CN113323747B

CN113323747B - Abnormality diagnosis of catalytic converter and electronic equipment

Info

Publication number: CN113323747B
Application number: CN202110697370.5A
Authority: CN
Inventors: 刘勇军; 李华龙; 孟艳玲; 于磊罡
Original assignee: Dongfeng Nissan Passenger Vehicle Co
Current assignee: Dongfeng Nissan Passenger Vehicle Co
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-08-23
Anticipated expiration: 2041-06-23
Also published as: CN113323747A

Abstract

The invention discloses a catalytic converter abnormity diagnosis method, electronic equipment and storage equipment, wherein the method comprises the following steps: monitoring a deceleration fuel cut judgment mark; if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, calculating the oxygen storage amount of the catalytic converter after the fuel supply is recovered, and judging whether the catalytic converter has an abnormal fault or not according to the oxygen storage amount. The abnormal condition fault detection is completely based on the natural driving state of the vehicle in daily use, and a specific idle speed working condition is not required to be selected, so that the influence of diagnosis on the idle speed start-stop of the vehicle with the idle speed start-stop function is avoided, and the influence of the diagnosis on the deterioration of the fuel consumption performance is avoided. The diagnosis mode is a passive observation type diagnosis, and the air-fuel ratio control cannot be specially and actively changed in the diagnosis process, the running state of the engine is not influenced, and the deterioration of emission and oil consumption performance caused by fault diagnosis needs is avoided.

Description

Abnormality diagnosis of catalytic converter and electronic device

Technical Field

The invention relates to the technical field of automobiles, in particular to a catalytic converter abnormity diagnosis method and electronic equipment.

Background

The catalytic converter is used for purifying pollutants in automobile exhaust. Such as a three-way catalytic converter that purifies hydrocarbon, carbon monoxide, and nitrogen oxides.

Generally, the catalyst abnormality diagnosis is based on monitoring the signal changes of two oxygen (air-fuel ratio) sensors installed upstream and downstream of the catalyst in real time, performing a series of calculation processing on the signals to obtain the oxygen storage capacity of the catalyst, and further performing fault judgment through an oxygen storage capacity index.

The implementation method of the diagnosis scheme has different influences due to the selection of diagnosis time, the calculation method of parameters (input and output of oxygen storage index, calculation process and the like), and whether to actively change the differences of oil injection of the engine controller during diagnosis. Correspondingly, the development workload in the vehicle development process, the exhaust emission amount and the fuel consumption amount of the vehicle in actual use of the vehicle and the like are affected differently.

The existing diagnosis of the catalyst adopts active intrusive diagnosis, the diagnosis requires that an engine is started at idle speed, and whether the catalyst breaks down or not is judged by sending an instruction to the catalyst and judging an active intervention diagnosis index of the catalyst after receiving the instruction.

However, such active intrusive diagnostics enrich and enleane engine combustion, which can lead to increased vehicle emissions. Secondly, for the vehicle type with the idling starting and stopping function, the engine is forbidden to stop by active intrusive diagnosis, so that the oil consumption is deteriorated. In addition, in the existing diagnosis, the catalyst temperature correction coefficient is adopted for actively involved diagnosis index correction, actual data shows that the influence of the parameter on the diagnosis can be ignored, and development work is additionally added. Furthermore, the diagnostic index filter factor is constant and is not representative, and the fault detection speed is slow after the catalyst is degraded. Finally, the existing active intrusive diagnostics only use the data of the downstream sensor disposed at the output of the three-way catalytic converter, and require a long period of stable operation time, such as stable vehicle speed, and the accuracy and frequency of the diagnostic results are difficult to meet increasingly strict regulatory requirements.

Another diagnostic method employs a passive observational diagnostic strategy in which the signal of the diagnostic evaluation parameter is based only on the downstream sensor signal in the vehicle exhaust system, ignoring catalytic converter performance indicators that react between the oxygen sensor signal mounted upstream of the catalytic converter and the downstream sensor signal variation.

The other diagnosis method adopts a combination mode of coarse screening by adopting a passive observation mode and rechecking confirmation by adopting an active intrusion mode, has long diagnosis process, generates additional emissions in the active intrusion stage, brings adverse effects to the environment, and is contradictory to increasingly strict emission regulations and social development requirements.

Disclosure of Invention

Accordingly, it is necessary to provide a method for diagnosing abnormality of a catalytic converter and an electronic apparatus, which are directed to a technical problem that the prior art is insufficient for diagnosing a malfunction of a three-way catalytic converter.

The invention provides a method for diagnosing abnormality of a catalytic converter, comprising the steps of:

monitoring a deceleration fuel cut judgment mark;

if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, calculating the oxygen storage amount of the catalytic converter after the fuel supply is recovered, and judging whether the catalytic converter has an abnormal fault or not according to the oxygen storage amount.

Further, if it is judged that the sign is established to detect deceleration fuel cut-off, then wait for the vehicle to resume fuel feeding, calculate the oxygen storage capacity of catalytic converter after resuming fuel feeding, specifically include:

and if the deceleration fuel cut judgment identification is detected to be established, waiting for the vehicle to recover the fuel supply, and calculating the oxygen storage amount of the catalytic converter in the metering time period after the fuel supply is recovered.

