Electronic Ignition System For Producing High Frequency Spark Trains For Internal Combustion Engines

Abstract

An electronic ignition system for internal combustion engines is disclosed, the ignition system comprising circuit means controlled in synchronism with the engine for producing a high frequency spark train capable of ensuring a perfect ignition of the mixture into each cylinder of the engine.

Description

The present invention generally relates to ignition systems and particularly concerns an electronic ignition system for internal combustion engines, that is able to produce, by the use of spark plugs of conventional type, a train of sparks instead of a single spark as is normally provided either by conventional ignition systems or by transistorized ignition systems.

In accordance with the subject invention, such a train of sparks is produced by employing an electronic device, a block diagram of which is shown in the accompanying drawing depicting a preferred operative embodiment.

Referring now in detail to the drawing, numeral 1 generally designates a disc connected with a rotary shaft 2 driven by the engine. From the peripheral edge of disc 1, symmetrically placed teeth 3 project outwardly, the number of the teeth being the same as that of the cylinders of the engine.

Near disc 1 is located an electromagnetic sensing device 4 adapted to produce signals every time a tooth passes in front of it, the signals being then applied to an amplifier 5. The signals, which are duly amplified in amplifier 5 are then applied to a differentiating circuit 6, where the signals are shaped and peaked so as to provide control pulses for a multivibrator 7.

As is well known, multivibrator 7 produces square waves in response to the control pulses. The square waves are then amplified by an additional amplifier 8 and cause starting of the operation of an oscillator 9, which produces oscillations for a time period equal to the duration of the square waves.

The oscillations which are generated by the oscillator 9 comprise a pulse train and are then fed to a transformer 10 which increases the voltage to the necessary high level, the oscillation than being fed to conductors 12 of the spark plugs (not shown in the drawing) by means of a distributor 11 which rotates in synchronism with the rotary movement of the disc 1 and which is driven, in turn, by the engine.

In response to each pulse of the pulse train sent by the oscillator 9, a spark is produced by the spark plugs; so that at the spark plugs, a real train of sparks exists, the duration of which is determined by the duration of the square pulses at the output of the multivibrator 7.

Having the above structure and operation now in mind, it will be apparent that, by employing the system of the invention, the ignition of the mixture in the engine cylinder is no longer obtained by means of a single spark, but, on the contrary, by means of a train of sparks at a very high frequency.

Experiments carried out by employing the ignition system of the invention has proved that the sparks of the train, which follow one another with very high frequencies of 80 kHz. to 150 kHz., for example insure the ignition of even weak mixtures, which, on the contrary, could be not ignited by utilizing conventional ignition systems. Moreover, as compared with the conventional ignition systems and with the same mixture strength, the system of the invention enables the achievement of a more perfect combustion, which results in the reduction of air pollution, as well as in the increase of the thermal efficiency of the engine.

Another advantage of the aforesaid system consists in the fact that the contact breaker provided in the conventional ignition systems is no longer necessary. As a result of the elimination of the breaker device, a greater reliability of operation can be obtained, since overhauling or periodical replacement of the contacts becomes unnecessary, these maintenance operations being those which frequently cause interruptions of engine operation.

The electronic circuit of the inventive ignition system is energized from the usual battery which is a part of the equipment of the motor vehicle.

It will be apparent that the system described and illustrated in the accompanying drawing should be considered as comprising an exemplary inventive embodiment and not as limiting the scope of the invention as the constituent components of the device of the invention as described could be replaced by other similar components which are operatively equivalent, either from a mechanical point of view or from an electronic one, without departing from the scope of the invention as sought to be defined in the following claims.

Claims

I claim:

1. An electronic ignition system for internal combustion engines, said ignition system comprising circuit means controlled in synchronism with the engine for providing sparks at the spark plugs, said circuit means producing a high frequency spark train capable of insuring a perfect ignition of the mixture into each cylinder of the engine, said circuit means comprising a plurality of electronic circuits including a first amplification stage means for providing a series of control signals in synchronism with the engine, differentiating circuit means for shaping said control signals, a multivibrator means for producing square waves in response to said shape control signals, a second amplification stage means for amplifying said square waves to provide a power source, and a final oscillator means powered by said second amplification stage means providing a power source and triggered in response to each amplified square wave to produce trains of spark pulses, each train having a time period equal to the duration of said square waves.

2. An electronic ignition system as defined in claim 1, further including a rotatable member driven by the engine rotating at a predetermined speed, said rotatable member including teeth projecting outwardly from the periphery thereof, an electromagnetic sensing device, said rotatable member being positioned so as to face said electromagnetic sensing device, said electromagnetic sensing device being adapted to produce signals applied to said first amplification stage means under the control of said outwardly projecting teeth; said rotatable member and said electromagnetic sensing device being provided at the input of said set of electronic circuits, and a transformer means provided at the output of said set of electronic circuits for increasing the voltage of said oscillations from said modulated final oscillator means to a high level, rotary distributor means rotating at predetermined speed and coupled with said transformer means for distributing the high voltage oscillations through conductors to the ignition spark plugs.

3. An electronic ignition system as defined in claim 2, further including battery means for energizing said set of electronic circuits.