CN116335798B - Diagnosis method and device for aging state of three-way catalyst - Google Patents
Diagnosis method and device for aging state of three-way catalystInfo
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- CN116335798B CN116335798B CN202310198041.5A CN202310198041A CN116335798B CN 116335798 B CN116335798 B CN 116335798B CN 202310198041 A CN202310198041 A CN 202310198041A CN 116335798 B CN116335798 B CN 116335798B
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- oxygen sensor
- nernst voltage
- way catalyst
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/101—Three-way catalysts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus
- F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Materials Engineering (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The application relates to a diagnosis method of an aging state of a three-way catalyst, which comprises the steps of acquiring a Nernst voltage value sequence of a front oxygen sensor from a first moment t 0 for a first moment t 0, acquiring a Nernst voltage value sequence of a rear oxygen sensor from a second moment t 1 after the first moment t 0 for a second moment t 1, wherein the Nernst voltage value sequence of the rear oxygen sensor corresponds to the Nernst voltage value sequence of the front oxygen sensor one by one, acquiring a difference value sequence of Nernst voltage values of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor according to the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor, calculating variance of the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, and judging the aging state of the three-way catalyst according to the variance of the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value of the rear oxygen sensor. The application can describe the working state of the three-way catalyst more accurately, reduce the generation of false alarm, and make the diagnosis result of the aging state more accurate.
Description
Technical Field
The application relates to the technical field of vehicles, in particular to a method and a device for diagnosing an aging state of a three-way catalyst.
Background
At present, with the increasing severity of environmental problems caused by automobile exhaust, three-way catalysts have become standard components of exhaust aftertreatment systems. Once the three-way catalyst fails, the normal operation of the engine is affected, and the emission performance of the automobile is reduced. The existing three-way catalyst aging state diagnosis is mainly characterized by extracting the voltage average value and the pressure difference value of the rear oxygen sensor, and the matching precision is lower.
Disclosure of Invention
In view of the problems existing in the background art, the application provides a diagnosis method for the aging state of the three-way catalyst, which can describe the working state of the three-way catalyst more accurately, reduce the occurrence of false alarm problems and enable the diagnosis result of the aging state of the three-way catalyst to be more accurate.
According to one aspect of the invention, a diagnosis method for the aging state of the three-way catalyst is provided, which comprises the steps of acquiring a Nernst voltage value sequence of a front oxygen sensor from a first time t 0 for a first time t 0, acquiring a Nernst voltage value sequence of a rear oxygen sensor from a second time t 1 for a second time t 1 after the first time t 0, wherein the Nernst voltage value sequence of the rear oxygen sensor corresponds to the Nernst voltage value sequence of the front oxygen sensor one by one, acquiring difference value sequences of Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor, calculating variances of the Nernst voltage value difference value sequences of the front oxygen sensor and the rear oxygen sensor, and judging the aging state of the three-way catalyst according to the variances of the Nernst voltage value difference value sequences of the front oxygen sensor and the rear oxygen sensor.
By using the method for diagnosing the aging state of the three-way catalyst in the technical scheme, for a healthy three-way catalyst, an aged three-way catalyst and a dead three-way catalyst, the Nernst voltage acquired by the rear oxygen sensor sequentially shows stable, small-amplitude fluctuation and large-amplitude fluctuation, so that the variances of the difference sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor are sequentially distributed from large to small, the working state of the three-way catalyst can be more accurately described according to the variances of the difference sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, the generation of false alarm problems is reduced, and the aging state diagnosis result of the three-way catalyst is more accurate.
In some embodiments of the invention, the first time t 0 is when the crankshaft and/or camshaft angle coincides with the injection phase.
In some embodiments of the present invention, the acquiring of the first time t 0 includes acquiring the crank shaft and/or the cam shaft angle in real time, starting the injection action by the injector or the air injection valve when the crank shaft and/or the cam shaft angle is consistent with the injection phase, and repeatedly acquiring the crank shaft and/or the cam shaft angle and matching the injection phase when the crank shaft and/or the cam shaft angle is inconsistent with the injection phase until the crank shaft and/or the cam shaft angle is consistent with the injection phase, and starting the injection action by the injector or the air injection valve.
In some embodiments of the invention, the second time t 1,t1＝t0 +L/V is the distance from the front oxygen sensor to the rear oxygen sensor, and V is the gas flow rate.
In some embodiments of the present invention, the slope of each voltage of the nernst voltage value sequence of the front oxygen sensor and the slope of each voltage of the nernst voltage value sequence of the rear oxygen sensor are obtained, whether the corresponding voltage has data abnormality is determined according to the slope, when the corresponding data is abnormal, filtering is performed before the variance calculation of the nernst voltage difference value is performed, and the filtering step length is a data abnormality point and a plurality of data points before and after the abnormal point.
In some embodiments of the invention, the filter step size is a data outlier and five data points before and after it.
In some embodiments of the present invention, the three-way catalyst is set to be in a failure state when the variance of the difference sequence of the nernst voltage values of the front and rear oxygen sensors is within [ a, b ], the three-way catalyst is set to be in an aging state when the variance is within [ b, c ], and the three-way catalyst is set to be in a health state when the variance is within [ c, d ], wherein a < b < c < d.
In some embodiments of the invention, a, b, c, d may be obtained by training using a machine learning method.
In some embodiments of the invention, the obtaining of the variance a, b, c, d comprises selecting three-way catalysts with gradually lengthened use time in a first use state, a second use state, a third use state and a fourth use state respectively, obtaining variances of difference sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor corresponding to the three-way catalysts for a plurality of times, and calculating an average value, wherein average values of variances of the difference sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor of the three-way catalysts in the first use state, the second use state, the third use state and the fourth use state correspond to d, c, b, a respectively.
According to another aspect of the present invention, there is provided a method of diagnosing an aging state of a three-way catalyst, including a front oxygen sensor voltage data collection module for performing collection of front oxygen sensor Nernst voltage data for a set period of time and continuously collecting a target number of times when an angle of a crankshaft and/or a camshaft coincides with an injection phase;
The post-oxygen sensor voltage data acquisition module is used for executing the steps of acquiring post-oxygen sensor Nernst voltage data in a set time length and continuously acquiring target times when the angle of a crankshaft and/or a camshaft is consistent with the injection phase and a certain time length is prolonged;
The diagnosis module calculates the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequences of the front oxygen sensor and the rear oxygen sensor, then calculates the variance of the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, and judges the aging state of the three-way catalyst according to the variance of the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor.
From the above technical solutions, the embodiment of the present application has the following advantages:
The embodiment of the application provides a diagnosis method of an aging state of a three-way catalyst, which comprises the steps of obtaining a Nernst voltage value sequence of a front oxygen sensor from a first time t 0 when a crank shaft and/or a cam shaft angle is consistent with an injection phase, prolonging the time length of gas flowing from the front oxygen sensor to a rear oxygen sensor from the first time t 0, namely, starting to obtain the Nernst voltage value sequence of the rear oxygen sensor at two times t 1, obtaining the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor without time delay, obtaining a difference value sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor, calculating the variance of the Nernst voltage value sequence of the front oxygen sensor and the rear oxygen sensor, and more accurately describing the working state of the three-way catalyst according to the variance of the Nernst voltage value sequence of the front oxygen sensor and the rear oxygen sensor, and reducing the generation of a time delay, so that the diagnosis result of the three-way catalyst is more accurate.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a flow chart of a method for diagnosing an aging state of a three-way catalyst according to an embodiment of the present application;
FIG. 2 is a graph comparing front and rear oxygen sensor signals of a healthy three-way catalyst;
FIG. 3 is a graph comparing front and rear oxygen sensor signals of an aged three-way catalyst;
FIG. 4 is a graph comparing front and rear oxygen sensor signals of a spent three-way catalyst;
Fig. 5 is a schematic structural diagram of a three-way catalyst aging state diagnosis device according to an embodiment of the present application.
Detailed Description
It should be understood that the described embodiments are merely some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the application as detailed in the accompanying claims.
In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art. Furthermore, in the description of the present application, unless otherwise indicated, "a plurality" means two or more. "and/or" describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate that there are three cases of a alone, a and B together, and B alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.
Three-way catalysis is the most important ring in exhaust gas aftertreatment systems, and is called a "three-way catalysis system" because it is mainly directed to three harmful gases, carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), during the treatment process.
Under normal working conditions, when the fuel injector or the air injection valve starts to execute injection action, fuel/gas is atomized through the nozzle and enters the cylinder. The piston makes oxygen-containing air enter the cylinder through alternate movement and mix with atomized fuel oil/gas, then the ignition coil is driven to ignite, the mixed gas is ignited to generate harmful gases such as carbon monoxide, hydrocarbon and oxynitride, and finally the harmful gas products generated by the combustion enter the three-way catalytic system to carry out tail gas aftertreatment, and the tail gas is discharged after chemical reaction of the three-way catalyst.
Components that play an oxidizing role in a three-way catalytic system are referred to as three-way catalysts. The oxygen sensor is an essential element for reducing exhaust pollution of the three-way catalyst, and the oxygen sensors positioned at the upstream and downstream of the three-way catalyst are respectively called a front oxygen sensor and a rear oxygen sensor.
The Nernst voltage is a potential difference formed on both sides of the electrode by the oxygen sensor depending on the ambient oxygen concentration, and ideally, the Nernst voltage of the oxygen sensor is 0.45V (i.e., the excess air ratio is equal to 1), the front oxygen sensor is used for detecting the oxygen concentration in the combustion product of the cylinder mixture after the combustion reaction, generally speaking, the higher the oxygen concentration is, the more diluted the mixture is, the front oxygen sensor collects the oxygen concentration and converts it into an electric signal to transmit to the ECU (electronic control unit), and the ECU can perform the configuration of the mixture according to the signal. The post oxygen sensor is used for detecting the conversion condition of harmful gases generated by the combustion reaction.
Therefore, in a three-way catalytic system, the front oxygen sensor is essentially a control relationship with the rear oxygen sensor. The front oxygen sensor is the environmental collection before the three-way catalyst works, and the rear oxygen sensor is the environmental collection after the three-way catalyst works.
The method and the device for diagnosing the aging state of the three-way catalyst provided by the embodiment of the application are described below with reference to the accompanying drawings.
The embodiment of the application discloses a diagnosis method for an aging state of a three-way catalyst. The method of diagnosing the three-way catalyst aged state may be performed by the ECU, and the method of diagnosing the three-way catalyst aged state includes:
1) Crankshaft and/or camshaft angle to engine injection event phase comparison
When the vehicle engine does not perform the injection operation, the three-way catalyst is hardly required to operate, and at this time, the nernst voltage of the post-oxygen sensor coincides with the environment, so that the aged state of the three-way catalyst cannot be accurately detected.
Therefore, considering the detection timing of the front and rear oxygen sensors, in the present embodiment, the ECU acquires the crank shaft and/or cam shaft angle in real time and compares it with the injection operation phase matched with the engine, and when the crank shaft and/or cam shaft angle is consistent with the injection phase, the injector or the air injection valve starts to perform the injection operation, and when the crank shaft and/or cam shaft angle is inconsistent with the injection phase, the crank shaft and/or cam shaft angle is repeatedly acquired and matched with the injection phase until the crank shaft and/or cam shaft angle is consistent with the injection phase, and the injector or the air injection valve starts to perform the injection operation.
2) Acquiring Nernst voltage of front oxygen sensor
At a first time t 0 when the crankshaft and/or camshaft angle coincides with the injection phase, the ECU starts to continuously acquire the sequence of nernst voltage values V (f) 1、V(f)2、V(f)3、V(f)4、…、V(f)n of the front oxygen sensor until the injection event execution ends.
3) Acquiring the Nernst voltage of a post-oxygen sensor
Because of the position limitation of the front and rear oxygen sensors in the three-way catalytic system and the conversion rate of the three-way catalyst, for the same gas before and after treatment, a certain time difference exists between the Nernst voltage values collected by the front and rear oxygen sensors, so in this embodiment, for a second time t 1 after a first time t 0, starting from the second time t 1, the ECU continuously acquires the Nernst voltage value sequence V (b) 1、V(b)2、V(b)3、V(b)4、…、V(b)n of the rear oxygen sensor until the injection is performed, and extends for a certain period, wherein the extended period is the time difference between the second time t 1 and the first time t 0, the Nernst voltage value sequence of the rear oxygen sensor corresponds to the Nernst voltage value sequence of the front oxygen sensor one by one,
t1＝t0+ L/V (1)
Wherein L is the distance between the front oxygen sensor and the rear oxygen sensor, and V is the gas flow rate. Therefore, the ECU needs to continuously acquire the sequence of the nernst voltage values of the front oxygen sensor from the first time t 0 and the sequence of the nernst voltage values of the rear oxygen sensor from the second time t 1 so that the waveform of the sequence of the nernst voltage values of the rear oxygen sensor coincides with the waveform phase of the sequence of the nernst voltage values of the front oxygen sensor.
4) Nernst voltage anomaly data processing
In the embodiment, the system also designs a filtering function, wherein the filtering function specifically comprises that an ECU acquires each voltage of the Nernst voltage value sequence of the front oxygen sensor and each voltage slope of the Nernst voltage value sequence of the rear oxygen sensor, judges whether data abnormality exists in corresponding voltages according to the slopes, when the change slopes of the Nernst voltages of the front angle and the rear angle reach a certain theoretical value or a preset value, the data abnormality is considered to exist, the abnormal data is filtered before variance calculation of the Nernst voltage difference value is carried out, and the filtering step length is preferably a data abnormal point and five data points before and after the abnormal point, so that the error is prevented from being generated in the subsequent calculation and judgment due to abrupt change of the Nernst voltage of the front oxygen sensor when the Nernst voltage is at a certain angle caused by certain special working conditions or reasons.
Thus, the Nernst voltage value sequence of the front and rear oxygen sensors without time lag delay can be obtained.
5) Acquiring variance of difference sequence of Nernst voltage values of front and rear oxygen sensors
Calculating a difference sequence X 1、X2、X3、X4、…、Xn of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequence V (f) 1、V(f)2、V(f)3、V(f)4、…、V(f)n of the front oxygen sensor and the Nernst voltage value sequence V (b) 1、V(b)2、V(b)3、V(b)4、…、V(b)n of the rear oxygen sensor, wherein,
X=| V(b)-V(f)| (2)
Then calculating the average value of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor,
Finally, calculating the variance of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor,
The three-way catalyst can judge whether the three-way catalyst is aged or not according to the variance of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, as shown in figure 2, the Nernst voltage acquired by the rear oxygen sensor is the most stable for the healthy three-way catalyst, so that the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor is the most intense and the variance is larger, as shown in figure 3, the three-way catalyst is aged, the Nernst voltage acquired by the rear oxygen sensor is the small-amplitude fluctuation, so that the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor is the small-amplitude fluctuation, the variance is moderate, as shown in figure 4, the Nernst voltage acquired by the rear oxygen sensor is almost consistent with the front oxygen sensor, so that the Nernst voltage difference sequence of the front oxygen sensor and the rear oxygen sensor is almost the fluctuation, the variance is smaller, and the error state of the three-way catalyst can be more accurately described according to the size of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, and the error state of the three-way catalyst is more accurate, and the problem of the aging state of the three-way catalyst is more accurately diagnosed.
Specifically, in this embodiment, when the variance of the difference sequence of the nernst voltage values of the current and the rear oxygen sensors is set to be within [ a, b), the three-way catalyst is in a failure state, when the variance is set to be within [ b, c), the three-way catalyst is in an aging state, and when the variance is set to be within [ c, d ], the three-way catalyst is in a health state, wherein specific numerical values of a < b < c < d, a, b, c, d can be obtained through training by a machine learning method.
For example, the three-way catalyst may be divided into four stages including a first use state in a brand-new state that has not been used yet, a second use state in which aging is started for a period of time, a third use state in which failure is started for a longer period of time, and a fourth use state in which failure is completed for a long period of time, after which the three-way catalyst in the first, second, third, and fourth use states is selected, respectively, and the variances of the difference sequences of the nernst voltage values of the front and rear oxygen sensors corresponding to the respective three-way catalyst are obtained according to the above-described procedure, for example, 2 times, 3 times, 4 times, etc., and the average is calculated, thereby obtaining a variance average d of the first use state, a variance average c of the second use state, a variance average b of the third use state, and a variance average a of the fourth use state.
When the ECU collects data in real time and calculates the variance of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor to be in [ a, b), in [ b, c) or in [ c, d ], the working state of the three-way catalyst can be accurately and conveniently described according to the setting, and a user can conveniently judge the aging state of the three-way catalyst in real time.
The present application also proposes a diagnostic apparatus, corresponding to the above-described method embodiment, for diagnosing an aged state of a three-way catalyst using the above-described diagnostic method, as shown in fig. 5, the diagnostic apparatus 100 comprising:
a front oxygen sensor voltage data acquisition module 101 for performing acquisition of front oxygen sensor Nernst voltage data for a set period of time and continuously acquiring a target number of times when the crank shaft and/or the cam shaft angle coincides with the injection phase;
A post-oxygen sensor voltage data acquisition module 102 for performing acquisition of post-oxygen sensor Nernst voltage data for a set period of time and continuously acquiring a target number of times when the crank shaft and/or the cam shaft angle is consistent with the injection phase and when a certain period of time is prolonged;
The diagnosis module 103 calculates the difference value sequences of the front and rear oxygen sensor's Nernst voltage values according to the Nernst voltage value sequences of the front and rear oxygen sensors, then calculates the variance of the difference value sequences of the front and rear oxygen sensor's Nernst voltage values, and judges the aging state of the three-way catalyst according to the variance of the difference value sequences of the front and rear oxygen sensor's Nernst voltage values.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (7)
1. A method for diagnosing an aging state of a three-way catalyst, comprising:
For a first time t 0, acquiring a Nernst voltage value sequence of a front oxygen sensor from a first time t 0, wherein the first time t 0 is when the angle of a crankshaft and/or a camshaft is consistent with the injection phase, the acquisition of the first time t 0 comprises the steps of acquiring the angle of the crankshaft and/or the camshaft in real time, and starting an injection action by an injector or an air injection valve when the angle of the crankshaft and/or the camshaft is consistent with the injection phase, and repeatedly acquiring the angle of the crankshaft and/or the camshaft and matching the injection phase when the angle of the crankshaft and/or the camshaft is inconsistent with the injection phase until the angle of the crankshaft and/or the camshaft is consistent with the injection phase, and starting the injection action by the injector or the air injection valve;
For a second time t 1 after the first time t 0, acquiring a Nernst voltage value sequence of a rear oxygen sensor from a second time t 1, wherein the Nernst voltage value sequence of the rear oxygen sensor corresponds to the Nernst voltage value sequence of a front oxygen sensor one by one, and the second time t 1,t1=t0 +L/V is the distance between the front oxygen sensor and the rear oxygen sensor, and V is the gas flow rate;
acquiring a difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequence of the front oxygen sensor and the Nernst voltage value sequence of the rear oxygen sensor;
calculating the variance of the difference sequence of the Nernst voltage values of the front and rear oxygen sensors;
And judging the aging state of the three-way catalyst according to the variance of the difference sequence of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor.
2. The method according to claim 1, wherein the slope of each voltage of the sequence of nernst voltage values of the front oxygen sensor and the slope of each voltage of the sequence of nernst voltage values of the rear oxygen sensor are obtained, and whether there is a data abnormality in the corresponding voltage is determined based on the slope, and when the corresponding data is abnormal, filtering is performed before performing variance calculation of the nernst voltage difference, and the step of filtering is a data abnormality point and a plurality of data points before and after.
3. The method for diagnosing an aging state of a three-way catalyst according to claim 2, wherein the filter step size is a data outlier and five data points before and after.
4. The method according to claim 1, wherein the three-way catalyst is in a deactivated state when a variance of a difference sequence of the nernst voltage values of the front and rear oxygen sensors is set to be within [ a, b ], the three-way catalyst is in an aged state when the variance is set to be within [ b, c ], and the three-way catalyst is in a healthy state when the variance is set to be within [ c, d ], wherein a < b < c < d.
5. The method for diagnosing a three-way catalyst aged condition according to claim 4, wherein said a, b, c, d is trainable by a machine learning method.
6. The method for diagnosing an aged three-way catalyst according to claim 4 or 5, wherein the obtaining of the variance a, b, c, d comprises selecting three-way catalysts in a first, second, third and fourth use states with gradually longer use times respectively, obtaining variances of difference sequences of the Nernst voltage values of the front and rear oxygen sensors corresponding to the three-way catalysts, and calculating average values, wherein the variance average values of the difference sequences of the Nernst voltage values of the front and rear oxygen sensors of the three-way catalysts in the first, second, third and fourth use states correspond to d, c, b, a respectively.
7. A diagnostic apparatus for an aged state of a three-way catalyst, wherein the diagnostic apparatus employs the diagnostic method according to any one of claims 1 to 5, the diagnostic apparatus comprising:
The front oxygen sensor voltage data acquisition module is used for acquiring front oxygen sensor Nernst voltage data within a set time length and continuously acquiring target times when the angle of a crankshaft and/or a camshaft is consistent with the injection phase;
The post-oxygen sensor voltage data acquisition module is used for executing the steps of acquiring post-oxygen sensor Nernst voltage data in a set time length and continuously acquiring target times when the angle of a crankshaft and/or a camshaft is consistent with the injection phase and a certain time length is prolonged;
The diagnosis module calculates the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor according to the Nernst voltage value sequences of the front oxygen sensor and the rear oxygen sensor, then calculates the variance of the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor, and judges the aging state of the three-way catalyst according to the variance of the difference value sequences of the Nernst voltage values of the front oxygen sensor and the rear oxygen sensor.
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| CN104471411A (en) * | 2012-07-25 | 2015-03-25 | 罗伯特·博世有限公司 | Fault simulator for checking the diagnosis implemented in a control device for a lambda sensor in an internal combustion engine |
| CN106988904A (en) * | 2016-01-20 | 2017-07-28 | 福特环球技术公司 | Oxygen sensor devices blackening is detected |
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| JP5287809B2 (en) * | 2010-08-31 | 2013-09-11 | 三菱自動車工業株式会社 | Degradation diagnosis device for exhaust gas sensor downstream of catalyst |
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| CN114961954B (en) * | 2022-06-16 | 2023-04-28 | 东风汽车集团股份有限公司 | Method for detecting fault of oxygen sensor behind catalyst |
| CN115657525A (en) * | 2022-10-11 | 2023-01-31 | 杭州纳瑙新材料科技有限公司 | Nitrogen-oxygen sensor control method and nitrogen-oxygen sensor |
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| CN104471411A (en) * | 2012-07-25 | 2015-03-25 | 罗伯特·博世有限公司 | Fault simulator for checking the diagnosis implemented in a control device for a lambda sensor in an internal combustion engine |
| CN106988904A (en) * | 2016-01-20 | 2017-07-28 | 福特环球技术公司 | Oxygen sensor devices blackening is detected |
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