EP0000652A1 - Dispositif d'allumage capacitif à décharge oscillatoire pour moteur à combustion interne - Google Patents

Dispositif d'allumage capacitif à décharge oscillatoire pour moteur à combustion interne Download PDF

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Publication number
EP0000652A1
EP0000652A1 EP78300178A EP78300178A EP0000652A1 EP 0000652 A1 EP0000652 A1 EP 0000652A1 EP 78300178 A EP78300178 A EP 78300178A EP 78300178 A EP78300178 A EP 78300178A EP 0000652 A1 EP0000652 A1 EP 0000652A1
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EP
European Patent Office
Prior art keywords
capacitor
thyristor
current
coil
firing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP78300178A
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German (de)
English (en)
Inventor
Basil Earle Wainwright
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0000652A1 publication Critical patent/EP0000652A1/fr
Withdrawn legal-status Critical Current

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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
    • F02P3/00—Other installations
    • F02P3/06—Other installations having capacitive energy storage
    • F02P3/08—Layout of circuits
    • F02P3/09—Layout of circuits for control of the charging current in the capacitor
    • F02P3/093—Closing the discharge circuit of the storage capacitor with semiconductor devices

Definitions

  • This inrsntion relates to improvements in and relating to apparatus for producing spark ignition of an internal soubmation engine.
  • the electrical sparks fed to the spark pluse of an internal combustion engine are comventionally produced by means of an ignition eoil having its high voltage secondary wimding connected to the engine's spark plugs through a distributor, and having its lew veltage primary winding sonnected to a lew voltage seurse, typisally a is volt battery or an alternator drivem by the engine.
  • An engine driven switohing devioe typieally a meahamieal contact breaker, produces iinterruptions im the surrent flowing in the eoil's primmary winding and consequently high voltage pulses are produced in the seil's secondary winding, wwhich are applied te the spark plugs.
  • an apparatus for producing spark ignition of an internal combustion engine comprising an ignition coil having primary and secondary windings, a capacitor connected in an electrical circuit with the primary winding, voltage generating means for receiving a supply voltage and charging said capacitor to a voltage greater than said supply voltage, switching means arranged to cause the capacitor to discharge a current through the primary winding of the coil, the apparatus being so arranged that the discharge current of the capacitor oscillates in the said circuit, and control circuit means adapted to operate the switching means to produce said discharge current in such a manner that more than one oscillation of the current passes through the primary winding whereby to induce in the secondary winding more than one cycle of an oscillatory voltage for producing spark ignition of the engine.
  • the voltage generating means comprises a d.c. to d.c. converter for producing from low voltage input supply of typically 12 volts of a battery or alternator, a high charging voltage, of typically 200 volts, for the capacitor.
  • a d.c. to d.c. converter for producing from low voltage input supply of typically 12 volts of a battery or alternator, a high charging voltage, of typically 200 volts, for the capacitor.
  • the switching meane comprieee a thyristor and the control circuit means is responsive to operation of a contact breaker which may be of the conventional mechanical kind or of the more recently developed photocell or magnetically operated types.
  • the control circuit is arranged to trigger the thyristor into conduction each time a apark is required, and to hold the thyristor in a conductive stats for more than one oscillation of the discharge current of the capacitor, thereby producing in the secandary winding an oscillatory voltage of more than one cycle.
  • the oscillatory voltage can be arranged to continue for substantially the whole operative firing period of each cylinder of the engine thereby producing improved combustion of the fuel/air mixture as coirpared with the shorter duration sparks produced by the prior proposal.
  • control circuit means is arranged to reduce the duration of conduction of the thyristor as the speed of the engine increases, so as to prevent the duration of sparking from extending from the firing period of one cylinder into the firing period of another cylinder.
  • a particularly preferred embodiment of the invention includes an ignition coil having primary and reeoadarprindinas, a capacitor connected in electrical circuit with the primary winding, voltage generating means for receiving a supply voltage and adapted to charge the capacitor to a voltage greater than said supply voltase, a thyristor connected in said circuit and arranged so that when fired to a conductive state the capacitor diseharges in an oscillatory manner through the thyriator and the secondary winding, and control circuit means adapted to apply to the gate of the thyristor a firing sisnal to render the thyristor conductive for a period sufficient for a plurality of oscillations of the capacitor diecharge current to pass through said primary winding, and wsans for inhibiting said voltage generating emans from charging the capacitor during the discharge thereof produced by firing of the thyristor.
  • the particularly preferred form of the apparatus of the invention includes means for inhibiting operation of the voltage senerating means during discharge of the capacitor, which has the advantage of permitting substantially the entire stered energy established in the capacitor to be dissipated through the primary winding to generate in the iscondary winding a voltage for producing spark ignition.
  • the firing pulse applied to the thyristor would have to be terminated before the peak oscillatory capacitor discharge current besame less than the current snpplied to the capacitor by the voltage generating means during the capacitor dissharge, otherwise the thyristor would be held in a permanently conducting state thereby preventing the capacitor from being recharged for further operations of the apparatus.
  • the inhibiting means permits the thyristor to be maintained conductive for a longer period than would otherwise be possible.
  • the apparatus comprises a conventional ignition coil 1 having a primary winding 1a, and a second winding 1b connected through a conventional distributor 2 to spark pluas 3 of the engine.
  • the prisary winding 1a is connected in series with a capacitor C1 and a tellching thyristor SCR, which together define a tuned oscillatory circuit when the thyristor SCR is conductive.
  • the capacitor C1 ia charged to a voltage of typically 200 volts by means of a d.c. to d.c. converter 4 shown in dotted outline.
  • the converter 4 is fed with a d.c. voltage of typically 12 volts from an input terstinal 3. connected in use to the engine's battery and alternator system (not shown).
  • the thyristor SCR is triggered by means of a control circuit 6, responsive to a contact breaker (not shown) either of the conventional mechanical or the photocell type.
  • d.c. to d.c. conyerter.4 comprises a step up transformer 7 having primary coils 8a, 8b and a secondary coil 9.
  • the primary coils 8 are connected in a push-pull tranristor oscillator arrangement which includes two sets of transistors TR1, TR2; TR3, TR4 connected as complementary Darlington pairs, each pair supplying current to a respective one of the coils 8a, 8b.
  • a pickup coil 8 0 is connected to supply positive feedback to the transistors, and a diode arrangement D1 to D4 is provided to bias the transistor pairs into conduction, the diodes being arranged so that when one of the Darlingtou pairs is switched on, the other is biased off and vice versa.
  • bias current is applied to the tranaistor pairs through a bias current path 4A which includes a voltage dropping resistor R.
  • current is fed through the coils 8a, 8b sequentially and in opposite directione at a frequency which is a function of the inductance of chokes L1, L2, the values of a resistor R1 and a capacitor C2, and the inductance preserved by the primary coils 8a, 8b, thereby inducing a stepped up alternating voltage in the secondary coil 9.
  • the output of the coil 9 is applied to a bridge rectifier 10 and thence to a smoothing arrangement comprieing resisters R2, R3 and a capacitor C3.
  • the d.c. to d.c. converter 4 applies a ateppsd up d.c. voltage of typically 200 volts to the capacitor C1.
  • the control circuit 6 for the switching thyristor SCR will now be described in more detail.
  • the control circuit has a 7.5 volt stabilised voltage rail 11 established from the 12 volt supply terminal by a resistor R4 and a Zener diode ZD.
  • the contact breaker of the engine (not shown) is connected between a terminal 12 connected to the supply rail 11, and a terminal 13 which is connected to the bass of a transistor TR5 connected as an emitter follower.
  • the tranaistor TR5 is provided with a biasing resistor chain including resistors R5, R6, R7.
  • a smoothing network including a capacitor °C4 and a diode D5 is provided to remove unwanted switching transients produced by the contact breaksr.
  • the output of the transistor TR5 thus comprises a chain of pulses the frequency of which is a function of the engine speed, the phase of the pulses being indicative of the desired timing of the sparks to be produced by the spark plugs.
  • the output of the transistor TR5 is applied to two signal paths.
  • the first path includes a capacitor C5.
  • the electrical charge of each pulsa is dumped in turn into the capacitor C5 which then discharges betwesn, pulses through series resistors R8, R9, resistor R10 and the collector emitter path of a transistor TR6.
  • a drive transistor TR? has its baas connected to the junction between the series resistors R8, R9, and is arranged, when switched on, to apply a switching drive signal to the gate of the thyristor SCR.
  • Thetramistor TR7 will switch off when the capacitor C5 has discharged to a voltage sufficient to allow an appropriate bias voltage to be developed across the resistor R9, and thus the thyristor SCR is switched on in response to each pulse in the pulse train from the contact breaker and for a tise depondent upon the discharge time of the capacitor C5. This discharge time is arranged to decrease with increased engine speed.
  • the pulse signal train from the transistor TR5 is applied to a second signal path including a differentiator comprising a capacitor C6 and a resistor R11, a diode pump circuit including a diode D6, a resistor R12 and a spacitor C?, and biasing resistors R13, R14.
  • a differentiator comprising a capacitor C6 and a resistor R11
  • a diode pump circuit including a diode D6, a resistor R12 and a spacitor C?
  • biasing resistors R13, R14 biasing resistors
  • the time for which the thyristor SCR is switched on is decreased with increased engine speed so as to prevent the high voltage signal produced in the secondary winding 1b of the coil for a particular cylinder firing, extending in time into the time appropriate for firing of another cylinder.
  • the capacitor C1 and the winding la of the ignition coil define a tuned circuit, so that when the thyristor SCR is fired, the capacitor C1 discharges current in an oscillatory manner.
  • the control circuit is arranged to hold the thyristor SCR conductive for a period which corresponds to substantially all of the firing period of a cylinder, and during that period, the oscillatory current flowing in priwary winding 1a and the capacitor C1 induces in the secondary winding a plurality of cycles of high voltage signal having the frequency of the oscillation of the current flowing through the primary winding.
  • this high voltage signal (typically of the order of 3,500 volts) produces an improved combustion in the cylinders because the spark produced by the spark plug extends for substantially the whole period that combustion can take place thereby maximising the likelihood of complete combustion of the fuel/air mixture applied to the engine.
  • the apparatus includes inhibiting means to be described hereinafter fpr inhibiting operation of the d.c. to d.e. converter 4 ⁇ during periods when the thyristor SCR is triggered into a conductive state, so as to stop a charging current being applied to the capacitor C1 whilst it is being dischargod.
  • inhibiting means to be described hereinafter fpr inhibiting operation of the d.c. to d.e. converter 4 ⁇ during periods when the thyristor SCR is triggered into a conductive state, so as to stop a charging current being applied to the capacitor C1 whilst it is being dischargod.
  • the firing pulse applied to the gate of the thyristor SCR terminates to terminate the conductive state of the thyristor, it is essential by virtue of the well known operating characteristics of the thyristor, that the curreat flowing in the thyrstor be decreased below a predetermined level in order for the thyristor to return to a non-conductive state.
  • a limit would be set on the period for which the thyristor could be triggered conductive by a pulse from the control circuit 4, because after the thyristor has been fired and at a time when the capacitor Cl has become partially discharged, the sum of the charging current from the converter 4 and the decaying oscillatory discharge current would reach a level which would no longer pass below the threshold value required to switch off the thyristor SCR.
  • the inhibiting means is provided to effectively switch off the charging current supplied to the capacitor Cl by the converter 4 whilst the capacitor is being discharged, which permits the firing pulses applied by the circuit 4 to the thyristor SCR to be msade longer than would otherwise be possible and still ensure that the thyristor will reliably turn off at the end of the firing pulse.
  • the inhibiting means thus permits the thyristor SCR to be turned on for a period which allows substantially all the oseillatory current produced by discharge of the capacitor C1 to be used to generate spark ignition.
  • the inhibiting means of the present embodiment is an inherent feature of the particular arrangement of the converter 4 shown in Figure 1.
  • the frequency of oscillation of the transistors TR1-4 is determined in part by the inductance presented by the primary coils 8a, 8b.
  • the inductance presented by the primary coils 8a, 8b is a function of the self-inductance of the primary coils and also the mutual inductance of the priimary and secondary coils 8 and 9.
  • the ends of the secondary coil 9 are short circuited.
  • the transformer 7 is so arranged that upon short circuiting of the secondary coil 9, the mutal inductance of the coils 8, 9 is reduced substantially by allowing flux from the primary to leak out of the transformer.
  • the inductance presented to the transistor oscillator by the coils 8a, 8b is reduced substantially when the thyristor SCR is fired, which causes the frequency of oscillation of the oscillator to increase substantially.
  • the traasforaer 7 is however extremely inefficient at the higher frequency and as a result substantially no charging current is induced in the secondary coil 9 whilst the thyristor SCR is conductive.
  • the operation of the transformer 7 and the transistor oscillator when the thyristor SCR is in its conductive state can also be understood in teerms of the leakage inductance of the transformer.
  • Leakage inductance is effectively the pre- portion of flux generated by one coil that does not intersect the others, and can be considered as a smpall indue tor in series with the main winding.
  • the converter When the secondary coil 9 is short circuited, the converter-operates at a frequency and power level determined by the value, of this leakage inductance.
  • the leakage inductance is preferably increased by winding the secondary coil on a bobbin first, followed by a relatively large inter-winding separation of about 0.025", which also provides primary/secondary insulation, followed by the primary coil which is wound Bifiler' to ensure good balance. This ensures that when the secondary is short circuited, the output current is typically less than 20 m.a. As soon as the thyristor SCR returns to its non-conducting state, the short circuit is removed and the d.c. to d.c. convertar 4 operates normally, charging up the capacitor Cl for the next spark.
  • FIG 3 Another example of the apparatus is shown in Figure 3, which has a different form of inhibiting means. Most of the circuit is the same as that shown in Figure 1 and like parts are marked with like reference numerals. Only those parts of the circuit which differ from those of Figure 2 will be described hereinafter.
  • the circuit of Figure 3 includes a further voltage dropping resistor R13 connected in the d.c. bias current supply path 4A, and a bias current by-pass path 14 connected to the path 4A between the resistors R R13.
  • the path 14 is connected to the positive side of the thyristor SCR and includes a diode 07 arranged to prevent the charging current from the rectifier 10 from passing to the transistor oscillator.
  • the path 14 provides a low impedance path to earth through the thyristor SCR for the bias currept for the transistors TR1-4 of the oacillator, and thus the bias current preferentially flows to earth through the by-pass current path 14 rather than to the transistors, which results in the transistors being turned off.
  • the oscillator is turned off whilst the thyriator SCR is in Its conductive state, so as to inhibit charging of the capacitor C1 whilat it is being discharged.
  • the apparatus of the present invention makes a such more efficient use of the charge established on the charged capacitor, as compared with the prior proposal, by letting the charge dissipate during the whole of a cylinder firing period.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
EP78300178A 1977-07-21 1978-07-21 Dispositif d'allumage capacitif à décharge oscillatoire pour moteur à combustion interne Withdrawn EP0000652A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB3068677 1977-07-21
GB3068677 1977-07-21

Publications (1)

Publication Number Publication Date
EP0000652A1 true EP0000652A1 (fr) 1979-02-07

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Application Number Title Priority Date Filing Date
EP78300178A Withdrawn EP0000652A1 (fr) 1977-07-21 1978-07-21 Dispositif d'allumage capacitif à décharge oscillatoire pour moteur à combustion interne

Country Status (8)

Country Link
EP (1) EP0000652A1 (fr)
JP (1) JPS5459530A (fr)
AU (1) AU3823978A (fr)
DK (1) DK325278A (fr)
ES (1) ES471943A1 (fr)
IT (1) IT1097200B (fr)
NO (1) NO782501L (fr)
ZA (1) ZA784170B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4457285A (en) * 1981-11-24 1984-07-03 Nissan Motor Company, Ltd. Sustained arc ignition system for an internal combustion engine
US7153442B2 (en) 1996-10-18 2006-12-26 Seiko Epson Corporation Method of manufacturing an ink jet print head

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714507A (en) * 1971-03-02 1973-01-30 Delta Prod Inc Controlled variable spark capacitor discharge ignition system
US3838328A (en) * 1973-03-19 1974-09-24 W Lundy Capacitive discharge ignition system
US3842816A (en) * 1971-07-14 1974-10-22 Motorola Inc Alternating current capacitor discharge ignition system
US3857376A (en) * 1973-02-09 1974-12-31 Int Harvester Co Regulated ignition amplifier circuit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714507A (en) * 1971-03-02 1973-01-30 Delta Prod Inc Controlled variable spark capacitor discharge ignition system
US3842816A (en) * 1971-07-14 1974-10-22 Motorola Inc Alternating current capacitor discharge ignition system
US3857376A (en) * 1973-02-09 1974-12-31 Int Harvester Co Regulated ignition amplifier circuit
US3838328A (en) * 1973-03-19 1974-09-24 W Lundy Capacitive discharge ignition system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4457285A (en) * 1981-11-24 1984-07-03 Nissan Motor Company, Ltd. Sustained arc ignition system for an internal combustion engine
US7153442B2 (en) 1996-10-18 2006-12-26 Seiko Epson Corporation Method of manufacturing an ink jet print head

Also Published As

Publication number Publication date
NO782501L (no) 1979-01-23
IT7825967A0 (it) 1978-07-21
DK325278A (da) 1979-01-22
ES471943A1 (es) 1979-02-16
IT1097200B (it) 1985-08-26
ZA784170B (en) 1979-07-25
AU3823978A (en) 1980-01-24
JPS5459530A (en) 1979-05-14

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