WO1996005420A1 - Procede de commande de combustion d'un melange pauvre a quasi-reaction utilisant une sonde lambda a bande etroite pour melanges stoechiometriques - Google Patents

Procede de commande de combustion d'un melange pauvre a quasi-reaction utilisant une sonde lambda a bande etroite pour melanges stoechiometriques Download PDF

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Publication number
WO1996005420A1
WO1996005420A1 PCT/SE1995/000913 SE9500913W WO9605420A1 WO 1996005420 A1 WO1996005420 A1 WO 1996005420A1 SE 9500913 W SE9500913 W SE 9500913W WO 9605420 A1 WO9605420 A1 WO 9605420A1
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WO
WIPO (PCT)
Prior art keywords
fuel
engine
operating
amount
lambda sensor
Prior art date
Application number
PCT/SE1995/000913
Other languages
English (en)
Inventor
Hans Johansson
Original Assignee
Mecel Ab
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 Mecel Ab filed Critical Mecel Ab
Publication of WO1996005420A1 publication Critical patent/WO1996005420A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2454—Learning of the air-fuel ratio control
    • F02D41/2458—Learning of the air-fuel ratio control with an additional dither signal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
    • F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition

Definitions

  • This invention relates to a method in accordance with the preamble of patent claim 1.
  • lambda sensor In order to regulate the engine in such a way mat the lambda value is maintained at this level, most engines have a special developed sensor located in the exhaust system. This sensor is called the lambda sensor, which monitors the residual amounts of air in the exhaust gases, and hence could correct the amount of fuel supplied in a feed-back manner if the lambda value deviates from 1,0.
  • a lambda sensor having a broad-band, which produce an output signal being proportional over a ⁇ -range in the interval 1,0-1,5 is very expensive and have not been implemented to any larger extent in mass-produced engines, due to costs and insufficient reliability.
  • the invention enables an optimal adjustment to the proper lean amount of fuel for the entire speed- and load range for the engine in concern.
  • a control system using an inexpensive and mass-produced lambda sensor be implemented in special engines mainly operating at leaner air-fuel mixtures.
  • a Diesel engine being converted for natural gas fuel operation advantageously used as propulsion source for city-buses or as a power source for stationary electric generators, could for example be equipped with an inexpensive but yet reliable control system.
  • the inventive method is characterised by the characterising clause of claim 1.
  • the regulation is obtained by an intermittent, non-continuos, and at several load- and speed cases activated feed-back of a parameter representative of a by force obtained non normal combustion in the combustion chamber, in a manner hereafter designated as a quasi feed-back.
  • Figure 1 shows a flow-chart for the inventive method
  • Figure 2 shows a flow-chart for correcting the fuel amount dependent of detected ignition failure
  • Figure 3 shows the output signal from a conventional narrow-banded lambda sensor, when the A/F ratio is subjected to a rapid change
  • Figure 4 shows the output signal from a conventional narrow-banded lambda sensor at ⁇ values ranging from 0,98 to 1,02,
  • Figure 5 shows schematically an arrangement for regulation of fuel supplied to a combustion engine.
  • figure 1 is shown a flow-chart for the inventive method.
  • the method is for example used in Diesel engines converted to natural gas fuel, where the ⁇ - value during operation should be maintained at 1,4-1,5 for a optimal fuel usage and minimising of exhausted pollutants.
  • step 1 the routine is started, which could be triggered by an interrupt routine at recurrent time intervals.
  • step 2 a control is made if a first condition is fulfilled which could be attainment of a certain predetermined temperature of the engine, which indicates that the lambda sensor should have reached a sufficiently high temperature in order to produce a reliable output signal, alternatively that the temperature or output signal of the lambda sensor itself is controlled to determine if the proper operating temperature have been reached.
  • the sequence will return to start as long as the lambda sensor has not reached its operating temperature, normally close to 300°C.
  • the routine proceeds to step 3.
  • step 3 a control is made if detection of ⁇ - value is of current interest
  • the regulating sequence following a demand of a new or renewed detection is dependent on two conditions.
  • the first condition is that the engine at the moment is operating at a preferably predetermined operating case, i.e. a combination of at least load and revs (number of revolutions), where a reference value is desired.
  • a reference value For example could reference values be desired at specific or close to specific revs and loads.
  • specific revs could be revs between 500-2000 rpm at intervals of 100 rpm, and the load levels different loads from the partial load range (20-30% of full load) up to full load (100% of maximum supply of fuel amount) at load intervals of 10%. If the engine is operating near a operating case which is a combination of any of these preferably predetermined revs/loads, then the first condition is fulfilled.
  • the second condition could be a time function determining if the renewed detection should be activated for the current operating case.
  • This time function could for example control when a reference value latest was determined for the current operating case, and if a certain predetermined rninimum time have elapsed since the latest renewed detection was made at the current operating case, then the second condition is fulfilled.
