ELECTRIC DISCHARGE

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for augmenting a primary electric discharge such as a discharge produced by a primary discharge system.

BACKGROUND OF THE INVENTION

One example of a primary discharge system to which the present invention may be applied includes an ignition system associated with an internal combustion (IC) engine. The present invention will be described below with reference to an IC engine although it should be appreciated that it is not thereby limited such applications.

Another example of a primary discharge system to which the present invention may be applied includes an arc based sensing system for use in an induction furnace or the like.

The present invention may augment spark energy and/or current generated by an ignition system associated with an IC engine. IC engines to which the present invention may be applied include automotive, marine, diesel/petrol hybrids, stratified charge, lean burn, biofuel and high compression engines. IC ignition systems to which the present invention may be applied include conventional kettering systems and electronic systems including capacitor discharge, transistor controlled or computer controlled systems with or without a distributor.

Air/fuel mixture in an IC engine is typically ignited by means of a spark generated by a spark plug. Because the spark provides the prime source of ignition for the air fuel mixture the quality and size of the spark can greatly influence the efficiency and power generated by the IC engine.

Ability of the spark to efficiently ignite the air/fuel mixture under a variety of conditions including under conditions of high compression and/or lean fuel mixtures is limited in prior art ignition systems. Moreover prior art attempts to add energy into the spark by various methods have met with limited success while introducing undesirable effects such as increased wear associated with electrodes of the spark plugs.

Efficiency of combustion in an IC engine may be limited by the speed of burn or combustion known as flame propagation speed. The latter may determine the timing of ignition which is usually set to give the air/fuel mixture enough time to burn completely.

The present invention may expand the ignition zone to cover a larger volume of the compressed air/fuel mixture. This may in turn reduce combustion delay and increase capacity of the IC engine to run on a leaner air/fuel mixture and/or under higher compression. Subsequent optimization of engine timing may further increase combustion efficiency and performance of the IC engine.

The present invention may include means to capture previously wasted or suppressed energy and to transform that energy into augmenting the ignition system, thus improving efficiency of the system as a whole.

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims. Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a method of augmenting a primary electric discharge produced by a primary discharge system including means for generating said primary discharge, said method including providing augmenting electrical energy to an electrical storage means and delivering said augmenting electrical energy to said primary electric discharge in response to said primary discharge.

In one form the primary discharge system may include an ignition system associated with an internal combustion (IC) engine. The method may include promoting unidirectional current flow of the augmenting electrical energy from the electrical storage means to the primary discharge produced by the ignition system associated with the IC engine. Unidirectional current flow may be promoted by means of an enclosed or open spark gap such as a surge arrestor.

According to another aspect of the present invention there is provided an apparatus for augmenting a primary electric discharge produced by a primary discharge system including means for generating said primary discharge, said apparatus including energy storage means for storing augmenting electrical energy and means for delivering said augmenting electrical energy to said primary electric discharge in response to said primary discharge. In one form the primary discharge system may include an ignition system associated with an internal combustion (IC) engine. The means for generating a primary voltage may include a conventional kettering ignition system or an electronic ignition system including a capacitor discharge, transistor controlled or computer controlled system with or without a distributor.

The apparatus may include means for promoting unidirectional current flow of the augmenting electrical energy from the energy storage means to the primary discharge produced by the ignition system associated with the IC engine. The means for promoting unidirectional current flow may include an enclosed or open spark gap. The spark gap may promote a relatively fast transfer of energy from the energy storage means to the IC engine. The spark gap may include a surge arrestor or suppressor. The surge arrestor or suppressor may include a breakdown voltage that is similar or substantially equivalent to the voltage at which the energy storage means is discharged.

Alternatively the means for promoting unidirectional current flow may include a one way switch (solid state or relay) but switching time will be slower and not as well damped. A solid state switch may also have difficulty dealing with the high transient voltages that may be present while requiring additional circuits to perform the switching.

