CN109519264B - Gasoline engine three-way catalyst diagnosis rapid diagnosis method and system - Google Patents
Gasoline engine three-way catalyst diagnosis rapid diagnosis method and system Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 101
- 238000003745 diagnosis Methods 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 23
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 132
- 239000001301 oxygen Substances 0.000 claims abstract description 132
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 132
- 239000000446 fuel Substances 0.000 claims abstract description 77
- 238000001514 detection method Methods 0.000 claims abstract description 24
- 238000002347 injection Methods 0.000 claims description 75
- 239000007924 injection Substances 0.000 claims description 75
- 230000003197 catalytic effect Effects 0.000 claims description 41
- 238000011144 upstream manufacturing Methods 0.000 claims description 12
- 238000011217 control strategy Methods 0.000 claims description 4
- 239000000725 suspension Substances 0.000 claims description 4
- 238000002405 diagnostic procedure Methods 0.000 claims description 3
- 238000010790 dilution Methods 0.000 claims description 3
- 239000012895 dilution Substances 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 claims 1
- 239000003344 environmental pollutant Substances 0.000 abstract description 4
- 231100000719 pollutant Toxicity 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 9
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
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- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002045 lasting effect Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
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- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
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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, e.g. for catalytic activity
- F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—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
- F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
- F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
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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
- F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
- F01N2430/06—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by varying fuel-air ratio, e.g. by enriching fuel-air mixture
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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)
- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
The invention discloses a gasoline engine three-way catalyst diagnosis rapid diagnosis method, which is suitable for rapid online detection of gasoline engine three-way catalyst faults; presetting a first threshold value for the air-fuel ratio of the gasoline engine; according to a first threshold value, dividing a detection stage of a downstream oxygen concentration signal into a relatively rich stage and a relatively lean stage; the gasoline engine three-way catalyst diagnosis rapid diagnosis method comprises the following steps: step S1, adjusting the gasoline engine to be in a partial concentration stage; step S2, determining whether the downstream oxygen concentration exceeds a second predetermined threshold within a first predetermined time period; step S3, adjusting the gasoline engine to be in a lean stage; in step S4, it is determined whether the downstream oxygen concentration exceeds a third predetermined threshold in a second predetermined time period. The technical scheme of the invention has the beneficial effects that: based on the three-way catalyst diagnosis carried out on the existing device, the time for diagnosing whether the three-way catalyst of the gasoline engine is aged or not is shortened as much as possible, and the emission pollutants are effectively reduced.
Description
Technical Field
The invention relates to the field of three-way catalyst diagnosis, in particular to a gasoline engine three-way catalyst diagnosis rapid diagnosis method and system.
Background
In the prior art, a three-way catalyst is the most important external purifying device arranged in an automobile exhaust system, when high-temperature automobile exhaust passes through the purifying device, the purifying agent in the three-way catalyst enhances the activity of three gases of CO, HC and NOx to promote the three gases to carry out certain oxidation-reduction chemical reaction, wherein CO is oxidized into colorless and nontoxic carbon dioxide gas at high temperature; HC compounds are oxidized at high temperature to water (H20) and carbon dioxide; NOx is reduced to nitrogen and oxygen. Three kinds of harmful gases are changed into harmless gases, so that the automobile exhaust can be purified. An oxygen sensor is added behind the three-way catalytic converter so as to detect the oxygen storage capacity of the three-way catalytic converter by a method of alternately using a 'rich' mixed gas and a 'lean' mixed gas; whether the voltage of the gas adding and measuring signal of the oxygen sensor exceeds a possible range, whether the response speed is too low, whether the ratio of the jump time exceeds a specified range, whether the fluctuation frequency is too low, whether the activity of the oxygen sensor is insufficient, and whether the heating of the oxygen sensor is too slow.
The current mainstream gasoline engine catalyst diagnosis strategy is an oxygen storage capacity method. The deterioration degree of the catalyst is detected by comparing values of oxygen sensors installed before and after the catalyst, which is different from the amplitude method in that the oxygen storage amount method is active monitoring and the amplitude method is passive monitoring; under the diagnosis working condition, the oxygen storage method observes the reaction time of the oxygen sensor to the air-fuel ratio by changing the air-fuel ratio (enriching and gradually diluting), simultaneously calculates the oxygen storage value according to the measured air inflow, the excess air coefficient and other parameters, and if the oxygen storage value is smaller than the threshold value, the system judges that the catalytic converter is aged and records the catalytic fault into a fault memory.