Furthermore, if it is determined that the deceleration fuel cut judgment flag is established, waiting for the vehicle to recover the fuel supply and calculating the oxygen storage amount of the catalytic converter in the metering time period after the fuel supply recovery specifically includes:

if the deceleration fuel cut judgment mark is detected to be established, acquiring the air-fuel ratio output by an upstream sensor and a downstream sensor of the vehicle-mounted catalytic converter;

if the air-fuel ratio output by the upstream sensor and the air-fuel ratio output by the downstream sensor are both larger than a preset first air-fuel ratio threshold value, judging that the catalytic converter fully stores oxygen;

after the catalytic converter is judged to store oxygen sufficiently, when the air-fuel ratio output by the upstream sensor is smaller than a second air-fuel ratio threshold value, the start of a metering time period is judged, and the air intake flow or the exhaust flow of the engine is acquired, wherein the second air-fuel ratio threshold value is smaller than or equal to the first air-fuel ratio threshold value;

and when the air-fuel ratio output by the downstream sensor is smaller than a second air-fuel ratio threshold value, judging that the metering time period is ended, and calculating the oxygen storage amount of the catalytic converter based on the air intake flow or the exhaust flow of the engine acquired in the metering time period.

Still further, if the air-fuel ratios output by the upstream sensor and the downstream sensor are both greater than a preset first air-fuel ratio threshold, monitoring whether the air-fuel ratio output by the upstream sensor is less than a second air-fuel ratio threshold specifically includes:

and if the duration of the establishment of the deceleration fuel cut-off judgment identification exceeds a preset deceleration fuel cut-off duration threshold value and the air-fuel ratios output by the upstream sensor and the downstream sensor are both greater than a preset first air-fuel ratio threshold value, monitoring whether the air-fuel ratio output by the upstream sensor is less than a second air-fuel ratio threshold value.

Further, the identification is judged in monitoring deceleration fuel cut-off specifically includes:

and monitoring the temperature of the catalytic converter, and if the temperature of the catalytic converter is greater than a preset temperature threshold value, monitoring a deceleration fuel cut judgment mark.

and recording and accumulating the running time of the engine after the vehicle is started, and monitoring the deceleration fuel cut judgment identifier if the running time of the engine exceeds a preset engine time threshold.

Further, if it is determined that the deceleration fuel cut-off judgment identification is established, then wait for the vehicle to recover the fuel supply, calculate the oxygen storage amount of the catalytic converter after recovering the fuel supply, and according to the oxygen storage amount, determine whether the catalytic converter has an abnormal fault, specifically include:

if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, and calculating the current oxygen storage amount of the catalytic converter after the fuel supply is recovered;

calculating the current oxygen storage capacity index according to the current oxygen storage amount and the previous oxygen storage amount;

and judging whether the catalytic converter has abnormal faults or not according to the current oxygen storage capacity index.

Further, the determining whether the catalytic converter has an abnormal fault according to the current oxygen storage capacity index specifically includes:

and if the secondary oxygen storage capacity index is smaller than a preset fault threshold value, judging that the catalytic converter has an abnormal fault, otherwise, judging that the catalytic converter has no fault, wherein the fault threshold value is between mu 1+ N & gtsigma 1 and mu 2-N & gtsigma 2, wherein mu 1 is an average value of the oxygen storage capacity indexes of the plurality of aged catalytic converters after a plurality of tests, sigma 1 is a standard deviation of the oxygen storage capacity indexes of the plurality of aged catalytic converters after a plurality of tests, mu 2 is an average value of the oxygen storage capacity indexes of the plurality of critical catalytic converters after a plurality of tests, sigma 2 is a standard deviation of the oxygen storage capacity indexes of the plurality of critical catalytic converters after a plurality of tests, and N is a preset range coefficient.

The present invention provides an electronic device, including:

at least one processor; and the number of the first and second groups,

a memory communicatively coupled to at least one of the processors; wherein the content of the first and second substances,

the memory stores instructions executable by at least one of the processors to enable the at least one of the processors to perform a method of diagnosing a catalytic converter abnormality as described above.

The present invention provides a storage medium storing computer instructions for performing all the steps of the catalytic converter abnormality diagnosis method as described above when a computer executes the computer instructions.

The abnormal condition fault detection is completely based on the natural driving state of the vehicle in daily use, and a specific idle speed working condition is not required to be selected, so that the influence of diagnosis on the idle speed start-stop of the vehicle with the idle speed start-stop function is avoided, and the influence of the diagnosis on the deterioration of the fuel consumption performance is avoided. The diagnosis mode is a passive observation type diagnosis, and the air-fuel ratio control cannot be specially and actively changed in the diagnosis process, the running state of the engine is not influenced, and the deterioration of emission and oil consumption performance caused by fault diagnosis needs is avoided.

