CN114962032B - Engine wide-range oxygen sensor degradation diagnosis method - Google Patents
Engine wide-range oxygen sensor degradation diagnosis method Download PDFInfo
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- CN114962032B CN114962032B CN202210642923.1A CN202210642923A CN114962032B CN 114962032 B CN114962032 B CN 114962032B CN 202210642923 A CN202210642923 A CN 202210642923A CN 114962032 B CN114962032 B CN 114962032B
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- 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
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D41/222—Safety or indicating devices for abnormal conditions relating to the failure of sensors or parameter detection devices
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- 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
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- 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
- F02D41/22—Safety or indicating devices for abnormal conditions
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- 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
- F02D41/30—Controlling fuel injection
- F02D41/3005—Details not otherwise provided for
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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- Y02T10/10—Internal combustion engine [ICE] based vehicles
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Abstract
The invention discloses a method for diagnosing the deterioration of an engine wide-area oxygen sensor, which comprises the following steps: collecting an oxygen concentration signal of exhaust gas in an exhaust pipe after combustion through a wide-range oxygen sensor; calculating an air-fuel ratio according to the oxygen concentration signal to generate an actual air-fuel ratio signal; controlling the fuel injection quantity and the fuel injection timing of the engine to adjust the air-fuel ratio according to the air-fuel ratio signal to generate an adjusted actual air-fuel ratio signal; respectively establishing an actual fuel equivalent ratio and a target fuel equivalent ratio according to the ideal air-fuel ratio, the adjusted actual air-fuel ratio and a preset target air-fuel ratio; and (4) selecting degradation diagnosis according to the comparison of the difference value between the actual fuel equivalence ratio and the target fuel equivalence ratio or the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount, and judging whether the wide-area oxygen sensor fails. According to the invention, whether the oxygen sensor is normal or not is monitored in real time, and the failure judgment of the oxygen sensor is rapidly carried out; meanwhile, the fuel equivalence ratio reflecting conditions in the air-fuel ratio control process of different degrees are monitored under the steady state working condition, and whether the wide-range oxygen sensor is deteriorated or invalid is verified.
Description
Technical Field
The invention belongs to the field of engine control, and particularly relates to a method for diagnosing the degradation of an engine wide-range oxygen sensor.
Background
The wide-range oxygen sensor is an important sensor for closed-loop control of the air-fuel ratio, and can accurately output a signal of the air-fuel ratio.
In the light automobile pollutant emission limit and measurement method (sixth stage of china), the diagnostic requirements for the front oxygen sensor are explicitly set forth: OBD systems monitor the failure of pre-oxygen sensors (sensors for fuel control, conventional switch-type oxygen sensors and/or wide-area or universal sensors) including output voltage, response rate and parameters that may affect emissions.
The hybrid vehicle type (including an engine, a driving motor and a generator) is a popular vehicle type at present, and the hybrid vehicle type includes the engine. The range and the running time of the engine running working condition in the hybrid vehicle type are much narrower than those of a transmission gasoline vehicle, and the purpose is to improve the fuel economy, the vehicle drivability, the emission performance, the NVH and the like.
When the wide-area oxygen sensor has performance faults, if the rich-lean change of the air-fuel ratio cannot be accurately reflected, the wide-area oxygen sensor needs to be diagnosed in time. After the fault occurs, the fault post-treatment is carried out in time, so that the influence on fuel economy, vehicle drivability, emission performance, NVH and the like is reduced.
Disclosure of Invention
The invention aims to provide a method for diagnosing the degradation of an engine wide-range oxygen sensor, which can quickly judge the failure of the oxygen sensor by monitoring whether the oxygen sensor is normal or not in real time; meanwhile, the fuel equivalence ratio reflecting conditions in the air-fuel ratio control process of different degrees are monitored under the steady state working condition, and whether the wide-range oxygen sensor is deteriorated or invalid is verified.
In order to solve the technical problems, the technical scheme of the invention is as follows: the method for diagnosing the degradation of the wide-range oxygen sensor of the engine comprises the following steps:
collecting an oxygen concentration signal of exhaust gas in an exhaust pipe after combustion through a wide-range oxygen sensor;
calculating an air-fuel ratio according to the oxygen concentration signal to generate an actual air-fuel ratio signal;
controlling the fuel injection quantity and the fuel injection timing of the engine to adjust the air-fuel ratio according to the air-fuel ratio signal, and generating an adjusted actual air-fuel ratio signal;
respectively establishing an actual fuel equivalence ratio and a target fuel equivalence ratio according to the ideal air-fuel ratio, the adjusted actual air-fuel ratio and a preset target air-fuel ratio; wherein, the actual fuel equivalence ratio is represented as the ratio of the adjusted actual air-fuel ratio to the ideal air-fuel ratio, and the target fuel equivalence ratio is represented as the ratio of the target air-fuel ratio to the ideal air-fuel ratio;
the target fuel equivalence ratio is a reference value relative to the actual fuel equivalence ratio and changes along with the sampling data of the actual fuel equivalence ratio, and the sampling data at least comprises an actual fuel quantity entering the cylinder in unit time and an actual fresh air quantity entering the cylinder in unit time;
and selecting corresponding degradation diagnosis according to the comparison of the difference value between the actual fuel equivalence ratio and the target fuel equivalence ratio or the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount, and judging whether the wide-area oxygen sensor fails.
According to actual combustionEstablishing a target fuel equivalence ratio FEQR when the fuel equivalence ratio is compared with a target fuel equivalence ratio difference value Normal The method comprises the following steps:
creating an array [ FEQR ] for actual fuel equivalence ratio 0 ,FEQR 1 ,…,FEQR s-1 ,FEQR s ,…FEQR j ]Each element in the array represents the actual fuel equivalence ratio provided by the real-time wide-range oxygen sensor, the initial values of the elements are equal, and the numerical values of the elements are updated once every other interval of one same preset sampling period;
determining the sampling number V of elements in the array according to the rotating speed of the engine after filtering and the fresh air intake flow of the cylinder after filtering;
after the sampling number V is obtained by calculation, the FEQR is obtained by calculation according to the following formula Normal ：
Wherein i =0,1,2, \8230;, V-1, when s-i < 0, FEQR s-i ＝FEQR j+s-i 。
With FEQR 0 For example, the method for updating the elements in the actual fuel equivalence ratio array is as follows:
wherein, the delta FEQR is the updated change value of the current sampling period,
is an updated change value of the last sample period, is asserted>
Actual fuel equivalence ratio read for the previous sampling period, Δ T being the sampling period, T c Is a constant of time, and is,
the target fuel equivalence ratio of the last sampling period;
sequentially updating the values of the elements in the above formula, wherein the FEQR is calculated 0 Replacing the numerical value of the target fuel-oil ratio read in the last sampling period with the numerical value of the target fuel-oil ratio read in the last sampling period;
namely, the following steps are included:
up to FEQR j Finishing the updating, namely finishing one-time updating;
jump to FEQR 0 With FEQR 0 And starting updating, namely starting the next updating and performing the next updating.
