CN114962034B - Degradation diagnosis method for wide-range oxygen sensor of hybrid vehicle type engine - Google Patents

Degradation diagnosis method for wide-range oxygen sensor of hybrid vehicle type engine Download PDF

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Publication number
CN114962034B
CN114962034B CN202210642965.5A CN202210642965A CN114962034B CN 114962034 B CN114962034 B CN 114962034B CN 202210642965 A CN202210642965 A CN 202210642965A CN 114962034 B CN114962034 B CN 114962034B
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oxygen sensor
ratio
wide
equivalent ratio
difference
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CN114962034A (en
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李京
王冬
张珍
张德全
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Dongfeng Motor Group Co Ltd
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Dongfeng Motor Group Co Ltd
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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
    • 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
    • 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
    • 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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

The invention discloses a degradation diagnosis method of a wide-range oxygen sensor of a hybrid vehicle type engine, which comprises the following steps: collecting an oxygen concentration signal of exhaust gas in the exhaust pipe after combustion through a wide-range oxygen sensor; calculating an air-fuel ratio from 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; and selecting corresponding degradation diagnosis according to 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, the fuel oil equivalent ratio reflecting condition in the air-fuel ratio control process of different degrees is monitored under the steady-state working condition, and whether the wide-range oxygen sensor is deteriorated and invalid is verified.

Description

Degradation diagnosis method for wide-range oxygen sensor of hybrid vehicle type engine
Technical Field
The invention belongs to the field of engine control, and particularly relates to a degradation diagnosis method of a wide-range oxygen sensor of a hybrid vehicle type engine.
Background
The wide-range oxygen sensor is an important sensor as an air-fuel ratio closed-loop control, which can accurately output a signal of the air-fuel ratio.
The requirements for diagnosing a front oxygen sensor are clearly set in the light automobile pollutant emission limit value and the measuring method (the sixth stage of China): the OBD system monitors for faults in the front oxygen sensor (sensors for fuel control, conventional switch-mode oxygen sensors and/or wide-area or general-purpose sensors), including output voltage, response rate, and parameters that may affect emissions.
The hybrid vehicle type (comprising an engine, a driving motor and a generator) is a popular vehicle type at present, and comprises the engine. The operating condition range and the operating time of the engine in the hybrid vehicle type are much narrower than those of the transmission gasoline vehicle, and the purpose is to improve fuel economy, vehicle drivability, emission performance, NVH and the like.
When the wide-range oxygen sensor has performance faults, such as the condition that the rich and lean changes of the air-fuel ratio cannot be accurately reflected, the wide-range oxygen sensor needs to be timely diagnosed. After the fault occurs, the fault post-treatment is performed 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 degradation diagnosis method for a wide-range oxygen sensor of a hybrid vehicle type engine, which is used for monitoring fuel equivalent ratio reflection conditions in different air-fuel ratio control processes under a steady-state working condition and verifying whether the wide-range oxygen sensor is degraded and invalid.
In order to solve the technical problems, the technical scheme of the invention is as follows: a degradation diagnosis method of a wide-range oxygen sensor of a hybrid vehicle type engine comprises the following steps:
collecting an oxygen concentration signal of exhaust gas in the exhaust pipe after combustion through a wide-range oxygen sensor;
calculating an air-fuel ratio from 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 equivalent ratio is expressed as a ratio of the adjusted actual air-fuel ratio to the stoichiometric air-fuel ratio, and the target fuel equivalent ratio is expressed as a ratio of the target air-fuel ratio to the stoichiometric air-fuel ratio;
and selecting corresponding degradation diagnosis according to 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.
Before degradation diagnosis is performed, detection of working conditions is performed, and the working conditions include:
the engine speed is in a certain range; the related diagnosis of the engine speed is free of faults;
the engine has no fuel cut;
the wide-area oxygen sensor is heated, i.e. the wide-area oxygen sensor is already within the normal working temperature; the wide-range oxygen sensor is heated to diagnose that no fault occurs;
the accelerator is not fully opened, and the opening of the accelerator pedal is in a certain range; the accelerator opening sensor diagnoses no fault;
the cooling water temperature of the engine exceeds a certain value; the cooling temperature sensor diagnoses no fault;
the temperature of an engine intake manifold exceeds a certain value; the intake manifold temperature sensor diagnoses no fault;
the engine running time exceeds a certain value, and the engine warmup is successful at the moment;
the air inflow in the air inlet cylinder is in a certain range; a relevant diagnosis for monitoring or calculating the intake air amount does not occur;
the speed of the vehicle exceeds a certain value; the related diagnosis of the vehicle speed has no fault;
and when the working conditions are all met, the degradation diagnosis of the wide-range oxygen sensor is allowed to be entered.