Drawings

Fig. 1 is a flowchart illustrating an abnormality diagnosis method for a catalytic converter according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a catalytic converter connected to an upstream sensor and a downstream sensor according to an embodiment of the present invention;

fig. 3 is a method for diagnosing abnormality of a catalytic converter according to a second embodiment of the present invention;

FIG. 4 is a schematic diagram of a catalytic converter in daily use of a vehicle;

FIG. 5a is a schematic view of the beginning stage when deceleration fuel cut-off occurs;

FIG. 5b is a schematic diagram of an ongoing intermediate stage when a deceleration fuel cut occurs;

FIG. 5c is a schematic diagram of a catalytic converter full oxygenation stage when a deceleration fuel cut occurs;

FIG. 6a is a schematic diagram of the beginning of a vehicle refueling event after deceleration fuel cut;

FIG. 6b is a schematic diagram of an intermediate stage of vehicle fueling recovery after deceleration fuel cut;

FIG. 6c is a schematic diagram illustrating the consumption of stored oxygen in the catalytic converter after fuel cut-off at deceleration and after fuel supply to the vehicle is resumed;

FIG. 7 is a graphical illustration of a catalytic converter performance parameter differentiation;

FIG. 8 is a flowchart illustrating a method for diagnosing abnormality of a catalytic converter in accordance with a preferred embodiment of the present invention;

fig. 9 is a schematic diagram of a hardware structure of an electronic device for diagnosing abnormality of a catalytic converter according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

Example one

Fig. 1 is a flowchart illustrating a method for diagnosing an abnormality of a catalytic converter according to an embodiment of the present invention, including:

step S101, monitoring a deceleration fuel cut judgment mark;

and step S102, if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, calculating the oxygen storage amount of the catalytic converter after the fuel supply is recovered, and judging whether the catalytic converter has an abnormal fault or not according to the oxygen storage amount.

Specifically, the present embodiment is applied to an Electronic Control Unit (ECU) of a vehicle. As shown in fig. 2, the catalytic converter 1 is preferably a three-way catalytic converter. An input, i.e. upstream, of the catalytic converter 1 is provided with an upstream sensor 2, and an output, i.e. downstream, of the catalytic converter 1 is provided with a downstream sensor 3. The upstream sensor 2 outputs the real-time air-fuel ratio at the input end of the catalytic converter 1 to the automotive electronic control unit 4, and the downstream sensor 3 outputs the real-time air-fuel ratio at the output end of the catalytic converter 1 to the automotive electronic control unit 4. The automotive electronic control unit 4 executes the catalytic converter abnormality diagnostic method of the present application. The upstream sensor 2 and the downstream sensor 3 may be oxygen sensors or flammability sensors.

During the use of the vehicle on the market, a large number of deceleration fuel cut-off working conditions exist, such as the condition that the vehicle is in front of a traffic light, on a downhill road, and the vehicle is recovered to normal speed after overtaking in high-speed running. The deceleration fuel cut-off working condition can be indicated whether the vehicle is in the deceleration fuel cut-off working condition or not by outputting a corresponding mark by a controller of the vehicle. The deceleration fuel cut-off condition is obtained, for example, from the engine Control module ecm (engine Control module). Step S101 continuously monitors the deceleration fuel cut judgment mark. When the fact that the monitored deceleration fuel cut-off judgment identification is established is detected, namely the vehicle is in the deceleration fuel cut-off working condition, the step S102 is triggered at the moment, the vehicle is waited for recovering the fuel supply, the oxygen storage amount of the catalytic converter after the fuel supply is recovered is calculated, and whether the catalytic converter has an abnormal fault or not is judged according to the oxygen storage amount.

When the vehicle is in the deceleration fuel cut-off working condition, harmful waste gas can be completely emptied after a certain time of gas atmosphere in the catalytic converter in the exhaust system, and oxygen is fully stored. Similarly, the catalytic converter is purged with fresh air.

After the deceleration fuel cut-off, the vehicle can recover the fuel supply in due time, the gas entering the catalytic converter is the harmful waste gas after the combustion of the oil-gas mixture, the waste gas generates the oxidation/reduction reaction in the catalytic converter, the oxygen stored in the catalytic converter during the previous deceleration fuel cut-off is consumed, the oxygen stored in the catalytic converter is completely consumed, the oxygen storage amount of the catalytic converter can be calculated, and whether the catalytic converter has the abnormal fault or not is judged according to the oxygen storage amount.

And judging that the catalytic converter has faults, and carrying out fault code recording and lightening an engine fault lamp by the fault diagnosis controller.

