US20060168943A1 - Method for operating an internal combustion engine and device for implementing the method - Google Patents
Method for operating an internal combustion engine and device for implementing the method Download PDFInfo
- Publication number
- US20060168943A1 US20060168943A1 US11/334,970 US33497006A US2006168943A1 US 20060168943 A1 US20060168943 A1 US 20060168943A1 US 33497006 A US33497006 A US 33497006A US 2006168943 A1 US2006168943 A1 US 2006168943A1
- Authority
- US
- United States
- Prior art keywords
- lambda
- catalytic converter
- oxygen
- change
- signal
- 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.)
- Abandoned
Links
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 39
- 230000003197 catalytic effect Effects 0.000 claims abstract description 120
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 85
- 239000001301 oxygen Substances 0.000 claims abstract description 85
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 85
- 238000003745 diagnosis Methods 0.000 claims abstract description 44
- 239000007789 gas Substances 0.000 claims abstract description 32
- 238000011156 evaluation Methods 0.000 claims abstract description 3
- 238000001514 detection method Methods 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 2
- 230000007704 transition Effects 0.000 description 13
- 230000006870 function Effects 0.000 description 11
- 238000011144 upstream manufacturing Methods 0.000 description 11
- 230000010354 integration Effects 0.000 description 9
- 239000000446 fuel Substances 0.000 description 8
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 230000003111 delayed effect Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 206010021143 Hypoxia Diseases 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
Images
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
- F02D41/02—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
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/0295—Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/08—Exhaust gas treatment apparatus parameters
- F02D2200/0816—Oxygen storage capacity
Definitions
- the present invention relates to a method for operating an internal combustion engine and to a device for implementing the method.
- One possibility for diagnosis of the catalytic converter is based on determining the oxygen storage capacity of the catalytic converter.
- a decrease in the oxygen storage capacity is considered a measure for the decline in the conversion capacity of the catalytic converter.
- the oxygen storage capacity of a catalytic converter can be determined by subjecting the excess-air factor lambda in the exhaust gas upstream from the catalytic converter to a cyclic change about the value 1.0 and comparing the lambda signal measured downstream from the catalytic converter to the lambda values predefined upstream.
- the oxygen storage capacity is high, in predefined lambda values of less than 1 the oxygen stored in the catalytic converter is able to largely oxidize the oxidizable exhaust-gas components, and in the case of predefined lambda values that are greater than 1 it is able to largely store the excess oxygen.
- the measurable lambda fluctuations downstream from the catalytic converter are relatively low if the catalytic converter has a high oxygen storage capacity and thus is functioning properly.
- the time integral of the product of gas mass flow and a term having the lambda value upstream from the catalytic converter, and the time integral of the product of gas mass flow and a term having the lambda value downstream from the catalytic converter are calculated. Used as a measure for the ageing condition of the catalytic converter is either the difference between the two integrals, or the quotient of the two integrals, or the quotient of the difference and one of the two integrals.
- German Published Patent Application No. 102 57 059 a method and a device are described, which provide a diagnosis of catalytic converters positioned in a plurality (number N) of exhaust tracts of an internal combustion engine. Situated downstream, following the merging of the n exhaust tracts, is a lambda sensor whose signal is compared to the individual lambda values that occur upstream from the catalytic converters.
- the diagnosis is based on an evaluation of the oxygen storage capacity of the catalytic converters.
- Broadband lambda sensors for example, are used as lambda sensors.
- Example embodiments of the present invention may provide a method for operating an internal combustion engine and a device for implementing the method, which may allow a reliable diagnosis of the catalytic converter.
- the method may assume that at least one catalytic converter is positioned in the exhaust-gas region of the internal combustion engine and a lambda sensor is positioned downstream from the catalytic converter or downstream from a section of the catalytic converter.
- a catalytic converter diagnosis is implemented, which is based on evaluating at least one measure for the oxygen storage capacity of the catalytic converter/inside the catalytic converter. An at least approximately empty/full oxygen reservoir of the catalytic converter is assumed. Subsequently, the lambda setpoint value of the internal combustion engine is changed to an excess-air factor lambda that is greater than 1/less than 1.
- a first change in a lambda signal is initially detected, which is provided by a lambda sensor positioned downstream from the catalytic converter or downstream from a section of the catalytic converter, the lambda sensor being configured as broadband lambda sensor.
- a measure is determined for the oxygen stored/discharged following the first change in the lambda signal. The determination of the stored/discharged oxygen is terminated if either a second change in the lambda signal is detected or if the oxygen exceeds a threshold value.
- the method may provide relatively high accuracy in the determination of at least one measure for the oxygen storage capacity of the catalytic converter, which may be utilized as a measure for the ageing condition of the catalytic converter.
- High oxygen storage capacity is a sign of a good catalytic converter.
- the method may be based both on the oxygen stored in the catalytic converter and on the oxygen discharged from the catalytic converter.
- a reducing agent such as hydrogen and/or carbon monoxide, which is produced when the internal combustion engine is operated at an excess air factor lambda of less than 1. Since the storing/discharging of the oxygen into/out of the catalytic converter is an equilibrium reaction, not all supplied oxygen is stored/discharged in a transition region. Due to the kinetics of the storing/discharging and due to diffusion processes, the characteristic of the oxygen concentration downstream from the catalytic converter is flattened in terms of time. A transition region is produced. An excess of oxygen/lack of oxygen occurs downstream from the catalytic converter before the maximum oxygen storage capacity is exhausted/all the oxygen stored is reduced.
- the determination of at least one measure for the stored/discharged oxygen is ended if either a second change in the lambda signal is detected or if the measure for stored/discharged oxygen has exceeded a threshold value. Accordingly, the diagnosis of the catalytic converter may be terminated prematurely, without waiting for the second change, if a sufficiently good oxygen storage capacity of the catalytic converter has already been established. If the second change in the lambda signal comes into effect as second criterion for terminating the determination of the measure for the stored/discharged oxygen, a relatively precise measure for the remaining oxygen storage capacity is able to be provided. By a comparison with a predefined storage capacity threshold value, it is then possible to decide whether the catalytic converter must be exchanged.
- the method may be able to selectively implement the diagnosis of the catalytic converter by influencing the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine in a corresponding manner so as to predefine the starting condition and the subsequent change in the excess-air factor lambda.
- the method may also be able to implement the catalytic converter diagnosis within the framework of normal operation of the internal combustion engine, provided both the starting condition, i.e., that a completely empty/full oxygen reservoir of the catalytic converter exists within the framework of normal operation is satisfied and, furthermore, a change in the excess-air factor lambda to a value greater than 1/smaller than 1 is implemented within the framework of normal operation.
- the change in the lambda signal may be determined from the gradient of the lambda signal.
- the gradient of the lambda signal which may be approximated as difference quotient, may be determined continuously, at predefined time intervals, for example.
- the change may be detected on the basis of, for example, the gradient having to exceed a predefined gradient threshold value.
- a minimum time during which the gradient threshold value must have been exceeded may be provided.
- An additional or alternative detection of the change provides that the gradient must have a maximum.
- Low-pass filtering of the lambda signal may be provided to block interference signals and rapid changes of the lambda signal due to dynamic processes during determination of the change.
- Oxygen may be determined from an integral over time, which is a function of a combustion lambda and the air signal provided by an air detection that detects the combustion air supplied to the internal combustion engine.
- the stored/discharged oxygen mass is determined by taking the combustion air into account and by implementing the integration.
