EP0810368A2 - Vorrichtung zur Erkennung von Fehlzündungen für eine Brennkraftmaschine - Google Patents

Vorrichtung zur Erkennung von Fehlzündungen für eine Brennkraftmaschine Download PDF

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Publication number
EP0810368A2
EP0810368A2 EP97108519A EP97108519A EP0810368A2 EP 0810368 A2 EP0810368 A2 EP 0810368A2 EP 97108519 A EP97108519 A EP 97108519A EP 97108519 A EP97108519 A EP 97108519A EP 0810368 A2 EP0810368 A2 EP 0810368A2
Authority
EP
European Patent Office
Prior art keywords
period
current
detecting
ignition plug
mixture
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Withdrawn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
EP97108519A
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English (en)
French (fr)
Other versions
EP0810368A3 (de
Inventor
Koichi Nakata
Kazuhisa Mogi
Youichi Kurebayashi
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.)
Denso Corp
Toyota Motor Corp
Original Assignee
Denso Corp
Toyota Motor Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Denso Corp, Toyota Motor Corp filed Critical Denso Corp
Publication of EP0810368A2 publication Critical patent/EP0810368A2/de
Publication of EP0810368A3 publication Critical patent/EP0810368A3/de
Withdrawn legal-status Critical Current

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    • 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
    • F02P17/00—Testing of ignition installations, e.g. in combination with adjusting; Testing of ignition timing in compression-ignition engines
    • F02P17/12—Testing characteristics of the spark, ignition voltage or current

