Abstract: An engine speed limiter includes a computing means for computing a value that is functionally related to the time between successive ignition pulses and for outputting a speed signal representative thereof. The speed limiter also includes generating means for generating a reference signal that is functionally related to the desired maximum limit speed. A comparison means compares the speed signal with the reference signal and generates a limit signal if the result of the comparison indicates that the actual engine speed is about equal to or greater than the desired maximum limit speed. The limit signal is used to interrupt engine ignition to thereby limit engine speed.

Abstract: This disclosure relates to apparatus for operating a combustion engine by controlling the spark ignition voltage to said engine. Said control is created by the application of two opposing currents to the input of an amplifying device which is used to selectively shunt a constant current source away from the control electrode of a second amplifying device connected to control the formation of said ignition voltage.

Abstract: An ignition device for an engine comprises a signal generator to generate a signal in synchronism with the rotation of an engine, a waveform shaping circuit to shape the waveform of an output signal produced from the signal generator, an ignition device to determine ignition timing on the basis of the output of the waveform shaping circuit and to cause ignition in the engine, an ignition-cut controlling circuit to cut the igniting operation of the ignition device when the engine operates at more than a predetermined revolution number, a tachometer signal output circuit to detect the revolution number of the engine on the basis of the output of the waveform shaping circuit, and a tachometer driving means to receive the output of the tachometer signal output circuit and to drive a tachometer so as to indicate an engine speed.

Abstract: A shift speed equalizer is provided in a marine transmission in a marine drive subject to a decrease in engine speed upon shifting from neutral to a forward or reverse gear due to a high propeller pitch or the like, such as in bass boat applications, and subject to an increase in engine speed upon shifting back to neutral. The shift from neutral to forward or reverse is sensed, and engine speed is increased in response thereto, to compensate the decrease in engine speed due to shifting. The return shift back to neutral is sensed, and engine speed is decreased in response thereto, to compensate the increase in engine speed due to shifting. Engine speed is increased by advancing engine spark ignition timing, and engine speed is decreased by retarding or returning engine ignition timing to its initial setting.

Abstract: The invention is directed to an ignition circuit for an internal combustion engine such as a two-stroke engine of a handheld, portable tool such as a motor-driven chain saw or the like. The engine has a cylinder and a piston conjointly defining a combustion chamber and a crankshaft connected to the piston. The ignition circuit includes a spark plug mounted in the cylinder and voltage source. A switch is actuable between an on-condition wherein the voltage source is connected to the spark plug for initiating a spark in the chamber and an off-condition wherein the voltage source is disconnected from the spark plug. An electronic control circuit actuates the switch between the two conditions in dependence upon the angular position of the crankshaft and other operating parameters of the engine such as the engine speed. The electronic control circuit includes a high-speed control circuit and an idle-speed control circuit for determining the firing time in the control range of the idle speed.

Abstract: An engine speed limiter is disclosed in which the ignition primary winding is shorted to limit engine speed whenever an ignition pulse is received by a switch at the same time that a switch is gated on by a positive output pulse from a timing circuit. A signal conditioning circuit receives a positive-going pulse from the ignition primary winding and outputs a conditioned signal to the timer to begin the timer's positive output signal. The speed limiter is suitable to be retrofit onto existing ignition systems.

Abstract: A number of embodiments of engine spark control systems wherein the engine speed is reduced in response to the sensing of an abnormal or an external condition and wherein the spark timing is altered when the spark is interrupted to preclude the likelihood of backfiring in the exhaust system or firing back in the induction system. In some embodiments, the sensed condition is an abnormal running condition and in other embodiments the sensed condition is shifting of the transmission. The backfiring and firing back is precluded primarily by advancing the spark from the idle spark advance.

Abstract: In a multicylinder internal combustion engine, an overspeed control circuit progressively cuts out ignition to the cylinders depending upon the amount the threshold is exceeded. A monostable multivibrator is set by the ignition pulse of a given cylinder to initiate a given timing interval of fixed duration. A charging capacitor circuit has a first capacitor charged by the output of the monostable multivibrator during the timing interval, and discharged during a second timing interval until the next ignition pulse of the given cylinder. A latching comparator is set by the ignition pulse of the given cylinder and disables a cut-out switch which in turn permits ignition pulses to the cylinders. A second capacitor is also charged during the first timing interval until it reaches a given threshold voltage, corresponding to a given engine threshold speed, and which resets the latching comparator, which in turn actuates the cut-out switch to cut out ignition pulses to the remaining cylinders.