After the working condition is satisfied, the working condition stable condition is detected, and the working condition stable condition comprises:
the engine speed fluctuates in a certain range;
the opening degree of the accelerator pedal fluctuates in a certain range;
the vehicle speed fluctuates in a certain range;
the amount of intake air into the cylinder fluctuates in a certain range;
and after the working condition stabilizing condition and the working condition are met, entering degradation diagnosis of the wide-range oxygen sensor.
After the stable working condition and the stable working condition are 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 r1, periodically controlling the target fuel oil equivalent ratio, and when the oxygen storage amount of the catalyst is insufficient, using a first preset time T Base And performing an enrichment operation, wherein the enrichment operation comprises: increasing oxygen concentration, and setting the fuel equivalent ratio of the enrichment target as r FEQRRichBase Greater than 1, then for a second preset time T Min Performing thinning operationThe lean operation includes: reducing oxygen concentration, and setting the target fuel equivalent ratio of the dilution as r FEQRLeanBase Less than 1; alternately repeating the enrichment operation and the thinning operation for N0 times respectively, recording the actual fuel equivalent ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first partial enrichment reflecting time T of the actual fuel equivalent ratio RichResDn And a second partial concentration reflecting time T RichResUp The method comprises the steps of carrying out a first treatment on the surface of the Wherein T is Base Greater than T Min ；
T RichResDn The method for judging the initial calculation time is as follows: actual fuel equivalence ratio in current sampling period and r FEQRRichBase The absolute value of the difference is smaller than the preset difference value delta C, and the actual fuel equivalent ratio and r in the next sampling period FEQRRichBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
T RichResDn the judging method of the end calculation time is as follows: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is greater than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
T RichResUp the method for starting the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRRichBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is smaller than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
T RichResUp the method for ending the calculation time comprises the following steps: actual fuel equivalence ratio in current sampling period and r FEQRRichBase The absolute value of the difference is smaller than delta C, and the next sampling period is realThe fuel equivalent ratio r FEQRRichBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
at T RichResDn Any reading of three elements T 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 last 2 elements are removed to obtain (N0-4) elements, and an average value corresponding to the (N0-4) elements is calculated to obtain And->
At T RichResUp Any reading of three elements T 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 last 2 elements are removed to obtain (N0-4) elements, and an average value corresponding to the (N0-4) elements is calculated to obtain And->
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
any time is greater thanJudging that the wide-area oxygen sensor fails; wherein->Fresh air intake flow for the average cylinder after intake diagnosis; d, d 2 ，d 1 ，d 0 A second evaluation coefficient, a first evaluation coefficient and an initial evaluation coefficient, respectively, wherein d 2 ，d 1 ，d 0 At different r FEQRRichBase Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
(2)any time is greater thanJudging that the wide-area oxygen sensor fails; d, d 5 ，d 4 ，d 3 A fifth evaluation coefficient, a fourth evaluation coefficient, and a third evaluation coefficient, respectively, wherein d 5 ，d 4 ，d 3 At different r FEQRRichBase Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
(3)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Any one of the absolute values of the differences is greater than +.>Judging that the wide-area oxygen sensor fails; d, d 9 ，d 8 A ninth evaluation coefficient and an eighth evaluation coefficient, respectively, wherein d 9 ，d 8 In a different->Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
after any fault judgment occurs in the above 3 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
After the working condition stabilizing condition and the working condition are 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 oil equivalent ratio is periodically controlled, and the oxygen storage amount of the catalyst is fully filled at the moment, and the first preset time T is used for Base Performing enrichment operation, and then performing enrichment operation for a first preset time T Base Performing thinning operation; alternately repeating the enrichment operation and the thinning operation for N0 times respectively, recording the actual fuel equivalent ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first partial enrichment reflecting time T of the actual fuel equivalent ratio RichResDn Second partial concentration reflecting time T RichResUp First lean reflection time T LeanResDn And a second lean reflection time T LeanResUp ；
T LeanResDn The method for judging the initial calculation time is as follows: the absolute value of the difference between the actual fuel equivalent 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 equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Prior to (+/-delta.C), current harvestThe actual fuel equivalent ratio of the sample period is greater than or equal to the actual fuel equivalent ratio of all subsequent sample periods;
T LeanResDn the judging method of the end calculation time is as follows: actual fuel equivalence ratio in current sampling period and r FEQRLeanBase The absolute value of the difference is smaller than delta C, and the actual fuel equivalent ratio in the next sampling period is equal to r FEQRLeanBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
T LeanResUp the method for starting the calculation time comprises the following steps: actual fuel equivalence ratio in current sampling period and r FEQRLeanBase The absolute value of the difference is smaller than delta C, and the actual fuel equivalent ratio in the next sampling period is equal to r FEQRLeanBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears more than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is smaller than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
