CA2124070C - Plasma-arc ignition system - Google Patents
Plasma-arc ignition system Download PDFInfo
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- CA2124070C CA2124070C CA002124070A CA2124070A CA2124070C CA 2124070 C CA2124070 C CA 2124070C CA 002124070 A CA002124070 A CA 002124070A CA 2124070 A CA2124070 A CA 2124070A CA 2124070 C CA2124070 C CA 2124070C
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- Prior art keywords
- current
- pulse generator
- ignition
- ignition system
- plug
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P9/00—Electric spark ignition control, not otherwise provided for
- F02P9/002—Control of spark intensity, intensifying, lengthening, suppression
- F02P9/007—Control of spark intensity, intensifying, lengthening, suppression by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition
Abstract
An ignition system for igniting fuel within an engine cylinder, comprising: at least one ignition plug disposed in the cylinder; high-voltage pulse generator means connected to he ignition plug for generating a pre-pulse of static charge within the cylinder so as to ionize the fuel in the en-gine cylinder and thereby increase conductivity thereof, the pre-pulse comprising a high negative voltage high frequency burst of full-wave rectified alternating current; high-current pulse generator means connected to the ignition plug for generating a high-current pulse within the engine cylinder so as to form a plasma adjacent the plug for initiating com-bustion of the fuel within the engine cylinder; and controller means for selectively enabling and disabling the high-vol-tage pulse generator means and the high-current pulse gen-erator means at predetermined times.
Description
'CVO 93f 10348 ~ ~ ~ ~~ ~ ~ ~ PCT/C~92/00510 PLASMA-ARC TGNITIDN SYSTEM
~'~e,ld of the Invention This invention relates in general to ignition systems in fuel powered engines. More particularly, the invention relates to an electrical current-generated plasma and ignition system for gas powered engines.
~~ckar~ound of the Invention Existing spark-ignition systems for automobiles date back to about 1905. Although modern materials ~.0 such as plastics and semiconductors have been used to improve the efficiency of the sparking coil, there has been little improvement to the basic principle, which provides for a 30-KV spark across two electrodes in the gasoline cylinder of the engine to ignite the fuel maxture. The s2ngle point ignition process effected by well known prior art spark plugs results in a slow moving f lame-front across the engine cylinder. The speed of combustion resulting from this slow moving flame front necessitates advancing initiation of the spark as the engine speed increases, resulting in loss of power .
As is well known; diesel engines do not use spark ~ylugs. Instead, fuel i~ injected into a preheated c~rlinder and e~spl~ded by heat of compression. Similarly, high performance racing engines use glow plugs and doped methane fuels'which end to auto-ignite in a similar ma~raer ~a~ the diesel principle, thereby achieving efficiency end p~rfox~an~e significantly higher than ;~p~i.~ igniti~n gasolane engines;
In'the field ~f radio frequency electronics, it is a well- known principle that A.C. coupling on transformers imprcwes ~.n proportion to f~, where f represents frequency, and that use'of a resonant transformer at radio fx°equencies will result in the generation of extremely high voltages.
Furthermore, it is known from semiconductor processing e~.ectronics that high voltage radio waves will exalts gases und~z° pressure, and that if the input radio energy is high enough, the radio waves will strip , rd ',.~'~.. 1 ~
WE) 93/10348 PCT/CA92/OO~,~..,p electrons from the gas molecules, and cause ionization of the gas into a plasma miatture which can be heated by electrical currents. If the plasma mixture consists of two combustible mixtures combined in the correct ~ proportions, then the mixture will explode under plasma heating. .
By the late 1970's, the effectiveness of the plasma jet igniter as eonceived by L. Gussak, L.A. Gussak, USSR., Energetikco Transport Academy Izvestijia (~.965~, tool. No. 4, pp. 98°1~.0 "New Principle of ignition and Combustion in Engines°°, was well accepted; although the practical aspects of its application to engines required engineering research to qualify data on fuel economy, emissions and the LML.
A number of outstanding well°~documented projects, .have exposed the geometry of the plasma jet igniter n~zzl~-cavity, they electromagnetic energy-package stressed into the cavity,~the time-scale of the pulse, and the velocity of the'blast~wave end jet plume ejected ~Q from the nozzle cavity, During this period, the work of ~.D. Dale at the University of A3berta,.Edmonton, A.K. Cppenheim at the University of Cal~.fornia, Berkeley, and D. Fitzgerald at Jet Propulsi~n/ ~LTE~CEi stand owt as def initi~re, authc~ritativ~ work l~adingr '~fl a true understanding of the applicati~n, benefits and seaperiority of plasma jet ~.gniti~n over c~nventional spark -agnition, for low-e~is~i~n lean-burn engines. Tt was found, fo~c example, ghat there was a'direct c~rrelati~n between reducing Nox 3~ emissions/sp~Gific lb/hr. fuel consumption and increasing the air-fuel~equivalence rati~; this was known from earlier engine experiments, but had tended t~ be linvited ~b ~~~:~ because of the misffiring'caus~d by the inability of c~nventional spark ignition to initiate combustion 3S consistently.
Application of plasma jet ignition to the misfiring pr~bl~m at the Lean Flammability Limit (LFL) showed that the equivalence ratio could be easily pushed to E=0.5 (air/fuel=20:1 in the case of air-methane mixtures), see SAE 780637, A.K. Oppenheim, K. Teichnao, K. Hom, H.E.
Steward, "Jet Ignition of an Ultra-Lean Mixture." In two cases, SAE 850077, C'.F. Edwards, H.E. Stewart, A.K.
Oppenheim, "a Photographic Study of Plasma Ignition Systems", and SAE 810146, J.D. Dale, A.K. Oppenheim, "Enhanced Ignition far IC Engines with pre-mixed gases", Oppenheim, Edwards and Stewart showed that for the propane/air mixture used in their tests a typical spark plug permitted lean operation down to the equivalence ratio of 0.7, after which mis-ignition occurred. The standard plasma jet igniters provided an extension of the lean limit to an equivalence ratio of 0.5 and it seemed that this limit was imposed by either extinction of the flame or too slow burning rate, rather than by misfire. A
minor section of this investigation noted that a plasma jet igniter with an HC-substance accelerator feedstock achieved an equivalence ratio of 0.4.
U.S. Patent 4,996,967 (Cummins Engine Company, Inc.) discloses an apparatus and method for generating a highly conductive channel far the flow of plasma current, in which a pre-pulse is utilized to ensure that an ionized channel is developed to a significantly conductive state prior to application of a sustaining voltage for sustaining plasma flaw through the channel. However, according to the '967 Patent, the pre-pulse signal is in the form of a simple DC pulse. It has been found that the use of a single DC pulse does not provide the best possible efficiency for ensuring complete ionization prior to onset of the plasma current.
3a Summary of the Invention An aspect of the present invention provides a ignition system for igniting fuel within an engine cylinder, comprising:
a) at least one ignition plug disposed in said cylinder;
b) high-voltage pulse generator means connected to said ignition plug f:or generating a pre-pulse of static charge within said cylinder so as to ionize said fuel in said engine cylinder and thereby increase conductivity thereof, said pre-pu7_se comprising a high voltage high frequency burst of alternating current;
c) high-current pulse generator means connected to said ignition plug for generating a high-current pulse within said engine cylinder so as to form a plasma adjacent said plug for initiating combustion of said fuel within said engine cylinder;
d) controller means for selectively enabling and disabling said high-voltage pulse generator means and said high-current pulse generator means at predetermined times; and e) a high voltage blocker for preventing said high voltage high frequency burst of alternating current from entering said high-current pulse generator means.
Brief Description of the Drawinas A further discussion of the prior art as well as a description of the present invention are provided herein below with reference to the following drawings in which:
Figures lA and 1B show a typical combustion cycle of a modern internal combustion engine;
~ ,. ~ , .,,.':, r : s. , r ,,. ... , . ,~ > "., .
o , ~.:, , ,. !'- ,,r, , f. , ," .. _.s . :i..r , ...
,~ai.:,~":~. , . > > , " , , . < . ,~ . , 'dV0 93/1018 ~ ~ ~ ( ~ ~ PCT/CA92/OOcx Figures 2A and 2S show a typical modern electronic ignition system and timing waveforms respectively;
Figures 3A and 3S show waveforms and spark current according to typical modern electronic ignition systems;
Figure 4 is a block diagram of a plasma-arc ignition system according to the present invention;
Figure 5 is a block diagram showing closed loop control of the high-current generator using a current probe;
Figure 6 shows typical ~S values of leakage current during a spark voltage pulse of the plasma-arc ignition system of the present invention;
Figure 7A is a pulse-timing diagram for the plasma-arc igniti~n system acc~rding to the present invention;
Figures 7B, 7C and 7~ show the high voltage pulse, the resulting i~nization current and arc current according to the preferred embodiment, Fagure BA i a schematic diagram of a high-voltage gener~rtor according to 'an alterna~ta.ve embodiment;
Figure ~~ shows the signal output from the high-voltage generator of Figure SA, and ionization current plotted with respect to time;
Figure gA is a schematicydiagram of a high-current generator according to the peferred embbdiment;
~5 Figure 9~ ie Pl~t of current gain amplitude by frequency for the high-current ~en~~ator of Fire 9A;
Figures 3C end 9D eho~ maximum and minimum output current sigr~~ls, respectively, from the high-current g~ne~ator of F'ig~re 9A;
3~ Figure 10A is a cross sectional view of a conventional plasma jet igniter;
Figure lad is a schematic representation of a basic jet plume generated by the plasma jet igniter of Figure 10A;
35 Figure 11A is a cross sectional view of a plasma jet ignites with t~x~idal vortex generator according to the present invention;
rf ,:
a :...3m .. Aa .'.'.:7: , . . . . . .
r,.W ., . . ,i.. .. . .. ~ v.. , . .. . . . . .. .n.