Abstract: A vehicle control system embodying an engine driving the vehicle and, selectively, a power takeoff shaft. When the power takeoff shaft is being driven, a governor controls the speed of the engine. A device is provided for detecting the shaft speed and the engine will be slowed when the shaft speed is exceeded to protect element being driven by the power takeoff shaft in the event the governor fails.

Abstract: An arrangement for protecting an engine from an abnormal condition such as overheating by slowing of the engine through periodic misfiring of the spark plugs. In order to prevent backfiring, the engine is stopped if the slowed condition is such that backfiring might occur.

Abstract: An ignition control system for an internal combustion engine of the type employed to power a watercraft wherein the engine speed is reduced upon the sensing of an abnormal engine condition. When the engine speed is reduced, the spark timing is also retarded to avoid backfiring in the exhaust system unless the engine conditions indicate that the exhaust gas temperatures might become too high under this retarded condition.

Abstract: An engine ignition control system comprising an ignition circuit of capacitor charge-discharge type is disclosed in which the ignition timing is determined by controlling the charge-discharge cycle of a capacitor by an output signal from an engine speed detection circuit. An overspeed control circuit stops the ignition when a detection output signal of the engine speed detection circuit exceeds a reference voltage level corresponding to a set engine speed. A slowing down control circuit is actuated in response to an engine slowing down operation start switch for realizing a hypothetical condition substantially equivalent to the one in which the engine speed detection circuit detects an engine speed higher than the actual engine speed thereby to accomplish engine slowing down operation by (a) increasing the reference voltage level gradually, or (b) increasing the output signal level of the engine speed detection circuit stepwise.

Abstract: The present invention discloses a multiple spark transistor ignition circuit which is able to provide negligible retardation of ignition time, and/or prevent ignition with reverse rotation and/or provide an additional advanced spark and/or govern maximum engine speed and/or progessively advance the moment of ignition with increasing engine speed. The basic circuit comprises an ignition circuit of the type disclosed in U.S. Pat. No. 4,163,437 (Notaras) with a diode interposed between the primary winding and the remainder of the circuit. Circuits having a single primary winding and dual remainders or dual primary windings and single remainders are also disclosed. A governor circuit having a control transistor, a further potential divider and a control capacitor, is also disclosed.

Abstract: In a marine propulsion system including an internal combustion engine driving a voltage generator (14) supplying system voltage (line 26) which is supplied to ignition circuitry (10) providing spark ignition for running the engine in normal operation, overvoltage protection is provided for both the voltage generator regulator (12) and the ignition circuitry. If sensed system voltage is below a given threshold (V.sub.T), normal operation of the engine is continued. If sensed system voltage is above the given threshold, engine speed is reduced to reduce the generated voltage.

Abstract: A method and a system for controlling the ignition timing of internal combustion engines, or more in particular for preventing engine over-revolutions by reducing the engine speed when it becomes excessively high. The ignition timing control system is realized by a microcomputer, so that when the engine speed exceeds a predetermined high level, ignition stop operations by an ignition stop unit and ignition retard operations by a retarded ignition unit are repeated as many times as determined by the number of cylinders involved to reduce the engine speed. When the engine speed is in a predetermined high range, the ignition retardation is controlled by feedback in accordance with the engine speed, and further controlled in combination with the ignition stop as required. The method and system according to the invention is suitably used for a multi-cylinder internal combustion engine having an ignition system of electronic distribution type with a carburetor and a simultaneous ignition coil.

Abstract: This disclosure relates to apparatus for operating a combustion engine by controlling the spark ignition voltage to said engine. Said control is created by the application of two opposing currents to the input of an amplifying device which is used to selectively shunt a constant current source away from the control electrode of a second amplifying device connected to control the formation of said ignition voltage.

Abstract: A magneto ignition system includes a rotating magnet driven past a primary winding for firing the engine. The magneto generates a speed dependent signal having a following current pulse and a leading current pulse of a smaller amplitude than the following pulse. A Darlington power transistor has a collector connected in series with a voltage dropping resistor or diode to the winding. A resistor bias circuit connects the primary winding to the input of the power transistor. A cut-off transistor is connected to by-pass the bias circuit of the Darlington power transistor and thereby generate a pulse in the primary winding. A timing capacitor is connected to the primary winding in series with a diode and charging resistor. A control transistor has its input circuit connected between the timing capacitor and the resistors of the bias circuit.