  • This predetermined minimum time could preferably be as long as a couple of tens of minutes, in order to prevent a renewed detection occurring unnecessary often and occupying computational capacity of the control system, and reduce unnecessary deviation from the ideal ⁇ - value for the combustion in the engine.
  • step 4 a change of the current ⁇ -control is initiated from having been regulating towards ⁇ - values in the range 1,4-1,5 to a regulation towards a ⁇ - value of 1,0.
  • the sequence proceeds to step 5 where the amount of fuel is corrected, i.e. a gradual enrichment of fuel is initiated.
  • step 6 the present fuel amount is stored, which amount of fuel F is the amount of fuel needed for the corresponding amount of air obtaining a ⁇ - value of 1 ,0 at the current operating case.
  • This reduced amount of fuel F w is obtained by extracting an empirically determined correction factor F t o for the present operating conditions from a map or table, for example 30% reduction of fuel, necessary for reaching a wanted ⁇ - value, for example a lambda value about 1,4.
  • step 7 returns to the main program and further regulation of fuel is made by using the established value F favor ⁇ as a regulating parameter in a nan closed loop manner, i.e. an open-loop regulatioa
  • FIG 3 is the inertia or response for a conventional lambda sensor shown when subjected to a rapid change of the residual amount of oxygen in the exhaust.
  • the number of combustion cycles At the vertical axis is indicated the output signal from the lambda sensor measured in volt(U).
  • the engine here an Otto engine, running at 9000 rpm and the ignition system is cut out at combustion cycle 0, where the output signal of the lambda sensor is stable at an output level U-.
  • the step-response shows on the other hand that deviations of very short duration from the ideal lean mixture proportions is needed for the combustion engine in question, before a new base value F is obtained for calculation of an updated F ⁇ for the present operating case, which is used for further regulation.
  • This type of lambda sensor could not be used in the lean operating range for closed loop regulation at lambda values exceeding 1,02, and definitely not at ⁇ - values in the interval 1,2-1,5.
  • FIG 5 is shown schematically an arrangement for controlling delivery of fuel to a combustion engine 31.
  • An electronic control unit 32 controls that the right amount of fuel is delivered to the combustion engine 31 proportionally to the amount of air drawn into the cylinders.
  • With the fuel dosing device 30 is the right proportions of the air-fuel mixtures delivered to the engine via the inlet manifold 36.
  • step 2 a flow-chart for a misfire dependent correction of the value F ⁇ , obtained from the routine shown in figure 1.
  • Regulation towards very lean mixture ratios of air-fuel leads to increased risk for misfiring, demanding a misfire control and a subsequent correction of F ⁇ towards richer mixture ratios if misfire occurs.
  • Misfire correction starts in step 8 and could be initiated at each ignition event
  • step 9 detection of a misfire is performed, which preferably could be obtained by supervision of the ionisation-current in the spark plug gap using a type of device shown in EP3.188180 or SE.C.457831. No ionisation current is developed during the so-called post- ionisation phase in the spark plug gap if a misfire occurs.
  • a correction variable F fa is increased by a correcting step ⁇ F fet for each misfire event detected.
  • F f e is reset to zero value at each start of the engine, but Ffet or a predetermined share of F fe could also be stored in a non- volatile memory to be used for the next start of the engine.
  • ⁇ F fe is preferably a predetermined fixed correction step which increases the amount of fuel some percent or share of percent of the fuel supplied to the engine.
  • step 9 If no misfire is detected in step 9, then the sequence will proceed to step 11 without increasing the correction variable F f a .
  • Ffe be resetting stepwise to a zero value.
  • Return to leaner air-fuel mixtures could then preferably be initiated by using smaller return steps than the correcting step ⁇ Ffe, initiated in the rich direction after a misfire. Return take place preferably after a predetermined number of combustion cycles or a predetermined lapse of time after the latest detected misfire, for example a couple of hundred cycles or a couple of seconds.
  • the regulating system will then continuously strive to return to the optimal lean ratio of air-fuel mixture, and an occasional misfire will not lead to any long term operation at non optimal lean ratios of air-fuel mixtures.
  • Fvi r t could as previously described be interpolated for each load and revs between the preferably predetermined operating cases where a reference value have managed to be established by the forced regulation down to a ⁇ - value at 1 ,0.
  • the operating cases where establishment of reference values Fvj, are made be selected automatically as soon as any operating case have reached a stable condition, i.e. the engine is not subjected to a transient load- or speed case.
  • For a smooth regulation could all operating cases where reference values Fvi,, are established be situated more closely together in operating ranges used more frequently.
  • a Diesel engine converted to natural gas fuel operation which could be used as a power source for stationary electric generators, almost 90% of the operating time take place at essentially constant speed with moderate changes in load.
  • the operating cases where reference values are established be located more closely together in the normal operating load- and speed range.

Abstract

Procédé de régulation d'un moteur à combustion possédant une sonde lambda à bande étroite pour rapports de mélanges stoechiométriques d'air-carburant (μ = 1,0) située dans le système d'échappement, la combustion dans le moteur à combustion pendant la plupart de son fonctionnement étant régulée de manière à obtenir des rapports de mélanges pauvres d'air-carburant dépassant μ = 1,1 et de préférence μ = 1,2-1,6 ou encore plus pauvres. En forçant le moteur pendant une courte durée vers des rapports de mélanges stoechiométriques dans différentes conditions de charge, on a pu déterminer une valeur de base de la quantité nécessaire de carburant Fgr permettant d'entretenir un fonctionnement stoechiométrique. La quantité de carburant nécessaire pour le fonctionnement à mélange pauvre a pu être déterminée à l'aide d'un facteur de correction Fkorr, où Fvirt = Fgr.Fkorr. Pendant le fonctionnement continué au rapport de mélange pauvre prédéterminé, on utilise Fvirt pour réguler la quantité de carburant fournie, dans les conditions de charge où Fvirt a été établi, ou par une valeur interpolée de Fvirt comprise dans les conditions de charge où l'on a pu établir Fvirt. Ce procédé a permis d'obtenir un réglage à quasi-réaction pour la combustion d'un mélange pauvre avec une sonde lambda peu coûteuse et fiable autorisant un rapport de mélange stoechiométrique plus riche.
PCT/SE1995/000913 1994-08-08 1995-08-08 Procede de commande de combustion d'un melange pauvre a quasi-reaction utilisant une sonde lambda a bande etroite pour melanges stoechiometriques WO1996005420A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9402651-5 1994-08-08
SE9402651A SE9402651L (sv) 1994-08-08 1994-08-08 Metod för kvasi-återkopplad lean-burn reglering med smalbandig lambda sensor

Publications (1)

Publication Number Publication Date
WO1996005420A1 true WO1996005420A1 (fr) 1996-02-22

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006052985A1 (de) * 2006-11-10 2008-05-15 Volkswagen Ag Verfahren zum Betreiben einer Brennkraftmaschine mit bivalenter Brennstoffzufuhr
CN106285985A (zh) * 2016-09-30 2017-01-04 广州汽车集团股份有限公司 汽油发动机过量空气系数燃烧控制方法及燃烧控制系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4526001A (en) * 1981-02-13 1985-07-02 Engelhard Corporation Method and means for controlling air-to-fuel ratio
US4562818A (en) * 1983-07-05 1986-01-07 Nippon Soken, Inc. Method and apparatus for controlling the air-fuel ratio in an internal combustion engine
US4681077A (en) * 1984-01-20 1987-07-21 Hitachi, Ltd. Air-fuel ratio controlling method and apparatus for an internal combustion engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4526001A (en) * 1981-02-13 1985-07-02 Engelhard Corporation Method and means for controlling air-to-fuel ratio
US4562818A (en) * 1983-07-05 1986-01-07 Nippon Soken, Inc. Method and apparatus for controlling the air-fuel ratio in an internal combustion engine
US4681077A (en) * 1984-01-20 1987-07-21 Hitachi, Ltd. Air-fuel ratio controlling method and apparatus for an internal combustion engine

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006052985A1 (de) * 2006-11-10 2008-05-15 Volkswagen Ag Verfahren zum Betreiben einer Brennkraftmaschine mit bivalenter Brennstoffzufuhr
DE102006052985B4 (de) * 2006-11-10 2015-08-06 Volkswagen Ag Verfahren zum Betreiben einer Brennkraftmaschine mit bivalenter Brennstoffzufuhr
CN106285985A (zh) * 2016-09-30 2017-01-04 广州汽车集团股份有限公司 汽油发动机过量空气系数燃烧控制方法及燃烧控制系统

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SE9402651D0 (sv) 1994-08-08
SE9402651L (sv) 1996-02-09

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