WO1991001448A1

WO1991001448A1 - Dual ignition system

Info

Publication number: WO1991001448A1
Application number: PCT/AU1990/000303
Authority: WO
Inventors: Christopher Colin Hirst
Original assignee: Christopher Colin Hirst
Priority date: 1989-07-17
Filing date: 1990-07-17
Publication date: 1991-02-07

Abstract

The invention provides an additional or ancillary ignition system for an internal combustion engine which comprises, in combination, one or more spark plugs (15, 16); one or more ignition coils (9, 10) for firing the or each spark plug (15, 16); an ignition lighter (4) providing means for sending and controlling a current to the or each ignition coil (9, 10); a triggering mechanism (8), by means of which the or each ignition lighter (4) is able to be charged; a direct current power supply; and electrical circuitry associated therewith.

Description

DUAL IGNITION SYSTEM

TECHNICAL FIELD

This invention relates to ignition systems for internal combustion engines and more particularly to an additional, or ancillary, ignition system which is able to be added onto an existing internal combustion engine. Especially, the system of the present invention is eminently suitable for incorporation in an "ultralight" aircraft engine.

BACKGROUND ART

It is known that benefits may be gained by the use of a second spark plug within a cylinder of an internal combustion engine. The extra spark that is generated by a second spark plug firing simultaneously with a first spark plug serves to provide a more complete and uniform combustion of the air/fuel mixture. The more efficient burn of the fuel renders in turn increased engine efficiency and larger life span for the spark plugs.

In certain applications, a second spark plug is advantageous for safety reasons. For example, a second ignition might well be employed as a back-up against failure of a primary ignition in aircraft engines.

Hitherto, the firing of two spark plugs has always been actuated ^ljy one system, notwithstanding that some dual ignition system engines have included separate ignition coils for each ignition. There are considerable disadvantages to such a prior art system, however, net the least of which encompass the following:

(1) Failure of the triggering mechanism may prevent the current pulses from reaching the spark plugs, regardless of the number of the plugs; and (2) considerable time is required, and difficulty encountered, to adapt an engine so that an extra spark plug - and perhaps an ignition coil - may be run off the existing systems.

The concept of a separate ignition system is not, per se, new. For example, Australian patent application No 24327/77 and US patents Nos 3,407,797 and 3,392,717 all disclose, to some degree at least, the firing of a second spark plug in each cylinder. In some cases - and particularly in the latter case mentioned, a significant amount of circuitry is provided within the second, ancillary, ignition system.

While US patent No 3,392,717 appears to be the most relevant of these cases, the present invention may well be considered to be "breakthrough" in as much that never before has there been provided a complete additional, or ancillary, ignition system which may be "retrofitted" onto an existing internal combustion engine. In the closest prior art mentioned above, that is to say, US patent No 3,392,717, a single power supply is required to ignite all the spark plugs in this prior art arrangement and, moreover, there is nowhere therein the merest hint of easily adapting an existing internal combustion engine to incorporate a dual ignition system.

It is an object of the present invention, therefore, to overcome the above and other disadvantages of the prior art ignition systems.

DISCLOSURE OF INVENTION

The inventive ignition system is adapted to take over from an "original" ignition system in the case of the latter's failure to operate, for whatever reason. In short, the inventive system is adapted to operate in conjunction with, but in autonomous relationship to, an original ignition system. Furthermore, the entire original ignition system may be fully replaced by the inventive "dual" ignition system.

The ignition system according to the present invention includes an automatic advance/retard mechanism which acts to alter, or vary, the timing of the ignition with relation to:

(a) engine RPM/performance, and/or

(b) engine operability as an advance/retard mechanism between engine RPM ranges and/or across the total engine RPM "spectrum".

The inventive ignition system has built into it an engine performance mechanism which controls advance/retard - and hence engine performance - dependent upon both internal engine environment and external atmospheric conditions such as pressure, altitude, ambient temperature, etc.

The dual ignition system employs an arrangement of semi¬ conductor devices to perform either (i) capacitor-discharge ignition or (ii) transistor-assisted ignition coil discharge.

