GB2235015A

GB2235015A - Engine multiple spark ignition circuit

Info

Publication number: GB2235015A
Application number: GB9005121A
Authority: GB
Inventors: Constantin Tanasov
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-05-23
Filing date: 1990-03-07
Publication date: 1991-02-20
Also published as: GB9005121D0; GB8911768D0

Abstract

An oscillator 18 is arranged to provide a continuous stream of sparks after an initial spark is produced by the coil 14. A transistor circuit 32 may be operated by the contact breaker 17 to reduce the current through the points. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO ELECTRONIC IGNITION APPARATUS This invention relates to an electronic ignition apparatus and is particularly though not exclusively concerned with an electronic ignition apparatus for the internal combustion engines of motor cars.

The apparatus according to the invention is adapted to be used in conjunction with an existing ignition system of an engine.

Existing ignition systems comprise ignition systems which have a contact breaker, and those systems which do not use a contact breaker, for example optical Hall effect systems, and others controlled by sensors and computers.

The present invention seeks to provide an electronic ignition apparatus which can be readily connected to an existing ignition apparatus of an internal combustion engine.

Further the present invention seeks to provide an electronic ignition apparatus which can provide more than one spark of sufficient strength to fire a combustible mixture of petrol and air in the engine.

The present invention also seeks to provide an electronic ignition apparatus which can include a switching system enabling a existing ignition apparatus using contact breakers to be converted to a pointless ignition system.

Accordingly the present invention provides an electronic ignition apparatus including an oscillator which in use is connected across the primary coil of an ignition apparatus of an internal combustion engine, the oscillator generating sparks of a first amplitude, and a predetermined number of sparks of a second amplitude initiated when a single spark is generated by the primary coil of the existing ignition apparatus, the second amplitude being greater than the first amplitude.

The frequency of approximately six sparks following the single spark generated by the existing engine ignition apparatus is generated by the oscillator at a frequency of 20KHz and a voltage of 30/40 kV.

The electronic ignition apparatus can include a switching arrangement in order to reduce the current across the points thereby to convert an existing ignition apparatus from an apparatus including contact breakers to a pointless ignition system.

The present invention will now be more particularly described with reference to the covering drawings in which: Fig. 1 shows one form of electronic ignition apparatus according to the present invention, Fig. 2 shows plots of the primary coil output at 1,000 engine RPM of the apparatus shown in Fig. 1, Fig. 3 shows plots similar to Fig. 3 except that the engine speed is 6,000 rpm, and Fig. 4 is a plot of the output of the primary coil of a conventional ignition apparatus at 6,000 engine rpm.

Referring to the drawings, in Fig. 1 a conventional engine ignition apparatus comprises a battery 10, an ignition switch 12, a coil 14 having primary and secondary windings, a condenser 16 and a contact breaker 17. In the usual way the primary winding of the coil is connected to the contact breaker 17 and the secondary winding is connected to a distributor (not shown).

One form of electronic apparatus according to the present invention comprises an oscillator 18 which is connected between the battery 10 and the coil 14. The oscillator 18 includes a transformer 20 having a resistance 22 and diode 24 connected across its windings. The oscillator 18 also includes a transistor 26 and a further resistance 28, another resistance 30 being provided in the supply to the transistor 26. By way of example only the transformer can consist of a primary winding of 35 turns of 0.4mm copper wire and a secondary winding of 25 turns of 0.71mm copper wire on a FX2243 core. The diode 24 can be a diode known by the reference number 1N4004 and the resistances of 22, 28 and 30 can be 15R, lOOR and lOOR respectively. The transistor 26 can be a transistor known by the reference BU208 and the capacitance of capacitor 16 can be 0.02 uF.

The ignition apparatus according to the present invention can also include a switching system 32 which comprises two transistors 34 and 36 and resistances 38, 40, 42 and 44. By way of example only the transistor 34 can be a transistor known by the reference BU208 the transistor 36 can be a transistor known by the reference Bss17 and the resistances 38, 40, 42 and 44 can be 470R, 27R, 1000R and 47R respectively.