Abstract: A circuit for disengaging an electrically actuated transmission brake of a racing car has a bank of transistors in series with the brake to hold the brake on at the beginning of a race. The bases of the transistors are connected through normally open contacts of a relay to the emitter of a transistor that can be turned on or off by an optoisolator and the brake is connected through diodes to the relay coil to isolate the transistor bases once the brake has been disengaged. The optoisolator is connected, through diodes, to the zero count terminals of two clocked, programmable counters either of which will turn the optoisolator off at the end of a count. Reset terminals of both counters are connected to the outputs of a flip-flop to disable one counter and toggling of the flip-flop is effected by closing normally open contacts of a second relay to complete a circuit between the flip-flop input and a voltage regulator output through a Schmitt trigger.

Abstract: An engine control system of a marine outboard engine has an oscillator which operates in response to an abnormality signal resulting from detection signals from an oil level sensor and a temperature sensor, and in response to a signal from a tachometric sensor to transmit normal and retarded ignition signals alternately and repeatedly to a firing timing control circuit, which thereupon controls the engine ignition with normal firing timing when receiving the normal ignition signal and with retarded firing timing when receiving the retarded ignition signal. The engine power output under retarded firing time is lower than that under normal firing timing, whereby the engine emits an abnormal humming sound, warning the operator that an abnormal condition has occurred.

Abstract: The present device for limiting the running speed is associated with an electronic ignition device comprising at least one energy storage member (21) which is normally charged so as to store at least a nominal quantity of energy, means (22, 23) for applying the said energy to an ignition coponent and electronic means (14, 25, 26) for generating the charging time of the energy storage member.

Abstract: A float switch and a control apparatus of an internal combustion engine are disclosed. This float switch comprises a float attached to a main body so as to be vertically swung around one end thereof, a magnetic material fixed to the float, and a contact adapted to be closed or opened in response to the approach or removal of the magnetic material. The float switch is provided in the pathway of a coolant passage and a lubricating oil passage of the engine. The control apparatus has a warning apparatus which is operative in response to an absence signal from the float switch which is indicative of the absence of the fluid that is being sensed, and has a rotating speed control apparatus to reduce the engine speed. The absence of the fluid is informed to the operator by the warning and the speed reduction. A warning apparatus for an outboard engine to control the engine speed when an abnormality occurs is also provided.

Abstract: Engine overspeed control circuitry (200) includes a comparator (206) comparing tachometer voltage against a reference voltage, and disabling the engine above a given speed. The overspeed protection is defeated by blowing a fuse (222) in circuit with a comparator input (212) changing the impedance thereat, which leaves a permanent record of the defeat for subsequent detection.

Abstract: A spark ignition interrupt system (24) is provided for a marine propulsion internal combustion engine (6) to reduce engine speed and facilitate shifting of a marine propulsion transmission (13). Spark ignition is terminated in response to a given shift condition until engine speed drops below a given cut-in speed or until completion of the shifting, whichever occurs first. A stall interval is also started in response to the given shift condition. The engine is stalled upon completion of the stall interval if the shifting is not complete, even if engine speed has dropped below the given cut-in speed.

Abstract: In the ignition apparatus for internal combustion engines, the internal combustion engine drives a generator and the generator charges a battery. The battery is connected to a boosting transformer which is connected with a semiconductor switch. The semiconductor switch causes a current to intermittently flow in the primary coil of the boosting transformer from the battery. An intermittence control circuit is connected between the semiconductor switch and the generator and controls the semiconductor switch to turn on and off a plurality of times per revolution of the generator in synchronism with the output of the generator. Thus, the semiconductor switch allows the transformer to generate a high voltage for ignition across the secondary coil. The intermittence control circuit includes an over-rotation preventing capacitor.

Abstract: A rotating speed control apparatus for controlling the rotating speed of an internal combustion engine includes: an ignition circuit of a capacitive discharge ignition (CDI) system; an overspeed preventing circuit having a rotating speed detecting circuit for reducing the rotating speed of the engine to a restricted value in response to an overspeed condition; and a cut-off circuit which temporarily inhibits the control of the engine speed by way of an overspeed prevention inhibiting operation and which is automatically returned to a condition in which it can control the engine speed during restarting of the engine after a stop of the engine. The overspeed preventing circuit is cut off by turning on the cut-off circuit when the engine is driven, so that the overspeed preventing function is inhibited. This cut-off circuit is automatically returned to its off-state when restarting the engine after a stop of the engine, thereby allowing an overspeed of the engine to be prevented.