Example two

Fig. 3 is a flowchart illustrating an abnormality diagnosis method for a catalytic converter according to a second embodiment of the present invention, including:

step S301, recording and accumulating the running time of the engine after the vehicle is started, and monitoring a deceleration fuel cut judgment identifier if the running time of the engine exceeds a preset engine time threshold;

step S302, if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, and calculating the oxygen storage amount of the catalytic converter in the metering time period after the fuel supply is recovered;

in one embodiment, if it is determined that the deceleration fuel cut determination flag is satisfied, waiting for the vehicle to resume fuel supply and calculating an oxygen storage amount of the catalytic converter in a metering time period after the fuel supply is resumed includes:

if the air-fuel ratio output by the upstream sensor and the air-fuel ratio output by the downstream sensor are both larger than a preset first air-fuel ratio threshold value, judging that the catalytic converter fully stores oxygen; (ii) a

In one embodiment, the monitoring whether the air-fuel ratio output by the upstream sensor is smaller than a second air-fuel ratio threshold if the air-fuel ratios output by the upstream sensor and the downstream sensor are both larger than a preset first air-fuel ratio threshold specifically includes:

and if the deceleration fuel cut-off judgment mark establishment duration time is detected to exceed a preset deceleration fuel cut-off duration time threshold, and the air-fuel ratios output by the upstream sensor and the downstream sensor are both greater than a preset first air-fuel ratio threshold, monitoring whether the air-fuel ratio output by the upstream sensor is less than a second air-fuel ratio threshold.

Step S303, judging whether the catalytic converter has abnormal faults or not according to the oxygen storage amount.

Specifically, step S301 calculates the engine operating time. The engine time threshold is experimentally calibrated. Different engine time thresholds can be set under different environmental conditions of different vehicle types. Specifically, when the engine run time reaches the engine time threshold, the vehicle model meets the C400 requirement for the catalytic converter under the current ambient conditions. The accumulated running time of the engine after each start is used for ensuring that the catalyst reaches the C400 requirement under different vehicle types and different environmental conditions. The indexes of the catalyst for representing the conversion efficiency generally comprise a T50 index and a C400 index, wherein T50 is the temperature reaching 50 percent of conversion rate, and C400 is the conversion rate reaching 400 ℃, and generally the conversion rate is more than 99 percent.

The oxygen storage capacity of the catalyst is affected by the temperature of the catalytic converter body, and when the temperature of the catalytic converter body is lower than a certain value, the measured OSC result is unstable and has a small value. For the case where a temperature sensor is not provided to measure the temperature of the catalytic converter itself, the temperature monitoring of this catalytic converter is often a model-based estimated value, which has a problem with accuracy. Therefore, in the diagnosis, in order to avoid the influence of the temperature on the calculation result of the oxygen storage capacity index, in addition to the reference of the estimated temperature based on the model as the judgment condition, an engine continuous operation time (high-temperature exhaust gas generated by the engine operation is a heat source) is set based on engineering experience to ensure that the catalytic converter is sufficiently heated.

When the running time of the engine reaches the engine time threshold, the catalytic converter reaches the requirement of C400 at the moment, the deceleration fuel cut-off judgment mark is monitored, and whether the vehicle enters the deceleration fuel cut-off working condition or not is judged.

And when the deceleration fuel cut-off judgment mark is met, indicating that the vehicle enters the deceleration fuel cut-off working condition, triggering step S302, waiting for the vehicle to recover the fuel supply, and calculating the oxygen storage amount of the catalytic converter in the metering time period after the fuel supply is recovered.

In one embodiment, the monitoring of the deceleration fuel cut judgment identifier specifically includes:

In the case where the temperature sensor is provided to measure the temperature of the catalytic converter itself, it is possible to determine whether or not the catalytic converter has been sufficiently heated based on the detected temperature of the catalytic converter.

Fig. 4 is a schematic diagram showing the state of the catalytic converter 1 in daily use of the vehicle. Harmful exhaust gas enters the catalytic converter 1, and catalytic reaction occurs in the catalytic converter to purify the exhaust gas.

Fig. 5a shows a schematic view of the beginning of a deceleration fuel cut-off, in which the catalytic converter 1 of the exhaust system is filled with exhaust gases, in which the fresh air is shown in white and the exhaust gases are shown in black. The upstream sensor 2 first detects that the exhaust system is lean.

As shown in fig. 5b, which is a schematic diagram of the ongoing phase when a deceleration fuel cut occurs, the gas atmosphere in the catalytic converter 1 in the exhaust system is gradually switched from exhaust gas to fresh air.

Fig. 5c is a schematic diagram showing the sufficient oxygen charging stage of the catalytic converter when deceleration fuel cut occurs, and at this time, after a certain period of time elapses from the atmosphere in the catalytic converter 1 in the exhaust system (the period of time does not exceed that of a fresh catalytic converter, which is determined by the model of the catalytic converter and can be obtained through experimental measurement), the downstream sensor 3 also monitors that the exhaust gas is lean. Similarly, the three-way catalyst is purged with fresh air, and at this time, signals of the upstream and

downstream sensors

2 and 3 of the catalytic converter 1 in the exhaust system are both shown to be lean in air-fuel ratio, and it is judged that the catalytic converter has sufficiently stored oxygen by using this phenomenon.

After deceleration and oil cut, the vehicle can recover oil supply in time.

Fig. 6a is a schematic diagram showing the beginning stage when the vehicle resumes fuel supply after deceleration and fuel cut, in which the gas entering the catalytic converter 1 (the catalytic converter 1 is preferably a three-way catalyst) is the harmful exhaust gas after the combustion of the fuel-air mixture.