Definitions

  • the present invention relates to an apparatus for detecting misfiring of an internal combustion engine. More particularly, this invention relates an apparatus for detecting misfiring of an internal combustion engines capable of detecting misfiring reliably when an ignition plug fouls.
  • An apparatus for detecting misfiring of an internal combustion engine based on a phenomena that a current flows via ions generated in the cylinder when mixture in a cylinder burns normally has already been known.
  • Figures. 2(A) to 2(D) are diagrams explaining the principles of misfire detection by a known misfire detecting system.
  • Figure. 2(A) shows a waveform generated when the ignition plug does not foul and a mixture is normally ignited.
  • Figure. 2(B) shows a waveform generated when the ignition plug does not foul but a misfire is caused.
  • Figure. 2(C) shows a waveform generated when the ignition plug fouls and a misfire is caused.
  • Figure. 2(D) shows a waveform generated when the ignition plug fouls and the mixture is normally ignited.
  • an upper graph shows the waveform of an ignition command signal
  • a lower graph shows the waveform of a voltage supplied to a microcomputer.
  • a pulse develops in the secondary winding of an ignition coil at a time t 1 , that is, at the leading edge of an ignition command signal, and the ignition plug discharges between a time t 2 , that is, at the trailing edge of the ignition command signal, and a time t 3 .
  • Noise deriving from residual energy develops in the secondary winding of the ignition coil between a time t 3 and a time t 4 .
  • an ion current occurs because the mixture has normally burnt.
  • the ion current has a peak value at a time t 5 , and, the ion current gradually decreases.
  • an apparatus for detecting misfirings of an internal combustion engine comprising: a voltage applying means for applying a voltage between an ignition plug and the ground; a current detecting means for detecting a current due to the voltage applied by said voltage applying means; a fouling degree detecting means for detecting a fouling degree of the ignition plug in accordance with the current detected by said current detecting means for a period except a period where ions are generated in mixture when the mixture is normally burnt by discharging of the ignition plug; and a misfire determining means for determining misfiring if the current detected by said current detecting means is smaller than a threshold current determined in accordance with the fouling degree detected said fouling degree detecting means for a period where ions are generated in a mixture when the mixture is normally burnt by a discharge at the ignition plug.
  • a leakage resistance due to fouling is detected for a period where an ion current never flows, and a threshold for detecting a misfiring is varied in accordance with the leakage resistance.
  • an apparatus for detecting misfirings in an internal combustion engine wherein, said fouling degree detecting means comprises: an on-period current detecting means for detecting a current with said current detection means for a period where a current is applied to the primary coil of an ignition coil contained in a period except a period where ions are generated in mixture when the mixture is normally burnt by discharging of the ignition plug; an off-period current detecting means for detecting a current with said current detecting means for a period except a period where a current is applied to the primary winding of an ignition coil contained in a period except a period where ions are generated in mixture when the mixture is normally burnt by discharging of the ignition plug; and a changing means for changing from said on-period current detecting means to said off-period current detecting means, or vice versa in accordance with fouling degree of the ignition plug.
  • a period for detecting the leakage resistance is changed in accordance with the fouling degree of the ignition plug.
  • an ion current detecting apparatus based on a phenomena that a leakage current due to fouling flow for a period that an ion current never flows has been proposed. This controls the timing of detecting a current. If a current is detected in the period when an ion current never flows, that is, the period between the time t 1 and time t 2 , the apparatus inhibits misfire detection to prevent misjudgment (Japanese Unexamined Patent Publication No. 4-259671).
  • an object of the present invention is to provide an apparatus for detecting misfirings in an internal combustion engines capable of detecting misfiring reliably although an ignition plug fouls.
  • the ignition plug does not foul it is possible to detect whether or not a misfire occurs by determining whether or not the ion current higher than a predetermined fixed threshold ⁇ is detected between the time t 4 and a time t 6 later than the time t 5 .
  • an apparatus for detecting misfirings of an internal combustion engine comprising: a voltage applying means for applying a voltage between an ignition plug and the ground; a current detecting means for detecting a current due to the voltage applied by said voltage applying means; a fouling degree detecting means for detecting a fouling degree of the ignition plug in accordance with the current detected by said current detecting means for a period except a period where ions are generated in mixture when the mixture is normally burnt by discharging of the ignition plug; and a misfire determining means for determining misfirings if the current detected by said current detecting means is smaller than a threshold current determined in accordance with the fouling degree detected said fouling degree detecting means for a period where ions are generated in mixture when the mixture is normally burnt by a discharge at the ignition plug.
  • a leakage resistance due to fouling is detected in a period when an ion current never flows, and a threshold for detecting a misfiring is varied in accordance with the leakage resistance.
  • an apparatus for detecting misfirings in an internal combustion engine, wherein said fouling degree detecting means comprises: an on-period current detecting means for detecting a current with said current detection means for a period where a current is applied to the primary coil of an ignition coil contained in a period except a period where ions are generated in mixture when the mixture is normally burnt by a discharge at the ignition plug; an off-period current detecting means for detecting a current with said current detecting means for a period except a period where a current is applied to the primary winding of an ignition coil contained in a period except a period where ions are generated in mixture when the mixture is normally burnt by a discharge at the ignition plug; and a changing means for changing from said on-period current detecting means to said off-period current detecting means, or vice versa in accordance with the fouling degree of the ignition plug.
  • a period for detecting the leakage resistance is changed in accordance with the fouling degree of the ignition plug.
  • FIG. 1 is a circuit diagram of an apparatus for detecting misfirings according to the present invention.
  • An ignition command is given to an ignition coil 11 by an ignition control system 10.
  • One terminal of a secondary winding of the ignition coil 11 is connected to an ignition plug 12, and the other terminal thereof is grounded through first and second zener diodes 13 and 14 connected in series with each other in opposite directions.
  • a capacitor 15 is connected in parallel with the first zener diode 13, and a detecting resistor 16 is connected in parallel with the second zener diode 14.
  • a voltage developed across the detecting resistor 16 is supplied to a microcomputer 18 through an inverting amplifier 17.
  • the ignition plug 12 when a pulsed ignition command is supplied from the ignition control system 10 to the primary winding of the ignition coil 11, the ignition plug 12 produces a discharge due to a high voltage induced in the secondary winding of the ignition coil 11 at the leading edge of the ignition command. At the same time, a voltage controlled by the first zener diode 13 is applied to the capacitor 15.
  • an ion current detection circuit is driven using the capacitor 15 as a power supply.
  • Fig. 3 shows an equivalent circuit of an ionization current detection circuit when ignition plug 12 fouls.
  • a leakage resistor 21 is connected in parallel with the ignition plug 12.
  • FIG. 4 shows the waveform of the monitoring voltage.
  • the abscissa indicates time, while the ordinate indicates the monitoring voltage.