Abstract: A water pump circulates cooling water to an outboard engine, and overheating does not generally occur unless the circulation is insufficient. A pressure sensor responsive to low pressures so as to actuate an alarm, except when the engine RPM are at or below a selected level, such as those corresponding to a trawling operation where an alarm would be bothersome. A temperature sensor can be provided to stop the engine or reduce its output in the event that the engine temperature exceeds a selected temperature.

Abstract: This disclosure relates to apparatus for selectively limiting the speed of an internal combustion engine by momentarily removing the ignition voltage to the spark plug of said engine at one or two preselected speeds below the maximum speed capability of the engine. Said speed limits are activated in response to electrical input signals generated by switches controlled by the operating condition of a vehicle driven by said engine. Such electrical signals could be determined by whether the vehicle transmission is in reverse and/or switches selectively operated by the operator. This emitter therefore controls the engine and thus vehicle speeds to increase the safety of the vehicle under selective operating conditions.

Abstract: The invention is directed to an RF means for terminating the normal operation of a selected motor vehicle. A plurality of motor vehicles each have an RF receiver tuned to a frequency and EIA tones specific to their license plate indica. Selected other motor vehicles have an RF transmitter and EIA tone generator which can be selectively tuned to transmit a signal which is receivable by a selected one of the motor vehicle receivers and when received stops the operation of that selected vehicle by terminating the fuel supply or removing ignition voltage to the motor vehicles internal combustion engine.

Abstract: Upon a kick-back of a motor saw, energy is transferred from the rotating parts of the engine into energy which generates the kick-back. This causes a tremendous decrease of the r.p.m. of the engine. In the saw there is an electronic control comprising a timer which measures the r.p.m. of the engine. During certain intervals the difference in r.p.m. is computed with respect to previous intervals and if the r.p.m. has decreased more than a predetermined value, a sensor in the electronic control emits a signal which releases an electrically controlled chain brake for stopping the chain.

Abstract: A system for automatically limiting the maximum speed of a vehicle to a predetermined maximum, particularly suitable for use with off-road vehicles such as aircraft deicing trucks. The system utilizes a magnetic Hall effect sensor to generate a speed signal which is compared to a signal representative of a preselected maximum vehicle speed. In response to the comparison a pulse-width modulated control signal is generated and used to control a transistor in series with the ignition coil primary thereby intermittently disrupting the ignition system.

Abstract: 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.

Abstract: In engine-powered machines (motor cutting saw, motor chain saw) with a centrifugal clutch a wearing on the clutch and belt takes place by a high load at an r.p.m. around or above the skidding r.p.m. of the centrifugal clutch. A step for reducing the said wearing can--according to the invention--be taken by limiting the driving torque of the engine in the above-said r.p.m. interval. The invention means that the cutting machine/motor saw is provided with electronic equipment counting r.p.m. and then controlling the ignition system so that the torque of the engine is lowered in a predetermined interval. In a cutting machine ignition is allowed in, for example, every third revolution within the interval 3000-6000 r.p.m. The working mode can also be widened so that the time difference between several revolutions is detected.

Abstract: An r.p.m. limiter for an internal combustion engine operates by gradually reducing the output voltage of the ignition coil until it reaches a point where ignition fails until the r.p.m. is reduced to a predetermined value.

Abstract: The invention provides a system applicable to various internal combustion engines, such as for automobiles, motorcycles, snowmobiles and outboards, to permit an authorized person, such as a police officer, to prevent their improper or illegal operation. The engine includes a detector detecting the speed of operation of the motor which is compared with a preset value. Upon an unusually high motor speed being reached a receiver is enabled for a preset period of time. During this preset period the engine can be disabled by a transmission from a transmitter operated by the police officer, preferably using a designated exclusive channel. The disabling slows the engine to an idle speed without stopping it, so that the power assist mechanisms of the vehicle remain operative to maintain normal braking and steering function.