T LeanResUp the method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is greater than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
at T LeanResDn Any reading of three elements T 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 last 2 elements are removed to obtain (N0-4) elements, and an average value corresponding to the (N0-4) elements is calculated to obtain And->
At T LeanResUp Respectively corresponding to the reading T 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 last 2 elements are removed to obtain (N0-4) elements, and an average value corresponding to the (N0-4) elements is calculated to obtainAnd->
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
(4)andany time of (2) is greater than->Judging that the wide-area oxygen sensor fails;
(5)andany time of (2) is greater than->Judging that the wide-area oxygen sensor fails;
(6)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Absolute value of difference +.>And->Absolute value of difference +.>And->Absolute value of difference +.>And->Any one of the absolute values of the differences is greater thanJudging that the wide-area oxygen sensor fails; d, d 7 ，d 6 Respectively, where d 7 ，d 6 At different r FEQRRichBase Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
(7)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Absolute value of difference +.>And->Absolute value of difference +.>And->Absolute value of difference +.>And->Any one of the absolute values of the differences is greater thanJudging that the wide-area oxygen sensor fails;
after any fault judgment occurs in the above 4 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
After the stable working condition and the stable working condition are satisfied, when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is larger than r2, the oxygen storage amount is too high at the moment, and the first preset time T is used Base Performing thinning operation, and then performing thinning operation for a second preset time T Min Performing enrichment operation; alternately repeating the thinning operation and the enrichment operation for N0 times, recording the actual fuel equivalent 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 equivalent ratio LeanResDn And a second lean reflection time T LeanResUp ；
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
(8)and->Any time is greater thanJudging that the wide-area oxygen sensor fails;
(9)and->Any time is greater thanJudging that the wide-area oxygen sensor fails;
(10)and->Absolute value of difference +.>And->Absolute value of difference +.>And->Any one of the absolute values of the differences is greater than +.>Judging that the wide-area oxygen sensor fails;
after any fault judgment occurs in the above 3 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
The stoichiometric air-fuel ratio was 14.3.
r1 is 0.13.
r2 is 0.89.
The preset difference Δc is 0.002.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the fuel oil equivalent ratio reflection condition in the air-fuel ratio control process of different degrees is monitored under the steady-state working condition, and whether the wide-range oxygen sensor is deteriorated and invalid can be verified.
Drawings
Fig. 1 is a schematic flow chart of an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The technical scheme of the invention is as follows: a degradation diagnosis method for a wide-range oxygen sensor of a hybrid vehicle type engine.
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 an oxygen concentration signal in the exhaust gas in the exhaust pipe after the current combustion for the engine controller EMS;
the intelligent driving chip of the wide-range oxygen sensor collects and processes the oxygen concentration signal monitored by the wide-range oxygen sensor, converts the oxygen concentration signal into an air-fuel ratio related signal, heats the wide-range oxygen sensor and ensures that the oxygen sensor works at normal temperature;
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 signals 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, called "over-concentration"; the oxygen concentration in the exhaust pipe is too high, which is called 'too thin';
the wide-range oxygen sensor provides the current concentration of air in the exhaust pipe to the engine controller EMS, and is characterized by using the inverse of the excess air coefficient lambda, namely the fuel equivalence ratio, which is denoted by FEQR in the embodiment:
then the target air-fuel ratio can be set by setting the target FEQR, then there is a target
The "actual fuel" refers to the actual amount of fuel that enters the cylinder per unit time, the "actual air" refers to the actual amount of fresh air that enters the cylinder per unit time, the "target fuel" refers to the target amount of fuel that enters the cylinder per unit time, the "target air" refers to the target amount of fresh air that enters the cylinder per unit time, the "ideal air" refers to the ideal amount of fresh air that enters the cylinder per unit time, and the "ideal fuel" refers to the ideal amount of fuel that enters the cylinder per unit time. The target value is not equal to the ideal value, 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 cut off, FEQR is 0; when the concentration is too high, the FEQR is larger than 1; when the liquid is too dilute, the FEQR is smaller than 1; when FEQR is equal to 1, the stoichiometric air-fuel ratio is currently set (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 is equal, 14.3 is taken as the stoichiometric air-fuel ratio in the present embodiment).
The fault diagnosis of the wide-range oxygen sensor needs to be carried out under a certain working condition;
1. the engine speed is in a certain range; diagnosis of engine rotational speed correlation (crank signal and cam signal diagnosis) does not occur;
2. the engine has no fuel cut;
3. the oxygen sensor is heated up, i.e. the oxygen sensor is already within normal operating temperature; the oxygen sensor is heated to diagnose that no fault occurs;
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 of the accelerator pedal is within a certain range (less than or equal to 95 percent); the accelerator opening sensor diagnoses no fault;
5. the cooling water temperature of the engine exceeds a certain value; the cooling temperature sensor diagnoses no fault;
6. the temperature of an engine intake manifold exceeds a certain value; the intake manifold temperature sensor diagnoses no fault;
7. the engine running time exceeds a certain value, and the engine warmup is successful at the moment;
8. the air inflow in the air inlet cylinder is in a certain range; related diagnostics (such as intake manifold pressure, throttle sensor, and throttle motor, etc.) for monitoring or calculating the intake air amount do not fail.