- the air signal and possibly the combustion lambda may be buffer-stored for a delay time, which at least approximately corresponds to the gas-propagation time in the catalytic converter before the broadband lambda sensor is reached. Due to this measure, an unsteady operating state of the internal combustion engine during the catalytic converter diagnosis may have an only negligible effect on the diagnosis result.
- Conditioning of the catalytic converter prior to the catalytic converter diagnosis may be provided in that the combustion lambda predefined for the internal combustion engine is specified to a value greater than 1/less than 1, so that the oxygen reservoir of the catalytic converter is at least approximately full/empty.
- the stipulation of the combustion lambda to a value greater than 1 may be omitted if the catalytic converter diagnosis is performed after a deceleration fuel cutoff phase of the internal combustion engine that continues at least to the point where the oxygen reservoir is at least approximately filled.
- the stored/discharged oxygen may be evaluated as a function of the catalytic converter temperature and/or the exhaust gas mass flow.
- the threshold value for the comparison of the measure for the catalytic converter storage capacity may be defined as a function of operating conditions of the catalytic converter.
- a device for implementing the method may provide a control device configured to implement the method.
- the control device includes, for example: a diagnostic controller which changes the lambda setpoint value; a change detection to process the lambda signal provided by the broadband lambda sensor; and an integrator to determine a measure for the stored/discharged oxygen.
- the control unit may include at least one electrical memory in which the method steps are stored in the form of a computer program.
- FIG. 1 is a schematic view of a technical environment in which a method according to an example embodiment of the present invention may be run.
- FIGS. 2 a to 2 e illustrate concentration characteristics as a function of location.
- FIG. 3 illustrates a signal characteristic of a lambda signal occurring downstream from a catalytic converter as a function of time.
- FIG. 1 schematically illustrates an internal combustion engine 10 in whose intake region 11 an air detection 12 is positioned, and in whose exhaust-gas region 13 an exhaust-gas temperature sensor 14 , a catalytic converter 15 and, downstream from catalytic converter 15 , a lambda sensor 16 are situated.
- Catalytic converter 15 has a catalytic converter input Kat_In and a catalytic converter output Kat_Out.
- Air detection 12 outputs an air signal msL to a control unit 20 .
- Internal combustion engine 10 emits a rotational speed n.
- Exhaust-gas temperature sensor 14 outputs an exhaust-gas temperature signal Tabg, and lambda sensor 16 outputs a lambda signal lam_nK.
- Control unit 20 emits a fuel signal mK to a fuel-metering device 21 .
- An exhaust-gas mass flow msabg occurs in exhaust-gas region 13 .
- Air signal msL is also provided to a deceleration fuel-cutoff controller 30 , a time delay 31 and a threshold-value definition 32 .
- Deceleration fuel-cutoff controller 30 provides a deceleration fuel-cutoff signal 34 to diagnostic controller 33 .
- Time delay 31 transmits a delayed air signal msL_d to an integrator 35 .
- Threshold value definition 32 supplies a first and a second threshold value 37 , 38 to a comparator 36 .
- Rotational speed n is supplied to deceleration fuel-cutoff controller 30 and to threshold-value definition 32 .
- Diagnostic controller 33 supplies a first diagnosis control signal 39 to threshold-value definition 32 , a second diagnosis control signal 41 to a change-determination 40 , and a diagnosis lambda lam_D to a lambda setpoint selection 42 . Diagnosis lambda lam_D is also supplied to time delay 31 , which outputs a delayed lambda signal lam_d and provides it to integrator 35 . Diagnostic controller 33 is supplied with a diagnosis stop signal 43 provided by comparator 36 .
- lambda setpoint selection 42 is supplied with a nominal operating lambda lam_N.
- Lambda-setpoint selection 42 transmits a lambda setpoint value lam_S to a lambda controller 50 , which provides fuel signal mK.
- Lambda signal lam_nk provided by lambda sensor 16 is not only supplied to lambda controller 50 , but to a low-pass filter 51 as well.
- Lambda controller 50 is additionally provided with a lambda signal lam_vk, which reflects the excess air factor lambda in the exhaust gas upstream from catalytic converter 15 .
- Integrator 35 provides integration result 52 to comparator 36 , which outputs a fault signal F.
- FIGS. 2 a to 2 e illustrate signal characteristics as a function of location x. Illustrated are oxygen concentration %02 as well as a reagent concentration % Rea.
- FIG. 2 a illustrates the situation at a first location x 1 after a rich-lean jump has occurred after which a high oxygen concentration %02 and a low reagent concentration % Rea are present.
- FIG. 2 b illustrates the situation at a later point in time when the concentration changes are present at a second location x 2 .
- FIG. 2 c illustrates the situation where a change occurs in concentrations %02, % Rea downstream from catalytic converter input Kat_In.
- a first transition region x 10 comes about in which oxygen concentration %02 changes only slightly.
- FIG. 2 d illustrates the situation at a later point in time when concentrations %02, % Rea change inside catalytic converter 15 .
- a second transition region x 20 occurs, which has a greater expansion than first transition region x 10 .
- FIG. 2 e illustrates the situation where concentrations %02, % Rea change largely downstream from catalytic converter output Kat_Out.
- a third transition region x 30 comes about, which in turn has a greater expansion than second transition region x 20 .
- FIG. 3 illustrates lambda signal lam_nK as a function of time t.
- lambda Up to a first point in time t 1 , lambda is to be 0.97.
- a first change 60 of lambda signal lam_nK occurs between the first and a second point in time t 2 .
- lambda signal lam_nK has at least approximately a plateau 61 at which lambda is at least approximately 1.
- a second change 62 of lambda signal lam_nK sets in, which is concluded at a fifth point in time t 5 .
- lambda is to be at 1.03.
- Lambda sensor 16 is arranged as broadband lambda sensor which is able to detect an excess air factor lambda lying in a wide range which, for example, is between 0.7 and 4.0.
- Lambda sensor 16 is located downstream from the at least one catalytic converter 15 .
- lambda sensor 16 may also be arranged downstream from a partial volume of the catalytic converter.
- Lambda signal lam_nK supplied by lambda sensor 16 may be used not only for diagnosis, but for regulation of the combustion lambda as well. For this reason, lambda signal lam_nK is supplied both to low-pass filter 51 and to lambda controller 50 , which is able to influence fuel signal mK as a function of lambda signal lam_nK.
- a lambda signal lam_vK may be taken into consideration, which is measured upstream from catalytic converter 15 by a lambda sensor and supplied to lambda controller 50 .
- Lambda controller 50 attempts to adjust a combustion lambda that corresponds to lambda setpoint value lam_S stipulated by lambda setpoint selection 42 .
- lambda setpoint value lam_S corresponds to nominal-operation lambda lam_N.
- An open-loop control may be provided instead of lambda controller 50 .
- lambda signal lam_vK which reflects the excess air factor lambda in the exhaust gas upstream from catalytic converter 15 , is not required.
- Lambda signal lam_nK detected downstream from catalytic converter 15 may be utilized instead.
- diagnostic controller 33 may stipulate diagnosis lambda lam_D, which lambda setpoint selection 42 is to provide as lambda setpoint value lam_S.