The predetermined failure difference value is represented as a × dm AirFilt + b, formula (I) is dm AirFilt For filtered post-cylinder fresh air intake flow, a is 204.53 (1/mgps), and b is-20.62.
Before catalyst converter oxygen storage volume accounts for total oxygen storage volume ratio and selects the degradation diagnosis, carry out operating mode condition and detect, be suitable for when satisfying operating mode condition and account for total oxygen storage volume ratio through catalyst converter oxygen storage volume and select the degradation diagnosis, operating mode condition includes:
the rotating speed of the engine is in a certain range; the relevant diagnosis of the engine speed does not have fault;
the engine has no oil cut;
the heating of the wide-range oxygen sensor is completed, namely the wide-range oxygen sensor is within the normal working temperature; no fault occurs in the wide-area oxygen sensor heating diagnosis;
the accelerator is not fully opened, and the opening degree of an accelerator pedal is in a certain range; the accelerator opening sensor diagnoses no fault;
the temperature of the engine cooling water exceeds a certain value; the cooling temperature sensor is diagnosed without fault;
the temperature of the intake manifold of the engine exceeds a certain value; no fault occurs in the intake manifold temperature sensor diagnosis;
when the running time of the engine exceeds a certain value, the engine is successfully warmed up;
the air inflow in the air inlet cylinder is in a certain range; relevant diagnosis for monitoring or calculating the air input does not have faults;
the vehicle speed exceeds a certain value; the relevant diagnosis of the vehicle speed does not have fault;
and when the working condition is met, allowing the wide-range oxygen sensor to enter the degradation diagnosis.
After the working condition is met, detecting the working condition stable condition, wherein the working condition stable condition comprises the following steps:
the engine speed fluctuates within a certain range;
the opening degree of an accelerator pedal fluctuates within a certain range;
the vehicle speed fluctuates within a certain range;
the amount of intake air entering the cylinder fluctuates within a certain range;
and after the working condition stable condition and the working condition are both met, performing degradation diagnosis on the wide-range oxygen sensor.
After the working condition stable condition and the working condition are both met, when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is smaller than a first oxygen storage amount threshold value r1, the target fuel equivalent ratio is periodically controlled, the oxygen storage amount of the catalyst is insufficient at the moment, and the first preset time T is used Base Performing an enrichment operation, the enrichment operation comprising: increasing the oxygen concentration and setting the equivalence ratio of the enriched target fuel oil to r FEQRRichBase Greater than 1, and then for a second preset time T Min Performing a lean-down operation, the lean-down operation comprising: reducing the oxygen concentration, and setting the lean target fuel equivalence ratio to r FEQRLeanBase Less than 1; alternately repeating enrichment operation and lean operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-area oxygen sensor in real time, and calculating the first rich-bias reflecting time T of the actual fuel equivalence ratio RichResDn And a second rich partial reflecting time T RichResUp (ii) a Wherein T is Base Greater than T Min ；
T RichResDn The method for judging the initial calculation time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRRichBase Is less than the preset difference value Delta C, and the actual fuel equivalence ratio and r in the next sampling period FEQRRichBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is greater than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
T RichResDn the judgment method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is greater than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T RichResUp the method for starting to calculate the time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to deltaC; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRRichBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is less than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T RichResUp method for ending calculation time: actual fuel equivalence ratio and r in current sampling period FEQRRichBase Is less than deltac and the actual fuel equivalence ratio is compared with r in the next sampling period FEQRRichBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is greater than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
at T RichResDn Read three elements T arbitrarily RichResDn11 ，T RichResDn12 And T RichResDn13 N0 elements corresponding to the number of enrichment operations exist in the TRichResDn array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
At T RichResUp Read three elements T arbitrarily RichResUp11 ，T RichResUp12 And T RichResUp13 ，T RichResUp N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
And when any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
is greater than
Judging that the wide-area oxygen sensor has a fault; wherein->
The average cylinder fresh air intake flow after diagnosis; d 2 ，d 1 ，d 0 Respectively a second evaluation coefficient, a first evaluation coefficient and an initial evaluation coefficient, wherein d 2 ，d 1 ，d 0 At different r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(2)
is greater than
Judging that the wide-area oxygen sensor has a fault; d 5 ，d 4 ，d 3 Respectively a fifth evaluation coefficient, a fourth evaluation coefficient and a third evaluation coefficient, wherein d 5 ，d 4 ，d 3 At different r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(3)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference between the two values,
and &>
Either the difference absolute value is greater than->
Judging that the wide-area oxygen sensor has a fault; d 9 ，d 8 Respectively a ninth evaluation coefficient and an eighth evaluation coefficient, wherein d 9 ，d 8 In different->
Then, the fitting data is obtained according to the calibration fitting data of the fault oxygen sensor and the fault-free oxygen sensor;
when any fault is determined in the above 3 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
After the working condition stable condition and the working condition are both met, when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is larger than or equal to a first oxygen storage amount threshold value r1 and smaller than or equal to a second oxygen storage amount threshold value r2, the target fuel equivalent ratio is periodically controlled, the oxygen storage amount of the catalyst is sufficient at the moment, and the first preset time T is used Base Carrying out an enrichment operation and then setting a first preset time T Base Carrying out a thinning operation; alternately repeating enrichment operation and lean operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-area oxygen sensor in real time, and calculating the first rich-bias reflecting time T of the actual fuel equivalence ratio RichResDn Second rich reflecting time T RichResUp First partial dilution reflecting time T LeanResDn And a second lean reaction time T LeanResUp ；
T LeanResDn The method for judging the initial calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than a preset difference value delta C, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is greater than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T LeanResDn the judgment method for ending the calculation time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRLeanBase Is less than deltac and the actual fuel equivalence ratio is compared with r in the next sampling period FEQRLeanBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is greater than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
T LeanResUp the method for starting to calculate the time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRLeanBase Is less than deltac and the actual fuel equivalence ratio is compared with r in the next sampling period FEQRLeanBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is less than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
T LeanResUp method for ending calculation time: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to deltaC; the actual fuel equivalence ratio is greater than r for the first occurrence in a subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is greater than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
at T LeanResDn Read three elements T arbitrarily LeanResDn11 ，T LeanResDn12 And T LeanResDn13 N0 elements corresponding to the number of enrichment operations exist in the TLeanResDn array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
At T LeanResUp Read three elements T arbitrarily LeanResUp11 ，T LeanResUp12 And T LeanResUp13 ，T LeanResUp N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
And when any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
and &>
Any one of (1) above time greater than or equal to>
Judging that the wide-area oxygen sensor has a fault;
(2)
and &>
Is greater than->
Judging that the wide-area oxygen sensor has a fault;
(3)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference between the two values,
and &>
Absolute value of the difference->
And &>
The absolute value of the difference, is greater than or equal to>
And
the absolute value of the difference, is greater than or equal to>
And &>
Either the difference absolute value is greater than->
Judging that the wide-area oxygen sensor has a fault; d 7 ，d 6 Respectively a seventh evaluation coefficient and a sixth evaluation coefficient, wherein d7 and d6 are different in r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(4)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
Absolute value of the difference，
And &>
The absolute value of the difference, is greater than or equal to>
And &>
Absolute value of the difference->
And
absolute value of the difference->
And &>
Any value greater than ^ on the absolute value of the difference>
Judging that the wide-area oxygen sensor has a fault;
when any fault is determined in the above 4 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
After the working condition stable condition and the working condition are both met, when the ratio of the oxygen storage amount of the catalytic converter to the total oxygen storage amount is larger than r2, the oxygen storage amount is too high, the thinning operation is carried out within a first preset time TBase, and then the thickening operation is carried out within a second preset time TMin; alternately repeating the lean operation and the rich operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first lean reflection time T of the actual fuel equivalence ratio LeanResDn And a second lean reflection time T LeanResUp ；
And when any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
and &>
Is greater than
Judging that the wide-area oxygen sensor has a fault;
(2)
and &>
Is greater than
Judging that the wide-area oxygen sensor has a fault;
(3)
and &>
Absolute value of the difference->
And &>
The absolute value of the difference between the two values,
and &>
Any one of the absolute values of the differenceGreater than or equal to>
Judging that the wide-area oxygen sensor has a fault;
when any fault is determined in the above 3 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
The stoichiometric air-fuel ratio was 14.3.
Compared with the prior art, the invention has the beneficial effects that:
rapidly judging the failure of the oxygen sensor by monitoring whether the oxygen sensor is normal or not in real time; meanwhile, the fuel equivalence ratio reflecting conditions in the air-fuel ratio control process of different degrees are monitored under the steady state working condition, and whether the wide-range oxygen sensor is deteriorated or invalid is verified.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The technical scheme of the invention is as follows: an engine wide-area oxygen sensor degradation diagnosis method.
Hardware level: the control system comprises an engine controller EMS, a wide-range oxygen sensor intelligent driving chip and a wide-range oxygen sensor.
The wide-range oxygen sensor is used for providing a current post-combustion oxygen concentration signal in exhaust gas in an exhaust pipe to an engine controller EMS;
the intelligent driving chip of the wide-area oxygen sensor collects and processes an oxygen concentration signal monitored by the wide-area oxygen sensor, converts the oxygen concentration signal into an air-fuel ratio related signal, and heats the wide-area oxygen sensor to ensure that the oxygen sensor works at a normal temperature;
and the engine controller EMS adjusts the air-fuel ratio in the engine cylinder by controlling the fuel injection quantity, the fuel injection timing and the like of the engine according to the air-fuel ratio related signal in the exhaust pipe processed by the intelligent chip of the wide-range oxygen sensor.
The oxygen concentration in the exhaust pipe is too low, and the exhaust pipe is called as 'over-concentration'; too high a concentration of oxygen in the exhaust pipe is called "over-lean";
the wide-range oxygen sensor provides the current concentration of air in the exhaust pipe to an engine controller EMS, and the current concentration is represented by using the reciprocal of an excess air coefficient lambda, namely a fuel equivalence ratio, in the embodiment, FEQR is used for representing the fuel equivalence ratio:
oxygen sensor reflects reality
/>
Then setting the target air-fuel ratio may be done by setting the target FEQR, then there is a target
"actual fuel" refers to the actual amount of fuel entering the cylinder per unit time, "actual air" refers to the actual amount of fresh air entering the cylinder per unit time, "target fuel" refers to the target amount of fuel entering the cylinder per unit time, "target air" refers to the target amount of fresh air entering the cylinder per unit time, "ideal air" refers to the ideal amount of fresh air entering the cylinder per unit time, and "ideal fuel" refers to the ideal amount of fuel entering the cylinder per unit time. The target is not equal to the ideal, and the target value can be actively changed according to the working condition of the engine, but the ideal value is determined by the oil product.
When the engine is out of oil, the FEQR is 0; when the concentration is too high, the FEQR is more than 1; when the concentration is too dilute, the FEQR is less than 1; when the FEQR is equal to 1, the air-fuel ratio is currently at the stoichiometric air-fuel ratio (FEQR is equal to 1, which means the ratio of the actual air amount to the actual fuel amount, and the ratio of the stoichiometric air amount to the stoichiometric fuel amount are equal to each other, the stoichiometric air-fuel ratio is 14.3 in the present embodiment).
The first wide-area oxygen sensor degradation diagnosis method includes:
and monitoring the actual FEQR fed back by the oxygen sensor in real time, estimating the real-time target FEQR, comparing the difference between the two, and when the difference deviation is overlarge, the wide-area oxygen sensor breaks down.
Establishing real-time target FEQR = FEQR Normal . First, an array [ FEQR ] is established 0 ,FEQR 1 ,…,FEQR s-1 ,FEQR s ,…FEQR j ](the number of elements of the array of the present embodiment is 9, i.e., j = 8). The array [ FEQR ] is set at the time of engine start 0 ,FEQR 1 ,…,FEQR s-1 ,FEQR s ,…FEQR j ]The initial values of the elements are the actual FEQR fed back by the oxygen sensor in real time, i.e., all values are equal. The array is updated all at the same time sample period Δ T (2 ms in this example).
1. And updating the numerical value of each element in real time based on the sampling period delta T.
1) First updating FEQR 0 The values of the other elements are unchanged:
wherein the content of the first and second substances,
is the value of the last sampling period of Δ FEQR @>
Actual FEQR, read for the last sample period, is initially @>
Take a fixed value C (1 in this embodiment), Δ T is the sampling period, T c Is a time constant (5 ms in this example). />
Target FEQR, particularly FEQR, for a previous time sampling period Normal (0) Is an initial value of the target FEQR model equal to the actual FEQR fed back by the real-time oxygen sensor. FEQR diagnostic apparatus Normal The calculation of (a) will be described in detail later.