Referring to the figures, when the existing ignition apparatus of an internal combustion engine is switched on and the contact breaker points are open, there is no current through the coil 14, and there is no high tension spark. When the points are closed, the current through the coil and the points is approximately 4A, and there is no high tension spark. As the points start to open one spark is emitted from the coil, as shown in Fig. 4.

When the oscillator 18 is connected to an existing engine ignition apparatus and the ignition is switched on, the coil 14 will generate a continuous stream of sparks of amplitude C (Fig. 2) when the points are open. The voltage of these sparks is about 700V at a frequency of approximately 5KHz, with a length of approximately 0.lmm. When the points are closed, there is no high tension spark.

When the points start to open the coil (secondary winding) will generate a first spark of amplitude A (Fig. 2), and then the oscillator 18 generates a stream of six sparks of amplitude B (Fig. 2). Thereafter, as the points are still open, the sparks from the oscillator 18 will have the amplitude C.

Fig. 3 is a plot of spark amplitude against time at an engine speed of 1000RPM, whilst Fig. 4 is a similar plot at an engine speed of 6000RPM. It will be noted that there is an initial spark of amplitude A, followed by six sparks of amplitude B, and a stream of sparks of amplitude C. The length of time during which the sparks of amplitude C are generated is shorter because the time during which the points are open is less.

The amplitude of the sparks C is around O.lmm and is not sufficient to jump the gap in each plug of the conventional engine ignition system. However when the spark with amplitude A from the existing ignition system arrives at the plug, the oscillator 18 provides a number of predetermined sparks, in this case six sparks, with amplitude B at a frequency of 20 KHz and voltage of 30 to 40 kV, which is sufficiently great to continue firing the combustible mixture. The number of sparks of amplitude B or of an amplitude sufficient to fire the combustible mixture is determined by the frequency of the oscillator 18.

The electronic apparatus according to the present invention can also employ the switching system 32 which enables a contact breaker type of ignition system to be converted to a pointless ignition system such an optical Hall effect system. The switching system 32 enables the current through the contact breaker points to be reduced substantially, for example from 4A to 20mA. It will be clear that this reduction in current prolongs the life of the contact breaker points significantly.

However it will be recognised that the switching system 32 is not required if the internal combustion engine to which an electronic ignition apparatus according to the present invention is to be fitted is already a pointless ignition system.

Claims

1. An electronic engine ignition apparatus having an oscillator which in use is connected across the primary coil of an engine ignition apparatus of an internal combustion engine, the oscillator generating sparks of a first amplitude and a pre-determined number of sparks of second amplitude initiated when a single spark is generated by the primary coil of the existing ignition apparatus, the second amplitude being greater than the first amplitude.

2. An apparatus as claimed in claim 1 in which the oscillator comprises a transistor, a diode in series with the transistor and a transformer, the diode being connected across the windings of the transformer.

3. An apparatus as claimed in claim 1 or claim 2 including a switching system arranged to reduce the current between the points of a conventional engine system by a factor of at least 100.

4. An apparatus as claimed in claim 3 in which the current is reduced from approximately 4A to approximately 20mA.

5. Aan apparatus as claimed in claim 4 in which the switching system includes two transistors connected in series.

6. An apparatus as claimed in claim 1 or claim 2 in which the generator can include a resistance connected in parallel across the primary winding of the transformer.

7. An apparatus as claimed in claim 1 in which the oscillator has a frequency of approximately 5 KHz and a voltage of approximately 700V when generating sparks of the first amplitude, and a frequency of approximately 20KHz and a voltage of 30 to 40 kV when generating sparks of the second amplitude.

8. An apparatus as claimed in claim 1 in which the number of sparks of the second amplitude is approximately six.

9. An electronic ignition apparatus constructed and arranged substantially as herein described and with reference to the accompanying drawings.