The means for promoting unidirectional current flow may include means for disrupting or producing blowout of the spark produced by the spark gap. An aim of spark disruption is to increase energy density relative to time to produce a relatively sharp energy pulse. The means for disrupting the spark may include any suitable or known means for disrupting the spark including magnetic, gas, mechanical or liquid insulator quenching as dictated by power requirements. In one form spark disruption may be provided by a relatively strong magnetic field oriented at a right angle to the direction of current flow in the spark gap. The magnetic field may be provided via a permanent magnet or an electro magnet.

The means for promoting unidirectional current flow may archive flow of energy from the energy storage means to the IC engine. The energy storage means may include a first storage capacitor. The first storage capacitor may be charged to a voltage that is substantially less than the spark voltage. In one form the first storage capacitor may be charged to substantially 200 to 500 volts. The apparatus may include means for charging the energy storage means. The means for charging may include an AC power source and an AC to DC converter. The AC power source may include a DC to AC converter and a step up transformer.

The apparatus may include means for collecting RF energy in the vicinity of the IC engine. The means for collecting RF energy may include an RF antenna and a second storage capacitor. The means for collecting RF energy may include a diode interposed between the RF antenna and the second storage capacitor.

DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings wherein:

Fig. 1 shows one form of apparatus according to the present invention;

Fig. 2 shows another form of apparatus according to the present invention;

Fig. 3 shows a graph of primary ignition current associated with a conventional capacitor discharge ignition system; and

Fig. 4 shows a graph of ignition current associated with an ignition system according to the present invention. Fig. 1 shows one form of apparatus according to the present invention for augmenting spark energy or current generated by an existing ignition system (not shown) associated with an IC engine. The existing ignition system may be connected to spark plug 10 via diode D3 if the existing ignition system has a path to ground via an ignition coil. Diode D3 may be omitted if the existing ignition system includes a distributor since the distributor may provide a break to ground.

The apparatus includes a main energy storage capacitor C2. Capacitor C2 is charged via an alternating current (AC) power source V1 of about 250-500 volts and rectifier diode D4. Voltage V1 may be increased or decreased to another voltage determined by discharge power requirements. Charge stored in capacitor C2 should provide a balance between efficiency and power to avoid electrode wear in spark plug 10. Diode D4 may be replaced with a full wave rectifier such as a diode bridge if desired. Diode D2 may prevent high voltage pulses from the existing ignition system passing to storage capacitor C2.

Efficiency of the apparatus may be enhanced by adding a charge gathering section including collection coil P, capacitor C1 , inductor P1 and diode D1 . The charge gathering section may collect ambient RF energy in the vicinity of the ignition system that may otherwise be wasted or have to be suppressed via resistors or the like.

Coil P may be wound around existing ignition cables or around a collector antenna, plate or RF shield such as a faraday shield. The shield may additionally act to suppress leakage of RF beyond the vicinity of the ignition system.

Capacitor C1 may store the collected RF energy and may optionally work with inductive coil P1 to set up an oscillation resonance to improve efficiency of energy collection. Diode D1 may rectify the collected RF energy and prevent charge stored in capacitor C1 from travelling back into coil P.

The apparatus may optionally include inductor P1 . Inductor P1 may be tuned to the discharge frequency characteristics of an existing ignition system such as an ignition system based on an ignition coil or capacitor delay oscillation. This may place the charging into resonance mode to improve charging efficiency.