...m .... . ~ .,. .,. ri' t ~. .,. n a ~Vfl 93/1034 P~T'/CA92/OOS10 Figure 11B is a detailed view of a portion of Figure 11A;
Figure 11~ is a schematic representation of a toroidal jet with immediate vortex ring effects produced 5 by the plasma jet igniter of Figures 11A and 11B;
Figure 12 is a cross-sectional view of a plasma jet igniter with vertex generator and contained substance for creating mufti-point ignition sources within the vortex torpid, according to an alternative embodiment of the invention;
Figure 13 is a cross-sectional view of a plasma ball.
igniter accord~.ng to a further alternative embodiment;
Figures l4A-14D show:additional modifications of the plasma ball igniter of Figure 13;
Figures 15A-15D are schematic representations of the plug body and plasma ball generated by various mufti-port plasma ball ignit~r variants;
Figure l6A is a cross sectional view of a plasma jet igniter with, D-shaped electrod~s according to a further 2o alternative embodiment; ~n~g Figure 16H'is an end view of the plasma plug shown in F'a.gure 16~.; and Figure 3.s~ is a schematic .g~p~~sentata.~n showing location of a plasma body (elliptoid) generated day the pl~~ma plug of Figures 16A
_.
and 16~.
~~~
t .~ a Figure i sh~w~ the typacal combustion cycle of a modlern 6-cylinder 3.3 litre gasoline fourstroke internal combustion enggne, wii~h the different taming effects on the combustion process at 1000 rpm and 600~ rpm. The red-line f~x engines in r~~rmal use occurs at 6000 rpm, whip 100 rpm is Tightly over the off-load idle cond i 4..bon o Figure 2A showy the typical modern electronic ignition system used to dreate the ignition spark, and s1~ s ~ '"~
WO 93/1Q348 ~' ~ ~ r~ ~~ ~ t' PC?/CA92/00~'.:
~'~e,ld of the Invention This invention relates in general to ignition systems in fuel powered engines. More particularly, the invention relates to an electrical current-generated plasma and ignition system for gas powered engines.
~~ckar~ound of the Invention Existing spark-ignition systems for automobiles date back to about 1905. Although modern materials ~.0 such as plastics and semiconductors have been used to improve the efficiency of the sparking coil, there has been little improvement to the basic principle, which provides for a 30-KV spark across two electrodes in the gasoline cylinder of the engine to ignite the fuel maxture. The s2ngle point ignition process effected by well known prior art spark plugs results in a slow moving f lame-front across the engine cylinder. The speed of combustion resulting from this slow moving flame front necessitates advancing initiation of the spark as the engine speed increases, resulting in loss of power .
As is well known; diesel engines do not use spark ~ylugs. Instead, fuel i~ injected into a preheated c~rlinder and e~spl~ded by heat of compression. Similarly, high performance racing engines use glow plugs and doped methane fuels'which end to auto-ignite in a similar ma~raer ~a~ the diesel principle, thereby achieving efficiency end p~rfox~an~e significantly higher than ;~p~i.~ igniti~n gasolane engines;
In'the field ~f radio frequency electronics, it is a well- known principle that A.C. coupling on transformers imprcwes ~.n proportion to f~, where f represents frequency, and that use'of a resonant transformer at radio fx°equencies will result in the generation of extremely high voltages.
Furthermore, it is known from semiconductor processing e~.ectronics that high voltage radio waves will exalts gases und~z° pressure, and that if the input radio energy is high enough, the radio waves will strip , rd ',.~'~.. 1 ~
WE) 93/10348 PCT/CA92/OO~,~..,p electrons from the gas molecules, and cause ionization of the gas into a plasma miatture which can be heated by electrical currents. If the plasma mixture consists of two combustible mixtures combined in the correct ~ proportions, then the mixture will explode under plasma heating. .
By the late 1970's, the effectiveness of the plasma jet igniter as eonceived by L. Gussak, L.A. Gussak, USSR., Energetikco Transport Academy Izvestijia (~.965~, tool. No. 4, pp. 98°1~.0 "New Principle of ignition and Combustion in Engines°°, was well accepted; although the practical aspects of its application to engines required engineering research to qualify data on fuel economy, emissions and the LML.
A number of outstanding well°~documented projects, .have exposed the geometry of the plasma jet igniter n~zzl~-cavity, they electromagnetic energy-package stressed into the cavity,~the time-scale of the pulse, and the velocity of the'blast~wave end jet plume ejected ~Q from the nozzle cavity, During this period, the work of ~.D. Dale at the University of A3berta,.Edmonton, A.K. Cppenheim at the University of Cal~.fornia, Berkeley, and D. Fitzgerald at Jet Propulsi~n/ ~LTE~CEi stand owt as def initi~re, authc~ritativ~ work l~adingr '~fl a true understanding of the applicati~n, benefits and seaperiority of plasma jet ~.gniti~n over c~nventional spark -agnition, for low-e~is~i~n lean-burn engines. Tt was found, fo~c example, ghat there was a'direct c~rrelati~n between reducing Nox 3~ emissions/sp~Gific lb/hr. fuel consumption and increasing the air-fuel~equivalence rati~; this was known from earlier engine experiments, but had tended t~ be linvited ~b ~~~:~ because of the misffiring'caus~d by the inability of c~nventional spark ignition to initiate combustion 3S consistently.
Application of plasma jet ignition to the misfiring pr~bl~m at the Lean Flammability Limit (LFL) showed that the equivalence ratio could be easily pushed to E=0.5 (air/fuel=20:1 in the case of air-methane mixtures), see SAE 780637, A.K. Oppenheim, K. Teichnao, K. Hom, H.E.
Steward, "Jet Ignition of an Ultra-Lean Mixture." In two cases, SAE 850077, C'.F. Edwards, H.E. Stewart, A.K.
Oppenheim, "a Photographic Study of Plasma Ignition Systems", and SAE 810146, J.D. Dale, A.K. Oppenheim, "Enhanced Ignition far IC Engines with pre-mixed gases", Oppenheim, Edwards and Stewart showed that for the propane/air mixture used in their tests a typical spark plug permitted lean operation down to the equivalence ratio of 0.7, after which mis-ignition occurred. The standard plasma jet igniters provided an extension of the lean limit to an equivalence ratio of 0.5 and it seemed that this limit was imposed by either extinction of the flame or too slow burning rate, rather than by misfire. A
minor section of this investigation noted that a plasma jet igniter with an HC-substance accelerator feedstock achieved an equivalence ratio of 0.4.
U.S. Patent 4,996,967 (Cummins Engine Company, Inc.) discloses an apparatus and method for generating a highly conductive channel far the flow of plasma current, in which a pre-pulse is utilized to ensure that an ionized channel is developed to a significantly conductive state prior to application of a sustaining voltage for sustaining plasma flaw through the channel. However, according to the '967 Patent, the pre-pulse signal is in the form of a simple DC pulse. It has been found that the use of a single DC pulse does not provide the best possible efficiency for ensuring complete ionization prior to onset of the plasma current.
3a Summary of the Invention An aspect of the present invention provides a ignition system for igniting fuel within an engine cylinder, comprising:
a) at least one ignition plug disposed in said cylinder;
b) high-voltage pulse generator means connected to said ignition plug f:or generating a pre-pulse of static charge within said cylinder so as to ionize said fuel in said engine cylinder and thereby increase conductivity thereof, said pre-pu7_se comprising a high voltage high frequency burst of alternating current;
c) high-current pulse generator means connected to said ignition plug for generating a high-current pulse within said engine cylinder so as to form a plasma adjacent said plug for initiating combustion of said fuel within said engine cylinder;
d) controller means for selectively enabling and disabling said high-voltage pulse generator means and said high-current pulse generator means at predetermined times; and e) a high voltage blocker for preventing said high voltage high frequency burst of alternating current from entering said high-current pulse generator means.
Brief Description of the Drawinas A further discussion of the prior art as well as a description of the present invention are provided herein below with reference to the following drawings in which:
Figures lA and 1B show a typical combustion cycle of a modern internal combustion engine;
~ ,. ~ , .,,.':, r : s. , r ,,. ... , . ,~ > "., .
o , ~.:, , ,. !'- ,,r, , f. , ," .. _.s . :i..r , ...
,~ai.:,~":~. , . > > , " , , . < . ,~ . , 'dV0 93/1018 ~ ~ ~ ( ~ ~ PCT/CA92/OOcx Figures 2A and 2S show a typical modern electronic ignition system and timing waveforms respectively;
Figures 3A and 3S show waveforms and spark current according to typical modern electronic ignition systems;
Figure 4 is a block diagram of a plasma-arc ignition system according to the present invention;
Figure 5 is a block diagram showing closed loop control of the high-current generator using a current probe;
Figure 6 shows typical ~S values of leakage current during a spark voltage pulse of the plasma-arc ignition system of the present invention;
Figure 7A is a pulse-timing diagram for the plasma-arc igniti~n system acc~rding to the present invention;
Figures 7B, 7C and 7~ show the high voltage pulse, the resulting i~nization current and arc current according to the preferred embodiment, Fagure BA i a schematic diagram of a high-voltage gener~rtor according to 'an alterna~ta.ve embodiment;
Figure ~~ shows the signal output from the high-voltage generator of Figure SA, and ionization current plotted with respect to time;
Figure gA is a schematicydiagram of a high-current generator according to the peferred embbdiment;
~5 Figure 9~ ie Pl~t of current gain amplitude by frequency for the high-current ~en~~ator of Fire 9A;
Figures 3C end 9D eho~ maximum and minimum output current sigr~~ls, respectively, from the high-current g~ne~ator of F'ig~re 9A;
3~ Figure 10A is a cross sectional view of a conventional plasma jet igniter;
Figure lad is a schematic representation of a basic jet plume generated by the plasma jet igniter of Figure 10A;
35 Figure 11A is a cross sectional view of a plasma jet ignites with t~x~idal vortex generator according to the present invention;
rf ,:
a :...3m .. Aa .'.'.:7: , . . . . . .
r,.W ., . . ,i.. .. . .. ~ v.. , . .. . . . . .. .n.
...m .... . ~ .,. .,. ri' t ~. .,. n a ~Vfl 93/1034 P~T'/CA92/OOS10 Figure 11B is a detailed view of a portion of Figure 11A;
Figure 11~ is a schematic representation of a toroidal jet with immediate vortex ring effects produced 5 by the plasma jet igniter of Figures 11A and 11B;
Figure 12 is a cross-sectional view of a plasma jet igniter with vertex generator and contained substance for creating mufti-point ignition sources within the vortex torpid, according to an alternative embodiment of the invention;
Figure 13 is a cross-sectional view of a plasma ball.
igniter accord~.ng to a further alternative embodiment;
Figures l4A-14D show:additional modifications of the plasma ball igniter of Figure 13;
Figures 15A-15D are schematic representations of the plug body and plasma ball generated by various mufti-port plasma ball ignit~r variants;
Figure l6A is a cross sectional view of a plasma jet igniter with, D-shaped electrod~s according to a further 2o alternative embodiment; ~n~g Figure 16H'is an end view of the plasma plug shown in F'a.gure 16~.; and Figure 3.s~ is a schematic .g~p~~sentata.~n showing location of a plasma body (elliptoid) generated day the pl~~ma plug of Figures 16A
_.
and 16~.
~~~
t .~ a Figure i sh~w~ the typacal combustion cycle of a modlern 6-cylinder 3.3 litre gasoline fourstroke internal combustion enggne, wii~h the different taming effects on the combustion process at 1000 rpm and 600~ rpm. The red-line f~x engines in r~~rmal use occurs at 6000 rpm, whip 100 rpm is Tightly over the off-load idle cond i 4..bon o Figure 2A showy the typical modern electronic ignition system used to dreate the ignition spark, and s1~ s ~ '"~
WO 93/1Q348 ~' ~ ~ r~ ~~ ~ t' PC?/CA92/00~'.:
Figure 3 shows the typical waveforms and current of the spark.
Referring to Figure 2A, the general characteristics of existing systems of sgark formation is based on a high-voltage step-up transformer T1 from the l2V battery supply, using the slow charge of a capacitor CI up to 12V
through transistor Ql. This occurs during the °'off"
cycle between Top Dead Centre (TDC) pulses. The charging circuit has to be designed such that the capacitor C1 can be fully charged between sparks at the maximum speed of the engine, which allows about 20 milliseconds (0.020 sec) for full charge: At the TDC pulse spark time, the pulse triggers the discharge circuit Q2, which allows the capacitor Ci to discharge its current rapidly through the primary of transformer Ti, which typically has a step-up ratio .off 100~.1. The rapid discharge of current through the primary coil of T1 coupled with the resonance effects paused by the'LC combination of C1-T1 reactances multiply the circulating current by up to 20 times, resulting in the ~5'-3OKV spark. The T1 secondary coil may be manufactured with additional or designed-in capacitances (sh;own dotted) to.cause resonance effects in the secondary:windinc~s of T1 (the high-voltage side). Once the discharging of C1 is'~omplete, the sparking cycle is over, and Cl starts charging again. Figure 3 showy the typical structure of the spark so generated:
Measuring the voltage from the transformer T~.; it quick3y rises in about 25-useconds (.0~0065 sacs) to about 25Kv at which point ionisation ~f the gases in the cylinder starts to occur and leakage current increases dramaticaily,causing self-resoaaance conelitions in the transformer T1. These resonances remain a further 35uS
as the discharge dissipates from the capacitor C1 and self--oscillation of T1 causes alternating peaks of voltage. The'current pulses which are created in the ionised gases in the cylinder cause ignition by Joule-heating effects, generally termed minimal arc-heating.
~,~~~.ini a i~
~V~ 93/10348 P~'!'/CA92/00510 The combination of current pulses, and the high-voltage coil T1 with its high-resistance leads to the plugs is essentially a~ self-quenching cycle; it begins with the high-voltage pulse causing ionisation, which causes current to flow in the gas, which increases hack-emf in T1, which reduces the high-voltage pulse, which extinguishes the leakage arc, which allows the high-voltage pulse to reappear, and the cycle repeats until all of the energy stored in capacitor C1 is dissipated.
The typical advantages of such ignition systems are that they are simple, low-cost and safe. znherent high-resistance in Ti i~ claimed as a safety feature, together with the high-resistance plug-leads, and it is true that one cannot be burned or xeceive dangerous shocks from these spark-ignition'systems: However, the inherent high-resistance of all of the components prevents efficient delivery of higher energies to the spark plug tip. The-typical energy delivered per spark is about :030 ~oules,,whereas the typical energy stored by the capacitor C1 is about .090 Joules, so that the process is Seen to be only 33% efficient.
Referring again to Figure 1, which shows the typical combustion cycle for a fr~ur=stroke engine, it can be seen that at 1000 rpm.(slow sg~ed, no-load) conditions appear to be near ideal (Figure lF~): _ rotation speed is 1l0 us~c per degree Spark time of 11 usec = .58 degree advahce of 3 degrees is all that is needed combustion flame burning time takes 1.5 mil sec =
3 ~ ~s ~ degrees , However,~at mid ranger 3000-6000 x°pm (max speed, full load) coa~di. ions' are marginal (Figure 1B?
rotation speed is 28 used per degree spark time is 100 usec ~ 3.6 degrees advance of 9 degrees needed (3000 rpm) advance of 18 degrees needed (6000 rpm) ~ : ; r, ~'J : .~
i,l ~. i . ' ~. a l ~ i WO 93!10348 PC'C/CA92/0~'"~.:'~:9 I
combustion flame burning time takes 1.5 milsecs 53.6 degrees (6000 rpm) The inventor has recognized that significant improvements can be made. Firstly, the spark time can be shortened to 50 usecs. Increased energy can be delivered to spark to .090 Joules, or higher, and the flame.
combustion time can be shortened to 0.5 milsecs (28 degrees at 6000 rpm).
From these improvements it is expected that the spark-advance can be reduced at high speeds, giving some increase in efficiency; combustion can be initiated nearer to 'TDC at all times, and burn faster; some fuel efficienc~.es will be achieved (or power improvements accepted); and emissions behaviour of exhaust gases may be improved.
Considerable prior art literature is available on the subject of spark ignition systems. The existing prior art can be classified generally into the following types (some of which are in use, others of rahich are G0 not,s, .
(a) min~r charage~ ~o spark. plugs (~GTC split-fire) (b) substitution of electronics for spark-gap points (c~ ac~diti,~n of voltage-doubters to +24V to increase capacit~r charging; _ ~d) uses of coaxial cable radio and radio-frequency energy pulge~
(e) uses of microwave plumbing and microwave frequency pules;
(f) uses of resonant chambers associated with the piston and cylinder diameters and radio and microwave frequen~i.es;
(g) uses of special plugs and extensive m~di~ications to the pltag electrodes;
(h) uses ~f charged,~c~pacitance transmission-line in'plug-leads and capacit~r load in spar3c-plug;
Referring to Figure 2A, the general characteristics of existing systems of sgark formation is based on a high-voltage step-up transformer T1 from the l2V battery supply, using the slow charge of a capacitor CI up to 12V
through transistor Ql. This occurs during the °'off"
cycle between Top Dead Centre (TDC) pulses. The charging circuit has to be designed such that the capacitor C1 can be fully charged between sparks at the maximum speed of the engine, which allows about 20 milliseconds (0.020 sec) for full charge: At the TDC pulse spark time, the pulse triggers the discharge circuit Q2, which allows the capacitor Ci to discharge its current rapidly through the primary of transformer Ti, which typically has a step-up ratio .off 100~.1. The rapid discharge of current through the primary coil of T1 coupled with the resonance effects paused by the'LC combination of C1-T1 reactances multiply the circulating current by up to 20 times, resulting in the ~5'-3OKV spark. The T1 secondary coil may be manufactured with additional or designed-in capacitances (sh;own dotted) to.cause resonance effects in the secondary:windinc~s of T1 (the high-voltage side). Once the discharging of C1 is'~omplete, the sparking cycle is over, and Cl starts charging again. Figure 3 showy the typical structure of the spark so generated:
Measuring the voltage from the transformer T~.; it quick3y rises in about 25-useconds (.0~0065 sacs) to about 25Kv at which point ionisation ~f the gases in the cylinder starts to occur and leakage current increases dramaticaily,causing self-resoaaance conelitions in the transformer T1. These resonances remain a further 35uS
as the discharge dissipates from the capacitor C1 and self--oscillation of T1 causes alternating peaks of voltage. The'current pulses which are created in the ionised gases in the cylinder cause ignition by Joule-heating effects, generally termed minimal arc-heating.
~,~~~.ini a i~
~V~ 93/10348 P~'!'/CA92/00510 The combination of current pulses, and the high-voltage coil T1 with its high-resistance leads to the plugs is essentially a~ self-quenching cycle; it begins with the high-voltage pulse causing ionisation, which causes current to flow in the gas, which increases hack-emf in T1, which reduces the high-voltage pulse, which extinguishes the leakage arc, which allows the high-voltage pulse to reappear, and the cycle repeats until all of the energy stored in capacitor C1 is dissipated.
The typical advantages of such ignition systems are that they are simple, low-cost and safe. znherent high-resistance in Ti i~ claimed as a safety feature, together with the high-resistance plug-leads, and it is true that one cannot be burned or xeceive dangerous shocks from these spark-ignition'systems: However, the inherent high-resistance of all of the components prevents efficient delivery of higher energies to the spark plug tip. The-typical energy delivered per spark is about :030 ~oules,,whereas the typical energy stored by the capacitor C1 is about .090 Joules, so that the process is Seen to be only 33% efficient.
Referring again to Figure 1, which shows the typical combustion cycle for a fr~ur=stroke engine, it can be seen that at 1000 rpm.(slow sg~ed, no-load) conditions appear to be near ideal (Figure lF~): _ rotation speed is 1l0 us~c per degree Spark time of 11 usec = .58 degree advahce of 3 degrees is all that is needed combustion flame burning time takes 1.5 mil sec =
3 ~ ~s ~ degrees , However,~at mid ranger 3000-6000 x°pm (max speed, full load) coa~di. ions' are marginal (Figure 1B?
rotation speed is 28 used per degree spark time is 100 usec ~ 3.6 degrees advance of 9 degrees needed (3000 rpm) advance of 18 degrees needed (6000 rpm) ~ : ; r, ~'J : .~
i,l ~. i . ' ~. a l ~ i WO 93!10348 PC'C/CA92/0~'"~.:'~:9 I
combustion flame burning time takes 1.5 milsecs 53.6 degrees (6000 rpm) The inventor has recognized that significant improvements can be made. Firstly, the spark time can be shortened to 50 usecs. Increased energy can be delivered to spark to .090 Joules, or higher, and the flame.
combustion time can be shortened to 0.5 milsecs (28 degrees at 6000 rpm).
From these improvements it is expected that the spark-advance can be reduced at high speeds, giving some increase in efficiency; combustion can be initiated nearer to 'TDC at all times, and burn faster; some fuel efficienc~.es will be achieved (or power improvements accepted); and emissions behaviour of exhaust gases may be improved.
Considerable prior art literature is available on the subject of spark ignition systems. The existing prior art can be classified generally into the following types (some of which are in use, others of rahich are G0 not,s, .
(a) min~r charage~ ~o spark. plugs (~GTC split-fire) (b) substitution of electronics for spark-gap points (c~ ac~diti,~n of voltage-doubters to +24V to increase capacit~r charging; _ ~d) uses of coaxial cable radio and radio-frequency energy pulge~
(e) uses of microwave plumbing and microwave frequency pules;
(f) uses of resonant chambers associated with the piston and cylinder diameters and radio and microwave frequen~i.es;
(g) uses of special plugs and extensive m~di~ications to the pltag electrodes;
(h) uses ~f charged,~c~pacitance transmission-line in'plug-leads and capacit~r load in spar3c-plug;
8 ~ ~ ~ ~~. ; ~ i~ P~'/CA921U0510 (i) modifications and adaptation of semi-conductors to means of sp~xk distribution;
(j) modifications of spark-plug leads for high resistance;
(k) mechanical modifications to introduce automatic advance with engine speed; .
(1) electronic madifications to replace mechanical spark advance timing;
Most of the inventions which have been adapted for use are simple; easy to manufacture, anal easy to install.
.The prior art of the time has been advanced in a~modest way, without any changes to the engine structure, Some examples are the use of semi-conductors and capacitor discharge ignition (CDI) to replace the spark-gap points, and electronic timing advance to replace the vacuum mechanical advande methods.
Most of the inventions which have not been adapted for use in engines required major modifications to the cylinder/pi~tons and/or additi~na1 combustion chambers.
Where as most of the pr~.or art relates t~ functional improvements in spark ignition technology, the present invention is directed to the problems of (1) controlled spark liming t~ schi~~re opt~.mum-engine combustion over a wide rane~e ~f engine type, fuels and atmospheric conditi~ns; (2~ aecelerat~:d Joule-heating effect to the air-fuel mixture; to reduce combustion time and therefore reduce spark advance needed at higher speeds; and (3~ adaptable spark liming, adaptable Joule-heating and duration to minimise emissions products over a range of 3~ engine operating conditipns, and (4) possible full-stroke ignition timing to bottoan dyad centre (HOC) for the p~~pose of continuing cbmbustion during the working stroke in fAUr-cycle engines'to ensure complete combustion of all hydro-carbon products, -Turning ~ figure 4, a pla~m-arc ignition system is shown according ts~ this invention having separate high-voltage generator l and high-current generator 2 for the WO 9311034 ~ ~ ~ ~; ~ ~ ~~ PC.'T/CA9Z/00.~'r purpose of producing controlled timing of the start of combustion, and faster and cleaner burning of the air-fuel mixture. In conjunction with this improvement, it is a further object of an aspect of the invention to 5 provide an Ionisation Current Detector (ICD 3) by means of which ionisation current can be detected during the high voltage pulse, and used as additional information control to start the high current pulse.
Therefore, according to the present invention, a 10 micro-controller plasma control system ~4 is provided for receiving engine operation parameters such as RPM and TDC
,timing, as well as manifold air density, and in response generating trigger pulses for selectively enabling and disabling the high-voltage generator 1 and high-current generator at predetermined times. The micro-controller 4 preferably incaude~ a microprocessor for integrating the received data, and calculating appropriate timing signals for the start of the current arG, amount of current and duration ~f fi:he arc on the basis of empirical formulae operating on the,receiving engine parameters. This optimizes the am~unt of ad~rar~ce required to a minimum, and optimizes to a maximum-the amount of energy coupled to the combustion flame-front f~r accelerating combustion.
The ionization current detector 3 px'ovides ou$put signals to bath the micro-controller 4 and the high-current gener2~tor 2. The purpose of its input to the micro-controller 4 is to signal readiness to turn-off the ~aigh voltage pulse while ionizat3.on is occurring. The purpose of the signal into the high-current generator 2 is to trigger it to provide the high-current pulse, which is contr~lled in ~m~li.tude ancD frequency by the input from the micro-controller 4, which i~ Cased on empirical formulae usihg engine-map data.
The high-v~ltage generator 1 receives the plasma timing pulse from the micro-controller ~ and immediately initiates an alternating high voltage discharge at iae~~ 93/~034~ ~ ~ ~ ~. ~ ~ '~.~ P~l'/~CA9~/00510 ~.1 approximately 35 KV and 500 kilohertz via a distribution system 5 which is connected to plasma plug 5 within engine cylinder 7 (fuel and exhaust ports have been omitted from the schematic representation of cylinder 7 for the purposes of clarity).
The ionization current detector is conneeted~to a sensor 8 which is connected in series with the high-voltage generator 1 and distribution system 5. The ionization current detector 3 detects when the small x0 leakage current around the plasma plug 6 suddenly increases, which is indicative of a change from the typical spark plug leakage current to the ionization break down associated with. an actual spark (in an SI
system). 2n a PJI system, it is at this time that the conditions exist for a plasma to be formed and subsequently maintained. This current boundary varies widely over the life and type of engine because it is mainly dependent on type of fuel used, and atmospheric conditions such as cold, dry air or warm, wet air. The ionization signal is sent to the controller 4, which in response immediately enables the high-current generator 2 for generating plasma current.
High current generator 2 receives the trigger pulse from ionisati~n detector 3 and magnitude control signal ~
as well as from contr~ll~r 4 to start the plasma current, further data defining the maximum plasma current and duration ~f the plasma pulse. A high voltage bloCker 9 prevents feed-back of the-high voltage pulse into the circuits ~f the current generator 2 which could otherwise be damaged. The plasma plug 6 and distribution system 5 are provided with a dedicated plasma current return circuit which d~~s n~t simply connect to the engine block and chassis. The distribution system 5 distributes the plasma ene~gy to the plugs (only 1 plug being shown for ease of illustrati~n); and as such is recquired to be a very low impedance device.
WO 93/ 1034 ~ ~ ~ ~~. ~~ ~ ~ PC.'T/CA92/00~ a iz The plasma plug 6 is discussed in greater detail below.
Turning to Figure 5, a circuit is shown for ~rrecise control of the plasma current by means of a current probe a or current sensor 20, such as a Hall effect sensor, to provide feed-back control in an error driven closed-loop circuit. This circuit is shown as comprising an analogue to digital converter ll connected to the current sensor for receiving and digitizing the current output from 10 the high-current pulse generator 2 and generating an actual current data signal in response thereto. A
subtractor 12 is connected to the output of analogue-to--digital converter 1l as we~'1 as to the controller 4 for subtracting the current demanded from the actual current data signal and in response generating an error signal.
A digital-to-analogue converter 13 receives and converts the errob signal to analogue form and in response generates the Qutput current.
Figure 6 shows an analysis of typical FtMS values of leakage current during the system's spark voltage pulse.
It should be noted that the time scale is approximately lOOusec (.0001 sec). Ionisati~n currents on the order of 10 ~ (Osleamp) fl~w before an .arc can be formed in the air-duel gas mixttare. The conditions of the induced air and the fuel composition affect the i~nisation current in the following ways:
0. ~ For' °°dry gaseous fuels°', such as methane, px'opane 0 ~o~d a~dist air has high moisture content (1000 particles per cc) and readily produces i~nisation current 0 riot dry air has zero (or very low) moisture content and it is difficult to produce ionisation current, except with maximum voltage ~tresa of 200 V per mm per atmosphere :1 ' .1 . r', .r. ... .
r .: ~ .,s c -S. ;~, ..n ... 3. , r ..r...::;,:, > ..a i:,.T ~ r,,r.
n M~., ..;a. t. ...... , ~~1"!~.,.;tz.."; . . , ; .. ...,''.:~ , ..,.,.,. . , .,_, .., ,.. , ~a,.~r _, ...:s.,~, . ..,..,. .. .. , ..... . ....
r~ a V~~ 93/103488 ~ ~ ~ ~ n ~ '.i FC'f/CA92/005 i () 0 Gas flash point is much higher than gasolines, so higher temperatures are required to initiate and continue combustion 0 Gases have a cooling effect on the intake, which tends to make ignition slower 0 over a wide range of ratios from '°rich" to stoichiometric to '°very lean", the air-fuel mixture ranges from 85% to 9~% air, but the "wetness" of the air-fuel mixture is dependent on the atmosphere, not on the fuelling ratio 2. For °~"wet°' fuels such as the gasolines, alcohols:
0 Fuel enters as ~ particulated aerosol, mixed with air, but his "wet" properties which helps ionisation of the air-fuel mixture Aerosol evaporation is slowed by increasing compression of the engine up to TDC
~ Cold moist air has high moisture content (as described abcave) and read~.ly produces ionization current' p Hot dry air has zero m~i tore content but is moderated by the '~raetness" of these fuels, in ~n air-fuel mixtuxe ~e~y ridh starting conditions can provide '°too-~~ w~~" db~~~s.~ion chamber conditions when coupled wfth Cblid moist aiz', and eowet'° the plug to the p4~nt where the powered resistance is too low for existing coil types, and their spark energy i~ dissipated internally The differences in these conditions can cause incc~rr~ct working of the high-voltage pulse-system, such that ~f ~t ~s ad,usted to suit hot dry air ( a. r a s a pxol~nged high-voltage pulse); it will burn the plug electrodes in ce~ld moist air c~~diti~ns: Further, if the high~voltaa~~ pulse i~,set to suit'the moist air conditions rit will not generate ens~ugh ionisation current in the hot dry air conditions. T~rese differences in !~V~ 93/i034~ ~ ~ ~ ~. ~~ ~ ~% PC?fCA92f00G1,:~
timing needed for ianisation to reach the trigger level in various air conditions are compensated for in the Ionisation Current Detector (ICD3) of the present invention.