9. The speed of the vehicle exceeds a certain value; vehicle speed related diagnostics have no faults.
After the working condition is met, fault diagnosis of the wide-range oxygen sensor is allowed to be carried out, but in the diagnosis process, the working condition stability is required to be ensured:
1. the engine speed fluctuates in a certain range; this example takes 20rpm
2. The opening degree of the accelerator pedal fluctuates in a certain range; this example takes + -2%
3. The vehicle speed fluctuates in a certain range; this example takes + -2 kmph
4. The amount of intake air taken into the cylinder fluctuates in a certain range. In this example, 2mgpl is obtained
After all working conditions and working condition stabilizing conditions are met, fault diagnosis of the wide-range oxygen sensor is carried out.
In any process of the fault diagnosis of the wide-range oxygen sensor, if any one of the working conditions (except the condition of the actual air-fuel ratio) is not satisfied or any one of the working conditions (except the condition of the actual air-fuel ratio) is not satisfied, the diagnosis is stopped, and the diagnosis is re-entered after the next working condition is satisfied.
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 present embodiment) and not more than r2 (0.89 is taken in the present embodiment), and the fault diagnosis of b and c in the present driving cycle is not completed. The catalyst has sufficient oxygen storage, and the active control of air-fuel ratio enrichment or air-fuel ratio dilution has less influence on emission.
After all the working conditions and the working condition stabilizing conditions are satisfied, the target FEQR is periodically controlled, namely the air-fuel ratio time T is controlled by enrichment Base (time T) Base In this embodiment, 1.4s is taken and the target FEQR is set to r FEQRRichBase Greater than 1) and then immediately thereafter lean-controlling the air-fuel ratio for a preset time T Base (set target FEQR to r FEQRLeanBase Less than 1), repeatedly controlling N0 times (10 are preferable in this embodiment, namely 10 periodic control FEQR), recording actual FEQR fed back by the upstream wide-area oxygen sensor in real time, and calculating actual FEQR bias concentration reflecting time T RichResDn And T RichResUp Calculating the actual FEQR dilution reflecting time T LeanResDn And T LeanResUp 。
T RichResDn The method for starting the calculation time comprises the following steps: actual FEQR and r for the current sampling period (all sampling periods take 2ms in this embodiment) FEQRRichBase The absolute value of the difference is smaller than ΔC (ΔC is 0.002 in this embodiment), and the actual FEQR and r are the next sampling period FEQRRichBase The absolute value of the difference is not less than deltac. Before the actual FEQR first appears to be greater than 1+/-delta C in the subsequent sampling period, the actual FEQR of the current sampling period is not less than the actual FEQR of all the subsequent sampling periods.
T RichResDn The method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual FEQR of the current sampling period and 1 is smaller than deltaC, and the absolute value of the difference between the actual FEQR of the next sampling period and 1 is not smaller than deltaC. The actual FEQR first appears to be greater than r in the subsequent sampling period FEQRLeanBase Before + -DeltaC, the actual FEQR of the current sampling period is not less than the actual FEQR of the subsequent all sampling periods.
T RichResUp The method for starting the calculation time comprises the following steps: the absolute value of the difference between the actual FEQR of the current sampling period and 1 is smaller than deltaC, and the absolute value of the difference between the actual FEQR of the next sampling period and 1 is not smaller than deltaC. The actual FEQR first appears to be greater than r in the subsequent sampling period FEQRRichBase Before + -DeltaC, the actual FEQR of the current sampling period is not greater than the actual FEQR of the subsequent all sampling periods.
T RichResUp The method for ending the calculation time comprises the following steps: front sampling period actual FEQR and r FEQRRichBase The absolute value of the difference is smaller than ΔC (ΔC is 0.002 in this embodiment), and the actual FEQR and r are the next sampling period FEQRRichBase The absolute value of the difference is not less than deltac. Before the actual FEQR first appears to be greater than 1+/-delta C in the subsequent sampling period, the actual FEQR of the current sampling period is not less than the actual FEQR of all the subsequent sampling periods.
T LeanResDn The method for starting the calculation time comprises the following steps: the absolute value of the difference between the actual FEQR of the current sampling period and 1 is smaller than deltaC, and the absolute value of the difference between the actual FEQR of the next sampling period and 1 is not smaller than deltaC. Actual FEQR first in subsequent adoption periodOccurrence of more than r FEQRLeanBase Before + -DeltaC, the actual FEQR of the current sampling period is not less than the actual FEQR of the subsequent all sampling periods.
T LeanResDn The method for ending the calculation time comprises the following steps: actual FEQR and r of current sampling period FEQRLeanBase The absolute value of the difference is smaller than ΔC (ΔC is 0.002 in this embodiment), and the actual FEQR and r are the next sampling period FEQRLeanBase The absolute value of the difference is not less than deltac. Before the actual FEQR first appears to be greater than 1+/-delta C in the subsequent sampling period, the actual FEQR of the current sampling period is not greater than the actual FEQR of all the subsequent sampling periods.