Fig. 6b is a schematic diagram of the vehicle at the middle stage of deceleration fuel cut-off when fuel supply is resumed, wherein the exhaust gas undergoes oxidation/reduction in the catalytic converter to consume the oxygen stored in the catalytic converter during the previous deceleration fuel cut-off.

As shown in fig. 6c, when the signal of the downstream sensor 3 of the catalytic converter 1 is changed from the lean state to the rich state during deceleration fuel cut, it is proved that the oxygen stored in the catalytic converter is completely consumed.

Using the above two natural phenomena, the signals monitored by the upstream sensor 2 and the downstream sensor 3 fitted to the catalytic converter 1 are recorded and developed as follows:

the method comprises the steps of monitoring and recording output signals of an upstream sensor 2 and a downstream sensor 3 which are assembled on a catalytic converter 1 in real time, utilizing the time difference of the air-fuel ratio signals from the lean to the rich switching time after the two sensors recover oil supply and the expansion integral calculation of the exhaust flow passing through a vehicle exhaust system in the period of time as an oxygen storage capacity index of the catalytic converter, and when the calculated oxygen storage capacity index is lower than a preset value, a fault diagnosis controller records fault codes and lights an engine fault lamp.

The air-fuel ratio a/F (a: air-air, F: fuel-fuel) represents the mixture ratio of air and combustible gas, and therefore the air-fuel ratio output by the upstream sensor 2 and the downstream sensor 3 is greater than the preset first air-fuel ratio threshold, indicating that the concentration of combustible gas in the mixture is lean, i.e., the catalytic converter has sufficiently stored oxygen.

Specifically, the upstream sensor and the downstream sensor may be wide-area air-fuel ratio sensors or switch-type oxygen sensors. The wide-range air-fuel ratio sensor can directly measure various specific values of the air-fuel ratio, and the switch type oxygen sensor can only judge the rich and lean levels. Whether the oxygen sensor is a switch type oxygen sensor or a wide-range oxygen sensor, the original signal output by the sensor is a voltage/current signal, and a specific air-fuel ratio value is obtained through conversion or the rich and lean levels are judged.

In the diagnosis logic, the converted air-fuel ratio signal is adopted, so that dependence on the specific type of the sensor can be eliminated, the decoupling of the type of the sensor and the diagnosis logic can be realized, and the universality of the diagnosis logic can be improved.

The wide-range air-fuel ratio sensor can determine the relationship with the air-fuel ratio threshold value according to the measured specific value of the air-fuel ratio. For the switching type oxygen sensor, when the output is a rich flag, it can be determined that the air-fuel ratio is smaller than the preset second air-fuel ratio threshold, and when the output is a lean flag, it can be determined that the air-fuel ratio is larger than the preset first air-fuel ratio threshold.

And when the air-fuel ratio output by the upstream sensor is smaller than a second air-fuel ratio threshold value, namely the starting stage when the vehicle resumes oil supply after deceleration and oil cut is started, judging that the metering time period is started, and acquiring the air intake flow or the exhaust flow of the engine.

And when the air-fuel ratio output by the downstream sensor is smaller than a second air-fuel ratio threshold value, namely the vehicle resumes oil supply after deceleration and oil cut, the consumption of the oxygen stored in the catalytic converter is finished. And judging that the metering time period is ended, and calculating the oxygen storage amount of the catalytic converter based on the intake air flow or the exhaust gas flow of the engine obtained in the metering time period.

The first air-fuel ratio threshold and the second air-fuel ratio threshold are oxygen sensor signal rich and lean judgment references, are determined by relevant factors such as sensor models and vehicle type differences, and are calibration quantities which can be flexibly adjusted.

Calculating the oxygen storage amount of the catalytic converter specifically comprises the following steps:

if the engine is charged in the metering time t, calculating the oxygen absorption amount in the metering time t as

If the engine exhausts in the metering time interval t, calculating the oxygen release amount in the metering time interval t as

Wherein the actual air-fuel ratio is a real-time air-fuel ratio output by the upstream sensor, the theoretical air-fuel ratio is a theoretical air-fuel ratio of the catalytic converter, the air amount is an engine flow rate and can be obtained by a flow sensor of the engine, and K is a preset proportionality coefficient.

In the embodiment, the change of the signals of the upstream and downstream oxygen sensors of the catalytic converter is used as the core input parameter of the judgment index calculation model to carry out passive observation type diagnosis, and the air-fuel ratio control (enrichment/enleanment) cannot be specially and actively changed in the diagnosis process, so that the running state of the engine is not influenced, and the deterioration of emission and oil consumption performance caused by fault diagnosis needs is avoided. The upstream air-fuel ratio sensor and the downstream oxygen sensor are used for diagnosing together, the diagnosis is quick, a long-term stable state is not needed, and even under a complex market use environment, the accuracy of a diagnosis result and the diagnosis frequency can meet increasingly strict regulation requirements.