The ICU3 of the present invention is designed to be sensitive to the level of the ionisation current at the plug gaps, as an indication of the breakdown voltage point of the various air-fuel mixtures and chamber pressures. Accoxc~ing to the present invention, the level l0 of ionization current is a standard measure for, and allowance of, predetermined leakage current through the plug°leads and plugs, which do not form part of the ionisation cuxrent and do.not contribute to the air°fuel ionisation process Figure 7A showy the control timing of the high-voltage pulse, resulting ionization current, ionization current detector pulse and plasma current pulse for the circuit of Figure ~. In particular, once the ionization threshold kaas been detested b~ ionization current detector, high current generator 2 is enabled for starting generation of plasma cuxrent, and once plasma current flow is ci~tected, the high voltage generator 1 is disabled via micro-controller 4.
Figures 7H, 7C and ?D show the highwvolkage pulse, the resulting typical ionisation'current, and'the-Joule°
heating plasana-arc ~urr~nt in greater detail. A
rectified sinus~adal alt~xnatinc~ system is used with harmonic content lower tiara 0.1~, to generate high ~roltage by means'of a resonating high-Q transformer at high-fx°equency. such harmonic purity prevents energy losses and waveform distortion, and maintains the highest voltages poss~.ble. High frequency is used and controlled by the high-voltage pulse generator 1 (Figure ~~ to run for a specific number of cycles, until the ionazation ,current reaches the trigger level for a plasma°arc to be initiated. The Ionisati~n Current Detectpr (TCD 3) then outputs a trigger pulse to the High-Current Pulse WO ~J3/10348 ~ 1 ~ ,!~. (~'~ ~ PCT/CA92/00510 Generator 2. A pure sinusoidal alternating system is used with harmonic content less than 1% to generate the high-current pulse by means of a resonating curre7t transformer with high-Q and low losses.
5 Turning to Figure 8A, a high voltage generator according to an alternative embodiment is shown f.or generating a full wave rectified negative high voltage pre-charge pulse. The system of Figure 8A comprises a high frequency oscillator 80 for receiving an on/off l0 trigger signal from the midro-controller 4, a tuned transformer 82, which is adapted to resonate at 500 kilohertz (i.e. the frequency of the signal output from ' oscillator 80)~ and a full-bridge rectifier 83 for converting the resulting high voltage sinusoidal waveform 15 into the full wave rectified signal of Figure 8B. The output from bridge 83 is; connected to the central electrode and side electrode of a suitable plasma plug (see Figures 10-16).
Figure 9A shows a block diagl"am for high current generator 2: The circuit comprises a variable frequency oscillator 90 for-receiving an/~ff trigger signal from cont=older 4;as well as demand current amplitude. The output of oscillator 90 is connected to a tuned transformer 92 which, in turn, is connected to the central and side electrodes of a suitable plasma plug (see Figuresl0-T6). The high current pulse (Figures 9C.
and 9~) provides the arc-current necessary to maintain the plasma by means of the resonating high-Q low loss current transformer ~2 operating at the desired frequency in the range of SO to 150'kilohertz. The frequency is preferably selectable in order to take advantage of operational benefits which may be identified with ~peci.fic frequencies in this range:
High intensity joule heating effects are caused in the plasma arc channel by the generation of the high current pulse at the plasma plug electrodes. The high current generator circuit of Figure 9A delivers a l i4 .:.7:
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predetermined number of precise current pulses each up to 20 amps with a resolution to fractions of an amp. The pulse shape and therefore the energy input, are determined by the micro-controller 4 from monitored engine parameters and internal look-up tables. Precise control of the current is also achieved by the feed-back control system discussed above with reference to Figure 5.
Figure 9B shows current gain amplitude for the high-current generator 2 of Figure 9A as a function of frequency.
The plasma-arc Joule-heating pulse complies with such prior art approaches ,as Tungsten Inert Gas Welding (TIGW) of which the primary parameters for the present invention are: .
0 Modifications of spark plug structure and material 0 Precise control (+/- 1~) of plasma-are current materials ap fl Pr~cis~ control (+r- s%) of plasma-arc current auratior~
0 Precise ~C balancing of the plasma-arc positive and negaative current Plasma-arc physics are Cased in the present invention for creating high-intens ty Joule-heating effects"in the plasma~~rc channel f~rmed by the High-Current Pulse at the spark plug tips, in ~ variety of embodiments (Figures 1~-16)a s~ that at range of precise head pulses can be delive~ced to 'the combustis~n ctaamber, as required by the specific engine type, end operating conditions and fuel, as def ~ned by tlae Spark, advance Timing ~rlgorithm.
I~ the limited dianensions of the spark plug gaps in the various embodiments illustrated in Figures ltd to 1~, the typioal resistance of the plasma-arc channel when heated and estalalish~d i~ in the range 0.5 ohms to 8.5 ohms, and is capable of carrying plasma-arc current in the range 2 amps to 150 amps. The lower levels of i~V~'93/1034$ ~ ~ ~ ~. ~ ~ ~.3 PLT/CA92/00510 ...;s current have been proven, by experiment, to be unstable and too weak to sustain Joule heating, whereas the higher currents at 90 amps and above are too powerful and can cause plug damage at higher rpm.
Figure 10A is a cross~sectional view of a conventional plasma jet igniter or plasma plug, comprising a central electrode 111 of copper and nickel, a standard plug steel body 112; standard plug washer 113, the steel body 112 having a threaded fit 114. A central insulator 5, preferably of alumi,na';'"surrounds the central electrode 111, and an additional epoxy fill 6 is provided in the cavity behind insulator 115. Preferably, a cavity 11? is drilled out in central electrode 111 (approximately 2 mm deep): An end plate 118 is provided (preferably fabricated of HS-14 steel silver-brazed to plug), having a cavity orifice 119 of approximately 2 mm diameter, 45° bevel.
Figure 10~ shows the basic jet plume produced by the standard plasma plug ~f Figure 10A.
Turning ~o figures 11A and 11~, an initial variant to the basic plasma plug ~.s provided in accordance with the present inv~en~i~ra.' Reference numera2s 111-115 de~igna~e parts'which ax°e similar tc~ those of the standard plasma plug sh~awn in figure 10A. However, acearding to the illustrated variant, epoxy 116A is p~'ovided for filling the rear cava.ty, add-on tungsten button 117A is prova,ded with chamfered edge t~ create a stress field at '~A'a . ' An end plate 118 is provided in the ~~~al ~~nner,, with annular gap 119A. However, according to the variant illustrated, ~ toroidal centre piece 110 is pr~vided for creating vortices. The centre Piece 110 may be gabxicated from ceramic alumina, witty epoxy ~o the central electrode 11I.
Figure 11C shows the toroidal jet created by the plasma plug design of Figures 11A and 11B, showing immediate vortex ring effects.
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Figure 12 illustrates an alternative plasma plug design according to the invention, comprising a central electrode 111, parts 112-115 being identical to tire conventional parts discussed above with reference to Figure 10A, epoxy fill 126 having a surface which faces the plasma arc area (A) and which is parabolic, the focus of which is identified by reference mark X and reference wumeral 129. An add-on tungsten button 127 with chamfered edge is provided to create the stress field at In "A". end plate l2~ is provided in the usual manner, the gap identified as the focus point X (reference numeral 129) can be optimized and shaped by formation of the centre piece 110 so ws to shape the plasma jet and direct it into a vortex. The centre piece 110 is preferably ceramic and may be of suitable sire and shape. A
recessed groove 121 is provided for containing an organic catalyst for creating mufti-point ignition sources within the vortex torpid. The organic catalyst may be described in gener~.c form aS .~NHa~, o~,, where CNI~zH is a polymerizable c~mpound where N is greater than 12, and is physically absorbed in the compound.
Turning to Figure 13, a plasma ball igniter is shown accor~ting t~ a further aspect of the present invention having a'c~ntral gl~ctr~de lil, standard parts 112-115, epoxy 116 to fill the gap, and a tip 137 which mayrhave different shapes (~.ge rounded, mufti-point, etc.), according to specific geometries fear open-plasma. The ring electrode Z38 is pr~fe~ably provided with eight pointy (tung~tet~ - 2% thorium alloy). Reference numeral 1~9 designates the locations (A) of the main arc channel.
Turning to Figures l4A-14~, there is shown a plurality of embodiments of plasma-plug according to the princig~.es of the present invention. For example, according to figure 1.4A a central angular tip electrode is shown surrounded by an alumina insulator (ALz03) which is in turn surrounded by a steel jacket-threaded body. A
pair of side electrodes extend from the steel body and ~If ~~:! - s ~ .. ~ . , iF-,:1. ., r .'.~.r err;:-'.'; fr -.r.~:..
~~y, f-~ ..,: t. . .:: ,... .. . f.. .... .. . ..... .... .
PC'f/CA9210051 ~
W4 93/1~3A8 are provided with rectangular faces. In Figures 14B and 14C, plasma-plugs are illustrated having three electrodes and four electrodes, respectively. A plasma arc is generated between the electrodes of the plasma plugs of Figures 14H and l4C as illustrated in Figures 15B and 15C, respectively.
Thus, the multi-port embodiment of Figures 14A-14D
incorporate multiple side electrodes for distributing the generated plasma arc:
The embodiment of Figures 14D and 15D utilizes pointed tip ~a.de'electrodes in number up to sixteen.
Figures 16A to 15C shows a further alternative embadi.ment of-plasma plug having D-shaped electrodes 161 and 162 each of equal area. In all other respects, the plug of Figures l6A-16C incorporates well %nown components identified by reference numerals common with Figures 10-I3:
Other modifications'and variations of the present invention are possible without departing from the sphere ane~ scope of the invention as defined by the claims appended hereto.
(j) modifications of spark-plug leads for high resistance;
(k) mechanical modifications to introduce automatic advance with engine speed; .