T LeanResUp The method for starting the calculation time comprises the following steps: actual FEQR and r of current sampling period FEQRLeanBase The absolute value of the difference is smaller than ΔC (ΔC is 0.002 in this embodiment), and the actual FEQR and r are the next sampling period FEQRLeanBase The absolute value of the difference is not less than deltac. Before the actual FEQR first appears to be greater than 1+/-delta C in the subsequent sampling period, the actual FEQR of the current sampling period is not greater than the actual FEQR of all the subsequent sampling periods.
T LeanResUp The method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual FEQR of the current sampling period and 1 is smaller than deltaC, and the absolute value of the difference between the actual FEQR of the next sampling period and 1 is not smaller than deltaC. The actual FEQR first appears to be greater than r in the subsequent adoption period FEQRLeanBase Before + -DeltaC, the actual FEQR of the current sampling period is not greater than the actual FEQR of the subsequent all sampling periods.
Reading the current actual FEQR, i.e. the actual FEQR at the time of entering the diagnosis, setting the target feqr=r FEQRRichBase The present embodiment is FEQR+0.02, FEQR+0.05, FEQR+0.1, and the target FEQR=r FEQRLeanBase Take 2FEQR-r FEQRRichBase (i.e., FEQR+0.02 and FEQR-0.02 for N0 cycles, FEQR+0.05 and FEQR-0.05 for N0 cycles, and FEQR+0.1 and FEQR-0.1 for N0 cycles).
T RichResDn Respectively corresponding to read T RichResDn11 ，T RichResDn12 And T RichResDn13 And consists of N0 number arrays, and the head 2 number and the tail 2 number are removed (avoiding the control system not being used when FEQR active regulation is just introducedStably causing data deviation to improve data accuracy), obtaining N0-4 numbers, and calculating average value corresponding to the N0-4 numbers to obtainAnd->
T RichResUp Respectively corresponding to read T RichResUp11 ，T RichResUp12 And T RichResUp13 And each consists of an array of N0 numbers, the head 2 numbers and the tail 2 numbers are removed to obtain N0-4 numbers, and an average value corresponding to the N0-4 numbers is calculated to obtainAnd->
T LeanResDn Respectively corresponding to read T LeanResDn11 ，T LeanResDn12 And T LeanResDn13 And each consists of an array of N0 numbers, the head 2 numbers and the tail 2 numbers are removed to obtain N0-4 numbers, and an average value corresponding to the N0-4 numbers is calculated to obtainAnd->
T LeanResUp Respectively corresponding to read T LeanResUp11 ，T LeanResUp12 And T LeanResUp13 And each consists of an array of N0 numbers, the head 2 numbers and the tail 2 numbers are removed to obtain N0-4 numbers, and an average value corresponding to the N0-4 numbers is calculated to obtainAnd->
The wide-area oxygen sensor fails if any of the following occurs:
1.andany 1 of the 6 times is greater than +.>The wide-area oxygen sensor fails; wherein->To average cylinder fresh air intake flow after intake diagnostics. d, d 2 ，d 1 ，d 0 Takes the value of-80.232 (ms.mgps) 2 ) 3520.23 (ms. Mgps), 0.034 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
2.Andany 1 of the 6 times is greater than +.>The wide-area oxygen sensor fails; d, d 5 ，d 4 ，d 3 The values are 4538.245 (ms/mgps) 2 ) -1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
3.And->Absolute value of difference (or->And->Absolute difference, or->And->Absolute difference value)>And->Absolute value of difference (orAnd->Absolute difference, or->And->Absolute difference value) is greater thanThe wide-area oxygen sensor fails; d, d 7 ，d 6 The values are respectively 0.12 (ms), 2.376 (ms) and r are different FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
4.And->Absolute value of difference (or->And->Absolute difference, or->And->Absolute difference value)>And->Absolute value of difference (orAnd->Absolute difference, or->And->Absolute difference value) is greater thanThe wide-area oxygen sensor fails; d, d 9 ，d 8 The values are respectively 0.201 (ms), 0.531 (ms) and are respectively equal to or less than the values of +.>And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
And after any fault occurs in the 4 kinds of fault diagnosis, the driving cycle is not diagnosed any more.