2) The next time sampling period deltat updates the FEQR 1 The updating method is the same as FEQR 0 And the last time sampling period DeltaT FEQR is calculated 0 Is replaced by
(Note here ` Break `)>
And calculating FEQR 0 Is used at times->
The values are different because the sampling periods are different)
3) By analogy, calculating the FEQR of any element in the array s The method is the same as FEQR 1 The method of (3). If the last element of the array is FEQR j Updating FEQR from the beginning when the update calculation is completed 0 I.e., the values of the array elements are continually updated in a loop.
2. Obtaining real-time array [ FEQR 0 ,FEQR 1 ,…,FEQR s-1 ,FEQR s ,…FEQR j ]Then, determining the sampling number V of the numbers in the array required to be used for the target FEQR, and selecting an optimal sampling number to timely and accurately carry out fault diagnosis, wherein the specific sampling number calculation method comprises the following steps:
based on filtered engine speed n Filt And filtering the intake flow dmAirFilt of the fresh air of the rear cylinder to determine the sampling times V, and referring to the data in the table 1;
TABLE 1
The purpose of the specific design is that the engine speed is fixed, the higher the fresh air intake flow of the cylinder is, the larger the exhaust gas flow is, the larger the change of the oxygen sensor FEQR is, and the smaller the sampling number is, the more real the oxygen sensor FEQR is. The larger the engine speed is, the larger the change of the oxygen sensor FEQR is, and at this time, the smaller the sampling number is, and the truer the oxygen sensor FEQR is.
3. Target FEQR, i.e. FEQR Normal The method of (1).
1) Assume that the current sampling period is updating the element FEQR s Calculating the intake pressure model FEQR in the current sampling period Normal The method comprises the following steps:
note here
Is compared with the previously calculated->
Not unlike, here->
Refers to the target FEQR calculated in the last sampling period.
2) Target FEQR = FEQR Normal Comprises the following steps:
wherein i =0,1,2, \ 8230;, V-1.
When s-i is less than 0, FEQR s-i ＝FEQR j+s-i
So far, target FEQR = FEQR Normal Has already been calculated.
If, the actual FEQR and the FEQR Normal The absolute value of the difference between the two values,
1.|FEQR Normal -FEQR|≥a×dm AirFilt + b, the wide-area oxygen sensor fails. In this example, 204.53 (1/mgps) was used for a, and-20.62 was used for b.
2.|FEQR Normal -FEQR|＜a×dm AirFilt + b, the wide-area oxygen sensor is not in fault.
The second wide-area oxygen sensor degradation diagnosis method:
fault diagnosis of the wide-range oxygen sensor needs to be carried out under certain working conditions;
1. the rotating speed of the engine is in a certain range; no fault occurs in the engine speed-related diagnosis (crankshaft signal and cam signal diagnosis);
2. the engine has no oil cut;
3. the oxygen sensor heating is completed, i.e. the oxygen sensor is already within normal operating temperature; no fault occurs in the heating diagnosis of the oxygen sensor;
4. the accelerator is not fully opened (the accelerator is fully opened to enrich the air-fuel ratio under the full accelerator so as to improve the torque capacity of the full accelerator), and the opening degree of an accelerator pedal is in a certain range (less than or equal to 95%); the accelerator opening sensor diagnoses no fault;
5. the temperature of the engine cooling water exceeds a certain value; the cooling temperature sensor is diagnosed without fault;
6. the temperature of the intake manifold of the engine exceeds a certain value; no fault occurs in the intake manifold temperature sensor diagnosis;
7. when the running time of the engine exceeds a certain value, the engine is successfully warmed up;
8. the air inflow in the air inlet cylinder is in a certain range; relevant diagnostics for monitoring or calculating intake air amount (e.g., intake manifold pressure, throttle sensor, and throttle motor, etc.) do not fail.
9. The vehicle speed exceeds a certain value; vehicle speed related diagnostics are not faulted.
After the working condition is met, the fault diagnosis of the wide-range oxygen sensor is allowed to enter, but in the diagnosis process, the working condition needs to be ensured to be stable:
1. the engine speed fluctuates within a certain range; this example takes 20rpm
2. The opening degree of an accelerator pedal fluctuates within a certain range; this example takes. + -. 2%
3. The vehicle speed fluctuates within a certain range; this example takes. + -.2 kmph
4. The amount of intake air taken into the cylinder fluctuates within a certain range. In this example, +/-2 mgpl is taken
And after all the working condition conditions and the working condition stable conditions are met, performing fault diagnosis on the wide-range oxygen sensor.
In any process of fault diagnosis of the wide-range oxygen sensor, if any one of the working condition conditions (except the condition of the actual air-fuel ratio) is not met or any one of the working condition stable conditions (except the condition of the actual air-fuel ratio) is not met, the diagnosis is stopped, and the diagnosis is started again after the next working condition is met.
a) Once the ratio of the catalyst oxygen storage amount to the total oxygen storage amount is not less than r1 (0.13 is taken in the embodiment) and not more than r2 (0.89 is taken in the embodiment), and the fault diagnosis of b and c in the current driving cycle is not completed. The oxygen storage amount of the catalyst is enough, and the emission is less influenced by actively controlling the air-fuel ratio to be rich or lean at the moment.
Periodically controlling target FEQR after all working condition conditions and working condition stable conditions are met, namely, controlling air-fuel ratio time T by enrichment Base (time T) Base In this example, 1.4s is taken, and the target FEQR is set to r FEQRRichBase Greater than 1), followed by lean-down control of the air-fuel ratio for a preset time T Base (setting target FEQR as r FEQRLeanBase Less than 1), repeating the control for N0 times (10 can be taken in the embodiment, namely 10 periodic control FEQR's), recording the actual FEQR fed back by the upstream wide-area oxygen sensor in real time, and calculating the partial concentration reflection time T of the actual FEQR RichResDn And T RichResUp Calculating the actual FEQR partial dilution reflecting time T LeanResDn And T LeanResUp 。
T RichResDn The method for starting to calculate the time comprises the following steps:actual FEQR and r at current sampling period (all sampling periods in this embodiment take 2 ms) FEQRRichBase The absolute value of the difference is smaller than Δ C (in this embodiment, Δ C is 0.002), and the actual FEQR and r in the next sampling period FEQRRichBase Is not less than Δ C. Before the actual FEQR appears for the first time in the subsequent sampling period to be more than 1 +/-delta C, the actual FEQR of the current sampling period is not less than the actual FEQR of all the subsequent sampling periods.
T RichResDn Method for ending calculation time: the absolute value of the difference between the actual FEQR and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual FEQR and 1 in the next sampling period is not smaller than deltaC. Actual FEQR first appears to be greater than r in subsequent sampling periods FEQRLeanBase Before Δ C, the actual FEQR for the current sampling period is not less than the actual FEQR for all of the subsequent sampling periods.
T RichResUp The method for starting to calculate the time comprises the following steps: the absolute value of the difference between the actual FEQR and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual FEQR and 1 in the next sampling period is not smaller than deltaC. Actual FEQR first occurrence of more than r in subsequent sampling periods FEQRRichBase Before Δ C, the actual FEQR for the current sampling period is not greater than the actual FEQR for all of the subsequent sampling periods.
T RichResUp Method for ending calculation time: pre-sampling period actual FEQR and r FEQRRichBase The absolute value of the difference is smaller than Δ C (in this embodiment, Δ C is 0.002), and the actual FEQR and r in the next sampling period FEQRRichBase Is not less than Δ C. Before the actual FEQR appears for the first time in a subsequent sampling period to be more than 1 +/-delta C, the actual FEQR of the current sampling period is not less than the actual FEQR of all the subsequent sampling periods.
Method for starting to calculate time TLeanResDn: the absolute value of the difference between the actual FEQR and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual FEQR and 1 in the next sampling period is not smaller than deltaC. Actual FEQR first appears to be greater than r in subsequent sampling cycles FEQRLeanBase Before Δ C, the actual FEQR for the current sampling period is not less than the actual FEQR for all of the subsequent sampling periods.
T LeanResDn Method for ending calculation timeThe method comprises the following steps: actual FEQR and r at current sampling period FEQRLeanBase The absolute value of the difference is smaller than Δ C (in this embodiment, Δ C is 0.002), and the actual FEQR and r in the next sampling period FEQRLeanBase Is not less than Δ C. Before the actual FEQR appears for the first time in the subsequent sampling period to be more than 1 +/-delta C, the actual FEQR of the current sampling period is not more than the actual FEQR of all the subsequent sampling periods.
T LeanResUp The method for starting to calculate the time comprises the following steps: actual FEQR and r at current sampling period FEQRLeanBase The absolute value of the difference is smaller than Δ C (in this embodiment, Δ C is 0.002), and the actual FEQR and r in the next sampling period FEQRLeanBase Is not less than Δ C. Before the actual FEQR appears for the first time in the subsequent sampling period to be more than 1 +/-delta C, the actual FEQR of the current sampling period is not more than the actual FEQR of all the subsequent sampling periods.
T LeanResUp Method for ending calculation time: the absolute value of the difference between the actual FEQR and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual FEQR and 1 in the next sampling period is not smaller than deltaC. Actual FEQR first appears to be greater than r in subsequent sampling cycles FEQRLeanBase Before Δ C, the actual FEQR for the current sampling period is not greater than the actual FEQR for all of the subsequent sampling periods.
Reading the current actual FEQR, that is, the actual FEQR at the time of entry into diagnosis, and setting the target FEQR = r FEQRRichBase The present embodiment is FEQR +0.02, FEQR +0.05, FEQR +0.1, respectively, and the target FEQR = r FEQRLeanBase Taking 2FEQR-r FEQRRichBase (i.e., N0 cycles of FEQR +0.02 and FEQR-0.02, N0 cycles of FEQR +0.05 and FEQR-0.05, N0 cycles of FEQR +0.1 and FEQR-0.1)
T RichResDn Respectively correspond to the read T RichResDn11 ，T RichResDn12 And T RichResDn13 And all the N-bit-based data acquisition and control method are composed of arrays with N0 numbers, the number of heads is 2, the number of tails is 2, data deviation caused by instability of a control system when FEQR active control is just introduced is avoided, data accuracy is improved, N0-4 numbers are obtained, and average values corresponding to the N0-4 numbers are calculated to obtain average values
And &>
T RichResUp Respectively correspond to the read T RichResUp11 ，T RichResUp12 And T RichResUp13 And the number of the head and the number of the tail are respectively eliminated by 2, so as to obtain N0-4 numbers, and the average value corresponding to the N0-4 numbers is calculated to obtain
And &>
T LeanResDn Respectively correspond to the read T LeanResDn11 ，T LeanResDn12 And T LeanResDn13 And all the N-bit-sequence-based data processing method comprises the steps of forming arrays by N0 numbers, removing 2 numbers of heads and 2 numbers of tails to obtain N0-4 numbers, and calculating the average values corresponding to the N0-4 numbers to obtain
And &>
T LeanResUp Respectively correspond to the read T LeanResUp11 ，T LeanResUp12 And T LeanResUp13 And all the N-bit-sequence-based data processing method comprises the steps of forming arrays by N0 numbers, removing 2 numbers of heads and 2 numbers of tails to obtain N0-4 numbers, and calculating the average values corresponding to the N0-4 numbers to obtain
And &>
The wide area oxygen sensor fails if any of the following occurs:
1.
and &>
Any 1 of 6 times greater than @>
The wide-area oxygen sensor fails; wherein->
The average cylinder fresh air intake flow after entering the diagnostics. d 2 ，d 1 ，d 0 Respectively taking the value of-80.232 (ms mgps) 2 ) 3520.23 (ms mgps), 0.034 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
2.
And &>
Any 1 of the 6 times greater than ∑ or>
The wide-area oxygen sensor fails; d is a radical of 5 ，d 4 ，d 3 Respectively takes the value of 4538.245 (ms/mgps) 2 ) 1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
3.
And &>
The absolute value of the difference (or +)>
And &>
The absolute value of the difference, or
And &>
Absolute value of difference), is greater than or equal to>
And &>
The absolute value of the difference (or +)>
And
the absolute value of the difference, or->
And &>
Absolute difference of value) greater than +>
The wide-area oxygen sensor fails; d 7 ，d 6 The values are respectively 0.12 (ms) and 2.376 (ms) at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
4.
And &>
The absolute value of the difference (or->
And &>
The absolute value of the difference, or
And &>
Absolute value of difference), is greater than or equal to>
And &>
The absolute value of the difference (or->
And
the absolute value of the difference, or->
And &>
Absolute difference of value) is greater than £ greater than>
The wide-area oxygen sensor fails; d is a radical of 9 ，d 8 Respectively takes a value of 0.201 (ms) and 0.531 (ms) at different times>
And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor. After any fault occurs in the above 4 fault diagnoses, the driving cycle is not diagnosed any more.
b) Once the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is smaller than r1 (0.13 is taken in the embodiment), the fault diagnosis of a and c in the driving cycle is not completed.
After all working condition conditions and working condition stable conditions are met, the oxygen storage amount is insufficient at the moment, and in order to reduce the influence on emission, the target FEQR is periodically controlled, namely the air-fuel ratio time T is controlled to be enriched Base (time T) Base In this example, 1.4s is taken, and the target FEQR is set to r FEQRRichBase Greater than 1), then immediately set the target FEQR to r FEQRLeanBase Less than 1 time T Min (time T) Min 0.1s is taken in the embodiment), the control is repeated for N0 times (10 is taken in the embodiment, namely 10 periodic control FEQR are taken), the actual FEQR fed back by the upstream wide-area oxygen sensor is recorded in real time, and the partial concentration reflecting time T of the actual FEQR is calculated RichResDn And T RichResUp . Obtained by the same method
And &>
The same method is used for fault diagnosis:
1.
any of 3Greater than or equal to 1 time>
The wide-area oxygen sensor fails; wherein->
The average cylinder fresh air intake flow after entering the diagnostics. d 2 ，d 1 ，d 0 Respectively taking the value of-80.232 (ms mgps) 2 ) 3520.23 (ms mgps), 0.034 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
2.
Any 1 of 3 times is greater than
The wide-area oxygen sensor fails; d 5 ，d 4 ，d 3 Respectively takes the value of 4538.245 (ms/mgps) 2 ) 1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
3.
And &>
The absolute value of the difference (or +)>
And &>
The absolute value of the difference, or
And &>
Absolute value of difference) greater than £ and @>
The wide-area oxygen sensor fails; d 9 ，d 8 Respectively takes a value of 0.201 (ms) and 0.531 (ms) at different times>
And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
After any fault occurs in the above 3 fault diagnoses, the driving cycle is not diagnosed any more.
c) The ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is larger than r2 (0.89 is taken in the embodiment) once the occurrence of the phenomenon, and
and the fault diagnosis of the a and the b in the driving cycle is not finished.
After all working condition conditions and working condition stable conditions are met, the oxygen storage amount is not enough, and in order to reduce the influence on the emission, the target FEQR is periodically controlled, namely the thinning ratio time T is reduced Base (time T) Base In this example, 1.4s is taken, and the target FEQR is set to r FEQRRichBase Small 1), then set the target FEQR to r FEQRLeanBase Less than 1 time T Min (time T) Min 0.1s is taken in the embodiment), the control is repeated for N0 times (10 is taken in the embodiment, namely 10 periodic control FEQR are taken), the actual FEQR fed back by the upstream wide-area oxygen sensor is recorded in real time, and the partial dilution reflecting time T of the actual FEQR is calculated LeanResDn And T LeanResUp . Obtained by the same method
And &>
And &>
The same method is used for fault diagnosis：
1.
And &>
Any 1 time greater than £ 3>
The wide-area oxygen sensor fails; wherein->
The average cylinder fresh air intake flow rate after the diagnosis is entered. d 2 ，d 1 ，d 0 Respectively taking the value of-80.232 (ms mgps) 2 ) 3520.23 (ms mgps), 0.034 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
2.
And &>
Any 1 time of 3 is greater than
The wide-area oxygen sensor fails; d 5 ，d 4 ，d 3 Respectively takes the value of 4538.245 (ms/mgps) 2 ) 1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
3.
And &>
The absolute value of the difference (or->
And &>
The absolute value of the difference, or
And &>
Absolute value of difference) is greater than->
The wide-area oxygen sensor fails; d is a radical of 9 ，d 8 Respectively takes a value of 0.201 (ms) and 0.531 (ms) at different times>
And then, obtaining the fitting data according to the fault oxygen sensor and the fault-free oxygen sensor.
After any fault occurs in the above 3 fault diagnoses, the driving cycle is not diagnosed any more.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. The method for diagnosing the deterioration of the wide-range oxygen sensor of the engine is characterized by comprising the following steps of:
collecting an oxygen concentration signal of exhaust gas in an exhaust pipe after combustion through a wide-range oxygen sensor;
calculating an air-fuel ratio according to the oxygen concentration signal to generate an actual air-fuel ratio signal;
controlling the fuel injection quantity and the fuel injection timing of the engine to adjust the air-fuel ratio according to the air-fuel ratio signal, and generating an adjusted actual air-fuel ratio signal;
respectively establishing an actual fuel equivalent ratio and a target fuel equivalent ratio according to the ideal air-fuel ratio, the adjusted actual air-fuel ratio and a preset target air-fuel ratio; wherein, the actual fuel equivalence ratio is represented as the ratio of the adjusted actual air-fuel ratio to the ideal air-fuel ratio, and the target fuel equivalence ratio is represented as the ratio of the target air-fuel ratio to the ideal air-fuel ratio;
the target fuel equivalence ratio is a reference value relative to the actual fuel equivalence ratio and changes along with the sampling data of the actual fuel equivalence ratio, and the sampling data at least comprises an actual fuel quantity entering the cylinder in unit time and an actual fresh air quantity entering the cylinder in unit time;
selecting corresponding degradation diagnosis according to the comparison of the difference value between the actual fuel equivalence ratio and the target fuel equivalence ratio or the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount, and judging whether the wide-area oxygen sensor fails;
establishing a target fuel equivalence ratio FEQR according to the comparison between the actual fuel equivalence ratio and the target fuel equivalence ratio Normal The method comprises the following steps:
creating an array [ FEQR ] for actual fuel equivalence ratio 0 ,FEQR 1 ,…,FEQR s-1 ,FEQR s ,…FEQR j ]Each element in the array represents the actual fuel equivalence ratio provided by the real-time wide-range oxygen sensor, the initial values of the elements are equal, and the numerical values of the elements are updated once every time every other interval of one same preset sampling period;
determining the sampling number V of elements in the array according to the rotating speed of the engine after filtering and the fresh air intake flow of the cylinder after filtering;
after the sampling number V is obtained by calculation, the FEQR is obtained by calculation according to the following formula Normal ：
Wherein i =0,1,2, \8230;, V-1, when s-i < 0, FEQR s-i ＝FEQR j+s-i 。
2. The engine wide-area oxygen sensing of claim 1The device deterioration diagnosis method is characterized by using FEQR 0 For example, the method for updating the elements in the actual fuel equivalence ratio array is as follows:
wherein, the delta FEQR is the updated change value of the current sampling period,
for the updated change value of the last sampling period,
actual fuel equivalence ratio read for the previous sampling period, Δ T being the sampling period, T c Is a constant of time, and is,
the target fuel equivalence ratio of the last sampling period;
sequentially updating the values of the elements in the above formula, wherein FEQR is calculated 0 Replacing the numerical value of the target fuel-oil ratio read in the last sampling period with the numerical value of the target fuel-oil ratio read in the last sampling period;
namely, the method comprises the following steps:
up to FEQR j Finishing the updating, namely finishing one-time updating;
jump to FEQR 0 With FEQR 0 And starting updating, namely starting the next updating and performing the next updating.
3. The method for diagnosing degradation of the engine wide-range oxygen sensor according to claim 1, wherein the method for judging whether the wide-range oxygen sensor fails or not according to the comparison between the difference value of the actual fuel equivalence ratio and the target fuel equivalence ratio specifically comprises the following steps:
if the actual fuel equivalence ratio FEQR and FEQR is not the same Normal Absolute value of the difference:
1.|FEQR Normal -FEQR|≥a×dm AirFilt + b, the wide-range oxygen sensor fails;
2.|FEQR Normal -FEQR|＜a×dm AirFilt + b, the wide-range oxygen sensor has no fault;
wherein the predetermined fault difference value is represented as a × dm AirFilt + b, formula (m) AirFilt For filtered post-cylinder fresh air intake flow, a is 204.53 (1/mgps), and b is-20.62.
4. The engine wide-range oxygen sensor degradation diagnosis method according to claim 1, wherein before the catalyst oxygen storage volume to total oxygen storage volume ratio is selected for degradation diagnosis, operating condition detection is performed, and when the operating condition is satisfied, the operating condition detection is adapted to select the degradation diagnosis by the catalyst oxygen storage volume to total oxygen storage volume ratio, and the operating condition includes:
the rotating speed of the engine is in a certain range; the relevant diagnosis of the engine speed does not have faults;
the engine has no oil cut;
the heating of the wide-range oxygen sensor is completed, namely the wide-range oxygen sensor is within the normal working temperature; no fault occurs in the wide-area oxygen sensor heating diagnosis;
the accelerator is not fully opened, and the opening degree of an accelerator pedal is in a certain range; the accelerator opening sensor diagnoses no fault;
the temperature of the engine cooling water exceeds a certain value; the cooling temperature sensor is diagnosed without fault;
the temperature of the intake manifold of the engine exceeds a certain value; no fault occurs in the intake manifold temperature sensor diagnosis;
when the running time of the engine exceeds a certain value, the engine is successfully warmed up at the moment;
the air inflow in the air inlet cylinder is in a certain range; relevant diagnosis for monitoring or calculating the air input does not have faults;
the vehicle speed exceeds a certain value; the related diagnosis of the vehicle speed does not have fault;
and when the working condition is met, allowing the wide-range oxygen sensor to enter the degradation diagnosis.
5. The engine wide-range oxygen sensor degradation diagnosis method according to claim 4, wherein the detection of the stable operating condition is performed after the stable operating condition is satisfied, and the stable operating condition includes:
the engine speed fluctuates within a certain range;
the opening degree of an accelerator pedal fluctuates within a certain range;
the vehicle speed fluctuates within a certain range;
the amount of intake air into the cylinder fluctuates within a certain range;
and after the working condition stable condition and the working condition are both met, performing degradation diagnosis on the wide-range oxygen sensor.
6. The engine wide-range oxygen sensor degradation diagnosis method according to claim 5, wherein after the steady-state condition and the steady-state condition are both satisfied, when the ratio of the catalyst oxygen storage amount to the total oxygen storage amount is smaller than a first oxygen storage amount threshold value r1, the target fuel equivalence ratio is periodically controlled, and when the catalyst oxygen storage amount is insufficient, the target fuel equivalence ratio is controlled for a first preset time T Base Performing an enrichment operation, the enrichment operation comprising: increasing the oxygen concentration and setting the equivalence ratio of the enriched target fuel oil to r FEQRRichBase Greater than 1, and then for a second preset time T Min Performing a lean-down operation, the lean-down operation comprising: reducing the oxygen concentration and setting the lean target fuel equivalence ratio to r FEQRLeanBase Less than 1; alternately repeating enrichment operation and lean operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-area oxygen sensor in real time, and calculating the first rich-bias reflecting time T of the actual fuel equivalence ratio RichResDn And a second rich partial reflecting time T RichResUp (ii) a Wherein T is Base Greater than T Min ；
T RichResDn The method for judging the initial calculation time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRRichBase Is less than the preset difference value Delta C, and the actual fuel equivalence ratio and r in the next sampling period FEQRRichBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is greater than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
T RichResDn the judgment method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to deltaC; the actual fuel equivalence ratio is greater than r for the first occurrence in a subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is greater than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T RichResUp the method for starting to calculate the time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to deltaC; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRRichBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is less than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T RichResUp method for ending calculation time: actual fuel equivalence ratio and r in current sampling period FEQRRichBase Is less than deltac and the actual fuel equivalence ratio is compared with r in the next sampling period FEQRRichBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is greater than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
at T RichResDn Read three elements T arbitrarily RichResDn11 ，T RichResDn12 And T RichResDn13 ，T RichResDn N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
At T RichResUp Read three elements T arbitrarily RichResUp11 ，T RichResUp12 And T RichResUp13 ，T RichResUp N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
When any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
is greater than
Judging that the wide-area oxygen sensor has a fault; wherein +>
The average cylinder fresh air intake flow after diagnosis; d is a radical of 2 ，d 1 ，d 0 Respectively, a second evaluation coefficient, a first evaluation coefficient and an initial evaluation coefficient, wherein d 2 ，d 1 ，d 0 At different r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(2)
is greater than
Judging that the wide-area oxygen sensor has a fault; d 5 ，d 4 ，d 3 Respectively a fifth evaluation coefficient, a fourth evaluation coefficient and a third evaluation coefficient, wherein d 5 ，d 4 ，d 3 At different r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(3)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And
either the difference absolute value is greater than->
Judging that the wide-area oxygen sensor has a fault; d 9 ，d 8 Respectively a ninth evaluation coefficient and an eighth evaluation coefficient, wherein d 9 ，d 8 In different->
Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
when any fault is determined in the above 3 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
7. The method of claim 6, wherein after both the steady state and steady state conditions are met, the target fuel equivalence ratio is periodically controlled when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is greater than or equal to a first threshold r1 and less than or equal to a second threshold r2, the oxygen storage amount of the catalyst is sufficient, and the first preset time T is used Base Carrying out an enrichment operation and then setting a first preset time T Base Carrying out a thinning operation; alternately repeating enrichment operation and lean operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-area oxygen sensor in real time, and calculating the first rich-bias reflecting time T of the actual fuel equivalence ratio RichResDn Second rich reflecting time T RichResUp First partial dilution reflecting time T LeanResDn And a second lean reaction time T LeanResUp ；
T LeanResDn The method for judging the initial calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than a preset difference value delta C, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is larger than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
T LeanResDn the judgment method for ending the calculation time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRLeanBase Is less than deltac and the actual fuel equivalence ratio in the next sampling period is less than r FEQRLeanBase Is greater than or equal to Δ C; the actual fuel equivalence ratio in the subsequent sampling period is more than 1 +/-for the first timeBefore Δ C, the actual fuel equivalence ratio of the current sampling period is greater than or equal to the actual fuel equivalence ratios of all subsequent sampling periods;
T LeanResUp the method for starting to calculate the time comprises the following steps: actual fuel equivalence ratio and r in current sampling period FEQRLeanBase Is less than deltac and the actual fuel equivalence ratio in the next sampling period is less than r FEQRLeanBase Is greater than or equal to Δ C; before the actual fuel equivalence ratio in the subsequent sampling period is greater than 1 +/-delta C for the first time, the actual fuel equivalence ratio in the current sampling period is less than or equal to the actual fuel equivalence ratios in all the subsequent sampling periods;
T LeanResUp method for ending calculation time: the absolute value of the difference between the actual fuel equivalence ratio and 1 in the current sampling period is smaller than deltaC, and the absolute value of the difference between the actual fuel equivalence ratio and 1 in the next sampling period is larger than or equal to deltaC; the actual fuel equivalence ratio is greater than r for the first time in the subsequent sampling period FEQRLeanBase Before +/-Delta C, the actual fuel equivalence ratio of the current sampling period is larger than or equal to the actual fuel equivalence ratios of all the subsequent sampling periods;
at T LeanResDn Read three elements T arbitrarily LeanResDn11 ，T LeanResDn12 And T LeanResDn13 ，T LeanResDn N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
At T LeanResUp Read three elements T arbitrarily LeanResUp11 ，T LeanResUp12 And T LeanResUp13 ，T LeanResUp N0 elements corresponding to the number of enrichment operations exist in the array, the initial 2 elements and the tail 2 elements are removed to obtain (N0-4) elements, and the average value corresponding to the (N0-4) elements is calculated to obtain
And &>
And when any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
and &>
Is greater than->
Judging that the wide-area oxygen sensor has a fault;
(2)
and &>
Any one of (1) above time greater than or equal to>
Judging that the wide-area oxygen sensor has a fault;
(3)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
Any value greater than ^ on the absolute value of the difference>
Judging that the wide-area oxygen sensor has a fault; d is a radical of 7 ，d 6 Respectively a seventh evaluation coefficient and a sixth evaluation coefficient, wherein d 7 ，d 6 At different r FEQRRichBase Then, the fitting data is obtained according to the calibration matching data of the fault oxygen sensor and the fault-free oxygen sensor;
(4)
and &>
Absolute value of the difference->
And &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
The absolute value of the difference, is greater than or equal to>
And &>
Absolute value of the difference->
And &>
Either the difference absolute value is greater than->
Judging that the wide-area oxygen sensor has a fault;
when any fault is determined in the above 4 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
8. The engine wide-range oxygen sensor degradation diagnosis method of claim 7, wherein after both the steady-state condition and the steady-state condition are satisfied, when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is greater than r2, the oxygen storage amount is too high for a first preset time T Base Performing a lean-down operation, and then performing a second preset time T Min Carrying out thickening operation; alternately repeating the lean operation and the rich operation for N0 times, recording the actual fuel equivalence ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first lean reflection time T of the actual fuel equivalence ratio LeanResDn And a second lean reflection time T LeanResUp ；
And when any one of the following conditions occurs, judging that the wide-area oxygen sensor has a fault:
(1)
and &>
Is greater than
Judging that the wide-area oxygen sensor has a fault;
(2)
and &>
Is greater than
Judging that the wide-area oxygen sensor has a fault;
(3)
and &>
The absolute value of the difference, is greater than or equal to>
And &>
Absolute value of the difference->
And &>
Either the difference absolute value is greater than->
Judging that the wide-area oxygen sensor has a fault;
when any fault is determined in the above 3 types of fault diagnosis, the degradation diagnosis is not performed in the current driving cycle.
9. The engine wide-range oxygen sensor degradation diagnosis method according to claim 1, characterized in that a stoichiometric air-fuel ratio is 14.3.
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| CN114962035A (en) * | 2022-06-08 | 2022-08-30 | 东风汽车集团股份有限公司 | Method for monitoring working performance of wide-area oxygen sensor of engine |
| CN114962038A (en) * | 2022-06-08 | 2022-08-30 | 东风汽车集团股份有限公司 | Performance failure monitoring method for engine wide-area oxygen sensor |
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| JP3908543B2 (en) * | 2002-01-21 | 2007-04-25 | 本田技研工業株式会社 | Air-fuel ratio control device |
| JP2005337213A (en) * | 2004-05-31 | 2005-12-08 | Hitachi Ltd | Diagnosis device for air fuel ratio sensor |
| JP5755021B2 (en) * | 2011-05-16 | 2015-07-29 | 本田技研工業株式会社 | Air-fuel ratio control device for internal combustion engine |
| JP5342618B2 (en) * | 2011-08-30 | 2013-11-13 | 本田技研工業株式会社 | Air-fuel ratio control device for internal combustion engine |
| US9057338B2 (en) * | 2012-11-09 | 2015-06-16 | GM Global Technology Operations LLC | Exhaust gas oxygen sensor fault detection systems and methods using fuel vapor purge rate |
| JP2017020417A (en) * | 2015-07-10 | 2017-01-26 | 本田技研工業株式会社 | Control device of internal combustion engine |
| US11255245B2 (en) * | 2016-12-09 | 2022-02-22 | Cummins Inc. | Systems and methods for catalyst sensor diagnostics |
| CN106996341B (en) * | 2017-03-27 | 2019-08-23 | 宁波吉利汽车研究开发有限公司 | A kind of diagnostic method of broad domain oxygen sensor response failure |
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| CN114962035A (en) * | 2022-06-08 | 2022-08-30 | 东风汽车集团股份有限公司 | Method for monitoring working performance of wide-area oxygen sensor of engine |
| CN114962038A (en) * | 2022-06-08 | 2022-08-30 | 东风汽车集团股份有限公司 | Performance failure monitoring method for engine wide-area oxygen sensor |
| CN114962035B (en) * | 2022-06-08 | 2023-11-24 | 东风汽车集团股份有限公司 | Method for monitoring working performance of wide-range oxygen sensor of engine |
| CN114962038B (en) * | 2022-06-08 | 2023-11-24 | 东风汽车集团股份有限公司 | Performance failure monitoring method for wide-range oxygen sensor of engine |
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