(1) electronic madifications to replace mechanical spark advance timing;
Most of the inventions which have been adapted for use are simple; easy to manufacture, anal easy to install.
.The prior art of the time has been advanced in a~modest way, without any changes to the engine structure, Some examples are the use of semi-conductors and capacitor discharge ignition (CDI) to replace the spark-gap points, and electronic timing advance to replace the vacuum mechanical advande methods.
Most of the inventions which have not been adapted for use in engines required major modifications to the cylinder/pi~tons and/or additi~na1 combustion chambers.
Where as most of the pr~.or art relates t~ functional improvements in spark ignition technology, the present invention is directed to the problems of (1) controlled spark liming t~ schi~~re opt~.mum-engine combustion over a wide rane~e ~f engine type, fuels and atmospheric conditi~ns; (2~ aecelerat~:d Joule-heating effect to the air-fuel mixture; to reduce combustion time and therefore reduce spark advance needed at higher speeds; and (3~ adaptable spark liming, adaptable Joule-heating and duration to minimise emissions products over a range of 3~ engine operating conditipns, and (4) possible full-stroke ignition timing to bottoan dyad centre (HOC) for the p~~pose of continuing cbmbustion during the working stroke in fAUr-cycle engines'to ensure complete combustion of all hydro-carbon products, -Turning ~ figure 4, a pla~m-arc ignition system is shown according ts~ this invention having separate high-voltage generator l and high-current generator 2 for the WO 9311034 ~ ~ ~ ~; ~ ~ ~~ PC.'T/CA9Z/00.~'r purpose of producing controlled timing of the start of combustion, and faster and cleaner burning of the air-fuel mixture. In conjunction with this improvement, it is a further object of an aspect of the invention to 5 provide an Ionisation Current Detector (ICD 3) by means of which ionisation current can be detected during the high voltage pulse, and used as additional information control to start the high current pulse.
Therefore, according to the present invention, a 10 micro-controller plasma control system ~4 is provided for receiving engine operation parameters such as RPM and TDC
,timing, as well as manifold air density, and in response generating trigger pulses for selectively enabling and disabling the high-voltage generator 1 and high-current generator at predetermined times. The micro-controller 4 preferably incaude~ a microprocessor for integrating the received data, and calculating appropriate timing signals for the start of the current arG, amount of current and duration ~f fi:he arc on the basis of empirical formulae operating on the,receiving engine parameters. This optimizes the am~unt of ad~rar~ce required to a minimum, and optimizes to a maximum-the amount of energy coupled to the combustion flame-front f~r accelerating combustion.
The ionization current detector 3 px'ovides ou$put signals to bath the micro-controller 4 and the high-current gener2~tor 2. The purpose of its input to the micro-controller 4 is to signal readiness to turn-off the ~aigh voltage pulse while ionizat3.on is occurring. The purpose of the signal into the high-current generator 2 is to trigger it to provide the high-current pulse, which is contr~lled in ~m~li.tude ancD frequency by the input from the micro-controller 4, which i~ Cased on empirical formulae usihg engine-map data.
The high-v~ltage generator 1 receives the plasma timing pulse from the micro-controller ~ and immediately initiates an alternating high voltage discharge at iae~~ 93/~034~ ~ ~ ~ ~. ~ ~ '~.~ P~l'/~CA9~/00510 ~.1 approximately 35 KV and 500 kilohertz via a distribution system 5 which is connected to plasma plug 5 within engine cylinder 7 (fuel and exhaust ports have been omitted from the schematic representation of cylinder 7 for the purposes of clarity).
The ionization current detector is conneeted~to a sensor 8 which is connected in series with the high-voltage generator 1 and distribution system 5. The ionization current detector 3 detects when the small x0 leakage current around the plasma plug 6 suddenly increases, which is indicative of a change from the typical spark plug leakage current to the ionization break down associated with. an actual spark (in an SI
system). 2n a PJI system, it is at this time that the conditions exist for a plasma to be formed and subsequently maintained. This current boundary varies widely over the life and type of engine because it is mainly dependent on type of fuel used, and atmospheric conditions such as cold, dry air or warm, wet air. The ionization signal is sent to the controller 4, which in response immediately enables the high-current generator 2 for generating plasma current.
High current generator 2 receives the trigger pulse from ionisati~n detector 3 and magnitude control signal ~
as well as from contr~ll~r 4 to start the plasma current, further data defining the maximum plasma current and duration ~f the plasma pulse. A high voltage bloCker 9 prevents feed-back of the-high voltage pulse into the circuits ~f the current generator 2 which could otherwise be damaged. The plasma plug 6 and distribution system 5 are provided with a dedicated plasma current return circuit which d~~s n~t simply connect to the engine block and chassis. The distribution system 5 distributes the plasma ene~gy to the plugs (only 1 plug being shown for ease of illustrati~n); and as such is recquired to be a very low impedance device.
WO 93/ 1034 ~ ~ ~ ~~. ~~ ~ ~ PC.'T/CA92/00~ a iz The plasma plug 6 is discussed in greater detail below.
Turning to Figure 5, a circuit is shown for ~rrecise control of the plasma current by means of a current probe a or current sensor 20, such as a Hall effect sensor, to provide feed-back control in an error driven closed-loop circuit. This circuit is shown as comprising an analogue to digital converter ll connected to the current sensor for receiving and digitizing the current output from 10 the high-current pulse generator 2 and generating an actual current data signal in response thereto. A
subtractor 12 is connected to the output of analogue-to--digital converter 1l as we~'1 as to the controller 4 for subtracting the current demanded from the actual current data signal and in response generating an error signal.
A digital-to-analogue converter 13 receives and converts the errob signal to analogue form and in response generates the Qutput current.
Figure 6 shows an analysis of typical FtMS values of leakage current during the system's spark voltage pulse.
It should be noted that the time scale is approximately lOOusec (.0001 sec). Ionisati~n currents on the order of 10 ~ (Osleamp) fl~w before an .arc can be formed in the air-duel gas mixttare. The conditions of the induced air and the fuel composition affect the i~nisation current in the following ways:
0. ~ For' °°dry gaseous fuels°', such as methane, px'opane 0 ~o~d a~dist air has high moisture content (1000 particles per cc) and readily produces i~nisation current 0 riot dry air has zero (or very low) moisture content and it is difficult to produce ionisation current, except with maximum voltage ~tresa of 200 V per mm per atmosphere :1 ' .1 . r', .r. ... .
r .: ~ .,s c -S. ;~, ..n ... 3. , r ..r...::;,:, > ..a i:,.T ~ r,,r.
n M~., ..;a. t. ...... , ~~1"!~.,.;tz.."; . . , ; .. ...,''.:~ , ..,.,.,. . , .,_, .., ,.. , ~a,.~r _, ...:s.,~, . ..,..,. .. .. , ..... . ....
r~ a V~~ 93/103488 ~ ~ ~ ~ n ~ '.i FC'f/CA92/005 i () 0 Gas flash point is much higher than gasolines, so higher temperatures are required to initiate and continue combustion 0 Gases have a cooling effect on the intake, which tends to make ignition slower 0 over a wide range of ratios from '°rich" to stoichiometric to '°very lean", the air-fuel mixture ranges from 85% to 9~% air, but the "wetness" of the air-fuel mixture is dependent on the atmosphere, not on the fuelling ratio 2. For °~"wet°' fuels such as the gasolines, alcohols:
0 Fuel enters as ~ particulated aerosol, mixed with air, but his "wet" properties which helps ionisation of the air-fuel mixture Aerosol evaporation is slowed by increasing compression of the engine up to TDC
~ Cold moist air has high moisture content (as described abcave) and read~.ly produces ionization current' p Hot dry air has zero m~i tore content but is moderated by the '~raetness" of these fuels, in ~n air-fuel mixtuxe ~e~y ridh starting conditions can provide '°too-~~ w~~" db~~~s.~ion chamber conditions when coupled wfth Cblid moist aiz', and eowet'° the plug to the p4~nt where the powered resistance is too low for existing coil types, and their spark energy i~ dissipated internally The differences in these conditions can cause incc~rr~ct working of the high-voltage pulse-system, such that ~f ~t ~s ad,usted to suit hot dry air ( a. r a s a pxol~nged high-voltage pulse); it will burn the plug electrodes in ce~ld moist air c~~diti~ns: Further, if the high~voltaa~~ pulse i~,set to suit'the moist air conditions rit will not generate ens~ugh ionisation current in the hot dry air conditions. T~rese differences in !~V~ 93/i034~ ~ ~ ~ ~. ~~ ~ ~% PC?fCA92f00G1,:~
timing needed for ianisation to reach the trigger level in various air conditions are compensated for in the Ionisation Current Detector (ICD3) of the present invention.
The ICU3 of the present invention is designed to be sensitive to the level of the ionisation current at the plug gaps, as an indication of the breakdown voltage point of the various air-fuel mixtures and chamber pressures. Accoxc~ing to the present invention, the level l0 of ionization current is a standard measure for, and allowance of, predetermined leakage current through the plug°leads and plugs, which do not form part of the ionisation cuxrent and do.not contribute to the air°fuel ionisation process Figure 7A showy the control timing of the high-voltage pulse, resulting ionization current, ionization current detector pulse and plasma current pulse for the circuit of Figure ~. In particular, once the ionization threshold kaas been detested b~ ionization current detector, high current generator 2 is enabled for starting generation of plasma cuxrent, and once plasma current flow is ci~tected, the high voltage generator 1 is disabled via micro-controller 4.
Figures 7H, 7C and ?D show the highwvolkage pulse, the resulting typical ionisation'current, and'the-Joule°
heating plasana-arc ~urr~nt in greater detail. A
rectified sinus~adal alt~xnatinc~ system is used with harmonic content lower tiara 0.1~, to generate high ~roltage by means'of a resonating high-Q transformer at high-fx°equency. such harmonic purity prevents energy losses and waveform distortion, and maintains the highest voltages poss~.ble. High frequency is used and controlled by the high-voltage pulse generator 1 (Figure ~~ to run for a specific number of cycles, until the ionazation ,current reaches the trigger level for a plasma°arc to be initiated. The Ionisati~n Current Detectpr (TCD 3) then outputs a trigger pulse to the High-Current Pulse WO ~J3/10348 ~ 1 ~ ,!~. (~'~ ~ PCT/CA92/00510 Generator 2. A pure sinusoidal alternating system is used with harmonic content less than 1% to generate the high-current pulse by means of a resonating curre7t transformer with high-Q and low losses.