In one embodiment, if it is determined that the deceleration fuel cut determination flag is satisfied, waiting for the vehicle to recover the fuel supply, calculating an oxygen storage amount of the catalytic converter after the fuel supply is recovered, and determining whether the catalytic converter has an abnormal fault according to the oxygen storage amount specifically includes:

Specifically, the cumulative amount OSCRAW of oxygen absorbed or released by the current catalyst is calculated _i Oxygen uptake or oxygen release, wherein:

the actual air-fuel ratio can be detected by an upstream sensor of the catalytic converter, and the air amount is an engine flow rate and can be obtained by a flow rate sensor of the engine.

Then, calculating the original value mutation parameter of the oxygen storage capacity of the catalyst:

ΔOSC＝OSCRAW _i -OSCRAW _i-1 wherein:

Δ OSC: determining parameters of oxygen storage quantity mutation (step change);

OSCRAW _i : the current test value of oxygen storage amount;

OSCRAW _i-1 the first initial value of the last oxygen storage amount is a default value of a 'passing' state;

and judging whether the state of the catalyst has mutation or not, and if the delta OSC is more than or equal to a threshold value A, selecting a mutation weighting correction coefficient to calculate the current oxygen storage capacity index:

OSCEWMA(i)＝OSCRAW _i *η _oscstep +OSCEWMA(i-1)*(1-η _oscstep ) Wherein:

oscewma (i): when the catalyst is tested, the oxygen storage capacity index of the catalyst is tested;

OSCEWMA (i-1): testing the oxygen storage capacity index of the catalyst at the last time;

OSCRAW _i : the current oxygen storage quantity test value;

η _oscstep : a mutation weighting correction coefficient;

and if the Delta OSC is less than the threshold value A, selecting a steady-state weighted correction coefficient to calculate a current oxygen storage capacity index:

OSCEWMA(i)＝OSCRAW _i *η _osccom +OSCEWMA(i-1)*(1-η _osccom ) Wherein:

OSCRAW _i : the current test value of oxygen storage amount;

η _osccom : a steady state weighted correction factor.

Finally, whether the catalytic converter is 'failed' is judged, if OSCEWMA (i) < threshold B, the state of the catalytic converter is judged to be failed, and an Engine Control Module (ECM) stores 'failure' fault information.

If the number of the cycle diagnosis reaches the maximum allowable diagnosis number, the state of the catalyst is judged to be good, the diagnosis is 'passed', otherwise, the deceleration fuel cut judgment mark is monitored again.

In the embodiment, multiple judgments are adopted, and for a new vehicle, when the oxygen storage capacity index is calculated for the first time, an OSCRAW default value is set, and the default value is calibrated according to the minimum oxygen storage capacity index of the fresh catalyst. Later on, the diagnostics, OSCRAW0 invoked when each driving cycle was first calculated, invokes the calculated value of the previous driving cycle.

In one embodiment, the determining whether the catalytic converter has an abnormal fault according to the current oxygen storage capacity index specifically includes:

As shown in fig. 7, a schematic diagram of performance parameter differentiation of the catalytic converter is shown, and vehicle development and calibration practices using the model prove that statistically, the worst level (aged catalytic converter after 20 kilometers of running) of the oxygen storage capacity index in the normal state and the best level (critical catalytic converter) of the oxygen storage capacity index in the fault state have obvious differentiation boundaries even when the fault differentiation is under 6 σ.

Wherein N is a natural number, preferably 6. The aged catalytic converter is preferably a 20 km post-trip catalytic converter, and the critical catalyst is a specially-made component having an emission performance meeting an OBD threshold required by emission regulations, such as: table j.1obd thresholds for GB18352.6-2016 emission limits of light duty car pollutants and methods of measurement (sixth stage of china).

The present embodiment achieves good discrimination by setting the failure threshold between the mean and standard deviation of the aged and critical catalytic converters, thereby having a distinct discrimination boundary.

Fig. 8 is a flowchart illustrating an abnormality diagnosis method for a catalytic converter according to a preferred embodiment of the present invention, including:

step S801, recording and accumulating the running time of the engine after the start;

step S802, if the accumulated running time of the current driving cycle of the engine is larger than a preset value (can be calibrated), step S803 is executed, otherwise, step S801 is continuously executed;

step S803, monitoring the deceleration fuel cut-off judgment identifier, if the deceleration fuel cut-off identifier is established, executing step S804, otherwise, continuing to execute step S803;

step S804, recording the deceleration fuel cut-off duration time, if the deceleration fuel cut-off duration time is larger than a preset value, executing step S805, otherwise, continuing to execute step S804;

step S805, monitoring and recording signals of upstream and downstream oxygen sensors and air inlet and exhaust flows of an engine;

step 806, if the signal of the upstream oxygen sensor is marked from thin to thick, executing step 807, otherwise, continuing to execute step 805, wherein the judgment reference of the signal of the oxygen sensor, namely the signal of the upstream oxygen sensor, is determined by the model of the sensor, the vehicle type difference and other related factors, and is a calibration quantity which can be flexibly adjusted;

step S807, the diagnosis condition meets the timer to start timing;

step S808, calculating a catalytic converter oxygen storage capacity index:

OSCRAW _i oxygen uptake or oxygen release, wherein:

step 809, if the downstream oxygen sensor signal is marked from thin to thick, executing step 810, otherwise executing step 808;

step S810, outputting OSCRAW by the calculation result of the oxygen storage capacity of the catalytic converter _i ；

Step S811, calculating an original value mutation parameter of the oxygen storage capacity of the catalytic converter:

ΔOSC＝OSCRAW _i -OSCRAW _i-1 wherein:

OSCRAW _i : the current test value of oxygen storage amount;

and for a new vehicle, setting an OSCRAW default value when the oxygen storage capacity is calculated for the first time, wherein the default value is calibrated according to the minimum oxygen storage capacity index of the fresh catalyst. Later diagnosis, OSCRAW0 invoked when each driving cycle was first calculated invokes the calculated value of the previous driving cycle;

step S812, judging whether the state of the catalyst has mutation, if the delta OSC is more than or equal to a threshold value A, executing step S813, otherwise executing step S814;

step S813, selecting the mutation weighting correction coefficient to calculate the current oxygen storage capacity index under the condition of mutation:

OSCEWMA(i)＝OSCRAW _i *η _oscstep +OSCEWMA(i-1)*(1-η _oscstep ) Then, the process proceeds to step S815,

wherein:

OSCRAW _i : the current test value of oxygen storage amount;

η _oscstep : a mutation weighting correction coefficient;

step S814, selecting the steady-state weighted correction coefficient to calculate the current oxygen storage capacity index when there is no mutation:

OSCEWMA(i)＝OSCRAW _i *η _osccom +OSCEWMA(i-1)*(1-η _osccom ) Then, the process proceeds to step S815,

wherein:

OSCRAW _i : the current test value of oxygen storage amount;

η _osccom : a steady state weighted correction factor.

Step S815, determining whether the catalytic converter is "failed", if oscewma (i) < threshold B, determining that the catalytic converter is in a failed state, and storing failure fault information in an Engine Control Module (ECM), otherwise, executing step S816;

step S816, if the number of times of diagnosis of the present cycle reaches the maximum allowable number of times of diagnosis, it is determined that the catalyst state is good, and the diagnosis "passes", otherwise, step S803 is executed.

The abnormal condition fault detection is completely based on natural driving states in daily use of the vehicle, and a specific idling working condition does not need to be selected, so that the influence of diagnosis on idling start and stop of the vehicle with the idling start and stop function is avoided, and the influence of the diagnosis on deterioration of fuel consumption performance is avoided. The method can well run under the national six WLTC circulating working conditions and the Chinese working conditions CLTC, and completely meets the requirements of the laws and regulations on diagnosis frequency and detection performance. The change of the signals of the upstream and downstream oxygen sensors of the three-way catalyst is used as the core input parameter of a judgment index calculation model to carry out passive observation type diagnosis, and the air-fuel ratio control (enrichment/lean) is not specially and actively changed in the diagnosis process, so that the running state of an engine is not influenced, and the deterioration of emission and oil consumption performance caused by fault diagnosis needs is avoided. The upstream air-fuel ratio sensor and the downstream oxygen sensor are used for diagnosing together, the diagnosis is quick, a long-term stable state is not needed, and even under a complex market use environment, the accuracy of a diagnosis result and the diagnosis frequency can meet increasingly strict regulation requirements. The practice of developing and calibrating the vehicle by adopting the model proves that the worst oxygen storage capacity index (an aged catalyst running for 20 kilometres) in a normal state and the best oxygen storage capacity index (a critical catalyst) in a fault state in a statistical sense still have obvious differentiation boundaries under the condition that the fault differentiation is 6 sigma.

EXAMPLE III

Fig. 9 is a schematic diagram of a hardware structure of an electronic device for diagnosing abnormality of a catalytic converter according to the present invention, including:

at least one processor 901; and (c) a second step of,

a memory 902 communicatively coupled to at least one of the processors 901; wherein, the first and the second end of the pipe are connected with each other,

the memory 902 stores instructions executable by at least one of the processors 901, the instructions being executable by the at least one of the processors 901 to enable the at least one of the processors 901 to:

monitoring an oxygen storage capacity index at an input of the catalytic converter;

if the oxygen storage capacity index meets a preset intervention condition, outputting an active operation instruction to the catalytic converter;

acquiring an oxygen storage time index of the catalytic converter when the catalytic converter executes the active operation instruction;

and if the oxygen storage time index meets a preset fault condition, judging that the catalytic converter has an abnormal fault.

The Electronic device is preferably an automotive Electronic Control Unit (ECU). Fig. 9 illustrates an example of a processor 901.

The electronic device may further include: an input device 903 and a display device 904.

The processor 901, the memory 902, the input device 903, and the display device 904 may be connected by a bus or other means, and are illustrated as being connected by a bus.

The memory 902, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules corresponding to the catalytic converter abnormality diagnosis method in the embodiment of the present application, for example, the method flow shown in fig. 1. The processor 901 executes various functional applications and data processing, that is, implements the catalytic converter abnormality diagnosis method in the above-described embodiment, by executing nonvolatile software programs, instructions, and modules stored in the memory 902.