The prior EMS system is provided with two oxygen sensors in front of and behind a catalyst, wherein front oxygen is used for realizing closed-loop control on a mixer, rear oxygen is used for correcting a front oxygen signal, and aging diagnosis of the catalyst can be realized by comparing the difference between the front oxygen sensor and the rear oxygen sensor. Through research, the catalytic converter has a certain nonlinear relation between the purification capacity of the catalytic converter for HC, CO and NOx and the Oxygen Storage Capacity (OSC) of the catalytic converter, and the catalytic converter OBD system formally realizes the online diagnosis of the catalytic converter of the real vehicle based on the principle. The oxygen storage capacity of the catalyst enables the catalyst to have an automatic regulating function of storing oxygen during oxygen enrichment and releasing oxygen during oxygen deficiency, when the oxygen storage capacity of the catalyst is high, and the oxygen content regulating capacity of the catalyst is high, so that the air-fuel ratio vibration amplitude behind the catalyst is small, when the catalyst is gradually deteriorated along with use, the oxygen content regulating capacity of the catalyst is gradually poor, the air-fuel ratio vibration measured by a rear oxygen sensor is increased, and the vibration amplitude of the catalyst is gradually close to that of a front oxygen sensor.
The oxygen storage method requires repeated averaging to ultimately determine the oxygen storage capacity of the catalyst and requires engine operating conditions to reach specified operating conditions before diagnosis can be made passively. This diagnostic approach is necessary for critical-condition catalysts, but for fresh or insufficiently degraded catalysts, repeated open-loop control to rich or lean air/fuel ratio releases relatively large amounts of exhaust pollutants
Disclosure of Invention
Aiming at the problems, the method and the system for diagnosing the three-way catalyst of the gasoline engine are provided based on the existing device, the time for diagnosing whether the three-way catalyst of the gasoline engine is aged is shortened as much as possible, and the pollutant emission is effectively reduced.
The specific technical scheme is as follows:
a gasoline engine three-way catalyst diagnosis rapid diagnosis method is suitable for rapid online detection of faults of the gasoline engine three-way catalyst, an upstream oxygen sensor is arranged at the upstream of the gasoline engine three-way catalyst and used for detecting upstream oxygen concentration and outputting an upstream oxygen concentration signal, a downstream oxygen sensor is arranged at the downstream of the gasoline engine three-way catalyst and used for detecting downstream oxygen concentration and outputting a downstream oxygen concentration signal;
presetting a first threshold value for the air-fuel ratio of the gasoline engine; dividing the detection stage of the downstream oxygen concentration signal according to the first threshold value;
the detection stage comprises a partial concentration stage and a partial dilution stage;
the gasoline engine three-way catalyst diagnosis rapid diagnosis method comprises the following steps:
step S1, adjusting the gasoline engine to be in the partial concentration stage;
step S2, determining whether the downstream oxygen concentration exceeds a second predetermined threshold within a first predetermined time period;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage, and exiting;
if not, judging that the three-way catalytic converter of the gasoline engine works normally in the rich period, and turning to the step S3;
step S3, adjusting the gasoline engine to be in the lean stage;
step S4, determining whether the downstream oxygen concentration exceeds a predetermined third threshold value within a predetermined second time period;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the lean stage;
if not, the three-way catalytic converter of the gasoline engine is judged to work normally in the lean stage.
Preferably, in step S1, the gasoline engine increases the fuel injection amount to make the air-fuel ratio of the gasoline engine less than or equal to the first threshold, and the gasoline engine is in the rich phase.
Preferably, the step S2 specifically includes:
step S21, presetting the first time period in the rich phase;
step S22, presetting the second threshold value for the downstream oxygen concentration;
step S23, determining whether the downstream oxygen is rich in the first period of time and exceeds the second threshold;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the partial concentration stage.
Preferably, in step S3, the gasoline engine decreases the fuel injection amount to make the air-fuel ratio of the gasoline engine greater than the first threshold, and the gasoline engine is in the lean phase.
Preferably, the step S4 specifically includes:
step S41, presetting the second time period in the lean phase;
step S42, presetting the third threshold value for the downstream oxygen concentration;
step S43, determining whether the downstream oxygen concentration exceeds the third threshold value within the first period of time;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the partial concentration stage.
A gasoline engine three-way catalyst diagnosis rapid diagnosis system comprises:
the receiving module is used for receiving and outputting a switching signal, and the switching signal controls the running or suspension of the gasoline engine three-way catalyst rapid diagnosis system.
The oil injection control module is connected with the receiving module and generates and outputs an oil injection control signal by adopting a preset oil injection control strategy according to the switching signal;
the oil injection module is connected with the oil injection control module and used for adjusting the oil injection quantity according to the oil injection control signal;
the downstream oxygen sensor module is connected with the receiving module and used for detecting the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine and outputting a downstream oxygen concentration signal;
and the diagnosis module is respectively connected with the oil injection control module and the downstream oxygen sensor module and is used for quickly diagnosing whether the three-way catalytic converter of the gasoline engine breaks down or not according to the downstream oxygen concentration signal by adopting a preset diagnosis model.
Preferably, the oil injection control module generates the oil injection control signal according to different preset working periods by adopting the oil injection strategy, and the oil injection module adjusts the oil injection quantity according to the oil injection control signal.
Preferably, the fuel injection module includes:
the first control unit is used for enabling the gasoline engine to be in the rich phase with the air-fuel ratio smaller than or equal to the first threshold value by increasing the fuel injection quantity;
and the second control unit is used for enabling the gasoline engine to be in the lean stage with the air-fuel ratio larger than the first threshold value by reducing the fuel injection quantity.
Preferably, the downstream oxygen sensor module continuously collects the downstream oxygen concentration of the three-way catalyst of the gasoline engine according to the switching signal and outputs the downstream oxygen concentration signal.
Preferably, the diagnostic module comprises:
the first diagnosis unit is used for comparing the downstream oxygen concentration with a preset first critical value and judging the working state of the gasoline engine three-way catalyst in the rich period;
and the second diagnosis unit is used for comparing the downstream oxygen concentration with a preset second critical value and judging the working state of the three-way catalyst of the gasoline engine in the lean stage.
The beneficial effects of the technical scheme are as follows: based on the three-way catalyst diagnosis carried out on the existing device, the time for diagnosing whether the three-way catalyst of the gasoline engine is aged or not is shortened as much as possible, and the emission pollutants are effectively reduced.
Drawings
Embodiments of the present invention will be described more fully with reference to the accompanying drawings. The drawings are, however, to be regarded as illustrative and explanatory only and are not restrictive of the scope of the invention.
FIG. 1 is a general flow chart of a gasoline engine three-way catalyst diagnostic rapid diagnostic method according to a preferred embodiment of the invention;
FIG. 2 is a flowchart illustrating the step S2 further based on FIG. 1 in accordance with a preferred embodiment of the present invention;
FIG. 3 is a flowchart illustrating step S4 further based on FIG. 1 according to a preferred embodiment of the present invention;
FIG. 4 is a schematic diagram of the general structure of a three-way catalytic converter diagnostic rapid diagnostic system of a gasoline engine according to a preferred embodiment of the present invention;
FIG. 5 is a schematic diagram of a fuel injection module in a three-way catalytic converter diagnostic rapid diagnostic system of a gasoline engine according to a preferred embodiment of the invention;
FIG. 6 is a schematic diagram of a fuel injection module in a three-way catalytic converter diagnostic rapid diagnostic system of a gasoline engine according to a preferred embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The invention provides a gasoline engine three-way catalyst diagnosis rapid diagnosis method, which is suitable for rapid online detection of gasoline engine three-way catalyst faults, wherein an upstream oxygen sensor is arranged at the upstream of the gasoline engine three-way catalyst and used for detecting upstream oxygen concentration and outputting an upstream oxygen concentration signal, a downstream oxygen sensor is arranged at the downstream of the gasoline engine three-way catalyst and used for detecting downstream oxygen concentration and outputting a downstream oxygen concentration signal;
presetting a first threshold value for the air-fuel ratio of the gasoline engine; dividing the detection stage of the downstream oxygen concentration signal according to a first threshold value;
the detection stage comprises a partial concentration stage and a partial dilution stage;
as shown in FIG. 1, the steps of the gasoline engine three-way catalyst diagnosis rapid diagnosis method comprise:
step S1, adjusting the gasoline engine to be in a partial concentration stage;
step S2, determining whether the downstream oxygen concentration exceeds a second predetermined threshold within a first predetermined time period;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in a partial concentration stage, and quitting;
if not, judging that the three-way catalytic converter of the gasoline engine works normally in the rich period, and turning to the step S3;
step S3, adjusting the gasoline engine to be in a lean stage;
step S4, determining whether the downstream oxygen concentration exceeds a predetermined third threshold within a predetermined second time period;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in a lean stage;
if not, the gasoline engine three-way catalyst is judged to work normally in a lean stage.
Specifically, the ratio of the mass of air to the mass of fuel in the combustible mixture is the air-fuel ratio, which indicates the mixing ratio of air and fuel. The air-fuel ratio is an important parameter when the engine is running, and has a great influence on exhaust emission, and the dynamic property and the economical efficiency of the engine. The stoichiometric air-fuel ratio represents the minimum air to fuel mass ratio required to completely combust the fuel. The composition of the fuel does not greatly affect the stoichiometric air-fuel ratio, which is about 14.7 for gasoline, that is, 14.7g of air is required to burn 1g of gasoline. The gasoline engine is usually over-rich and over-lean in mixture, and the standard is the theoretical air-fuel ratio. When the air-fuel ratio is smaller than the theoretical air-fuel ratio, the gasoline content in the mixed gas is high, which is called as over-rich; when the air-fuel ratio is larger than the stoichiometric air-fuel ratio, the air content in the mixture is high, which is called over lean.
In particular embodiments of the present invention, the first threshold is set to 14.7, or other suitable value. Firstly, an electronic control unit controls to send an oil injection instruction for increasing the oil injection quantity to an oil injector, the oil injector lengthens the oil injection time, the oil injection quantity is increased, and the air-fuel ratio of the gasoline engine is adjusted to be less than 14.7; the first time period setting may be set to 30 seconds, or other suitable value. The downstream oxygen sensor detects the downstream oxygen concentration for 30 seconds. The second threshold may be set to 450mv, or other suitable value. If the downstream oxygen concentration during the detection period is lower than 450mv, the gasoline engine three-way catalyst can be judged to have a working fault in a rich-bias stage, namely the gasoline engine three-way catalyst has a fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period exceeds 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the rich-bias phase. Then, the air-fuel ratio of the gasoline engine is adjusted to be more than or equal to 14.7 by reducing the fuel injection quantity; the second period setting may be set to 30 seconds, or other suitable value. The downstream oxygen sensor detects the downstream oxygen concentration for 30 seconds. The third threshold may be set to 450mv, or other suitable value. If the downstream oxygen concentration during the detection period exceeds 450mv, the gasoline engine three-way catalyst can be judged to work in a lean stage, namely the gasoline engine three-way catalyst is in fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period does not exceed 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the lean phase, i.e., the gasoline catalyst is operating normally.
In a preferred embodiment of the present invention, in step S1, the gasoline engine increases the fuel injection amount to make the air-fuel ratio of the gasoline engine greater than the first threshold, and the gasoline engine is in a richer stage.
Specifically, the gasoline engine is usually too rich or too lean, and the standard is the theoretical air-fuel ratio. When the air-fuel ratio is smaller than the stoichiometric air-fuel ratio, the gasoline content in the mixture is high, which is called over-rich. In the above embodiment, the first threshold is set to 14.7.
In a preferred embodiment of the present invention, as shown in fig. 2, step S2 specifically includes:
step S21, presetting a first time period in the rich stage;
step S22, presetting a second threshold value for the downstream oxygen concentration;
step S23, judging whether the downstream oxygen concentration exceeds a second threshold value in a first time interval;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in a partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the rich-bias stage.
Specifically, the first time period setting may be set to 30 seconds, or other suitable value. The downstream oxygen sensor detects the downstream oxygen concentration for 30 seconds. The second threshold may be set to 450mv, or other suitable value. If the downstream oxygen concentration during the detection period is lower than 450mv, the gasoline engine three-way catalyst can be judged to have a working fault in a rich-bias stage, namely the gasoline engine three-way catalyst has a fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period exceeds 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the rich-bias phase.
In a preferred embodiment of the present invention, in step S3, the gasoline engine decreases the fuel injection amount to make the air-fuel ratio of the gasoline engine less than or equal to the first threshold, and the gasoline engine is in a lean stage.
Specifically, when the air-fuel ratio is larger than the stoichiometric air-fuel ratio, the air content in the mixture is high, which is referred to as being excessively lean. In the above embodiment, the first threshold is set to 14.7.
In a preferred embodiment of the present invention, as shown in fig. 3, step S4 specifically includes:
step S41, presetting a second time period in the lean phase;
step S42, presetting a third threshold value for the downstream oxygen concentration;
step S43, judging whether the downstream oxygen concentration exceeds a third threshold value in a first time interval;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in a partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the rich-bias stage.
Specifically, the second period setting may be set to 30 seconds, or other suitable value. The downstream oxygen sensor detects the downstream oxygen concentration for 30 seconds. The third threshold may be set to 450mv, or other suitable value. If the downstream oxygen concentration during the detection period exceeds 450mv, the gasoline engine three-way catalyst can be judged to work in a lean stage, namely the gasoline engine three-way catalyst is in fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period does not exceed 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the lean phase, i.e., the gasoline catalyst is operating normally.
A gasoline engine three-way catalyst diagnosis rapid diagnosis system is shown in figure 4, and comprises:
the receiving module 1 is used for receiving and outputting a switching signal, and the switching signal controls the running or suspension of the gasoline engine three-way catalyst rapid diagnosis system.
The oil injection control module 2 is connected with the receiving module 1, and the oil injection control module 2 generates and outputs an oil injection control signal by adopting a preset oil injection control strategy according to the switching signal;
the oil injection module 3 is connected with the oil injection control module 2 and used for adjusting the oil injection quantity according to the oil injection control signal;
the downstream oxygen sensor module 4 is connected with the receiving module 1 and is used for detecting the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine and outputting a downstream oxygen concentration signal;
and the diagnosis module 5 is respectively connected with the oil injection control module 2 and the downstream oxygen sensor module 4 and is used for quickly diagnosing whether the three-way catalytic converter of the gasoline engine breaks down or not according to the downstream oxygen concentration signal by adopting a preset diagnosis model.
Specifically, the receiving module 1 receives a switch signal for controlling the running or suspension of a three-way catalytic converter rapid diagnosis system of the gasoline engine; the oil injection control module 2 generates an oil injection control signal by adopting a preset oil injection control strategy according to the switch signal; the oil injection module 3 adjusts the oil injection quantity according to the oil injection control signal; the downstream oxygen sensor module 4 detects the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine and outputs a downstream oxygen concentration signal; the diagnosis module 5 adopts a preset diagnosis model to quickly diagnose whether the three-way catalytic converter of the gasoline engine breaks down or not according to the downstream oxygen concentration signal.
In a preferred embodiment of the present invention, the fuel injection control module 2 generates the fuel injection control signal according to different preset working periods by using the fuel injection strategy, and the fuel injection module 3 adjusts the fuel injection amount according to the fuel injection control signal.
Specifically, in the fuel injection strategy, the detection period of the three-way catalyst of the gasoline engine is divided into a first working period and a second working period; the oil injection control signal controls the oil injection module 3 to spray different oil quantities in the two working periods, so that the working air-fuel ratio of the gasoline engine is adjusted.
In a preferred embodiment of the present invention, as shown in fig. 5, the injection module 3 includes:
the first control unit 31 is used for enabling the gasoline engine to be in a richer stage when the air-fuel ratio is larger than a first threshold value by increasing the fuel injection quantity;
and the second control unit 32 is used for enabling the gasoline engine to be in a lean stage with the air-fuel ratio less than or equal to the first threshold value by reducing the fuel injection quantity.
Specifically, the first threshold is set to 14.7, or other suitable value. The first control unit 31 increases the fuel injection quantity to enable the gasoline engine to be in a richer stage with the air-fuel ratio being greater than 14.7; the second control unit 32 reduces the fuel injection amount to make the gasoline engine in a lean stage in which the air-fuel ratio is less than or equal to 14.7.
In the preferred embodiment of the invention, the downstream oxygen sensor module 4 continuously collects the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine and outputs a downstream oxygen concentration signal according to the switching signal.
Specifically, after the downstream oxygen sensor identifies a diagnosis starting instruction in the switching signal, data acquisition is continuously carried out on the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine, and a downstream oxygen concentration signal is generated and output to the diagnosis module 5; and after the downstream oxygen sensor identifies a diagnosis stopping instruction in the switching signal, stopping data acquisition of the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine.
In a preferred embodiment of the present invention, as shown in fig. 6, the diagnostic module 5 includes:
the first diagnosis unit 51 is used for comparing a preset first critical value with the downstream oxygen concentration and judging the working state of the gasoline engine three-way catalyst in a rich stage;
and the second diagnosis unit 52 is used for comparing the downstream oxygen concentration with a preset second critical value and judging the working state of the gasoline engine three-way catalyst in the lean stage.
Specifically, in the above embodiment, the first threshold value may be set to 450mv, or other suitable values. The diagnostic module 5 judges the working state of the gasoline engine three-way catalyst in the rich phase. If the downstream oxygen concentration is lower than 450mv in the detection period lasting for 30 seconds, the three-way catalyst of the gasoline engine can be judged to have a working fault in a richer stage, namely the gasoline catalyst has a fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period exceeds 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the rich-bias phase.
In the above embodiments, the second threshold value may be set to 450mv, or other suitable values. The diagnostic module 5 judges the working state of the gasoline engine three-way catalyst in the rich phase. If the downstream oxygen concentration exceeds 450mv within the detection period lasting for 30 seconds, the three-way catalyst of the gasoline engine can be judged to have a working fault in a lean stage, namely the gasoline catalyst has a fault, and the diagnosis is quit; if the downstream oxygen concentration during the detection period does not exceed 450mv, it can be determined that the three-way catalyst of the gasoline engine is operating normally in the lean phase, i.e., the gasoline catalyst is operating normally.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (10)
1. A gasoline engine three-way catalyst diagnosis rapid diagnosis method is suitable for rapid online detection of faults of the gasoline engine three-way catalyst, an upstream oxygen sensor is arranged at the upstream of the gasoline engine three-way catalyst and used for detecting upstream oxygen concentration and outputting an upstream oxygen concentration signal, a downstream oxygen sensor is arranged at the downstream of the gasoline engine three-way catalyst and used for detecting downstream oxygen concentration and outputting a downstream oxygen concentration signal; the method is characterized in that a first threshold value is preset for the air-fuel ratio of the gasoline engine; dividing the detection stage of the downstream oxygen concentration signal according to the first threshold value; the detection stage comprises a partial concentration stage and a partial dilution stage;
the gasoline engine three-way catalyst diagnosis rapid diagnosis method comprises the following steps:
step S1, adjusting the gasoline engine to be in the partial concentration stage;
step S2, determining whether the downstream oxygen concentration exceeds a second predetermined threshold within a first predetermined time period;
if yes, judging that the three-way catalytic converter of the gasoline engine works normally in the rich-bias stage, and turning to step S3;
if not, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage, and exiting;
step S3, adjusting the gasoline engine to be in the lean stage;
step S4, determining whether the downstream oxygen concentration exceeds a predetermined third threshold value within a predetermined second time period;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the lean stage;
if not, the three-way catalytic converter of the gasoline engine is judged to work normally in the lean stage.
2. The method for diagnosing the three-way catalyst of the gasoline engine as claimed in claim 1, wherein the gasoline engine is in the rich phase by increasing the amount of fuel injected so that the air-fuel ratio of the gasoline engine is equal to or less than the first threshold in step S1.
3. The gasoline engine three-way catalyst diagnosis rapid diagnosis method as claimed in claim 1, wherein the step S2 specifically comprises:
step S21, presetting the first time period in the rich phase;
step S22, presetting the second threshold value for the downstream oxygen concentration;
step S23, determining whether the downstream oxygen is rich in the first period of time and exceeds the second threshold;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the partial concentration stage.
4. The diagnostic method for diagnosing the three-way catalyst of the gasoline engine as claimed in claim 1, wherein the gasoline engine is in the lean phase by decreasing the fuel injection amount to make the air-fuel ratio of the gasoline engine greater than the first threshold in step S3.
5. The gasoline engine three-way catalyst diagnosis rapid diagnosis method as claimed in claim 1, wherein the step S4 specifically comprises:
step S41, presetting the second time period in the lean phase;
step S42, presetting the third threshold value for the downstream oxygen concentration;
step S43, determining whether the downstream oxygen concentration exceeds the third threshold value within the second period of time;
if yes, judging that the three-way catalytic converter of the gasoline engine has a working fault in the partial concentration stage;
if not, the gasoline engine three-way catalyst is judged to work normally in the partial concentration stage.
6. A gasoline engine three-way catalyst diagnostic rapid diagnostic system for operating the gasoline engine three-way catalyst diagnostic rapid diagnostic method as set forth in one of claims 1 to 5, comprising:
the receiving module is used for receiving and outputting a switching signal, and the switching signal controls the running or suspension of the gasoline engine three-way catalyst rapid diagnosis system;
the oil injection control module is connected with the receiving module and generates and outputs an oil injection control signal by adopting a preset oil injection control strategy according to the switching signal;
the oil injection module is connected with the oil injection control module and used for adjusting the oil injection quantity according to the oil injection control signal;
the downstream oxygen sensor module is connected with the receiving module and used for detecting the downstream oxygen concentration of the three-way catalytic converter of the gasoline engine and outputting a downstream oxygen concentration signal;
and the diagnosis module is respectively connected with the oil injection control module and the downstream oxygen sensor module and is used for quickly diagnosing whether the three-way catalytic converter of the gasoline engine breaks down or not according to the downstream oxygen concentration signal by adopting a preset diagnosis model.
7. The gasoline engine three-way catalyst diagnosis rapid diagnosis system as claimed in claim 6, wherein the fuel injection control module generates the fuel injection control signal according to different preset working periods by adopting a fuel injection strategy, and the fuel injection module adjusts the fuel injection amount according to the fuel injection control signal.
8. The gasoline engine three-way catalyst diagnostic rapid diagnostic system of claim 6, wherein the fuel injection module comprises:
the first control unit is used for enabling the gasoline engine to be in the rich phase with the air-fuel ratio smaller than or equal to the first threshold value by increasing the fuel injection quantity;
and the second control unit is used for enabling the gasoline engine to be in the lean stage with the air-fuel ratio larger than the first threshold value by reducing the fuel injection quantity.
9. The gasoline engine three-way catalyst diagnostic rapid diagnostic system as defined in claim 6, wherein the downstream oxygen sensor module continuously collects the downstream oxygen concentration of the gasoline engine three-way catalyst and outputs the downstream oxygen concentration signal according to the switching signal.
10. The gasoline engine three-way catalyst diagnostic rapid diagnostic system of claim 6, wherein the diagnostic module comprises:
the first diagnosis unit is used for comparing the downstream oxygen concentration with a preset first critical value and judging the working state of the gasoline engine three-way catalyst in the rich period;
and the second diagnosis unit is used for comparing the downstream oxygen concentration with a preset second critical value and judging the working state of the three-way catalyst of the gasoline engine in the lean stage.
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| CN114483274B8 (en) * | 2020-11-12 | 2023-04-14 | 宇通客车股份有限公司 | Hybrid vehicle and three-way catalyst diagnosis method and device thereof |
| CN113446098B (en) * | 2021-08-18 | 2022-09-23 | 潍柴动力股份有限公司 | Anti-cheating diagnosis method and device for three-way catalyst of engine |
| CN114233446B (en) * | 2021-12-17 | 2023-03-21 | 潍柴动力股份有限公司 | Three-way catalyst efficiency diagnosis method, device and equipment |
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