Therefore, in accordance with the present invention, there is provided an additional, or ancillary, ignition system for an internal combustion engine, comprising, in combination, at least one spark plug; at least one ignition coil for firing the or each spark plug; ignition lighter means providing means for sending and controlling a current to the or each ignition coil; a triggering mechanism by means of which the or each ignition lighter is able to be charged; a direct- current power supply; and electrical circuitry associated therewith. Ideally, the additional, or ancillary, ignition system is independent of a first ignition system incorporated into the internal combustion engine and is easily attachable to an engine housing exterior. Preferably, the triggering mechanism will include at least a pair of magnets disposed adjacent to, or so as to surround, the crankshaft of the internal combustion engine; whereby rotation of the crankshaft causes the trigger mechanism to become energized.

BRIEF DESCRIPTION OF DRAWINGS

The present invention, both as to its construction and its method of operation together with additional objects and advantages thereof, will be better understood from the following description of a preferred embodiment when read in conjunction with the accompanying drawings in which:

IN THE DRAWINGS

Fig. 1 is a schematic diagram of an ignition system according to the present invention installed on an internal combustion engine; Fig. 2 is a circuit diagram of one embodiment of the invention: Fig. 3 is a plan view of the invention, located upon an engine housing; Fig. 4 is a sectional view of an engine head with one bore to receive a spark plug, the bore having been filled in as a partial adaptation to accommodate the invention; and Fig. 5 is a sectional view corresponding to that of Fig.

4, further adapted to accommodate a second spark plug in respect of each cylinder.

Wherever possible throughout the drawings, like integers have been referenced by the same numeral. DETAILED DESCRIPTION OF INVENTION

In Fig. 1 is to be seen a conventional internal combustion engine 1 having a starter device 2 and a head 3 adapted to accommodate the present invention. Generally referenced 4 is an ignition lighter assembly, box 5 represents an arrangement of switches and fuses, box 6 represents a battery, preferably a 12-volt battery and box 7 represents a rectifier/regulator arrangement.

Referring now to Fig. 2, a triggering mechanism generally referenced 8 is attached to the engine housing by such means as to be able to activate the ignition lighter 4 - see Fig. 1. Ignition lighter 4 thereafter initiates a pulse, or pulses in synchronisation with the rotation of the rotary engine parts, to one or more ignition coils 9 and 10. The ignition circuit also includes a plug 11 and a ballast resistor 12. As is to be seen in Fig. 2, the triggering mechanism 8 includes a pair of magnets 13, 14 disposed adjacent to, or so as to surround, the crankshaft, whereby rotation of the crankshaft, timing rotor 13 or the like rotary integer, causes energisation of magnets 13, 14. Thus, by means of ignition lighter 4 and ignition coils 9, 10, high voltage currents are generated such as to fire the spark plugs 15 and 16; spark plug 15 being associated with rear ignition coil 9 and spark plug 16 with front ignition coil 10.

Triggering mechanisms are diverse and well known and may include, for example, points systems, photoelectric means, and copper coil magnet systems. The present invention is by no means confined te any one kind of triggering mechanism, although those means for triggering which may be adapted to be attachable to the exterior of the engine housing are most desirable. Similarly, ignition lighters and the like may be of various forms and kinds, including transistor-assisted and capacitor- discharge embodiments. The present invention is not limited to any particular kind of ignition lighter, although, in Fig. 2, the latter kind is illustrated, a capacitor 17 being associated with coil 9 and another capacitor 18 being associated with coil 10.

As is alsς to be seen in Figs 1 and 2, the inventive additional, or ancillary, ignition system is powered by a separate, or discrete, energy source or power supply such as a 12-volt battery 6. This ensures a totally independent system and enhances the ease with which the inventive ignition system is able to be added onto, or removed from, an internal combustion engine.

The present invention may be provided with a separate ignition switch 19 by means of which the additional ignition system may be turned on or off. With switch 19 turned on, the inventive system may be used in conjunction with the previously existing conventional ignition system of the engine. Alternatively, with switch 19 turned off, and the circuit thereby broken, the existing conventional ignition system may operate by itself to fire only those spark plugs comprised in the conventional ignition system. Fig. 2 also shows a master switch 20 - which may well be a so-called "key-lock", if required - , an earthed suppressor 21 and a usual alternator 22.

As will be realised from the abovegoing, a considerable advantage of the present invention lies in the ease with which it may be attached to, and removed from, an existing internal combustion engine.

