the alternating voltage signals and in which the control unit determines that the crankshaft is in reverse rotation and stops the ignition control.

Abstract: An ignition control circuit and method of operation provides a very simple but highly effective prevention of engine reverse rotation upon starting by prohibiting ignition when a reverse rotation situation arises.

Abstract: An ignition control circuit and method of operation provides a very simple but highly effective prevention of engine reverse rotation upon starting by prohibiting ignition when a reverse rotation situation arises.

Abstract: A reverse rotation preventive device wherein an engine can be restarted without once stopping the vehicle even in the case where a reverse rotation preventive function is operated in response to momentary locking of a rear wheel. A plurality of reluctors are arranged at regular intervals, exclusive of a toothless part at one location with a crank pulse rotor rotated synchronously with a crankshaft of the engine, and a first and second pulse generators each of which outputs a pulse signal corresponding to the interval of the reluctors. Reverse rotation preventive means inhibits ignition of a spark plug by operating the reverse rotation preventive function when the interpulse time of the pulse signal exceeds a predetermined time and cancels the inhibition of the ignition when it is detected that a crankshaft is in normal rotation after the ignition is inhibited by the operation of the reverse rotation preventive function.

Abstract: A method of determining reverse engine rotation includes calculating a ratio of on time to off time of a camshaft position signal during camshaft rotation, determining whether a predetermined camshaft state has been entered based on said ratio, comparing the most recently determined camshaft state with a predetermined camshaft state pattern for forward engine rotation and determining a engine rotation direction based on said comparison.

Abstract: An internal combustion engine performs an ignition timing control by an electronic control in accordance with a pulse signal from a pulser. The pulser generates a plurality of the pulser signals per one rotation of the internal combustion engine. An ignition timing control system calculates a reduction amount of a rotational speed of the internal combustion engine based on a plurality of the pulse signals immediately before performing an ignition in the internal combustion engine to determine whether the reduction amount produces ignition combustion kickback and performs a hard ignition or an ignition at an angle which is delayed more than the hard ignition.

Abstract: An internal combustion engine performs an ignition timing control by an electronic control in accordance with a pulse signal from a pulser. The pulser generates a plurality of the pulser signals per one rotation of the internal combustion engine. An ignition timing control system calculates a reduction amount of a rotational speed of the internal combustion engine based on a plurality of the pulse signals immediately before performing an ignition in the internal combustion engine to determine whether the reduction amount produces ignition combustion ketching and performs a hard ignition or an ignition at an angle which is delayed more than the hard ignition.

Abstract: A control apparatus for an internal combustion engine, comprising crank angle calculation means for calculating a crank angle between edges which are detected by a first crank angle sensor and a second crank angle sensor, on the basis of a crank cycle between the edges, and engine-rotation-direction detection inhibit means for inhibiting detection of an engine rotation direction on the basis of the calculated crank angle, wherein the engine-rotation-direction detection inhibit means inhibits the detection of the engine rotation direction in a case where the crank angle calculated by the crank angle calculation means has satisfied a predetermined inhibit decision condition.

Abstract: In a method for detecting reverse rotation when starting an internal combustion engine having a sensor disk which is coupled to a crankshaft of the engine, the sensor disk having a marking via an alternating arrangement of teeth and tooth spaces, and a first sensor and a second sensor each capable of generating an electric signal which may assume at least two signal levels, being associated with the sensor disk, one of the signal levels being associated with a tooth and the other signal level with a tooth space, a rising or falling signal edge of the one signal and the signal level of the other signal being used for determining the direction of rotation and increment of the angle of rotation of the crankshaft, the start characteristics are improved by determining the direction of rotation during the start of the engine as early as at the first signal edge.

Abstract: A control apparatus for an internal combustion engine includes a crankshaft, a camshaft for actuating a valve of the engine, and a rotating electrical machine that is coupled to one of the crankshaft and the camshaft. The apparatus includes a computer that controls the rotating electrical machine. The rotating electrical machine includes a rotor and a plurality of rotation sensors, each of which outputs a signal corresponding to induced voltage generated by rotation of the rotor. The computer controls the rotating electrical machine based on the signals from the rotation sensors, and detects the occurrence of reverse rotation in the engine when an output pattern of the signals from the rotation sensors is different from an output pattern during forward rotation of the engine. As a result, the apparatus promptly detects the occurrence of reverse rotation of the internal combustion engine without providing additional sensors or rotors.