  • the resistance R 1 of the detection resistor 16, the capacitance C of the capacitor 15, and the initial value V 0 of the voltage across the capacitor 15 shall be provided as known values.
  • the resistance R 2 of the leakage resistor 21 can be calculated by measuring the monitoring voltage V M (t M ) according to the above expression. The fouling degree of the ignition plug 12 can therefore be assessed quantitatively.
  • FIG. 5 is a flowchart of a misfire detecting routine executed by the microcomputer 18 on the basis of the aforesaid principles. The processing is started at the trailing edge of an ignition command signal outputted from the ignition control system 10 (at time t 2 ).
  • a standby state is held until a period T 25 has elapsed after the start of this routine period.
  • the period T 25 is set as a period between a time when the ignition command signal vanishes and a time when an ion current reaches its peak after noise due to discharging and/or residual energy is suppressed.
  • step 52 a voltage V(t 5 ) developing across the detecting resistor 16 is read.
  • step 53 a standby state is held until a period T 2M has elapsed after the start of routine.
  • the time T 2M is set as a time longer than the time T 25 .
  • step 53 When the period T 2M has elapsed, the determination at step 53 becomes affirmative.
  • step 54 a voltage V(t M ) developing across the detecting resistor 16 is read at time t M . This routine is terminated after a misfire detecting subroutine is executed at step 55.
  • Fig. 6 is a detailed flowchart of a misfire detecting subroutine executed at step 55.
  • step 553 it is determined whether or not the voltage V(t 5 ) developed across the detecting resistor 16, which is read at step 53, is bigger than a sum of the leakage voltage V L and a predetermined threshold value ⁇ .
  • the threshold value ⁇ is set at a suitable value to detect a peak value of an ion current when the ignition plug does not foul.
  • step 553 When the determination at step 553 is affirmative, it is determined that mixture has burnt normally at step 554. If the determination at step 553 is negative, it is determined that a misfire occurred at step 555. This subroutine is then terminated.
  • a vehicle is actually designed so that if misfiring is frequently detected for a given period, that is, if a misfire rate exceeds a given value, an alarm is activated because a catalyst placed in an exhaust pipe in an internal combustion engine may be damaged.
  • the degree of fouling of the ignition plug 12 is determined on the basis of the voltage V(t M ) developing across the detecting resistor 16 at the monitoring time t M .
  • V(t M ) developing across the detecting resistor 16 at the monitoring time t M .
  • the precision for determining a fouling degree that is, the precision for calculating a leakage resistance, deteriorates accordingly. Eventually, it becomes unavoidable that misfiring is incorrectly detected.
  • a leakage current flows when the ignition control system 10 is outputting an ignition command signal, that is, for period between the time t 1 and time t 2 .
  • the leakage current is usually larger than a current proportional to the voltage V(t M ) developed across the detecting resistor 16 at the monitoring time t M . This fact can be utilized for solving the above-mentioned problem.
  • Figure. 7 is a graph indicating the relationship between a voltage V 16 developed across the detecting resistor 16 while the ignition control system 10 is outputting an ignition command signal when the ignition plug 12 has been fouling and the insulation resistance of the ignition plug 12.
  • the abscissa indicates the insulation resistance on the logarithmic scale, and the ordinate indicates the voltage.
  • black dots indicate measured values, and a solid line is a curve to which the measured values are fitted.
  • the leakage resistance R 2 of the ignition plug 12 can be expressed as a function of the voltage V 16 .
  • R 2 R 2 (V 16 )
  • the precision for determining the fouling degree is retained by changing the timing of reading a voltage.
  • Fig. 8 is a flowchart of a second misfire detecting routine executed by the microcomputer 18. Execution is started at the leading edge of an ignition command signal outputted from the ignition control system 10.
  • a standby state is held until a period T 1P has elapsed after the start of execution of the second misfire detecting routine.
  • the time T 1P is set as a period where the ignition control system 10 is outputting the ignition command signal.
  • step 81 When the time T 1P has elapsed, the determination at step 81 becomes affirmative. Control proceeds to step 82 where a voltage V(t P ) developed across the detection resistor 16 is read.
  • a standby state is held until a predetermined period T 15 elapses.
  • the period T 15 is set as a period between a time when the ignition command signal vanishes and a time when an ion current reaches its peak after noise due to discharging and/or residual energy is suppressed.
  • step 83 When the period T 15 has elapsed, the determination at step 83 becomes affirmative. Control proceeds to step 84 when a voltage V(t 5 ) developed across the detecting resistor 16 is then read.
  • a standby state is held until a predetermined period T 1M has elapsed.
  • the period T 1M is set as a time longer than the period T 15 .
  • step 85 When the period T 1M has elapsed, the determination at step 85 becomes affirmative.
  • step 86 a voltage V(t M ) developed across the detecting resistor 16 is read at time instant t M .
  • step 87 the second misfire detecting subroutine is executed and then this routine is terminated.
  • Fig. 9 is a detailed flowchart of the second misfire detecting subroutine executed at step 87.
  • step 871 it is determined whether or not a voltage V(t P ) at time t P is equal to or larger than a predetermined upper limit voltage V U .
  • the upper limit voltage V U is defined as a voltage slightly lower than the maximum voltage readable by the microcomputer 18.
  • step 871 determines whether or not a voltage V(t M ) at time t M is equal to or lower than a predetermined lower limit voltage V L .
  • the lower limit voltage V L is defined as a voltage slightly higher than a minimum voltage readable by the microcomputer 18.
  • step 871 or 872 If the determination at step 871 or 872 is affirmative, the resistance R 2 of the leakage resistor 21 is calculated according to the expression (3) at step 873. Control proceeds to step 875.
  • step 872 determines whether the leakage resistance R 2 of 21 in accordance with the voltage V(t P ). Control proceeds to step 875.
  • the leakage resistance R 2 obtained at step 873 or 874 is assigned to the expression (2).
  • the leakage voltage V L at time t 5 is calculated.
  • step 876 it is determined whether or not the voltage V(t 5 ) at time t 5 is larger than a sum of the leakage voltage V L and a predetermined threshold value ⁇ .
  • the threshold value ⁇ is set as a value enabled to detect a peak value of an ion current when the ignition plug does not foul.
  • step 876 If the determination at step 876 is affirmative, it is determined that a mixture has burnt normally at step 877. If the determination at step 876 is negative, it is determined a misfire occurred at step 878. The processing is then terminated.
  • a drop in insulation resistance can be calculated accurately.
  • the precision for determining misfiring can be improved.
  • An object of the present invention is to provide an apparatus for detecting misfiring of internal combustion engines capable of detecting the misfiring reliably even though an ignition plug fouls.
  • a voltage developed across a detection resistor 16 is fetched into a microcomputer 18 during a period other than a period where ions are generated.
  • an insulation resistance due to fouling of the ignition plug 12 is measured. If the voltage developed across the detecting resistor 16 which is fetched into the microcomputer 18 during the period where ions are generated is equal to or larger than a threshold value, it is determined that mixture has burnt normally. If the voltage is smaller than the threshold value, it is determined that a misfire has occurred. The threshold value is corrected according to the decrease of insulation resistance. Consequently, though the ignition plug fouls, misfiring can be detected reliably.
EP97108519A 1996-05-28 1997-05-27 Vorrichtung zur Erkennung von Fehlzündungen für eine Brennkraftmaschine Withdrawn EP0810368A3 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP13363896A JPH09317619A (ja) 1996-05-28 1996-05-28 内燃機関の失火検出装置
JP13363896 1996-05-28
JP133638/96 1996-05-28

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EP0810368A2 true EP0810368A2 (de) 1997-12-03
EP0810368A3 EP0810368A3 (de) 1999-08-18

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EP97108519A Withdrawn EP0810368A3 (de) 1996-05-28 1997-05-27 Vorrichtung zur Erkennung von Fehlzündungen für eine Brennkraftmaschine

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0982496A1 (de) * 1998-08-22 2000-03-01 DaimlerChrysler AG Verfahren zur Auswertung eines Ionenstromsignales einer selbstzündenden Brennkraftmaschine
EP1081375A2 (de) * 1999-09-02 2001-03-07 Ngk Spark Plug Co., Ltd. Methode zum Ermitteln der Beschmutzung einer Zündkerze und Zündsystems, zur Durchführung der Methode
WO2001034972A1 (de) * 1999-11-08 2001-05-17 Robert Bosch Gmbh Verfahren und vorrichtung zur messfenster-positionierung für die ionenstrommessung
US6371078B1 (en) 1999-08-23 2002-04-16 Ngk Spark Plug Co., Ltd. Method of controlling a direct fuel injection engine and storage medium storing the same
US7348782B2 (en) 2005-04-22 2008-03-25 Denso Corporation Ignition device and spark condition detection method
DE10229848B4 (de) * 2001-07-03 2010-05-12 Honda Giken Kogyo K.K. Feuerungszustandsermittlungssystem für Verbrennungsmotoren

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100346428B1 (ko) * 2000-07-18 2002-08-01 기아자동차주식회사 자동차용 가솔린 엔진의 점화 플러그 실화 진단 방법
JP5685066B2 (ja) * 2010-11-30 2015-03-18 ダイヤモンド電機株式会社 内燃機関用のイオン電流検出処理装置
JP5904768B2 (ja) * 2011-11-25 2016-04-20 ダイハツ工業株式会社 内燃機関の燃焼状態判定装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4349782A (en) * 1980-11-21 1982-09-14 Doss James D Shielded differentiator for automotive ignition applications
JPS61169669A (ja) * 1985-01-22 1986-07-31 Nissan Motor Co Ltd 点火栓の点火不良検出装置
JPH04259671A (ja) * 1991-02-13 1992-09-16 Mitsubishi Electric Corp イオン電流検出装置
US5337716A (en) * 1992-02-04 1994-08-16 Mitsubishi Denki Kabushiki Kaisha Control apparatus for internal combustion engine
JPH07286552A (ja) * 1994-04-19 1995-10-31 Hitachi Ltd 内燃機関の失火検出装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4349782A (en) * 1980-11-21 1982-09-14 Doss James D Shielded differentiator for automotive ignition applications
JPS61169669A (ja) * 1985-01-22 1986-07-31 Nissan Motor Co Ltd 点火栓の点火不良検出装置
JPH04259671A (ja) * 1991-02-13 1992-09-16 Mitsubishi Electric Corp イオン電流検出装置
US5337716A (en) * 1992-02-04 1994-08-16 Mitsubishi Denki Kabushiki Kaisha Control apparatus for internal combustion engine
JPH07286552A (ja) * 1994-04-19 1995-10-31 Hitachi Ltd 内燃機関の失火検出装置

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 010, no. 378 (M-546), 17 December 1986 & JP 61 169669 A (NISSAN MOTOR CO LTD), 31 July 1986 *
PATENT ABSTRACTS OF JAPAN vol. 017, no. 041 (M-1359), 26 January 1993 & JP 04 259671 A (MITSUBISHI ELECTRIC CORP), 16 September 1992 *
PATENT ABSTRACTS OF JAPAN vol. 096, no. 002, 29 February 1996 & JP 07 286552 A (HITACHI LTD), 31 October 1995 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0982496A1 (de) * 1998-08-22 2000-03-01 DaimlerChrysler AG Verfahren zur Auswertung eines Ionenstromsignales einer selbstzündenden Brennkraftmaschine
US6279538B1 (en) 1998-08-22 2001-08-28 Daimlerchrysler Ag Method for evaluating an ion current signal of a self-igniting internal combustion engine
US6371078B1 (en) 1999-08-23 2002-04-16 Ngk Spark Plug Co., Ltd. Method of controlling a direct fuel injection engine and storage medium storing the same
EP1081375A2 (de) * 1999-09-02 2001-03-07 Ngk Spark Plug Co., Ltd. Methode zum Ermitteln der Beschmutzung einer Zündkerze und Zündsystems, zur Durchführung der Methode
US6512375B1 (en) 1999-09-02 2003-01-28 Ngk Spark Plug.Co., Ltd. Method of detecting spark plug fouling and ignition system having means for carrying out the same
EP1081375A3 (de) * 1999-09-02 2003-04-23 Ngk Spark Plug Co., Ltd. Methode zum Ermitteln der Beschmutzung einer Zündkerze und Zündsystems, zur Durchführung der Methode
WO2001034972A1 (de) * 1999-11-08 2001-05-17 Robert Bosch Gmbh Verfahren und vorrichtung zur messfenster-positionierung für die ionenstrommessung
US6813933B1 (en) 1999-11-08 2004-11-09 Robert Bosch Gmbh Method and device for positioning measuring displays for measuring ion currents
DE10229848B4 (de) * 2001-07-03 2010-05-12 Honda Giken Kogyo K.K. Feuerungszustandsermittlungssystem für Verbrennungsmotoren
US7348782B2 (en) 2005-04-22 2008-03-25 Denso Corporation Ignition device and spark condition detection method

Also Published As

Publication number Publication date
EP0810368A3 (de) 1999-08-18
JPH09317619A (ja) 1997-12-09

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