- the diagnosis is prepared in that the oxygen reservoir of catalytic converter 15 is either approximately fully filled or emptied. Under the conditions illustrated in FIGS. 2 a to 2 e, a rich-lean jump at the beginning of the diagnosis is assumed in which oxygen concentration %02 is changed from a low to a high value. Due to the change in the lambda of the internal combustion engine from a rich to a lean value, a corresponding change from a high to a low value occurs in reagent concentration % Rea. To allow the diagnosis to be carried out, it may therefore be necessary that catalytic converter 15 be initially acted upon by a low oxygen concentration %02, until the point is reached where the oxygen reservoir is at least approximately empty.
- an at least approximately completely full oxygen reservoir of catalytic converter 15 may be assumed in which catalytic converter 15 is to be acted upon by a high oxygen concentration %02 in he beginning. This operating state is already present in a sufficiently long deceleration fuel-cutoff phase of internal combustion engine 10 .
- deceleration fuel-cutoff controller 30 which determines the deceleration fuel-cutoff of internal combustion engine 10 , from air signal msL and rotational speed n, for example, signals to diagnostic controller 30 via deceleration fuel-cutoff signal 34 that the diagnosis is able to be started. Deceleration fuel-cutoff signal 34 is supplied when the deceleration fuel-cutoff phase has been present for a sufficient length of time.
- the change in lambda setpoint value lam_S to diagnosis lambda lam_D occurs upstream from catalytic converter 15 in the form of a jump of oxygen concentration %02 and in the form of a jump of reagent concentration % Rea in a first location x 1 .
- the concentration changes move to second location x 2 where the concentration transitions still have relatively steep characteristics.
- the originally jump-like concentration changes are already slightly flattened by diffusion and turbulence in exhaust-gas region 13 .
- the lean exhaust gas having a high oxygen concentration %02 displaces the rich exhaust gas having a high reagent concentration % Rea, which has only a very low oxygen concentration %02.
- the concentration changes meanwhile have arrived at a location downstream from catalytic converter input Kat_In.
- the excess oxygen is stored in catalytic converter 15 .
- First transition region x 10 is created in which the oxygen concentration %02 exhibits first change 60 .
- An at least short plateau 61 then occurs, which is left upon second change 62 .
- the reagent concentration % Rea drops to low values during first change 60 . Since catalytic converter 15 is unable to store the entire available oxygen, oxygen concentration %02 that remains in first transition region x 10 is higher than that in the rich exhaust gas.
- FIG. 2 d illustrates the situation in the concentration changes at a later point in time.
- Second transition region x 20 has become longer compared to first transition region x 10 .
- FIG. 2 e illustrates the situation at an even later point in time when the concentration changes occur at least partially already downstream from catalytic converter output Kat_Out or downstream from a section of catalytic converter 15 . It is only at this point in time that the concentration changes may be measured by lambda sensor 16 .
- lambda signal lam_nK of lambda sensor 16 will indicate a rich exhaust gas lambda, which is set to 0.97, for example.
- FIG. 3 illustrates the time characteristic in which the oxygen deficiency is to exist up to first point in time t 1 .
- the change in the oxygen concentration %02 is to begin at first point in time t 1 , with first change 60 .
- the analysis of lambda signal lam_nK takes place in change determination 40 after diagnostic controller 33 has output second diagnosis control signal 41 to change determination 40 .
- low-pass filter 51 is provided, which rids lambda signal lam_nK of high-frequency interference signals on the one hand and of rapid changes caused by dynamic processes that are unrelated to first change 60 on the other hand.
- Change determination 40 may then be provided with filtered lambda signal lam_nKF instead of lambda signal lam_nK.
- change detection 40 may determine, for example, the gradient of lambda signal lam_nk or filtered lambda signal lam_nKF.
- the gradient may be ascertained continuously, in rapid time succession. It may be approximated by difference quotients, for example.
- the gradient may be compared to a predefined gradient threshold value. When the gradient threshold value is exceeded, integrator enable signal 53 is supplied. It may be provided that the gradient must exceed the gradient threshold value for a predefined period of time before integrator enable signal 53 is made available. Additionally or alternatively, the presence of a point of inflection of lambda signal lam_nK or of filtered lambda signal lam_nKF may be determined and utilized to provide integrator enable signal 53 . Furthermore, in addition or as an alternative, it may be provided that the maximum of the gradient is determined first and that it is then checked whether the gradient falls below a threshold value before integrator enable signal 53 is provided.
- the diagnosis of the catalytic converter may begin as soon as first change 60 is detected. Ascertained is the oxygen being stored in catalytic converter 15 . This may be the oxygen mass or the oxygen quantity.
- the determination may be implemented, for example, in that integrator 35 multiplies the value (1 ⁇ 1/lambda) by air signal msL and a constant that corresponds to the percentage oxygen content of the air and integrates it as a function of time. For a relative valuation, the constant may be set to equal 1.
- air signal msL provided by air detection 12 may be delayed in time delay 31 and made available to integrator 35 as delayed air signal msL_d.
- the lambda on which the integration is based may be delayed in time delay 31 .
- the combustion lambda during the diagnosis corresponds to the predefined diagnosis lambda lam_D, which is forwarded to integrator 35 as delayed lambda signal lam_d.
- the delay of lambda may be omitted since diagnosis lambda lam_D is generally kept constant during the diagnosis.
- the delay time to be input may depend on air signal msL. Furthermore, the delay time may be a function of the load of internal combustion engine 10 .
- the load may be indicated by fuel signal mK, possibly in conjunction with rotational speed n, or by a torque of the combustion engine known to control unit 20 .
- the determination of the oxygen takes place in the region of plateau 61 of lambda signal lam_nK or filtered lambda signal lam_nKF.
- Plateau 61 is more or less pronounced.
- lambda may change from a value of just below 1 to a value of just above 1.
- the lambda values may change between 0.99 and 1.01 in a rich-lean jump and between 0.998 and 1.002 in a lean-rich jump.
- the integration is ended when second change 62 occurring at fourth point in time t 4 is detected.
- the determination of second change 62 may be implemented analogously to the already described determination of first change 60 .
- integrator enable signal 53 is reversed and the integration concluded.
- Integration result 52 which reflects a measure of the oxygen storage/oxygen discharge or reagent storage, is compared to first threshold value 37 provided by threshold-value definition 32 . If a threshold has been exceeded, which signals a poor catalytic converter, comparator 36 provides fault signal F which is stored in a fault memory, for example, or is able to be displayed.
- the integration may be ended even before second change 62 is reached.
- integration result 52 is compared to second threshold value 38 , which is provided by threshold-value definition 32 and defined to a value that corresponds to a good or properly functioning catalytic converter 15 . If integration result 52 already corresponds to a properly functioning catalytic converter 15 , the catalytic converter diagnosis may be terminated even before second change 62 is able to be detected.
- comparator 36 provides diagnosis stop signal 43 , which induces diagnostic controller 33 to terminate the diagnosis.
- First and second diagnosis control signals 39 , 41 are canceled for this purpose.
- Change determination 40 cancels integrator enable signal 53 , thereby resetting integrator 35 to an initial state, which is subsequently available for a new determination of the oxygen.
- Threshold-value definition 32 may stipulate first and/or second threshold value 37 , 38 as a function of air signal msL, rotational speed n and/or the temperature of the catalytic converter.
- Exhaust-gas temperature Tabg occurring upstream from catalytic converter 15 may be utilized as measure for the temperature of the catalytic converter.
- Air signal msL is a measure for exhaust gas mass flow msabg, which, just as the catalytic converter temperature/exhaust gas temperature Tabg, has an influence on the oxygen storage capacity of catalytic converter.
- Exhaust gas temperature Tabg may be measured by temperature sensor 14 .
- Exhaust gas temperature Tabg may be able to be measured at least approximately on the basis of air signal msL and, for example, fuel signal mK as a measure for the load of internal combustion engine 10 .
Abstract
A method for operating an internal combustion engine and a device for implementing the method may allow a catalytic converter diagnosis with a high degree of accuracy. At least one catalytic converter is positioned in the exhaust-gas region of the internal combustion engine, and a lambda sensor, which is configured as broadband lambda sensor, is positioned downstream from the catalytic converter or downstream from a section of the catalytic converter. The catalytic converter diagnosis is based on the evaluation of a measure for the oxygen storage capacity of the catalytic converter/within the catalytic converter. An at least approximately empty/filled oxygen reservoir of the catalytic converter is assumed. A change in the lambda setpoint value of the internal combustion engine to an excess air factor lambda that is greater than 1/less than 1 follows. Subsequently, a first change of the lambda signal is detected initially. Determined is a measure for the oxygen stored/discharged following the first change of the lambda signal. The determination of the stored/discharged oxygen is terminated if either a second change in the lambda signal is detected or if the measure of oxygen exceeds a threshold value.
Description
- The present application claims priority to Application No. 10 2005 002 237.5, filed in the Federal Republic of Germany on Jan. 18, 2005, which is expressly incorporated herein in its entirety by reference thereto.
- The present invention relates to a method for operating an internal combustion engine and to a device for implementing the method.
- One possibility for diagnosis of the catalytic converter is based on determining the oxygen storage capacity of the catalytic converter. A decrease in the oxygen storage capacity is considered a measure for the decline in the conversion capacity of the catalytic converter. The oxygen storage capacity of a catalytic converter can be determined by subjecting the excess-air factor lambda in the exhaust gas upstream from the catalytic converter to a cyclic change about the value 1.0 and comparing the lambda signal measured downstream from the catalytic converter to the lambda values predefined upstream. If the oxygen storage capacity is high, in predefined lambda values of less than 1 the oxygen stored in the catalytic converter is able to largely oxidize the oxidizable exhaust-gas components, and in the case of predefined lambda values that are greater than 1 it is able to largely store the excess oxygen. The measurable lambda fluctuations downstream from the catalytic converter are relatively low if the catalytic converter has a high oxygen storage capacity and thus is functioning properly.
- A technical implementation of the described method is described in German Published Patent Application No. 41 12 478, for example, according to which a jump lambda sensor is positioned upstream from the catalytic converter and a jump lambda sensor is positioned downstream from the catalytic converter. First, it is determined whether, given a lambda control oscillation from rich to lean or vice versa upstream from the catalytic converter, the lambda value downstream from the catalytic converter shows a corresponding transition. If this is the case, it can be assumed that the oxygen reservoir of the catalytic converter is either completely full or empty, so that a defined initial state is present. The gas mass flow flowing through the catalytic converter is determined subsequently. The time integral of the product of gas mass flow and a term having the lambda value upstream from the catalytic converter, and the time integral of the product of gas mass flow and a term having the lambda value downstream from the catalytic converter are calculated. Used as a measure for the ageing condition of the catalytic converter is either the difference between the two integrals, or the quotient of the two integrals, or the quotient of the difference and one of the two integrals.
- In German Published Patent Application No. 102 57 059, a method and a device are described, which provide a diagnosis of catalytic converters positioned in a plurality (number N) of exhaust tracts of an internal combustion engine. Situated downstream, following the merging of the n exhaust tracts, is a lambda sensor whose signal is compared to the individual lambda values that occur upstream from the catalytic converters. Here, too, the diagnosis is based on an evaluation of the oxygen storage capacity of the catalytic converters. Broadband lambda sensors, for example, are used as lambda sensors.
- Example embodiments of the present invention may provide a method for operating an internal combustion engine and a device for implementing the method, which may allow a reliable diagnosis of the catalytic converter.
- The method may assume that at least one catalytic converter is positioned in the exhaust-gas region of the internal combustion engine and a lambda sensor is positioned downstream from the catalytic converter or downstream from a section of the catalytic converter. A catalytic converter diagnosis is implemented, which is based on evaluating at least one measure for the oxygen storage capacity of the catalytic converter/inside the catalytic converter. An at least approximately empty/full oxygen reservoir of the catalytic converter is assumed. Subsequently, the lambda setpoint value of the internal combustion engine is changed to an excess-air factor lambda that is greater than 1/less than 1. A first change in a lambda signal is initially detected, which is provided by a lambda sensor positioned downstream from the catalytic converter or downstream from a section of the catalytic converter, the lambda sensor being configured as broadband lambda sensor. A measure is determined for the oxygen stored/discharged following the first change in the lambda signal. The determination of the stored/discharged oxygen is terminated if either a second change in the lambda signal is detected or if the oxygen exceeds a threshold value.
- Due to the use of a broadband lambda sensor, the method may provide relatively high accuracy in the determination of at least one measure for the oxygen storage capacity of the catalytic converter, which may be utilized as a measure for the ageing condition of the catalytic converter. High oxygen storage capacity is a sign of a good catalytic converter.
- The method may be based both on the oxygen stored in the catalytic converter and on the oxygen discharged from the catalytic converter. Comparable to the discharge of the oxygen is the storing of a reducing agent such as hydrogen and/or carbon monoxide, which is produced when the internal combustion engine is operated at an excess air factor lambda of less than 1. Since the storing/discharging of the oxygen into/out of the catalytic converter is an equilibrium reaction, not all supplied oxygen is stored/discharged in a transition region. Due to the kinetics of the storing/discharging and due to diffusion processes, the characteristic of the oxygen concentration downstream from the catalytic converter is flattened in terms of time. A transition region is produced. An excess of oxygen/lack of oxygen occurs downstream from the catalytic converter before the maximum oxygen storage capacity is exhausted/all the oxygen stored is reduced.
- The determination of at least one measure for the stored/discharged oxygen, which begins following a detected first change in the lambda signal, is ended if either a second change in the lambda signal is detected or if the measure for stored/discharged oxygen has exceeded a threshold value. Accordingly, the diagnosis of the catalytic converter may be terminated prematurely, without waiting for the second change, if a sufficiently good oxygen storage capacity of the catalytic converter has already been established. If the second change in the lambda signal comes into effect as second criterion for terminating the determination of the measure for the stored/discharged oxygen, a relatively precise measure for the remaining oxygen storage capacity is able to be provided. By a comparison with a predefined storage capacity threshold value, it is then possible to decide whether the catalytic converter must be exchanged.
- The method may be able to selectively implement the diagnosis of the catalytic converter by influencing the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine in a corresponding manner so as to predefine the starting condition and the subsequent change in the excess-air factor lambda.
- However, the method may also be able to implement the catalytic converter diagnosis within the framework of normal operation of the internal combustion engine, provided both the starting condition, i.e., that a completely empty/full oxygen reservoir of the catalytic converter exists within the framework of normal operation is satisfied and, furthermore, a change in the excess-air factor lambda to a value greater than 1/smaller than 1 is implemented within the framework of normal operation.
- The change in the lambda signal may be determined from the gradient of the lambda signal. The gradient of the lambda signal, which may be approximated as difference quotient, may be determined continuously, at predefined time intervals, for example. The change may be detected on the basis of, for example, the gradient having to exceed a predefined gradient threshold value. In addition, a minimum time during which the gradient threshold value must have been exceeded may be provided. An additional or alternative detection of the change provides that the gradient must have a maximum. Furthermore, in addition or as an alternative, it may be provided that the change be considered detected when the gradient initially has a maximum and then falls below a gradient threshold value in the subsequent decrease.
- Low-pass filtering of the lambda signal may be provided to block interference signals and rapid changes of the lambda signal due to dynamic processes during determination of the change.
- Oxygen may be determined from an integral over time, which is a function of a combustion lambda and the air signal provided by an air detection that detects the combustion air supplied to the internal combustion engine. The stored/discharged oxygen mass is determined by taking the combustion air into account and by implementing the integration. The air signal and possibly the combustion lambda may be buffer-stored for a delay time, which at least approximately corresponds to the gas-propagation time in the catalytic converter before the broadband lambda sensor is reached. Due to this measure, an unsteady operating state of the internal combustion engine during the catalytic converter diagnosis may have an only negligible effect on the diagnosis result.
- Conditioning of the catalytic converter prior to the catalytic converter diagnosis may be provided in that the combustion lambda predefined for the internal combustion engine is specified to a value greater than 1/less than 1, so that the oxygen reservoir of the catalytic converter is at least approximately full/empty. The stipulation of the combustion lambda to a value greater than 1 may be omitted if the catalytic converter diagnosis is performed after a deceleration fuel cutoff phase of the internal combustion engine that continues at least to the point where the oxygen reservoir is at least approximately filled.
- The stored/discharged oxygen may be evaluated as a function of the catalytic converter temperature and/or the exhaust gas mass flow. With this measure, the threshold value for the comparison of the measure for the catalytic converter storage capacity may be defined as a function of operating conditions of the catalytic converter.
- A device for implementing the method may provide a control device configured to implement the method.
- The control device includes, for example: a diagnostic controller which changes the lambda setpoint value; a change detection to process the lambda signal provided by the broadband lambda sensor; and an integrator to determine a measure for the stored/discharged oxygen. The control unit may include at least one electrical memory in which the method steps are stored in the form of a computer program.
- Additional aspects and features hereof are described in more detail below with reference to the appended Figures.
-
FIG. 1 is a schematic view of a technical environment in which a method according to an example embodiment of the present invention may be run. -
FIGS. 2 a to 2 e illustrate concentration characteristics as a function of location. -
FIG. 3 illustrates a signal characteristic of a lambda signal occurring downstream from a catalytic converter as a function of time. -
FIG. 1 schematically illustrates aninternal combustion engine 10 in whoseintake region 11 anair detection 12 is positioned, and in whose exhaust-gas region 13 an exhaust-gas temperature sensor 14, acatalytic converter 15 and, downstream fromcatalytic converter 15, alambda sensor 16 are situated.Catalytic converter 15 has a catalytic converter input Kat_In and a catalytic converter output Kat_Out. -
Air detection 12 outputs an air signal msL to acontrol unit 20.Internal combustion engine 10 emits a rotational speed n. Exhaust-gas temperature sensor 14 outputs an exhaust-gas temperature signal Tabg, andlambda sensor 16 outputs a lambda signal lam_nK.Control unit 20 emits a fuel signal mK to a fuel-metering device 21. An exhaust-gas mass flow msabg occurs in exhaust-gas region 13. - Air signal msL is also provided to a deceleration fuel-
cutoff controller 30, atime delay 31 and a threshold-value definition 32. Deceleration fuel-cutoff controller 30 provides a deceleration fuel-cutoff signal 34 todiagnostic controller 33.Time delay 31 transmits a delayed air signal msL_d to anintegrator 35.Threshold value definition 32 supplies a first and asecond threshold value comparator 36. Rotational speed n is supplied to deceleration fuel-cutoff controller 30 and to threshold-value definition 32. -
Diagnostic controller 33 supplies a firstdiagnosis control signal 39 to threshold-value definition 32, a seconddiagnosis control signal 41 to a change-determination 40, and a diagnosis lambda lam_D to alambda setpoint selection 42. Diagnosis lambda lam_D is also supplied totime delay 31, which outputs a delayed lambda signal lam_d and provides it tointegrator 35.Diagnostic controller 33 is supplied with adiagnosis stop signal 43 provided bycomparator 36. - In addition to diagnosis lambda lam_D,
lambda setpoint selection 42 is supplied with a nominal operating lambda lam_N. Lambda-setpoint selection 42 transmits a lambda setpoint value lam_S to alambda controller 50, which provides fuel signal mK. Lambda signal lam_nk provided bylambda sensor 16 is not only supplied tolambda controller 50, but to a low-pass filter 51 as well.Lambda controller 50 is additionally provided with a lambda signal lam_vk, which reflects the excess air factor lambda in the exhaust gas upstream fromcatalytic converter 15. - Filtered lambda signal lam_nKF provided by low-
pass filter 51 arrives atchange determination 40.Integrator 35 providesintegration result 52 tocomparator 36, which outputs a fault signal F. -
FIGS. 2 a to 2 e illustrate signal characteristics as a function of location x. Illustrated areoxygen concentration % 02 as well as a reagent concentration % Rea.FIG. 2 a illustrates the situation at a first location x1 after a rich-lean jump has occurred after which a highoxygen concentration % 02 and a low reagent concentration % Rea are present.FIG. 2 b illustrates the situation at a later point in time when the concentration changes are present at a second location x2.FIG. 2 c illustrates the situation where a change occurs inconcentrations % 02, % Rea downstream from catalytic converter input Kat_In. A first transition region x10 comes about in whichoxygen concentration % 02 changes only slightly.FIG. 2 d illustrates the situation at a later point in time whenconcentrations % 02, % Rea change insidecatalytic converter 15. A second transition region x20 occurs, which has a greater expansion than first transition region x10.FIG. 2 e illustrates the situation whereconcentrations % 02, % Rea change largely downstream from catalytic converter output Kat_Out. A third transition region x30 comes about, which in turn has a greater expansion than second transition region x20. -
FIG. 3 illustrates lambda signal lam_nK as a function of time t. Up to a first point in time t1, lambda is to be 0.97. Afirst change 60 of lambda signal lam_nK occurs between the first and a second point in time t2. At a third point in time t3, lambda signal lam_nK has at least approximately aplateau 61 at which lambda is at least approximately 1. At a fourth point in time t4, asecond change 62 of lambda signal lam_nK sets in, which is concluded at a fifth point in time t5. After fifth point in time t5, lambda is to be at 1.03. - A method according to an example embodiment of the present invention operates as follows:
-
Lambda sensor 16 is arranged as broadband lambda sensor which is able to detect an excess air factor lambda lying in a wide range which, for example, is between 0.7 and 4.0.Lambda sensor 16 is located downstream from the at least onecatalytic converter 15. In larger catalytic converters,lambda sensor 16 may also be arranged downstream from a partial volume of the catalytic converter. Lambda signal lam_nK supplied bylambda sensor 16 may be used not only for diagnosis, but for regulation of the combustion lambda as well. For this reason, lambda signal lam_nK is supplied both to low-pass filter 51 and tolambda controller 50, which is able to influence fuel signal mK as a function of lambda signal lam_nK. A lambda signal lam_vK may be taken into consideration, which is measured upstream fromcatalytic converter 15 by a lambda sensor and supplied tolambda controller 50. -
Lambda controller 50 attempts to adjust a combustion lambda that corresponds to lambda setpoint value lam_S stipulated bylambda setpoint selection 42. During normal operation ofinternal combustion engine 10, lambda setpoint value lam_S corresponds to nominal-operation lambda lam_N. An open-loop control may be provided instead oflambda controller 50. Furthermore, lambda signal lam_vK, which reflects the excess air factor lambda in the exhaust gas upstream fromcatalytic converter 15, is not required. Lambda signal lam_nK detected downstream fromcatalytic converter 15 may be utilized instead. - To implement the catalytic converter diagnosis,
diagnostic controller 33 may stipulate diagnosis lambda lam_D, whichlambda setpoint selection 42 is to provide as lambda setpoint value lam_S. The diagnosis is prepared in that the oxygen reservoir ofcatalytic converter 15 is either approximately fully filled or emptied. Under the conditions illustrated inFIGS. 2 a to 2 e, a rich-lean jump at the beginning of the diagnosis is assumed in whichoxygen concentration % 02 is changed from a low to a high value. Due to the change in the lambda of the internal combustion engine from a rich to a lean value, a corresponding change from a high to a low value occurs in reagent concentration % Rea. To allow the diagnosis to be carried out, it may therefore be necessary thatcatalytic converter 15 be initially acted upon by a lowoxygen concentration % 02, until the point is reached where the oxygen reservoir is at least approximately empty. - As an alternative, an at least approximately completely full oxygen reservoir of
catalytic converter 15 may be assumed in whichcatalytic converter 15 is to be acted upon by a highoxygen concentration % 02 in he beginning. This operating state is already present in a sufficiently long deceleration fuel-cutoff phase ofinternal combustion engine 10. - It may therefore be provided that deceleration fuel-
cutoff controller 30, which determines the deceleration fuel-cutoff ofinternal combustion engine 10, from air signal msL and rotational speed n, for example, signals todiagnostic controller 30 via deceleration fuel-cutoff signal 34 that the diagnosis is able to be started. Deceleration fuel-cutoff signal 34 is supplied when the deceleration fuel-cutoff phase has been present for a sufficient length of time. - According to
FIG. 2 a, the change in lambda setpoint value lam_S to diagnosis lambda lam_D occurs upstream fromcatalytic converter 15 in the form of a jump ofoxygen concentration % 02 and in the form of a jump of reagent concentration % Rea in a first location x1. At a later point in time, the concentration changes move to second location x2 where the concentration transitions still have relatively steep characteristics. The originally jump-like concentration changes are already slightly flattened by diffusion and turbulence in exhaust-gas region 13. - The lean exhaust gas having a high
oxygen concentration % 02 displaces the rich exhaust gas having a high reagent concentration % Rea, which has only a very lowoxygen concentration % 02. In the situation illustrated inFIG. 2 c, the concentration changes meanwhile have arrived at a location downstream from catalytic converter input Kat_In. Once the highoxygen concentration % 02 has reachedcatalytic converter 15, the excess oxygen is stored incatalytic converter 15. First transition region x10 is created in which theoxygen concentration % 02 exhibitsfirst change 60. An at leastshort plateau 61 then occurs, which is left uponsecond change 62. - The reagent concentration % Rea drops to low values during
first change 60. Sincecatalytic converter 15 is unable to store the entire available oxygen,oxygen concentration % 02 that remains in first transition region x10 is higher than that in the rich exhaust gas. -
FIG. 2 d illustrates the situation in the concentration changes at a later point in time. Second transition region x20 has become longer compared to first transition region x10. -
FIG. 2 e illustrates the situation at an even later point in time when the concentration changes occur at least partially already downstream from catalytic converter output Kat_Out or downstream from a section ofcatalytic converter 15. It is only at this point in time that the concentration changes may be measured bylambda sensor 16. - In the beginning, lambda signal lam_nK of
lambda sensor 16 will indicate a rich exhaust gas lambda, which is set to 0.97, for example.FIG. 3 illustrates the time characteristic in which the oxygen deficiency is to exist up to first point in time t1. The change in theoxygen concentration % 02 is to begin at first point in time t1, withfirst change 60. The analysis of lambda signal lam_nK takes place inchange determination 40 afterdiagnostic controller 33 has output seconddiagnosis control signal 41 to changedetermination 40. - In order to prevent faulty measurements, low-
pass filter 51 is provided, which rids lambda signal lam_nK of high-frequency interference signals on the one hand and of rapid changes caused by dynamic processes that are unrelated tofirst change 60 on the other hand.Change determination 40 may then be provided with filtered lambda signal lam_nKF instead of lambda signal lam_nK. - To detect
first change 60,change detection 40 may determine, for example, the gradient of lambda signal lam_nk or filtered lambda signal lam_nKF. The gradient may be ascertained continuously, in rapid time succession. It may be approximated by difference quotients, for example. For example, the gradient may be compared to a predefined gradient threshold value. When the gradient threshold value is exceeded, integrator enablesignal 53 is supplied. It may be provided that the gradient must exceed the gradient threshold value for a predefined period of time before integrator enablesignal 53 is made available. Additionally or alternatively, the presence of a point of inflection of lambda signal lam_nK or of filtered lambda signal lam_nKF may be determined and utilized to provide integrator enablesignal 53. Furthermore, in addition or as an alternative, it may be provided that the maximum of the gradient is determined first and that it is then checked whether the gradient falls below a threshold value before integrator enablesignal 53 is provided. - The diagnosis of the catalytic converter may begin as soon as
first change 60 is detected. Ascertained is the oxygen being stored incatalytic converter 15. This may be the oxygen mass or the oxygen quantity. The determination may be implemented, for example, in thatintegrator 35 multiplies the value (1−1/lambda) by air signal msL and a constant that corresponds to the percentage oxygen content of the air and integrates it as a function of time. For a relative valuation, the constant may be set to equal 1. To take the gas propagation time throughcatalytic converter 15 into account, air signal msL provided byair detection 12 may be delayed intime delay 31 and made available tointegrator 35 as delayed air signal msL_d. In addition, the lambda on which the integration is based may be delayed intime delay 31. The combustion lambda during the diagnosis corresponds to the predefined diagnosis lambda lam_D, which is forwarded tointegrator 35 as delayed lambda signal lam_d. The delay of lambda may be omitted since diagnosis lambda lam_D is generally kept constant during the diagnosis. - The delay time to be input may depend on air signal msL. Furthermore, the delay time may be a function of the load of
internal combustion engine 10. For example, the load may be indicated by fuel signal mK, possibly in conjunction with rotational speed n, or by a torque of the combustion engine known to controlunit 20. - As illustrated in
FIG. 3 , the determination of the oxygen takes place in the region ofplateau 61 of lambda signal lam_nK or filtered lambda signal lam_nKF.Plateau 61 is more or less pronounced. Duringplateau 61, lambda may change from a value of just below 1 to a value of just above 1. The lambda values may change between 0.99 and 1.01 in a rich-lean jump and between 0.998 and 1.002 in a lean-rich jump. - According to an example embodiment of the present invention, the integration is ended when
second change 62 occurring at fourth point in time t4 is detected. The determination ofsecond change 62 may be implemented analogously to the already described determination offirst change 60. With the occurrence ofsecond change 62, integrator enablesignal 53 is reversed and the integration concluded.Integration result 52, which reflects a measure of the oxygen storage/oxygen discharge or reagent storage, is compared tofirst threshold value 37 provided by threshold-value definition 32. If a threshold has been exceeded, which signals a poor catalytic converter,comparator 36 provides fault signal F which is stored in a fault memory, for example, or is able to be displayed. - According to an example embodiment of the present invention, the integration may be ended even before
second change 62 is reached. In this situation,integration result 52 is compared tosecond threshold value 38, which is provided by threshold-value definition 32 and defined to a value that corresponds to a good or properly functioningcatalytic converter 15. If integration result 52 already corresponds to a properly functioningcatalytic converter 15, the catalytic converter diagnosis may be terminated even beforesecond change 62 is able to be detected. - If first or
second threshold value comparator 36 providesdiagnosis stop signal 43, which inducesdiagnostic controller 33 to terminate the diagnosis. First and second diagnosis control signals 39, 41 are canceled for this purpose.Change determination 40 cancels integrator enablesignal 53, thereby resettingintegrator 35 to an initial state, which is subsequently available for a new determination of the oxygen. - Threshold-
value definition 32 may stipulate first and/orsecond threshold value catalytic converter 15 may be utilized as measure for the temperature of the catalytic converter. Air signal msL is a measure for exhaust gas mass flow msabg, which, just as the catalytic converter temperature/exhaust gas temperature Tabg, has an influence on the oxygen storage capacity of catalytic converter. - Exhaust gas temperature Tabg may be measured by
temperature sensor 14. Exhaust gas temperature Tabg may be able to be measured at least approximately on the basis of air signal msL and, for example, fuel signal mK as a measure for the load ofinternal combustion engine 10.