b) Once the ratio of the catalyst oxygen storage amount 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 the working conditions and the working condition stabilizing conditions are satisfied, the oxygen storage amount is insufficient at the moment, and in order to reduce the influence on the emission, the target FEQR is periodically controlled, namely the air-fuel ratio time T is controlled by enrichment Base (time T) Base In this embodiment, 1.4s is taken and the target FEQR is set to r FEQRRichBase Greater than 1) and then immediately setting the target FEQR to r FEQRLeanBase Less than 1 time T Min (time T) Min 0.1s is taken in the embodiment), repeatedly controlling for N0 times (10 are taken in the embodiment, namely 10 periodic control FEQR are taken), recording actual FEQR fed back by an upstream wide-area oxygen sensor in real time, and calculating actual FEQR bias concentration reflecting time T RichResDn And T RichResUp . The same method obtains Andthe same method performs fault diagnosis:
1.any 1 of 3 times is greater thanThe wide-area oxygen sensor fails; wherein->To average cylinder fresh air intake flow after intake diagnostics. d, d 2 ，d 1 ，d 0 Takes the value of-80.232 (ms.mgps) 2 ) 3520.23 (ms. Mgps), 0.034 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
2.Any 1 of 3 times is greater thanThe wide-area oxygen sensor fails; d, d 5 ，d 4 ，d 3 The values are 4538.245 (ms/mgps) 2 ) -1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
3.And->Absolute value of difference (or->And->Absolute difference, or->And->Absolute difference value) of greater than->The wide-area oxygen sensor fails; d, d 9 ，d 8 The values are respectively 0.201 (ms), 0.531 (ms) and are respectively equal to or less than the values of +.>And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
And after any fault occurs in the 3 fault diagnoses, the driving cycle is not diagnosed.
c) Once the ratio of the catalyst oxygen storage amount to the total oxygen storage amount is larger than r2 (0.89 is taken in the embodiment), and the fault diagnosis of a and b in the driving cycle is not completed.
After all the working conditions and the working condition stabilizing conditions are satisfied, the oxygen storage amount is insufficient at the moment, and in order to reduce the influence on the emission, the target FEQR is periodically controlled, namely the lean ratio time T Base (time T) Base In this embodiment, 1.4s is taken and the target FEQR is set to r FEQRRichBase Small 1), then immediately sets the target FEQR to r FEQRLeanBase Less than 1 time T Min (time T) Min 0.1s is taken in the embodiment), repeatedly controlling for N0 times (10 are taken in the embodiment, namely 10 periodic control FEQR are taken), recording actual FEQR fed back by an upstream wide-area oxygen sensor in real time, and calculating actual FEQR dilution reflection time T LeanResDn And T LeanResUp . The same method obtains And->And->The same method performs fault diagnosis:
1.and->3 is greater than 1 timeThe wide-area oxygen sensor fails; wherein->To average cylinder fresh air intake flow after intake diagnostics. d, d 2 ，d 1 ，d 0 Takes the value of-80.232 (ms.mgps) 2 ) 3520.23 (ms. Mgps), 0.034 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
2.And->3 is greater than 1 timeThe wide-area oxygen sensor fails; d, d 5 ，d 4 ，d 3 The values are 4538.245 (ms/mgps) 2 ) -1108.524 (ms/mgps), 77.376 (ms), at different r FEQRRichBase And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor.
3.And->Absolute value of difference (or->And->Absolute difference, or->And->Absolute difference value) is greater than +.>The wide-area oxygen sensor fails; d, d 9 ，d 8 The values are respectively 0.201 (ms), 0.531 (ms) and are respectively equal to or less than the values of +.>And fitting data according to the calibration of the fault oxygen sensor and the fault-free oxygen sensor. />
And after any fault occurs in the 3 fault diagnoses, the driving cycle is not diagnosed.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (9)

1. The degradation diagnosis method of the wide-range oxygen sensor of the hybrid vehicle type engine is characterized by comprising the following steps of:
collecting an oxygen concentration signal of exhaust gas in the exhaust pipe after combustion through a wide-range oxygen sensor;
calculating an air-fuel ratio from 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 equivalent ratio is expressed as a ratio of the adjusted actual air-fuel ratio to the stoichiometric air-fuel ratio, and the target fuel equivalent ratio is expressed as a ratio of the target air-fuel ratio to the stoichiometric air-fuel ratio;
selecting corresponding degradation diagnosis according to 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;
the degradation diagnosis step specifically includes:
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 r1, periodically controlling the target fuel equivalent ratio, wherein the oxygen storage amount of the catalyst is insufficient at the moment, and the first preset time T is used for Base And performing an enrichment operation, wherein the enrichment operation comprises: increasing oxygen concentration, and setting the fuel equivalent ratio of the enrichment target as r FEQRRichBase Greater than 1, then for a second preset time T Min Performing an thinning operation, the thinning operation comprising: reducing oxygen concentration, and setting the target fuel equivalent ratio of the dilution as r FEQRLeanBase Less than 1; alternately repeating the enrichment operation and the thinning operation for N0 times respectively, recording the actual fuel equivalent ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first partial enrichment reflecting time T of the actual fuel equivalent ratio RichResDn And a second partial concentration reflecting time T RichResUp The method comprises the steps of carrying out a first treatment on the surface of the Wherein T is Base Greater than T Min ；