Fig. 3 illustrates one example of a means of attachment of the triggering means. There, a plate 23, preferably of aluminium, is mounted on the rear end of engine housing 24, utilising the existing screw holes. Upon, or otherwise adjacent to, plate 23 is further mounted the triggering assembly so that the triggering magnets are disposed diametrically on either side of the rotor. The triggering mechanism may well be bolted to plate 23, each such bolt 25 being located in a slot 26, the elongation of these slots providing means for rotationally adjusting the triggering mechanism, thereby providing for adjustment of the triggering timing. As is to be seen in Fig. 3, lugs 27 serve to position the trigger assembly on plate 23; a conventional starter motor is referenced 28.

In order for each cylinder to receive a second spark plug, it is necessary to convert, or to adapt, the engine head; Fig. 4 shows an engine head 29 originally designed to receive one spark plug per cylinder. In such a case, there exists only

one bore, or through-hole, 30 for receiving a spark plug in each cylinder.

In order to convert the engine head, whether it be a water- cooled or an air-cooled engine, so as to receive two spark plugs per cylinder, existing bore, or through-hole, 30 may be filled in by such as a build-up of welding metal. In the case of a water-cooled engine, great care must be taken in stopping up bore, or through-hole, 30 and a solid plug 31 may be employed in this regard. Subsequently, two new passageways may be formed in each cyl. ider, as by drilling and tapping or the like.

In Fig. 5 there is shown one example of an engine head 29 which has been adapted so as to receive two spark plugs per cylinder, the spark plugs being in communication with the combustion chamber in each respective cylinder. To be mechanically independent, the inventive ignition system should be mounted outside the flywheel and should have an independent electrical source. In this regard, any self- exciting system is impractical as the installing of such as extra generating coils etc. adds weight, requires horsepower to drive them, and has very limited room for the inventive system.

The present invention, in all its aspects, presents considerable advantages over hitherto known dual ignition systems. These advantages include the ease with which an existing internal combustion engine may be adapted to receive the present invention and thereby be converted to a dual ignition system; the total independence of the system which enables each such system to operate individually or both systems to operate simultaneously; the portability of the device; and the consequent ease by which a second ignition system may be transferred from one engine to another. The triggers may be moulded to any shape and therefore adapted to any engine.

It is realised in the invention that some engines may be more accommodating to a second ignition system, as herein described, and it may be that there are considerable advantages in using the present invention in a two stroke engine over a four stroke engine. Such advantages would result from the available space in, and ability to adapt, the engine head for receiving the extra spark plugs.

In view of the foregoing it is envisaged that there are other modifications and changes which may be made in the present invention without departing from the spirit or scope herein intended, and it is given that the invention should not be limited in scope to the descriptive examples and drawings herein contained.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An additional, or ancillary, ignition system for an internal combustion engine comprising, in combination, at one or more spark plugs; one or more ignition coils for firing the or each spark plug; ignition lighter means providing means for sending and controlling a current to the or each ignition coil; a triggering mechanism by means of which the or each ignition lighter is able to be charged; a direct- current power supply; and electrical circuitry associated therewith.

2. The ignition system as claimed in claim 1, wherein the said additional, or ancillary, system is independent of a first ignition system incorporated into said internal combustion engine and is easily attachable to an engine housing exterior.

3. The ignition system as claimed in claim 1 or claim 2, wherein said triggering mechanism includes at least a pair of magnets disposed adjacent to, or so as to surround, the crankshaft of said internal combustion engine; whereby rotation of said crankshaft causes said triggering mechanism to become energized.

4. The ignition system as claimed in any one of the preceding claims, wherein said triggering mechanism is chosen from the group consisting of photoelectric means; points systems; and copper coil magnet systems.

5. The ignition system as claimed in any one of the preceding claims, wherein the or each ignition lighter includes at least one semi-conductor device adapted to cause capacitor-discharge ignition or transistor-assisted coil- discharge ignition.

6. The ignition system as claimed in any one of the preceding claims, wherein said direct-current power supply is a separate twelve-volt battery, to thereby ensure total independence of the system and to enhance the ease with which the said additional, or ancillary, ignition system is able to be added onto, or removed from, an existing internal combustion engine.

7. An additional, or ancillary, ignition system or an internal combustion engine, substantially as hereinbefore described with reference to the accompanying drawings.