Abstract: The period required to start a rope-start, two-cycle engine is reduced by enabling the engine's firing sequence to be initiated immediately upon determining the absolute rotational position of the engine and before determining the engine's direction of rotation. The rotational direction of the engine is then determined, and the firing sequence is disabled if the engine is counter-rotating. In this manner, the firing sequence is enabled much sooner in the engine's cycle than if the engine's rotational direction were determined before the firing sequence is enabled. The engine therefore starts more quickly. The method is particularly useful in battery-less engines which experience a delay in start-up due to the fact that the engine must rotate through at least part of a revolution before generating enough electrical power to operate the computer controlling operation of the engine.

Abstract: A number of embodiments of ignition systems wherein reverse rotation also known as kickback is detected particularly upon engine starting and stopped until the condition has been cleared and forward running is assured.

Abstract: The ignition system for internal combustion engines includes a rotor and an armature having an ignition coil in which voltage signals, each having pulses of opposite polarities are cyclically induced during each rotor revolution; a control unit for the ignition current includes a current-control switch which can be triggered during a positive pulse of the voltage signals, to cut off the current in the primary winding and generate a high voltage on the secondary winding of the ignition coil. A second control switch has the control electrode connected to a current-control resistor in series with the current-control switch, and to the outlet of a voltage comparator connected to a timing circuit enabling the sparking within a pre-established time interval, preventing sparking when the engine is running below a minimum rotational speed, during the forward rotation and at the reverse rotation of the same engine.

Abstract: A start control apparatus includes a starter, a number-of-revolutions detection unit of an internal combustion engine, a crank angle sensor, a cam sensor, and a control unit for controlling cylinder ignition based on a crank angle signal and a cam signal. The control unit has a start determination unit for determining whether starting the engine is to be continued or stopped based on the crank angle and fluctuation in the number of revolutions when the starter being switched from on to off is detected, and controls continuing or stopping ignition control in accordance with the determination of the start determination unit.

Abstract: A circuit to achieve a large ignition advance, limitation of speed of revolutions and to prevent backfiring and reverse direction running in a magnetic ignition system that comprises a flywheel with two poles and a two-legged iron core. An ignition transformer (L3/L4), a charging coil (L1) and a triggering coil (L2) that may be connected in antiphase to the charging coil are arranged on the first leg in the direction of rotation of the flywheel. A time-constant circuit (an RC net) and a control switch (T2) are arranged between the charging coil and a main switch (T1) that open/block triggering pulses such that charging takes place one revolution later than triggering. Limitation of the speed of revolutions is achieved with a time constant that can be determined.

Abstract: The present invention includes a method for preventing a reverse rotation of an engine. In connection with starting an engine, when an operation of a starter motor stops while a predetermined monitoring condition for a reverse rotation is satisfied, it is determined whether a reverse rotation of the engine is occurring, and then at least one of fuel injection and ignition of the engine is stopped for a certain period if it is determined that the engine undergoes reverse rotation.

Abstract: An ignition control circuit and method of operation provides a very simple but highly effective prevention of engine reverse rotation upon starting by prohibiting ignition when a reverse rotation situation arises.

Abstract: Even if the engine is started from any crank angle position, it is possible to correctly determine the rotational direction of a crankshaft, so that fuel injection or ignition can be stopped when the crankshaft is rotating in the reverse direction. A measurement member has a plurality of angular position detection portions arranged at equal intervals in a circumferential direction of the crankshaft and a plurality of reference position detection portions at which a part of the angular position detection portions is missing. A crank angle sensor is arranged near the measurement member for generating a crank angle signal representative of the rotational position of the crankshaft. A period detector detects periods of pulses of the crank angle signal. A reference position determiner determines a plurality of reference positions based on the signal periods. A counter counts the pulses of the crank angle signal.