Claims (15)
1. A method for operating an internal combustion engine, at least one catalytic converter arranged in an exhaust-gas region of the internal combustion engine, a lambda sensor arranged as a broadband lambda sensor and arranged downstream from one of (a) the catalytic converter and (b) a section of the catalytic converter, comprising:
performing a catalytic converter diagnosis based on a measure for an oxygen storage capacity at least one of (a) of and (b) within the catalytic converter based on an oxygen reservoir of the catalytic converter that is at least approximately one of (a) empty and (b) full, and in which a change in a lambda setpoint value of the internal combustion engine to an excess air lambda that is one of (a) greater than 1 and (b) less than 1 is implemented;
detecting a first change in a lambda signal provided by the broadband lambda sensor;
ascertaining an oxygen stored/discharged after the first change; and
terminating ascertaining of the stored/discharged oxygen when either: (a) a second change of the lambda signal is determined; or (b) a predefined measure of oxygen was stored/discharged.
2. The method according to claim 1 , wherein the change of the lambda signal is determined from a gradient of the lambda signal.
3. The method according to claim 2 , wherein the change is detected when the gradient exceeds a predefined gradient threshold value for a predefined time period.
4. The method according to claim 2 , wherein the change is detected when the gradient has a maximum.
5. The method according to claim 2 , wherein the change is detected when the gradient has exceeded a maximum and subsequently falls below a gradient threshold value.
6. The method according to claim 1 , further comprising low-pass filtering of the lambda signal provided by the lambda sensor.
7. The method according to claim 1 , wherein the oxygen is determined from an integral over time, which is a function of a diagnosis lambda predefined during the diagnosis, and of an air signal, which is provided by an air detection, which detects combustion air provided to the internal combustion engine.
8. The method according to claim 7 , wherein the air signal is buffer-stored for a delay time that corresponds to a gas propagation time before the broadband lambda sensor is reached.
9. The method according to claim 8 , wherein the delay time is a function of at least one of (a) the air signal and (b) a load of the internal combustion engine.
10. The method according to claim 1 , wherein one of (a) the oxygen reservoir of the catalytic converter and (b) a section of the catalytic converter is at least approximately completely one of (a) filled and (b) emptied prior to the catalytic converter diagnosis by specifying a combustion lambda that is one of (a) greater than 1 and (b) less than 1.
11. The method according to claim 10 , wherein the combustion lambda that is one of (a) greater than 1 and (b) less than 1 is specified within the framework of normal operation of the internal combustion engine.
12. The method according to claim 1 , wherein the catalytic converter diagnosis is implemented following a deceleration fuel-cutoff phase of the internal combustion engine by which the oxygen reservoir of the catalytic converter is at least approximately filled.
13. The method according to claim 1 , wherein the evaluation of the stored/discharged oxygen is implemented as a function of at least one of (a) a catalytic converter temperature, (b) an exhaust gas temperature and (b) an exhaust gas mass flow.
14. A device for operating an internal combustion engine, comprising:
a control device configured to perform a method, at least one catalytic converter arranged in an exhaust-gas region of the internal combustion engine, a lambda sensor arranged as a broadband lambda sensor and arranged downstream from one of (a) the catalytic converter and (b) a section of the catalytic converter, the method including:
performing a catalytic converter diagnosis based on a measure for an oxygen storage capacity at least one of (a) of and (b) within the catalytic converter based on an oxygen reservoir of the catalytic converter that is at least approximately one of (a) empty and (b) full, and in which a change in a lambda setpoint value of the internal combustion engine to an excess air lambda that is one of (a) greater than 1 and (b) less than 1 is implemented;
detecting a first change in a lambda signal provided by the broadband lambda sensor;
ascertaining an oxygen stored/discharged after the first change; and
terminating ascertaining of the stored/discharged oxygen when either: (a) a second change of the lambda signal is determined; or (b) a predefined measure of oxygen was stored/discharged.