5 Turning to Figure 8A, a high voltage generator according to an alternative embodiment is shown f.or generating a full wave rectified negative high voltage pre-charge pulse. The system of Figure 8A comprises a high frequency oscillator 80 for receiving an on/off l0 trigger signal from the midro-controller 4, a tuned transformer 82, which is adapted to resonate at 500 kilohertz (i.e. the frequency of the signal output from ' oscillator 80)~ and a full-bridge rectifier 83 for converting the resulting high voltage sinusoidal waveform 15 into the full wave rectified signal of Figure 8B. The output from bridge 83 is; connected to the central electrode and side electrode of a suitable plasma plug (see Figures 10-16).
Figure 9A shows a block diagl"am for high current generator 2: The circuit comprises a variable frequency oscillator 90 for-receiving an/~ff trigger signal from cont=older 4;as well as demand current amplitude. The output of oscillator 90 is connected to a tuned transformer 92 which, in turn, is connected to the central and side electrodes of a suitable plasma plug (see Figuresl0-T6). The high current pulse (Figures 9C.
and 9~) provides the arc-current necessary to maintain the plasma by means of the resonating high-Q low loss current transformer ~2 operating at the desired frequency in the range of SO to 150'kilohertz. The frequency is preferably selectable in order to take advantage of operational benefits which may be identified with ~peci.fic frequencies in this range:
High intensity joule heating effects are caused in the plasma arc channel by the generation of the high current pulse at the plasma plug electrodes. The high current generator circuit of Figure 9A delivers a l i4 .:.7:
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.:." A..'.
~; vy.~-~, ! .
i .' 'f.~ ", v I r.
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.., ..... ... . ...
i ,~~a..~:.,.,.. , .. . .....v.. , . .. ., .., . . .
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VVO <93/ 10348 PC'f/CA92/005'.I,t>
predetermined number of precise current pulses each up to 20 amps with a resolution to fractions of an amp. The pulse shape and therefore the energy input, are determined by the micro-controller 4 from monitored engine parameters and internal look-up tables. Precise control of the current is also achieved by the feed-back control system discussed above with reference to Figure 5.
Figure 9B shows current gain amplitude for the high-current generator 2 of Figure 9A as a function of frequency.
The plasma-arc Joule-heating pulse complies with such prior art approaches ,as Tungsten Inert Gas Welding (TIGW) of which the primary parameters for the present invention are: .
0 Modifications of spark plug structure and material 0 Precise control (+/- 1~) of plasma-are current materials ap fl Pr~cis~ control (+r- s%) of plasma-arc current auratior~
0 Precise ~C balancing of the plasma-arc positive and negaative current Plasma-arc physics are Cased in the present invention for creating high-intens ty Joule-heating effects"in the plasma~~rc channel f~rmed by the High-Current Pulse at the spark plug tips, in ~ variety of embodiments (Figures 1~-16)a s~ that at range of precise head pulses can be delive~ced to 'the combustis~n ctaamber, as required by the specific engine type, end operating conditions and fuel, as def ~ned by tlae Spark, advance Timing ~rlgorithm.
I~ the limited dianensions of the spark plug gaps in the various embodiments illustrated in Figures ltd to 1~, the typioal resistance of the plasma-arc channel when heated and estalalish~d i~ in the range 0.5 ohms to 8.5 ohms, and is capable of carrying plasma-arc current in the range 2 amps to 150 amps. The lower levels of i~V~'93/1034$ ~ ~ ~ ~. ~ ~ ~.3 PLT/CA92/00510 ...;s current have been proven, by experiment, to be unstable and too weak to sustain Joule heating, whereas the higher currents at 90 amps and above are too powerful and can cause plug damage at higher rpm.
Figure 10A is a cross~sectional view of a conventional plasma jet igniter or plasma plug, comprising a central electrode 111 of copper and nickel, a standard plug steel body 112; standard plug washer 113, the steel body 112 having a threaded fit 114. A central insulator 5, preferably of alumi,na';'"surrounds the central electrode 111, and an additional epoxy fill 6 is provided in the cavity behind insulator 115. Preferably, a cavity 11? is drilled out in central electrode 111 (approximately 2 mm deep): An end plate 118 is provided (preferably fabricated of HS-14 steel silver-brazed to plug), having a cavity orifice 119 of approximately 2 mm diameter, 45° bevel.
Figure 10~ shows the basic jet plume produced by the standard plasma plug ~f Figure 10A.
Turning ~o figures 11A and 11~, an initial variant to the basic plasma plug ~.s provided in accordance with the present inv~en~i~ra.' Reference numera2s 111-115 de~igna~e parts'which ax°e similar tc~ those of the standard plasma plug sh~awn in figure 10A. However, acearding to the illustrated variant, epoxy 116A is p~'ovided for filling the rear cava.ty, add-on tungsten button 117A is prova,ded with chamfered edge t~ create a stress field at '~A'a . ' An end plate 118 is provided in the ~~~al ~~nner,, with annular gap 119A. However, according to the variant illustrated, ~ toroidal centre piece 110 is pr~vided for creating vortices. The centre Piece 110 may be gabxicated from ceramic alumina, witty epoxy ~o the central electrode 11I.
Figure 11C shows the toroidal jet created by the plasma plug design of Figures 11A and 11B, showing immediate vortex ring effects.
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:: . ;:~ ;, ,...., . .... .. .,.:: . .... ... .. . :, ... . ,., , >.... ,,..;,r , , ...,..
.....::..
>P.. .,. .. , ,:.~., .,r"...... ..",...,.....~ ......... ....".:.....:..,.....
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..,... .. . ... . ~ :....,..
..~v..
n::' ~C, t , r .., .<~ .:. , ~ .~~.,~ ,. .', ,. -:.::' ;" .~. : . . .'v .... .',: a . . :.. ~:::' .' ~ -..:' 2 ~~.~.~, .. ;...'. . '.:.,.:; .,.'.: . . ~. ~ . .
,j.Alff~,'A';~.vi: , ".. . , .. ~" ... " . ..... W .. .. .. . . ..., ... . . , . .. ....~..... . . .. v, PCI'ICA92/00' '?
WOl 931 t 03~ ~ ~ !"' ~ ll ~ u~
Figure 12 illustrates an alternative plasma plug design according to the invention, comprising a central electrode 111, parts 112-115 being identical to tire conventional parts discussed above with reference to Figure 10A, epoxy fill 126 having a surface which faces the plasma arc area (A) and which is parabolic, the focus of which is identified by reference mark X and reference wumeral 129. An add-on tungsten button 127 with chamfered edge is provided to create the stress field at In "A". end plate l2~ is provided in the usual manner, the gap identified as the focus point X (reference numeral 129) can be optimized and shaped by formation of the centre piece 110 so ws to shape the plasma jet and direct it into a vortex. The centre piece 110 is preferably ceramic and may be of suitable sire and shape. A
recessed groove 121 is provided for containing an organic catalyst for creating mufti-point ignition sources within the vortex torpid. The organic catalyst may be described in gener~.c form aS .~NHa~, o~,, where CNI~zH is a polymerizable c~mpound where N is greater than 12, and is physically absorbed in the compound.
Turning to Figure 13, a plasma ball igniter is shown accor~ting t~ a further aspect of the present invention having a'c~ntral gl~ctr~de lil, standard parts 112-115, epoxy 116 to fill the gap, and a tip 137 which mayrhave different shapes (~.ge rounded, mufti-point, etc.), according to specific geometries fear open-plasma. The ring electrode Z38 is pr~fe~ably provided with eight pointy (tung~tet~ - 2% thorium alloy). Reference numeral 1~9 designates the locations (A) of the main arc channel.
Turning to Figures l4A-14~, there is shown a plurality of embodiments of plasma-plug according to the princig~.es of the present invention. For example, according to figure 1.4A a central angular tip electrode is shown surrounded by an alumina insulator (ALz03) which is in turn surrounded by a steel jacket-threaded body. A
pair of side electrodes extend from the steel body and ~If ~~:! - s ~ .. ~ . , iF-,:1. ., r .'.~.r err;:-'.'; fr -.r.~:..
~~y, f-~ ..,: t. . .:: ,... .. . f.. .... .. . ..... .... .
PC'f/CA9210051 ~
W4 93/1~3A8 are provided with rectangular faces. In Figures 14B and 14C, plasma-plugs are illustrated having three electrodes and four electrodes, respectively. A plasma arc is generated between the electrodes of the plasma plugs of Figures 14H and l4C as illustrated in Figures 15B and 15C, respectively.
Thus, the multi-port embodiment of Figures 14A-14D
incorporate multiple side electrodes for distributing the generated plasma arc:
The embodiment of Figures 14D and 15D utilizes pointed tip ~a.de'electrodes in number up to sixteen.
Figures 16A to 15C shows a further alternative embadi.ment of-plasma plug having D-shaped electrodes 161 and 162 each of equal area. In all other respects, the plug of Figures l6A-16C incorporates well %nown components identified by reference numerals common with Figures 10-I3:
Other modifications'and variations of the present invention are possible without departing from the sphere ane~ scope of the invention as defined by the claims appended hereto.
Claims (23)
1. An ignition system for igniting fuel within an engine cylinder, comprising:
a) at least one ignition plug disposed in said cylinder;
b) high-voltage pulse generator means connected to said ignition plug for generating a pre-pulse of static charge within said cylinder so as to ionize said fuel in said engine cylinder and thereby increase conductivity thereof, said pre-pulse comprising a high voltage high frequency burst of alternating current;
c) high-current pulse generator means connected to said ignition plug for generating a high-current pulse within said engine cylinder so as to form a plasma adjacent said plug for initiating combustion of said fuel within said engine cylinder;
d) controller means for selectively enabling and disabling said high-voltage pulse generator means and said high-current pulse generator means at predetermined times; and e) a high voltage blocker for preventing said high voltage high frequency burst of alternating current from entering said high-current pulse generator means.
a) at least one ignition plug disposed in said cylinder;
b) high-voltage pulse generator means connected to said ignition plug for generating a pre-pulse of static charge within said cylinder so as to ionize said fuel in said engine cylinder and thereby increase conductivity thereof, said pre-pulse comprising a high voltage high frequency burst of alternating current;
c) high-current pulse generator means connected to said ignition plug for generating a high-current pulse within said engine cylinder so as to form a plasma adjacent said plug for initiating combustion of said fuel within said engine cylinder;
d) controller means for selectively enabling and disabling said high-voltage pulse generator means and said high-current pulse generator means at predetermined times; and e) a high voltage blocker for preventing said high voltage high frequency burst of alternating current from entering said high-current pulse generator means.
2. The ignition system of Claim 1, wherein said controller means selectively enables and disables said high-voltage pulse generator means and said high-current pulse generator means at said predetermined times in accordance with one or more engine operation parameters.
3. The ignition system of Claim 1, wherein said controller means enables said high-voltage pulse generator means for a predetermined number of cycles of said alternating current in accordance with engine fuel-charge requirements.
4. The ignition system of Claim 1, further comprising an ionization current detector connected to said high-voltage pulse generator means and said controller means for detecting ionisation current resulting from said pre-pulse and in response enabling said high-current pulse generator means and causing said controller means to disable said high-voltage pulse generator means.
5. The ignition system of Claim 1, further comprising a current probe connected to an output of said high-current pulse generator means for sensing current output from said high-current pulse generator means.
6. The ignition system of Claim 5, wherein said high-current pulse generator means further includes an error driven closed-loop feedback circuit for controlling amplitude of said high-current pulse in response to current demanded by said controller means and output current sensed by said current probe.
7. The ignition system of Claim 6, wherein said error driven closed-loop feedback circuit comprises an analog-to-digital converter connected to said current probe for receiving and digitizing said current output from said high-current pulse generator means and generating an actual current data signal in response thereto, a subtracter connected to said analog-to-digital converter and said controller means for subtracting said current demanded from said actual current data signal and in response generating an error signal, a digital-to-analog converter for receiving and converting said error signal to analog form and in response generating said output current.
8. The ignition system of any one of Claims 5-7, wherein said current probe is a Hall effect device.
9. The ignition system of Claim 2, wherein said controller means receives said engine parameters in the form of one or more of fuel composition data, air density data, air temperature data, engine physical data, and RPM
data.
data.
10. The ignition system of Claim 1, wherein said high-voltage pulse generator means further comprises a high frequency oscillator for generating a sinusoidal output signal of predetermined frequency, a transformer with capacitors on primary and secondary circuits thereof for tuning said transformer to said predetermined frequency, said transformer receiving said sinusoidal output signal and in response resonating at said predetermined frequency and generating said high voltage high frequency burst of alternating current.
11. The ignition system of Claim 10, wherein said predetermined frequency is approximately 500kHz and said high voltage is approximately 35KV.
12. The ignition system of Claim 1 wherein said high voltage blocker is a double-octave filter.
13. The ignition system of Claim 1, wherein said high-current pulse generator further includes an oscillator for generating a sinusoidal signal having predetermined amplitude and shape dictated by said controller means, and a resonating high-Q low loss current transformer for receiving said variable amplitude sinusoidal signal and in response generating said high-current pulse for application to said ignition plug.
14. The ignition system of Claim 13, wherein said sinusoidal signal is in the range of from 50kHz to 150kHz.
15. The ignition system of Claim 13, wherein said ignition plug further comprises a central electrode connected to one terminal of said current transformer, an insulator surrounding said central electrode, a metallic threaded jacket surrounding said insulator and having a plug electrode extending therefrom adjacent said central electrode, said jacket being connected to a remaining terminal of said current transformer, whereby said ignition plug and said high-current pulse generator form a fully balanced-to-ground AC circuit.
16. The ignition system of Claim 15, wherein said ignition plug further includes means adjacent said central electrode aid said plug electrode for generating a toroidal vortex of said plasma.
17. The ignition system of Claim 16, wherein said ignition plug further includes means for focusing said toroidal vortex at a predetermined point, and means for storing a predetermined substance in the vicinity of said predetermined point for creating multi-point ignition sources within said toroidal vortex.
18. The ignition system of Claim 15, wherein said plug electrode comprises a plurality of generally triangular points arranged circularly around said metallic threaded jacket.
19. The ignition system of Claim 13, wherein said ignition plug further comprises a pair of D-shaped central electrodes having a gap therebetween and connected to opposite terminals of said current transformer, an insulator surrounding said central electrodes, and a threaded jacket surrounding said insulator, such that said ignition plug and said high-current pulse generator form a fully balanced-to-ground AC circuit.
20. The ignition system of Claim 19, wherein said ignition plug further includes an organic catalyst disposed in said jacket adjacent said pair of D-shaped central electrodes.
21. The ignition system of Claim 20, wherein said organic catalyst comprises a combination of carbon, hydrogen and oxygen and does not contain traces or metallic residues or salts of platinum, palladium, silver, gold, copper, rubidium, lead, arsenic, cobalt, mercury, cadmium or cesium.
22. The ignition system of Claim 1, further comprising a plurality of additional ignition plugs connected to said high-voltage pulse generator and said high-current pulse generator via a distribution system, each of said additional ignition plugs being connected to said distribution system via a co-axial cable.
23. The ignition system of Claim 10, wherein said high-voltage pulse generator means further comprises a full-bridge rectifier connected to said secondary circuit of said transformer for negative rectifying said high-voltage alternating current.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919124824A GB9124824D0 (en) | 1991-11-22 | 1991-11-22 | Plasma-arc ignition system |
| GB9124824.5 | 1991-11-22 | ||
| PCT/CA1992/000510 WO1993010348A1 (en) | 1991-11-22 | 1992-11-23 | Plasma-arc ignition system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2124070A1 CA2124070A1 (en) | 1993-05-27 |
| CA2124070C true CA2124070C (en) | 2001-10-30 |
Family
ID=10705052
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002124070A Expired - Lifetime CA2124070C (en) | 1991-11-22 | 1992-11-23 | Plasma-arc ignition system |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2124070C (en) |
| GB (1) | GB9124824D0 (en) |
| WO (1) | WO1993010348A1 (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5555862A (en) * | 1994-07-19 | 1996-09-17 | Cummins Engine Company, Inc. | Spark plug including magnetic field producing means for generating a variable length arc |
| US5619959A (en) * | 1994-07-19 | 1997-04-15 | Cummins Engine Company, Inc. | Spark plug including magnetic field producing means for generating a variable length arc |
| US5704321A (en) * | 1996-05-29 | 1998-01-06 | The Trustees Of Princeton University | Traveling spark ignition system |
| WO2000077391A1 (en) | 1999-06-16 | 2000-12-21 | Knite, Inc. | Add on unit to conventional ignition systems to provide a follow-on current through a spark plug |
| MXPA02002941A (en) | 1999-09-15 | 2003-07-14 | Knite Inc | Electronic circuits for plasma generating devices. |
| ATE321206T1 (en) | 1999-09-15 | 2006-04-15 | Knite Inc | LONG LIFE, FORWARD-PROVING SPARK PLUG AND ASSOCIATED IGNITION CIRCUIT |
| DE10061672A1 (en) * | 2000-12-12 | 2002-06-13 | Volkswagen Ag | Spark ignition circuit for motor vehicle internal combustion engine involves limiting power to spark electrode dependent on cylinder conditions |
| DE10061674A1 (en) * | 2000-12-12 | 2002-06-13 | Volkswagen Ag | Spark ignition power feed for motor vehicle engine cylinder, has spark electrode extending into combustion chamber and having high frequency transformer connected directly to it |
| CN101218722B (en) | 2005-04-19 | 2011-11-30 | 奈特公司 | Method and apparatus for operating traveling spark igniter at high pressure |
| RU2333381C2 (en) * | 2005-11-03 | 2008-09-10 | Нек Лаб Холдинг Инк. | Method of initation ignition, intensifying combustion or reforming of fuel-air and fuel-oxygen mixes |
| FR2913297B1 (en) * | 2007-03-01 | 2014-06-20 | Renault Sas | OPTIMIZING THE GENERATION OF A RADIO FREQUENCY IGNITION SPARK |
| US20120210968A1 (en) * | 2010-12-14 | 2012-08-23 | John Antony Burrows | Corona igniter with improved corona control |
| WO2013016592A1 (en) | 2011-07-26 | 2013-01-31 | Knite, Inc. | Traveling spark igniter |
| US20150053178A1 (en) * | 2012-03-29 | 2015-02-26 | Wayne State University | Combustion modification and emissions reduction utilizing an electrically insulated engine member in internal combustion engines |
| US9617965B2 (en) * | 2013-12-16 | 2017-04-11 | Transient Plasma Systems, Inc. | Repetitive ignition system for enhanced combustion |
| JP7058084B2 (en) * | 2017-06-14 | 2022-04-21 | 株式会社Soken | Ignition system |
| CN114704416B (en) * | 2022-04-12 | 2023-04-28 | 山东大学 | Multi-channel discharge large-area distributed ignition system and method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5732069A (en) * | 1980-07-31 | 1982-02-20 | Nissan Motor Co Ltd | Igniter for internal combustion engine |
| US4364342A (en) * | 1980-10-01 | 1982-12-21 | Ford Motor Company | Ignition system employing plasma spray |
| US4996967A (en) * | 1989-11-21 | 1991-03-05 | Cummins Engine Company, Inc. | Apparatus and method for generating a highly conductive channel for the flow of plasma current |
-
1991
- 1991-11-22 GB GB919124824A patent/GB9124824D0/en active Pending
-
1992
- 1992-11-23 CA CA002124070A patent/CA2124070C/en not_active Expired - Lifetime
- 1992-11-23 WO PCT/CA1992/000510 patent/WO1993010348A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| CA2124070A1 (en) | 1993-05-27 |
| WO1993010348A1 (en) | 1993-05-27 |
| GB9124824D0 (en) | 1992-01-15 |
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