Abstract: Even if the engine is started from any crank angle position, it is possible to correctly determine the rotational direction of a crankshaft, so that fuel injection or ignition can be stopped when the crankshaft is rotating in the reverse direction. A measurement member has a plurality of angular position detection portions arranged at equal intervals in a circumferential direction of the crankshaft and a plurality of reference position detection portions at which a part of the angular position detection portions is missing. A crank angle sensor is arranged near the measurement member for generating a crank angle signal representative of the rotational position of the crankshaft. A period detector detects periods of pulses of the crank angle signal. A reference position determiner determines a plurality of reference positions based on the signal periods. A counter counts the pulses of the crank angle signal.

Abstract: A rotor of a crankshaft has protrusions. A timing sensor produces a rotation leading signal and a rotation trailing signal. A control unit measures a previous signal production interval and a present signal production interval based on the rotation signals, and determines that the rotor is in the forward rotation if an inequality of Tn/Tn−1≧K holds alternately but consecutively by four times on the side of the rotation trailing signal. As a result, at the time of manufacturing the rotor, the degree of freedom of design in the positional relations of the protrusions can be enhanced to control the ignition timing precisely and stably.

Abstract: The present invention relates to a method and system for preventing reverse rotation operation of an engine using a system that includes a crank angle sensor (CAS), a cam position sensor (CPS), and an engine control unit for receiving signals from the CAS and the CPS to perform engine control. The method includes determining if a piston in a specific cylinder is at a predetermined location using a level of a CPS signal at a leading edge and a trailing edge of a CAS signal; determining if the engine is rotating in reverse using the CPS signal level at the leading edge and trailing edge of the CAS signal in the case where it is determined that the piston of the specific cylinder is at the predetermined location; and discontinuing operation of the engine if it is determined that the engine is undergoing reverse rotation.

Abstract: In an engine ignition system having a fail-safe function, a battery, a coil and a transistor are connected in series. A capacitor is connected to the coil by way of a diode. The capacitor, a primary winding of an ignition coil and a transistor are connected in series. A transistor and a diode in serial connection are connected in parallel to the coil and diode in serial connection. A drive circuit turns on and off the transistor to charge the capacitor and operates the transistor to implement the ignition operation. The drive circuit, in the event of system failure, turns on and off the transistor, while retaining the transistor in the on state, thereby to feed energy of the battery to the primary winding.

Abstract: The invention relates to a device for detecting the reverse rotation of a rotating part of an internal combustion engine, having a crankshaft (3) whose rotation, by means of a sensor (6) and a detector disk (2) which is connected to the crankshaft (3) and has a reference mark (5) and a multitude of similar angle marks (4), are sent by the sensor (6) to a control unit (1) in the form of pulses, having a camshaft (7) whose rotation is detected by means of an absolute angle detector (8), wherein the output signal of the absolute angle detector (8) steadily rises or falls within a period depending on the rotation direction of the camshaft 7. The output signal of the absolute angle detector (8) is supplied to the control unit (1) for processing.

Abstract: The present invention relates to a method and system for preventing reverse rotation operation of an engine using a system that includes a crank angle sensor (CAS), a cam position sensor (CPS), and an engine control unit for receiving signals from the CAS and the CPS to perform engine control. The method includes determining if a piston in a specific cylinder is at a predetermined location using a level of a CPS signal at a leading edge and a trailing edge of a CAS signal; determining if the engine is rotating in reverse using the CPS signal level at the leading edge and trailing edge of the CAS signal in the case where it is determined that the piston of the specific cylinder is at the predetermined location; and discontinuing operation of the engine if it is determined that the engine is undergoing reverse rotation.

Abstract: A method for preventing reverse running of an internal combustion engine includes determining the operational state of the vehicle starter motor, determining whether a stall or imminent stall condition exists, and suspending operation of the engine based on the stall or imminent stall condition.

Abstract: In an engine ignition system having a fail-safe function, a battery, a coil and a transistor are connected in series. A capacitor is connected to the coil by way of a diode. The capacitor, a primary winding of an ignition coil and a transistor are connected in series. A transistor and a diode in serial connection are connected in parallel to the coil and diode in serial connection. A drive circuit turns on and off the transistor to charge the capacitor and operates the transistor to implement the ignition operation. The drive circuit, in the event of system failure, turns on and off the transistor, while retaining the transistor in the on state, thereby to feed energy of the battery to the primary winding.

Abstract: In an ignition controller for an internal combustion engine, an angle sensor includes a plurality of sensor means for individually outputting a pulse signal SGT1 corresponding to a first reference crank angle and a pulse signal SGT2 corresponding to a second reference crank angle and a control/arithmetic operation circuit includes a timing calculation means for calculating the timings at which ignition coils are controlled according to an operating state, count means for counting the number of the pulses of one of respective pulse signals which are detected between two continuous pulses of the other of them, reverse rotation discriminating means for discriminating the reverse rotation of the internal combustion engine based on the count values CA1 and CA2 of the respective pulse signals and control prohibition means for prohibiting the output of drive signals P1 and P2 in response to a reverse rotation discriminating signal to thereby prohibit ignition control in the occurrence of the reverse rotation by disc

Abstract: For detecting a backward revolution of a revolving component of an internal combustion engine, with a sensor which senses a revolving component having at least one angular mark, the backward revolution is assumed when a prescribable value between two pulses of the signal of the sensor is exceeded, and stalling is detected after it is ensured that the backward revolution of the internal combustion engine has taken place, and outputting of further injections and/or ignitions is suppressed until a resynchronization of the system takes place after a prescribable time has passed.

Abstract: Ignition system for an internal-combustion engine, in particular for use in a chain saw or the like, comprising a magnetically conducting core supporting a charging winding and a triggering winding, a flywheel having at least one magnetic field generating member and adapted to cooperate with the magnetically conducting core to cause, when passing, voltages to be induced in the windings, and an electronic switch means adapted to trigger, in response to a trigger pulse generated by the triggering winding, the discharge of a capacitor, which has been charged by a voltage generated in the charging winding, via the primary of an ignition coil the secondary of which comprises a spark plug.

Abstract: The device comprises a magnet which induces several current pulses of alternating polarity in a primary winding, the current being restored in a resistance (R1) in series with a transistor (Ti). The voltage developed across the terminals of the resistance is applied to the input terminal (9) of a control circuit (7), via a capacitance (C), said control circuit (7) causing an interruption of the current generating an overvoltage. The capacitance (C) is charged by a first pulse, via a diode (D), connected in parallel with the transistor (Ti), and a resistance (10). The charge thus acquired remains active at the start of the subsequent principal pulse of opposite polarity, which follows, so that in the case of reverse operation of the engine, reversing the order of appearance of the pulses, no ignition takes place.

Abstract: An engine igniter has a reference signal coil which generates an advance-side reference signal and a lag-side reference signal during a half-cycle of the alternating current output of a generator. An ignition timing control circuit determines the direction of rotation of the engine based on the polarity of the alternating current when the reference signals are generated. The ignition timing control circuit controls the ignition timing of an ignition circuit, using the lag-side reference signal as a reference at low engine speeds and using the advance-side reference signal as a reference at high engine speeds. When the engine begins to rotate in reverse, the ignition timing control circuit prevents ignition and stops reverse rotation.

Abstract: Disclosed is an ignition apparatus for an internal combustion engine adapted to be started by the rotation of a crank shaft upon rotation of a starter. A sensor detects first and second different angular positions of the crank shaft to change the output level at the respective angular positions. In response to the output of the sensor, the ignition coil is energized and then de-energized. When a voltage generated by the starter is detected upon the reverse rotation of the rotary member, the state of the ignition coil is maintained unchanged.

Abstract: An ignition apparatus of an internal combustion engine includes a detecting circuit for detecting a state of the engine in which reverse rotation is taking place, and an ignition blocking circuit for blocking the generation of ignition sparks when such reverse rotation is detected. The detecting circuit comprises circuitry for measuring the duration of an output from a sensor circuit which allows current to flow in a primary winding of an ignition coil, and circuitry for detecting whether the measured time duration is longer than a predetermined time.

Abstract: An ignition apparatus for an internal combustion engine started by rotation of the crank shaft in one direction by the driving of a starter. An ignition coil and an ignition plug connected to the ignition coil are provided to generate ignition sparks at a predetermined interval of time. A sensor senses first and second predetermined angular positions in one rotation of the crank shaft and the output of the sensor changes between first and second levels every time each of the angular positions is sensed. The ignition coil is energized during a period when the output of the sensor is at the first level and de-energized to generate a spark at the ignition plug at the time when the output of the sensor changes from the first level to the second level.

Abstract: An ignition system for an internal combustion engine for preventing the generating of ignition sparks when the engine is reversely rotated, wherein an ignition coil for energizing a spark plug is slowly deenergized when the engine is in reverse rotation, whereby engine damage is avoided.

Abstract: The present invention is directed to an improved capacitive discharge ignition system for a two cylinder internal combustion engine, such as an outboard marine engine. The system is adapted to be located beneath the flywheel of the engine and has overspeed and overheat protection. The overheat protection is of the type which is automatically deactivated after the overheat condition dissipates, but the deactivation will only occur when the operator slows the engine to a reduced speed before resuming normal operation.

Abstract: An ignition device for an internal combustion engine comprises a sensor for producing a first and a second angular angle corresponding to a first and a second crank position, respectively, a flip-flop circuit which is set or reset by the first angular signal of the sensor and is reset or set by the second angular signal, ignition control unit for controlling the primary current of an ignition coil based on the output of the flip-flop circuit and carrying out the ignition operation based on the second angular signal, unit for producing a voltage when the internal combustion engine reverses, and unit for comparing the voltage produced by the voltage producing unit with a predetermined voltage, and causing the second angular signal to be ignored depending on the results of comparison so as to prevent the flip-flop circuit from being reset or set.

Abstract: An ignition apparatus of a capacitor discharge ignition type comprises: an ignition timing signal generator to generate an ignition timing signal synchronized with the rotation of the engine; a capacitor; a blocking oscillator; a rectifier for rectifying the output voltage of the blocking oscillator and applying the rectified voltage to the capacitor thereby charging the capacitor; a switching device which is turned on in response to the ignition timing signal and discharges the stored charges of the capacitor, thereby generating a pulse voltage across the terminals of the primary winding of an ignition coil; and an ignition plug to generate a spark discharge by a high voltage generated in the secondary winding of the ignition coil. The blocking oscillator oscillates concurrently with the engine rotation. When the ignition timing signal is generated, the oscillation of the blocking oscillator is stopped in accordance with a phase of the output voltage of the AC generator.

Abstract: Solid state inductive magneto ignition system with antireverse running circuit has a switching transistor connected in circuit with the primary of an ignition coil. A control circuit is connected for cutting "off" the switching transistor to generate ignition pulses. A first by-pass circuit for shunting current from the control circuit includes a silicon controlled rectifier (SCR) which is turned "on" by discharge of voltage from a capacitor in combination with a resistor which serves as a time delay to hold the by-pass circuit "on" for the duration of a voltage pulse developed by reverse running of the magneto. A voltage polarity sensing circuit for by-passing the by-pass circuit in response to a forward running pulse includes a silicon controlled rectifier (SCR) connected in parallel with the first SCR and a choke coil and a resistor to cause the second SCR to be turned "on" by a first negative pulse developed during forward running of the magneto.

Abstract: An ignition system for a two-cycle engine which comprises a rotational body rotatable in synchronism with the crank shaft of the engine and having thereon a detectable portion extending circumferentially thereof, and a detector placed in the vicinity of the rotational body for detecting the circumferential edge portions of the detectable portion and for producing an electric signal containing amplitude variations appearing at the passage of the edge portions near the detector. The electric signal is processed by an ignition pulse generator which produces an ignition pulse at each time when a selected one of the amplitude variations of the electric signal occurs. The circumferential length of the detectable portion is selected so that the ignition pulse appears when the crank angle of the crank shaft is outside of the reverse rotation allowing angular region.

Abstract: A magneto for two-cycle engines comprises a rotor provided with a magnet and a pair of poles, and a stationary assembly including a U-shaped iron core having a pair of legs and an ignition coil wound around one of the legs. The magnetic circuit provided by the pair of core legs, the pair of poles and the magnet includes a magnetic path through the other leg which path is given an increased magnetic resistance by a gap portion. The gap portion is formed in the end face or a side face of the other leg or in one of the poles in the end face thereof opposed to the other leg.