T RichResDn The method for judging the initial calculation time is as follows: actual fuel equivalence ratio in current sampling period and r FEQRRichBase The absolute value of the difference is smaller than the preset difference value delta C, and the actual fuel equivalent ratio and r in the next sampling period FEQRRichBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
T RichResDn the judging method of the end calculation time is as follows: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Prior to ± Δc, the current sampling weekThe actual fuel equivalent ratio of the period is greater than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
T RichResUp the method for starting the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRRichBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is smaller than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
T RichResUp the method for ending the calculation time comprises the following steps: actual fuel equivalence ratio in current sampling period and r FEQRRichBase The absolute value of the difference is smaller than delta C, and the actual fuel equivalent ratio in the next sampling period is equal to r FEQRRichBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
at T RichResDn Any reading of three elements T 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 final 2 elements are removed to obtain N0-4 elements, and an average value corresponding to the N0-4 elements is calculated to obtain And->
At T RichResUp Any reading of three elements T RichResUp11 ，T RichResUp12 And T RichResUp13 ，T RichResUp N0 elements corresponding to the number of enrichment operations exist in the array, and the initial 2 elements are removed andthe last 2 elements are used for obtaining N0-4 elements, and the average value corresponding to the N0-4 elements is calculated to obtain And->
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
(1)any time is greater thanJudging that the wide-area oxygen sensor fails; wherein->
Fresh air intake flow for the average cylinder after intake diagnosis; d, d 2 ，d 1 ，d 0 A second evaluation coefficient, a first evaluation coefficient and an initial evaluation coefficient, respectively, wherein d 2 ，d 1 ，d 0 At different r FEQRRichBase Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
(2)any time is greater thanJudging that the wide-area oxygen sensor fails; d, d 5 ，d 4 ，d 3 A fifth evaluation coefficient, a fourth evaluation coefficient, and a third evaluation coefficient, respectively, wherein d 5 ，d 4 ，d 3 At different r FEQRRichBase The following basisObtaining standard fitting data of the fault oxygen sensor and the fault-free oxygen sensor;
(3)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Any one of the absolute values of the differences is greater than +.>Judging that the wide-area oxygen sensor fails; d, d 9 ，d 8 A ninth evaluation coefficient and an eighth evaluation coefficient, respectively, wherein d 9 ，d 8 In a different->Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
after any fault judgment occurs in the above 3 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
2. The degradation diagnosis method of a wide-range oxygen sensor of a hybrid vehicle type engine according to claim 1, wherein, before the degradation diagnosis is performed, the detection of the operating condition is performed, the operating condition including:
the engine speed is in a certain range; the related diagnosis of the engine speed is free of faults;
the engine has no fuel cut;
the wide-area oxygen sensor is heated, i.e. the wide-area oxygen sensor is already within the normal working temperature; the wide-range oxygen sensor is heated to diagnose that no fault occurs;
the accelerator is not fully opened, and the opening of the accelerator pedal is in a certain range; the accelerator opening sensor diagnoses no fault;
the cooling water temperature of the engine exceeds a certain value; the cooling temperature sensor diagnoses no fault;
the temperature of an engine intake manifold exceeds a certain value; the intake manifold temperature sensor diagnoses no fault;
the engine running time exceeds a certain value, and the engine warmup is successful at the moment;
the air inflow in the air inlet cylinder is in a certain range; a relevant diagnosis for monitoring or calculating the intake air amount does not occur;
the speed of the vehicle exceeds a certain value; the related diagnosis of the vehicle speed has no fault;
and when the working conditions are all met, the degradation diagnosis of the wide-range oxygen sensor is allowed to be entered.
3. The degradation diagnosis method for a wide-range oxygen sensor of a hybrid vehicle type engine according to claim 2, wherein after the condition is satisfied, the condition stable condition detection is performed, the condition stable condition comprising:
the engine speed fluctuates in a certain range;
the opening degree of the accelerator pedal fluctuates in a certain range;
the vehicle speed fluctuates in a certain range;
the amount of intake air into the cylinder fluctuates in a certain range;
and after the working condition stabilizing condition and the working condition are met, entering degradation diagnosis of the wide-range oxygen sensor.
4. The degradation diagnosis method of a wide-area oxygen sensor of a hybrid vehicle type engine according to claim 3, characterized in that the degradation diagnosis step further comprises: under the working condition of stable condition and working conditionAfter all the conditions are 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, and the oxygen storage amount of the catalyst is fully filled at the moment, and the first preset time T is used for Base Performing enrichment operation, and then performing enrichment operation for a first preset time T Base Performing thinning operation; alternately repeating the enrichment operation and the thinning operation for N0 times respectively, recording the actual fuel equivalent ratio fed back by the upstream wide-range oxygen sensor in real time, and calculating the first partial enrichment reflecting time T of the actual fuel equivalent ratio RichResDn Second partial concentration reflecting time T RichResUp First lean reflection time T LeanResDn And a second lean reflection time T LeanResUp ；
T LeanResDn The method for judging the initial calculation time is as follows: the absolute value of the difference between the actual fuel equivalent 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 equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is greater than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
T LeanResDn the judging method of the end calculation time is as follows: actual fuel equivalence ratio in current sampling period and r FEQRLeanBase The absolute value of the difference is smaller than delta C, and the actual fuel equivalent ratio in the next sampling period is equal to r FEQRLeanBase The absolute value of the difference is greater than or equal to Δc; before the actual fuel equivalent ratio in the subsequent sampling period appears larger than 1+/-delta C for the first time, the actual fuel equivalent ratio in the current sampling period is larger than or equal to the actual fuel equivalent ratio in all the subsequent sampling periods;
T LeanResUp the method for starting the calculation time comprises the following steps: actual fuel equivalence ratio in current sampling period and r FEQRLeanBase The absolute value of the difference is smaller than delta C, and the actual fuel equivalent ratio in the next sampling period is equal to r FEQRLeanBase The absolute value of the difference is greater than or equal to Δc; the actual fuel equivalence ratio of the current sampling period is greater than 1 + -DeltaC before the actual fuel equivalence ratio of the subsequent sampling period first occursThe fuel equivalence ratio is less than or equal to the actual fuel equivalence ratio for all subsequent sampling periods;
T LeanResUp the method for ending the calculation time comprises the following steps: the absolute value of the difference between the actual fuel equivalent ratio and 1 in the current sampling period is smaller than delta C, and the absolute value of the difference between the actual fuel equivalent ratio and 1 in the next sampling period is larger than or equal to delta C; the actual fuel equivalence ratio first appears to be greater than r in the subsequent sampling period FEQRLeanBase Before (+/-delta) C, the actual fuel equivalent ratio of the current sampling period is greater than or equal to the actual fuel equivalent ratio of all the subsequent sampling periods;
at T LeanResDn Any reading of three elements T 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 final 2 elements are removed to obtain N0-4 elements, and an average value corresponding to the N0-4 elements is calculated to obtain And->
At T LeanResUp Any reading of three elements T 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 final 2 elements are removed to obtain N0-4 elements, and an average value corresponding to the N0-4 elements is calculated to obtain And->
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
(4)andany time of (2) is greater than->Judging that the wide-area oxygen sensor fails;
(5)andany time of (2) is greater than->Judging that the wide-area oxygen sensor fails;
(6)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Absolute value of difference +.>And->Absolute value of difference +.>Andabsolute value of difference +.>And->Any one of the absolute values of the differences is greater thanJudging that the wide-area oxygen sensor fails; d, d 7 ，d 6 A seventh evaluation coefficient and a sixth evaluation coefficient, respectively, wherein d 7 ，d 6 At different r FEQRRichBase Obtaining standard fitting data according to the fault oxygen sensor and the fault-free oxygen sensor;
(7)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Absolute value of difference +.>And->Absolute value of difference +.>And->Absolute value of difference +.>And->Any one of the absolute values of the differences is greater thanJudging that the wide-area oxygen sensor fails;
after any fault judgment occurs in the above 4 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
5. The degradation diagnosis method of a wide-area oxygen sensor of a hybrid vehicle type engine according to claim 4, characterized in that the degradation diagnosis step further comprises: after the stable working condition and the stable working condition are satisfied, when the ratio of the oxygen storage amount of the catalyst to the total oxygen storage amount is larger than r2, the oxygen storage amount is too high at the moment, and the first preset time T is used Base Performing thinning operation, and then performing thinning operation for a second preset time T Min Performing enrichment operation; alternately repeating the thinning operation and the enrichment operation for N0 times, recording the actual fuel equivalent 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 equivalent ratio LeanResDn And a second lean reflection time T LeanResUp ；
Judging that the wide-area oxygen sensor fails when any one of the following conditions occurs:
(8)and->Any time is greater thanJudging that the wide-area oxygen sensor fails;
(9)and->Any time is greater thanJudging that the wide-area oxygen sensor fails;
(10)and->Absolute value of difference +.>And->The absolute value of the difference between the two,and->Any one of absolute values of differencesIs greater than->Judging that the wide-area oxygen sensor fails;
after any fault judgment occurs in the above 3 kinds of fault diagnosis, the present driving cycle does not perform degradation diagnosis any more.
6. The hybrid vehicle type engine wide area oxygen sensor degradation diagnosis method according to claim 1, characterized in that the stoichiometric air-fuel ratio is 14.3.
7. The hybrid vehicle type engine wide area oxygen sensor degradation diagnosis method according to any one of claims 1 to 4, wherein r1 is 0.13.
8. The hybrid vehicle type engine wide area oxygen sensor degradation diagnosis method according to claim 4 or 5, characterized in that r2 is 0.89.
9. The degradation diagnosis method for a wide-range oxygen sensor of a hybrid vehicle type engine according to any one of claims 1 to 5, characterized in that the preset difference value Δc is 0.002.
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