The memory 902 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the catalytic converter abnormality diagnosis method, and the like. Further, the memory 902 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory 902 may optionally include a memory remotely disposed from the processor 901, and these remote memories may be connected via a network to a device that performs the catalytic converter abnormality diagnosis method. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The input device 903 may receive input of a user click and generate signal inputs related to user settings and function control of the catalytic converter abnormality diagnosis method. The display device 904 may include a display screen or the like.

The one or more modules stored in the memory 902, when executed by the one or more processors 901, perform the catalytic converter abnormality diagnosis method of any of the method embodiments described above.

The abnormal condition fault detection is completely based on the natural driving state of the vehicle in daily use, and a specific idle speed working condition is not required to be selected, so that the influence of diagnosis on the idle speed start-stop of the vehicle with the idle speed start-stop function is avoided, and the influence of the diagnosis on the deterioration of the fuel consumption performance is avoided. The diagnosis mode is a passive observation type diagnosis mode, and during the diagnosis process, the air-fuel ratio control is not specially and actively changed, the running state of the engine is not influenced, and the deterioration of emission and oil consumption performance caused by fault diagnosis needs is avoided.

An embodiment of the present invention provides a storage medium storing computer instructions for executing all the steps of the catalytic converter abnormality diagnosis method as described above, when the computer executes the computer instructions.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A catalytic converter abnormality diagnosis method characterized by comprising:

monitoring a deceleration fuel cut judgment mark;

if the deceleration fuel cut judgment mark is detected to be established, waiting for the vehicle to recover the fuel supply, calculating the oxygen storage amount of the catalytic converter after the fuel supply is recovered, and judging whether the catalytic converter has an abnormal fault or not according to the oxygen storage amount;

if it is true to detect the speed reduction fuel cut-off judgment sign, then wait for the vehicle to resume the fuel feeding, calculate the oxygen storage amount of the catalytic converter after resuming the fuel feeding, specifically include:

if the deceleration fuel cut judgment identification is detected to be established, waiting for the vehicle to recover the fuel supply, and calculating the oxygen storage amount of the catalytic converter in the metering time period after the fuel supply is recovered;

if it is true to detect the speed reduction fuel cut-off judgment sign, then wait for the vehicle to resume the fuel feeding, calculate the oxygen storage amount of catalytic converter in the metering interval after resuming the fuel feeding, specifically include:

2. The abnormality diagnostic method for a catalytic converter according to claim 1, wherein the monitoring of whether the air-fuel ratio output by the upstream sensor is smaller than a second air-fuel ratio threshold value if the air-fuel ratio output by the upstream sensor and the air-fuel ratio output by the downstream sensor are both larger than a preset first air-fuel ratio threshold value, specifically includes:

3. The abnormality diagnosis method for a catalytic converter according to claim 1, wherein the monitoring of the deceleration fuel cut determination flag specifically includes:

4. The abnormality diagnosis method for a catalytic converter according to claim 1, wherein the monitoring of the deceleration fuel cut determination flag specifically includes:

5. The abnormality diagnosis method for the catalytic converter according to claim 1, wherein the waiting for the fuel cut-off of the vehicle if the deceleration fuel cut-off judgment flag is detected to be established, calculating an oxygen storage amount of the catalytic converter after the fuel cut-off is resumed, and judging whether the catalytic converter has an abnormal fault or not according to the oxygen storage amount specifically includes:

if the deceleration fuel cut judgment identification is detected to be established, waiting for the vehicle to recover the fuel supply, and calculating the current oxygen storage amount of the catalytic converter after the fuel supply is recovered;

and judging whether the catalytic converter has an abnormal fault or not according to the current oxygen storage capacity index.

6. The method for diagnosing an abnormality of a catalytic converter according to claim 5, wherein the determining whether the catalytic converter has an abnormal fault or not based on the current oxygen storage capacity index specifically includes:

and if the secondary oxygen storage capacity index is smaller than a preset fault threshold value, judging that the catalytic converter has an abnormal fault, otherwise, judging that the catalytic converter has no fault, wherein the fault threshold value is between mu 1+ N & gtsigma 1 and mu 2-N & gtsigma 1, wherein mu 1 is an average value of the oxygen storage capacity indexes of the plurality of aged catalytic converters after a plurality of tests, sigma 1 is a standard deviation of the oxygen storage capacity indexes of the plurality of aged catalytic converters after a plurality of tests, mu 2 is an average value of the oxygen storage capacity indexes of the plurality of critical catalytic converters after a plurality of tests, sigma 2 is a standard deviation of the oxygen storage capacity indexes of the plurality of critical catalytic converters after a plurality of tests, and N is a preset range coefficient.

7. An electronic device, comprising:

at least one processor; and the number of the first and second groups,

the memory stores instructions executable by at least one of the processors to enable the at least one of the processors to perform a catalytic converter abnormality diagnostic method according to any one of claims 1 to 6.

8. A storage medium storing computer instructions for performing all the steps of the catalytic converter abnormality diagnosis method according to any one of claims 1 to 6 when the computer instructions are executed by a computer.