The apparatus may include a closed or open spark gap U1 such as a surge arrestor. Spark gap U1 may effectively act as a voltage sensitive switch that switches on when its breakdown voltage is reached and switches off when the voltage on its electrodes is reduced after discharge of capacitor C1 . When capacitor C1 is charged by HF energy collected from the ignition system (including by resonance with inductor P1 ) the energy is conveyed and added to capacitor C2 after reaching the breakdown voltage of spark gap U1 . Spark gap U1 provides a unidirectional and damped energy pulse into capacitor C2. The pulse is unidirectional and damped because the current path is disrupted after discharge of capacitor C1 preventing reverse current flow or oscillation back to capacitor C1 . This produces a disruptive collapse of current in inductor P1 and provides a relatively sharp or high voltage spike to capacitor C2. Spark gap U1 may be quenched in any suitable manner and by any suitable means such as by means of a strong magnetic field oriented at a right angle to the direction of current flow across spark gap U1 . Quenching has the effect of disrupting the discharge current path more rapidly upon discharge of capacitor C1 .

The apparatus of Fig. 1 additionally includes device 1 1 for promoting unidirectional flow of current from capacitor C2 to spark plug 10. Device 1 1 may include a closed or open spark gap not unlike spark gap U1 or a one way switch or diode. Fig. 2 shows a modification of the apparatus shown in Fig. 1 wherein like parts include like reference numerals. Fig. 2 shows an alternative coupling method for coupling the charge gathering section (P, D1 , C1 ) to capacitor C2 wherein inductor P1 in Fig. 1 is replaced by transformer U2 in Fig. 2. Transformer U2 may be resonantly coupled to capacitor C1 to improve efficiency of energy transfer to capacitor C2. Fig. 2 includes full wave bridge rectifier D5 for rectifying energy pulses from capacitor C1 into DC current transferred to capacitor C2. Alternatively bridge rectifier D5 may be replaced with a single rectifying diode.

Fig. 2 includes a closed or open spark gap U3 such as a surge arrestor in the circuit coupling main storage capacitor C2 to spark plug 10. Spark gap U3 provides a unidirectional and damped energy pulse into spark plug 10 which archives the unidirectional current flow and associated magnetic field. Spark gap U3 is preferably a disruptive spark gap or is quenched as described above. This provides a rapid breach of the circuit as described above in relation to spark gap U1 to effectively remove capacitor C2 from the spark discharge. By disrupting the current path rapidly spark gap U3 is effective to prevent reverse current flow or oscillation back to capacitor C2.

The above arrangement may generate a relatively high energy, high volume spark with unidirectional current. A unidirectional and short current flow may promote formation and growth of a spark by an associated unidirectional and expanding magnetic field. The unidirectional magnetic field that accompanies the unidirectional current may act to propel the spark deeper into the combustion chamber or cylinder. This process may be assisted by design changes to spark electrodes to optimise or take advantage of the magnetic field that accompanies the unidirectional current. The relatively higher energy contained in the spark, gives rise to high UV which aids in breakdown and dispersal of the air fuel mixture. Alternatively a high voltage/high current diode or a solid state switch may be employed in place of spark gap U3 or capacitor C2 may be shunted from the circuit to ground by various known methods.

Fig. 3 shows a graph of capacitor discharge current through primary windings of an ignition coil for a conventional capacitor discharge ignition (CDI) system. The vertical current scale is 10 amps per division (10A/div) and the horizontal time scale is 50 microseconds per division (δθμε/ ϊν). The graph shows a primary pulse that reaches 30-32 amps in an ideal discharge with the pulse completing in a little over 50 microseconds. Note the current oscillation that follows the initial primary current pulse and how much energy is left in the oscillation. Only the initial pulse plays a major role in creating the spark. Typical current in production systems is normally less, around 10-20 amps, though this serves to illustrate an ideal system.

Fig. 4 shows an oscilloscope image of current flowing through a spark plug when augmented by apparatus according to the present invention. The vertical current scale is 100 amps per division (100A/div) and the horizontal time scale is 20 microseconds per division (20μεΑ-ϋν). The oscilloscope image reads over 200 amps in less than 40 microseconds. The high current is due to a capacitor discharging through a very low resistance spark. The spark almost looks like a short circuit to the capacitor so it can discharge its energy very quickly. Note the very sharp and abrupt discharge and an absence of oscillations following the initial primary current pulse.

Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention.