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
• • 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
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
  • F02D41/1456—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with sensor output signal being linear or quasi-linear with the concentration of oxygen
• • 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
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
  • F02D41/1458—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with determination means using an estimation
• • 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
  • F02D41/2474—Characteristics of sensors
• • 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
  • F02D41/2441—Methods of calibrating or learning characterised by the learning conditions

Definitions

• the invention relates to a method for determining a lambda value with the The preamble of claim 1 mentioned features.
• so-called broadband lambda probes are found in practice, for example two-cell limit current probes, application.
• the exhaust gas first overcome a diffusion barrier before it enters a measuring chamber.
• the catalytically active analogous to the jump lambda probe Electrodes arranged as a concentration cell.
• An output signal from this Regulator controls a current through a second cell of the probe, a so-called Pumping cell.
• this current causes oxygen transport from the Measuring chamber out, this after an equilibrium to the Electrodes corresponds to a diffusion current through the diffusion barrier.
• an output signal of the probe in the form of a measuring current is available is proportional to the oxygen partial pressure in the exhaust gas.
• reducing agents such as CO, HC or H 2 diffuse to an increased extent through the diffusion barrier into the measuring chamber and react there at the catalytically active electrodes with the oxygen now brought in by the pump cell.
• the flowing measuring current is a function of a sum of the partial pressures of the reducing agents multiplied by their respective diffusion coefficients.
• a disadvantage of such broadband lambda probes is that an essential height parameters influencing the measuring current are inadequate or not at all be taken into account. So it is known that the measuring current except from the Exhaust gas composition also from a geometry of the probe, a porosity of the Diffusion barrier, a gas pressure and a temperature in the area of the probe prevails, depends. It is known to compensate for manufacturing tolerances multiply the output signal by a predefinable correction value (Calibration). However, the sensitivity of the probe changes influencing parameters due to aging effects or pollution during operation of the internal combustion engine.
• the object of the present invention is to provide a method which it enables the lambda value of the exhaust gas of the internal combustion engine long-term stable and to be determined with a high accuracy.
• the predefinable Correction value also largely compensate for the operational tolerances.
• the correction value is advantageously determined as a function of selected calibration parameters. It is conceivable to take into account a temperature and / or a water content of an intake air of the internal combustion engine when determining the correction value. If, for example, the temperature of the intake air exceeds a limit temperature during the determination of the correction value, the calibration is aborted. The same procedure can be followed if a predefinable threshold value for the water content of the intake air, a pipe wall temperature or an exhaust gas temperature is used. These measures subsequently influence the water gas content of the exhaust gas (CO and H 2 content). Of course, the water gas content can also be recorded directly, thus preventing a disruptive influence on the calibration of the lambda sensor.
• the position of the measurement signal or of the predeterminable measurement signal range is also advantageous to be taken into account during calibration. So it makes sense to have different ones Correction values in lean operation or rich operation of the internal combustion engine for the Determine the lambda value to use.
• calibration parameters such as the temperature or the predefinable temperature range of the lambda probe at which Calibration of the lambda probe are taken into account.
• a change from the operating point p 1 to the operating point p 2 with ⁇ > 1 of the internal combustion engine should preferably take place by a measure which essentially influences the air mass flow, since the efficiency of the internal combustion engine changes only to a relatively small extent and the air mass flows are recorded particularly precisely can. It is also advantageous if a change in the supplied fuel mass m K1 when changing from the operating point p 1 to the operating point p 2 essentially serves to compensate for a change in output of the internal combustion engine.
• a change to an operating point p 2 with ⁇ ⁇ 1 rich operation
• can only be forced by changing the fuel mass m K1 if the operating point p 2 is in a lambda range of ⁇ 0.8 to 0.9.
• ⁇ 0.8 to 0.9
• the correction value can be specified periodically after a predefinable one Period of time to be initiated or takes place during dynamic operation of the Internal combustion engine, if at random two successive suitable ones Operating points can be reached.
• lambda sensors in an exhaust duct of the internal combustion engine to arrange.
• the position and shape of such lambda sensors are known.
• the Functioning should be briefly based on a two-cell limit current probe, one so-called broadband lambda probe.
• An output signal from the controller controls a current through the pumping cell such that in a lean operation of the internal combustion engine ( ⁇ > 1) Oxygen is transported out of the measuring chamber. After a Setting the equilibrium of the oxygen concentration at the catalytically active electrodes this current is equal to a diffusion current through the diffusion barrier and serves as the output signal of the probe (measuring current).
• the measuring current is proportional an oxygen partial pressure in the exhaust gas.
• reducing agents such as CO, HC or H 2 additionally diffuse through the diffusion barrier into the measuring chamber to an increased extent. Oxidation of the reducing agents by the oxygen brought in by the pump cell takes place on the catalytically active electrodes.
• the flowing current is thus a function of the sums of the partial pressures of the reducing agents, multiplied by their respective diffusion coefficients.
• an additional calibration of the lambda probe is necessary in order to prevent disturbing influences, such as, for example, geometric properties, a porosity of the diffusion barrier, a gas pressure or a temperature of the probes on the measuring current. It is therefore known to multiply the measurement signal by an adjustable correction value k w to compensate for manufacturing-related tolerances. However, this does not take into account that contamination or aging effects can lead to a drift of the measurement signal and operational tolerances are not taken into account.
• Means are usually assigned to the internal combustion engine Detection of an air mass flow and a supplied fuel mass within allow a predefinable injection time.
• the air mass flow can be from one Air mass meter measured or based on an existing load signal to Example of an intake manifold pressure.
• An accuracy of the available Air mass meter is better than 3% of the measured value as long as the pulsation amplitudes of an intake air are sufficiently small.
• the correction value k w is determined in lean operation, taking into account the following conditions:
• a fuel mass m K1 and an air mass flow m L1 are detected within an injection time t 1 .
• the following applies to the measuring current I 1 of the two-cell limit current probe: I. 1 k w ⁇ X ( O 2 ) 1 X (O 2 ) 1 indicates a residual oxygen content of the exhaust gas at the operating point p 1 .
• a ratio of the air mass flow m L1 to the fuel mass m K1 supplied within the injection time t 1 gives the lambda value ⁇ 1 at the operating point p 1 .
• ⁇ 1 m L 1 m K 1 ⁇ k st
• the supplied fuel mass m K1 during the injection time t 1 at the operating point p 1 can be expressed as the product of the injection time t 1 and a proportionality factor k in .
• m K 1 k in ⁇ t 1
• the correction value k w taking into account calibration parameters such as a position of the measurement signal, a predeterminable measurement signal range, a temperature or a water content of an intake air, a temperature or a predefinable temperature range of the lambda probe, a water gas content or a temperature of the exhaust gas or a combination thereof.
• the height of the oxygen flow corresponds to the diffusion flow from CO and H 2 , so that ultimately there is a measuring current I 2 which corresponds to the exhaust gas components of CO and H 2 multiplied by their respective diffusion coefficients, and from which a correction value k w for the Fat operation can be calculated.
• correction values k w determined in this way can be periodically redefined to take aging processes or soiling of the lambda probe into account after a predefinable period of time has elapsed. It is also conceivable that the correction values k w are determined during dynamic operation of the internal combustion engine as a result of two randomly successive, suitable operating points.
• the temperature of the intake air should not be above during calibration a predetermined limit temperature. This is advantageously Limit temperature 35 ° C, because below this temperature the water gas content of the Intake air is negligible.
• the correction value can be determined be stopped if the water content of the intake air is above a predefinable threshold.
• the calibration should also only be carried out if the exhaust gas temperature in the area of the lambda probe is above a predefinable threshold value during the determination of the correction value k w .
• the exhaust gas temperature can be recorded directly with an exhaust gas temperature sensor or calculated from the engine operating data using a model.
• a pipe wall temperature between the exhaust valves of the internal combustion engine and the installation location of the lambda sensor should also be above a threshold value.
• the threshold value for the exhaust gas temperature and the pipe wall temperature are preferably selected such that the calibration only takes place from a temperature above 60 ° C., in particular 100 ° C. At a temperature of> 60 ° C of the exhaust gas, the dew point of the exhaust gas is surely exceeded.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Testing Of Engines (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

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• 1999
  • 1999-08-20 DE DE19939555A patent/DE19939555A1/de not_active Ceased
• 2000
  • 2000-08-04 AT AT00116857T patent/ATE325266T1/de not_active IP Right Cessation
  • 2000-08-04 EP EP00116857A patent/EP1079090B1/fr not_active Expired - Lifetime
  • 2000-08-04 DE DE50012679T patent/DE50012679D1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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