Abstract: A speed-limiting device of the electronic ignition type for the internal combustion engine of a motor vehicle is equipped with an AC generator driven to rotation by the engine, such a generator comprising a feeding coil for the electronic ignition circuitry and a pickup winding for controlling the sparking of the engine spark plugs is characterized in that the signal of said control of the sparking for the igniting spark is cut off by short-circuiting to ground the pickup winding via a diode which is governed by the voltage generated by said feeding coil of the ignition circuitry, a voltage which is appropriately processed by a specially provided electric circuitry so as to become proportional to the generator speed as the voltage in question overtakes a threshold magnitude as preset by a specially provided sensing member.

Abstract: A control system for a drag race vehicle limits engine RPM to a selected Launch RPM limit when the vehicle is staged at the starting line and which limits engine RPM to an Elapsed Time RPM limit after the vehicle is shifted to high gear. The Launch RPM control is controlled by the same driver-controlled Launch switch which controls the line lock or transmission brake solenoid, so that the Launch RPM limit is removed at the same time that the vehicle is permitted to move forward. The Elapsed Time RPM control is actuated by a second driver-controlled Elapsed Time Enable switch. The control system is particularly useful for Super Class drag racers, in which the winner must be the first to the finish line without going under a predetermined elapsed time.

Abstract: An electronic revolution rate limiting apparatus is described which generally comprises a transducer for generating a tachometer signal which is indicative of the revolution rate of the internal combustion engine, a circuit for generating a rate signal which is derived from an oscillator and is responsive to the operation state of the engine to determine the maximum revolution rate for each of a plurality of operation states, a circuit for producing a control signal which is responsive to the tachometer signal and the rate signal, and a switch for interacting with the ignition system of the engine to prevent a sparking voltage from being induced in the ignition system in response to the value of the control signal.

Abstract: Disclosed herein is an internal combustion engine including a mechanism for providing a potential capable of producing a spark when applied to a spark plug, first and second trigger means respectively and selectively operable for applying the potential to the spark plug to produce a spark at a normal timing relative to top dead center and at a retarded timing relative to top dead center, and a switch connected to the first trigger means and operable in response to engine rotation above a given speed for interrupting the operation of the first trigger means so as to change the timing of sparking operation from the normal timing to the retarded timing.

Abstract: A microcomputer is used in the invention for the control of the ignition function of an ignition system of an i.c. engine. The limitation of r.p.m. of the engine at high r.p.m. is brought about by an acurately developed procedure of delayed ignition in two steps. The control of ignition timing is carried out by counting timer pulses between reference points, whereby the number of pulses between such points constitutes an address of a position in the ROM of the computer, where a reference number of the ignition time is stored. In manufacturing of a great assortment of engines several demands for limitation of maximum r.p.m. can be fulfilled in that the microcomputer has a spacing for storing several characteristics. The selection of a particular characteristic for a sort of engine is made by establishing permanent connections (or disconnections) in separate inputs of the computer which reads the combination and choses the corresponding characteristic.

Abstract: An electronic ignition system for an internal combustion engine. In a first embodiment an input pulse is generated at the same point in each revolution of the engine. Clock pulses at a first pulse rate are counted between consecutive input pulses. The resulting count signal is transferred to a down counter which, between the consecutive input pulses, counts down at a faster rate. For an eight cylinder engine this faster rate is four times the first pulse rate, for a six cylinder engine it is three times the first pulse rate, and for a four cylinder engine it is twice the first pulse rate. In a second embodiment a computed count signal is reset into a down counter which is then counted down. In each embodiment, when the down counter reaches its zero count level the count signal is again preset into it so that it recycles. Each time the down counter passes a pre-selected count level, an output pulse is generated.

Abstract: A microcomputer is used in the invention for control of the ignition functions of an ignition system of an i.c. engine. A switch (17) in an operating handle or the like is connected via a transistor to a digital input of the computer. This reads the status of the switch once every revolution of the engine and as long as the switch is closed the ignition is delayed at an r.p.m. above a predetermined, programmed value (e.g. 3000 r.p.m.) and the r.p.m. of the engine is restricted. When the engine shall work the switch is opened and the ignition is normal. The restriction is used at start in order to avoid speeding during the start procedure. As a complement to said switch a parallel switch (27) can be connected and operated by a brake device of the engine. During braking the r.p.m. of the engine is thereby restricted to the same value as the r.p.m. during the start.

Abstract: An ignition time controlling device having a trigger circuit employing a programmable unijunction transistor which will be ON at a timing when a primary short-circuiting current of an ignition coil is at or a little past a peak. The device includes a charging and discharging circuit for the primary short-circuiting current; a switching controlling circuit interrupting the primary short-circuiting current when the trigger circuit is ON; an ignition coil inducing a high voltage in a secondary coil when the primary short-circuiting current is interrupted; a spark plug generating a spark on receiving the high voltage of the secondary winding and an angle advancing circuit connected between the programmable unijunction transistor and the switching controlling circuit.

Abstract: An electronic circuit for disengaging an electronic speed control system when the rate of change of the automobile engine speed exceeds a predetermined amount is disclosed. A ferrite or powdered iron ring current transformer generates an input signal to the electronic circuit from one of the spark plug wires in the engine. The pulses from the ring current transformer are passed through a monostable multivibrator circuit and a filter network to a differentiator. The output of the differentiator is connected to a high limit detector and a low limit detector. When the rate of change of engine speed exceeds a predetermined amount, a signal is generated to disengage the speed control circuit.

Abstract: The invention relates to limiting of the r.p.m. on start of a power tool. At the same time the throttle control is locked in a starting position by a retaining member, a circuit in the ignition system is switched in to prevent ignition at an r.p.m. higher than the switching r.p.m. of the centrifugal clutch. The tool thus remains at low speeds during starting.

Abstract: Supercharging pressure produced by a supercharger driven by the exhaust gasses is detected so that frequency of combustion in an internal combustion engine is reduced to lower the engine output power. In order to reduce the frequency of combustion, the number of times of fuel injection may be thinned out or fuel injection into one or some of the cylinders of the engine may be stopped for a given period of time. Alternatively, the frequency of ignition may be reduced or ignition in one or some of the cylinders may be stopped for a given period of time. The control of fuel injection and the control of ignition may be combined. A microcomputer may be used to perform the method according to the present invention where the microprocessor thereof is arranged to execute a main routine and an interrupt service routine. In the main routine, data related to the supercharging pressure is stored in a memory, and the interrupt service routine, fuel injection and/or ignition is performed.

Abstract: Voltage halfwaves generated by a magneto in one polarity are utilized for powering and timing ignition of an internal combustion engine, and voltage halfwaves of the opposite polarity, taken from the circuit of the primary winding, are utilized both to feed a regulated d.c. voltage source for a timing circuit and to provide a recurring trigger voltage for a monostable circuit that keeps the ignition control circuit operative only so long as the speed of the engine does not exceed a predetermined limit. The monostable circuit is constituted by appropriate connecting up of an available timer integrated circuit unit.

Abstract: A system for preventing overheating of an internal combustion engine comprised of a temperature detector which activates an electronic circuit to intermittently interrupt engine ignition spark to gradually decelerate the engine. The electronic circuit has an oscillator which is activated by the temperature detector whose duty cycle is gradually increased up to a maximum. The oscillator output energizes a gating circuit to turn on a thyristor which connects an ignition charging circuit to ground. Thus interrupting the ignition spark.

Abstract: An ignition circuit according to the present invention has the properties of trigging, i.e. releasing the spark at a predetermined point behind the top of the primary voltage (the ignition generator voltage). During the ascending primary voltage the ignition switch (12) is conducting while a capacitor voltage (U.sub.K) is developed. When the primary voltage has passed its top value a potential difference to the capacitor voltage (U.sub.K) is created, which is used for the control of the switch to make it break. By the interruption of the primary current an ignition voltage is induced at duty r.p.m. in an ignition coil (11). At an extremely high r.p.m. the ignition is delayed behind the voltage top whereby the induced voltage will be too low for ignition. Too high an r.p.m. is thereby avoided.

Abstract: An ignition system has an electronic control unit which produces trigger pulses in response to received ignition control signals, the control unit also receiving test pulses indicating the period of time for which current supplied to the primary winding of the ignition coil is at its maximum value, the control unit extending the test pulses and supplying the extended pulses to a logic circuit which, when a trigger pulse occurs without an extended pulse simultaneously occurring, produces an output signal to indicate misfiring, and to temporarily switch off the control.

Abstract: A spark ignition interrupt system (24) is provided for a marine propulsion internal combustion engine (6) to reduce engine speed and facilitate shifting of a marine propulsion transmission (13). Spark ignition is terminated in response to a given shift condition until engine speed drops below a given cut-in speed or until completion of the shifting, whichever occurs first. A stall interval is also started in response to the given shift condition. The engine is stalled upon completion of the stall interval if the shifting is not complete, even if engine speed has dropped below the given cut-in speed.