15. The device according to claim 14 , wherein the control unit includes:
a diagnostic controller adapted to change the lambda setpoint value;
a change determination adapted to process the lambda signal; and
an integrator adapted to determine a measure for the stored/discharged oxygen.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102005002237.5 | 2005-01-18 | ||
DE102005002237A DE102005002237A1 (en) | 2005-01-18 | 2005-01-18 | Method for operation of internal combustion engine involves broadband lambda sensor whereby first change of lambda signal by sensor is determined and oxygen discharged after first change is determined |
Publications (1)
Publication Number | Publication Date |
---|---|
US20060168943A1 true US20060168943A1 (en) | 2006-08-03 |
Family
ID=36636844
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/334,970 Abandoned US20060168943A1 (en) | 2005-01-18 | 2006-01-18 | Method for operating an internal combustion engine and device for implementing the method |
Country Status (4)
Country | Link |
---|---|
US (1) | US20060168943A1 (en) |
DE (1) | DE102005002237A1 (en) |
FR (1) | FR2880921A1 (en) |
SE (1) | SE529485C2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110082665A1 (en) * | 2009-10-05 | 2011-04-07 | Yamatake Corporation | Stick-slip detecting device and detecting method |
US20110106396A1 (en) * | 2008-01-14 | 2011-05-05 | Robert Bosch Gmbh | Method and controller for checking an exhaust gas aftertreatment system of an internal combustion engine |
US20110224949A1 (en) * | 2010-03-12 | 2011-09-15 | Yamatake Corporation | Stick-slip detecting device and detecting method |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102006041479B4 (en) | 2006-09-05 | 2023-03-30 | Robert Bosch Gmbh | Method for determining the oxygen storage capacity of an exhaust gas cleaning system |
DE102006059587A1 (en) * | 2006-12-16 | 2008-06-19 | Volkswagen Ag | Method for determining condition value of catalyzer arranged in exhaust gas unit of internal combustion engine, involves operating internal combustion engine to certain time point in throttle cutoff phase |
DE102006062516A1 (en) * | 2006-12-29 | 2008-07-03 | Volkswagen Ag | Catalytic converter i.e. three-way catalytic converter, oxygen storage capacity determining method for exhaust gas system of internal combustion engine of motor vehicle, involves determining oxygen storage capacity based on oxygen amount |
DE102017219185A1 (en) * | 2017-10-26 | 2019-05-02 | Bayerische Motoren Werke Aktiengesellschaft | A method of determining a condition of a catalyst and exhaust aftertreatment device |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3962866A (en) * | 1973-01-31 | 1976-06-15 | Robert Bosch G.M.B.H. | Internal combustion exhaust catalytic reactor monitoring system |
US5088281A (en) * | 1988-07-20 | 1992-02-18 | Toyota Jidosha Kabushiki Kaisha | Method and apparatus for determining deterioration of three-way catalysts in double air-fuel ratio sensor system |
US5267472A (en) * | 1991-04-17 | 1993-12-07 | Robert Bosch Gmbh | Method and arrangement for determining the performance loss of a catalyzer |
US5303580A (en) * | 1991-04-17 | 1994-04-19 | Robert Bosch Gmbh | Method and arrangement for determining the state of deterioration of a catalyzer |
US6874313B2 (en) * | 2003-02-18 | 2005-04-05 | General Motors Corporation | Automotive catalyst oxygen storage capacity diagnostic |
US7028464B2 (en) * | 2001-04-05 | 2006-04-18 | Siemens Aktiengellschaft | Method for purifying exhaust gas of an internal combustion engine |
US7159385B2 (en) * | 2003-12-16 | 2007-01-09 | Toyota Jidosha Kabushiki Kaisha | Apparatus for and method of detecting deterioration of catalyst in internal combustion engine |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3310336A1 (en) * | 1982-03-23 | 1983-10-06 | Toyota Motor Co Ltd | METHOD FOR MEASURING AN OXYGEN CONCENTRATION AND METHOD FOR REGULATING AN AIR / FUEL RATIO BASED ON THE MEASURED OXYGEN CONCENTRATION |
US6292739B1 (en) * | 1998-12-17 | 2001-09-18 | Honda Giken Kogyo Kabushiki Kaisha | Air-fuel ratio control system for internal combustion engine |
JP3680217B2 (en) * | 2000-06-26 | 2005-08-10 | トヨタ自動車株式会社 | Air-fuel ratio control device for internal combustion engine |
-
2005
- 2005-01-18 DE DE102005002237A patent/DE102005002237A1/en not_active Withdrawn
- 2005-12-21 SE SE0502840A patent/SE529485C2/en not_active IP Right Cessation
-
2006
- 2006-01-17 FR FR0650147A patent/FR2880921A1/en active Pending
- 2006-01-18 US US11/334,970 patent/US20060168943A1/en not_active Abandoned
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3962866A (en) * | 1973-01-31 | 1976-06-15 | Robert Bosch G.M.B.H. | Internal combustion exhaust catalytic reactor monitoring system |
US5088281A (en) * | 1988-07-20 | 1992-02-18 | Toyota Jidosha Kabushiki Kaisha | Method and apparatus for determining deterioration of three-way catalysts in double air-fuel ratio sensor system |
US5267472A (en) * | 1991-04-17 | 1993-12-07 | Robert Bosch Gmbh | Method and arrangement for determining the performance loss of a catalyzer |
US5303580A (en) * | 1991-04-17 | 1994-04-19 | Robert Bosch Gmbh | Method and arrangement for determining the state of deterioration of a catalyzer |
US7028464B2 (en) * | 2001-04-05 | 2006-04-18 | Siemens Aktiengellschaft | Method for purifying exhaust gas of an internal combustion engine |
US6874313B2 (en) * | 2003-02-18 | 2005-04-05 | General Motors Corporation | Automotive catalyst oxygen storage capacity diagnostic |
US7159385B2 (en) * | 2003-12-16 | 2007-01-09 | Toyota Jidosha Kabushiki Kaisha | Apparatus for and method of detecting deterioration of catalyst in internal combustion engine |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110106396A1 (en) * | 2008-01-14 | 2011-05-05 | Robert Bosch Gmbh | Method and controller for checking an exhaust gas aftertreatment system of an internal combustion engine |
US20110082665A1 (en) * | 2009-10-05 | 2011-04-07 | Yamatake Corporation | Stick-slip detecting device and detecting method |
US9026397B2 (en) | 2009-10-05 | 2015-05-05 | Azbil Corporation | Stick-slip detecting device and detecting method |
US20110224949A1 (en) * | 2010-03-12 | 2011-09-15 | Yamatake Corporation | Stick-slip detecting device and detecting method |
Also Published As
Publication number | Publication date |
---|---|
SE529485C2 (en) | 2007-08-21 |
SE0502840L (en) | 2006-07-19 |
FR2880921A1 (en) | 2006-07-21 |
DE102005002237A1 (en) | 2006-07-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6843240B1 (en) | Method for monitoring the functioning of a NOx sensor arranged in an exhaust gas channel of an internal combustion engine | |
KR101261363B1 (en) | Method and device for determining the oxygen storage capacity of the exhaust gas catalytic converter of an internal combustion engine, and method and device for determining a dynamic time duration for exhaust gas probes of an internal combustion engine | |
JP4490913B2 (en) | Method for inspecting at least three sensors for detecting measurement variables within the range of an internal combustion engine | |
JP5024405B2 (en) | Catalyst degradation detector | |
US7520274B2 (en) | Air fuel ratio sensor deterioration determination system for compression ignition internal combustion engine | |
US20040074226A1 (en) | Exhaust emission control system and method | |
US7918086B2 (en) | System and method for determining a NOx storage capacity of catalytic device | |
US20060168943A1 (en) | Method for operating an internal combustion engine and device for implementing the method | |
US6804951B2 (en) | On-board diagnostic catalyst monitoring system | |
US9309799B2 (en) | Method and device for determining the oxygen storage capacity of an emission control system | |
EP3255257A1 (en) | Internal combustion engine and exhaust-gas-component estimating method | |
EP3124763A1 (en) | Abnormality diagnosis apparatus for nox storage reduction catalyst | |
US10161329B2 (en) | Upstream NOx estimation | |
US7513105B2 (en) | Exhaust gas purifying system and abnormality determining method therefor | |
JP2007332914A (en) | Catalyst deterioration detecting device | |
US6632764B2 (en) | Method for controlling the regeneration of an NOx storage converter | |
US20070084196A1 (en) | System and method for determining a NOx storage capacity of a catalytic device | |
US20040226282A1 (en) | Abnormality detecting system for oxygen sensor and abnormality detecting method | |
EP1544441B1 (en) | System for and method of detecting deterioration of catalyst in internal combustion engine | |
US20110106396A1 (en) | Method and controller for checking an exhaust gas aftertreatment system of an internal combustion engine | |
JP2010001803A (en) | Catalyst deterioration determination device | |
US5815828A (en) | Method of measuring temperature of a catalytic converter | |
JP6610874B2 (en) | Catalyst deterioration judgment device | |
US20150275737A1 (en) | Method for monitoring the formation of nitrogen dioxide at an oxidation catalytic converter, and exhaust system | |
GB2542229A (en) | Method for determining a state of aging of an NOx storage catalyst of an exhaust gas aftertreatment system of an internal combustion engine designed for |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ROBERT BOSCH GMBH, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SCHNAIBEL, EBERHARD;WAGNER, JENS;WEHMEIER, KERSTEN;AND OTHERS;REEL/FRAME:017796/0236;SIGNING DATES FROM 20060224 TO 20060315 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |