CN113530651A - Method for testing gasoline engine catalyst converter window, electronic equipment and readable storage medium - Google Patents

Method for testing gasoline engine catalyst converter window, electronic equipment and readable storage medium Download PDF

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Publication number
CN113530651A
CN113530651A CN202010306185.4A CN202010306185A CN113530651A CN 113530651 A CN113530651 A CN 113530651A CN 202010306185 A CN202010306185 A CN 202010306185A CN 113530651 A CN113530651 A CN 113530651A
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fuel ratio
air
boundary
preset
gasoline engine
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CN113530651B (en
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包松杰
李星源
沈飞
方芳
张光辉
季玮
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United Automotive Electronic Systems Co Ltd
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United Automotive Electronic Systems Co Ltd
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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
    • 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
    • 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
    • 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 ; Methods of operation or control of catalytic converters
    • 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
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • 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
    • 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

Abstract

The invention provides a testing method of a gasoline engine catalyst window, an electronic device and a readable storage medium, firstly, roughly adjusting an air-fuel ratio, gradually increasing the air-fuel ratio or decreasing the air-fuel ratio in a mode of gradually changing the correction amount of the air-fuel ratio until the air-fuel ratio correspondingly reaches a second preset boundary or a first preset boundary, further creating an initial interval according to the last two air-fuel ratio correction amounts, then finely adjusting, obtaining an optimal target air-fuel ratio by using the concept of dichotomy, namely obtaining a midpoint value of the initial interval, judging whether the air-fuel ratio correspondingly exceeds the first preset boundary or the second preset boundary when the air-fuel ratio is increased or decreased according to the midpoint value, further judging that the midpoint value is used as an upper boundary or a lower boundary of a new interval until the difference value between the midpoint value and the lower boundary of the final new interval is smaller than a preset minimum step length, thereby forming the catalyst window. Compared with the prior art, the method can abandon the test of a large number of invalid points, thereby greatly saving the test time of the catalyst window and laboratory resources.

Description

Method for testing gasoline engine catalyst converter window, electronic equipment and readable storage medium
Technical Field
The invention relates to the technical field of gasoline engines, in particular to a method for testing a gasoline engine catalyst converter window, electronic equipment and a readable storage medium.
Background
The three-way catalyst plays a vital role in reducing the emission of gasoline engines, namely CO, HC and NO in tail gasXEtc. can react with each other in the catalyst to produce CO2、H2O and the like to reduce the influence of the tail gas on the environment and the human body. Generally, when the air-fuel ratio in the engine cylinder is larger, the CO and HC conversion efficiency is higher, but as the air-fuel ratio increases, NO is convertedXThe conversion efficiency rapidly decreases. Conversely, when the air-fuel ratio is small, NOXThe conversion efficiency is higher, but the CO and HC conversion efficiency is lower. Therefore, to ensure high conversion efficiency of the three pollutants simultaneously, the engine needs to operate in a narrow air-fuel ratio range, also referred to as a catalyst window.
The calibration of the catalyst window, i.e., the calibration of the target air-fuel ratio correction value, greatly affects the emission level of the engine. In addition, it determines the behavior of the post-oxygen sensor voltage, which is generally higher for smaller air-fuel ratios. It also has an important influence on functions in the engine control system that require the use of the post-oxygen voltage, such as oxygen sensor diagnosis, catalyst diagnosis, and the like.
A table of catalyst window versus target air-fuel ratio corrections is typically present in engine control systems. The calibration method of the table is as follows: and a matching engineer divides a plurality of rotating speed and load breakpoints according to the common operating conditions of the engine. And then adjusting the engine to various rotating speeds and load points, fixing the target air-fuel ratio of the engine at the moment, and recording the current working condition after the emission and the post-oxygen voltage are stabilized. Then, the target air-fuel ratio is modified according to a certain step length, the test process is repeated until the discharge and the post-oxygen voltage are in a reasonable range, and the offset correction quantity of the target air-fuel ratio is filled into a table.
Due to the influence of the oxygen storage amount of the catalyst, a longer waiting time is needed for each step of modification so that the emission and the post-oxygen voltage are sufficiently stabilized. Although the test method of step-by-step can obtain more comprehensive performance of emission and post-oxygen voltage under different air-fuel ratios, the test efficiency is low, and a large amount of manpower and laboratory resources of engineers are consumed. Therefore, a new testing method needs to be developed to improve the testing efficiency of the catalyst window on the premise of ensuring the testing quality.
Disclosure of Invention
The invention aims to provide a method for testing a gasoline engine catalyst window, electronic equipment and a readable storage medium, so as to improve the testing efficiency of the gasoline engine catalyst window on the premise of not influencing the testing quality.
Based on the thought, the invention provides a method for testing a gasoline engine catalyst window, which comprises the following steps:
testing an initial working condition of a theoretical air-fuel ratio to judge whether the air-fuel ratio exceeds a first preset boundary;
if the voltage exceeds the preset threshold, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, reducing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches a second preset boundary, and recording the last two air-fuel ratio correction amounts to create an initial interval; when the air-fuel ratio is reduced according to the midpoint value of the initial interval, judging whether the reduced air-fuel ratio exceeds the second preset boundary, if so, taking the midpoint value as the lower boundary of a new interval, if not, taking the midpoint value as the upper boundary of the new interval until the difference value between the midpoint value and the lower boundary of the final new interval is smaller than a preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window;
if the voltage does not exceed the preset limit, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, increasing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches the first preset limit, and recording the last two air-fuel ratio correction amounts to create an initial interval; and judging whether the increased air-fuel ratio exceeds the first preset boundary or not when the air-fuel ratio is increased according to the midpoint value of the initial interval, if so, taking the midpoint value as the upper boundary of a new interval, and if not, taking the midpoint value as the lower boundary of the new interval until the difference between the midpoint value and the lower boundary of the final new interval is smaller than the preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window.
Optionally, in the method for testing a catalyst window of a gasoline engine, the method for testing a catalyst window of a gasoline engine further includes:
if the air-fuel ratio is gradually reduced, judging whether the current air-fuel ratio reaches a second preset boundary or not every time one step is started;
and if the air-fuel ratio is gradually increased, judging whether the current air-fuel ratio reaches a first preset boundary or not every beginning step.
Optionally, in the method for testing a catalyst window of a gasoline engine, the first preset boundary is determined under the following conditions: NOX is currently≥NOXLimitAnd UAt present≤UminAt least one of which is satisfied, wherein,
NOx is currentlyRepresents NOXCurrent value, NOXLimitRepresents NOXMaximum allowable value, UAt presentRepresents the current value of the post-oxygen voltage, UminRepresents the lower rear oxygen voltage limit.
Optionally, in the method for testing a catalyst window of a gasoline engine, the second preset boundary is determined under the following conditions: CO 2At present≥COLimit、HCAt present≥HCLimitAnd UAt present≥UmaxAt least one of which is satisfied, wherein,
COat presentRepresenting the current value of CO, COLimitIndicating the maximum allowable value of CO, HCAt presentIndicates the current value of HC, HCLimitDenotes the maximum allowable value of HC, UAt presentRepresents the current value of the post-oxygen voltage, UmaxRepresents the upper limit of the post-oxygen voltage.
Optionally, in the method for testing a catalyst window of a gasoline engine, the method for adjusting the air-fuel ratio correction amount according to the current oxygen voltage comprises:
inquiring in a preset step length curve according to the current oxygen voltage and the current oxygen voltage to obtain a step length;
if the air-fuel ratio is to be decreased, the air-fuel ratio correction amount is decreased according to the obtained step size, and if the air-fuel ratio is to be increased, the air-fuel ratio correction amount is increased according to the obtained step size.
Optionally, in the method for testing a catalyst window of a gasoline engine, the preset step curve is a curve of step length about an absolute value of a difference value between the upper limit and the lower limit of the post-oxygen voltage and an average value of the post-oxygen voltage.
Optionally, in the method for testing a catalyst window of a gasoline engine, the method for testing a catalyst window of a gasoline engine further includes:
when the air-fuel ratio is decreased or increased, if the air-fuel ratio correction amount is less than or equal to the lower limit of the preset target air-fuel ratio correction amount or greater than or equal to the upper limit of the preset target air-fuel ratio correction amount, the decrease or increase of the air-fuel ratio is stopped.
Optionally, in the method for testing a catalyst window of a gasoline engine, before the initial condition when the theoretical air-fuel ratio is tested, the method for testing the catalyst window of the gasoline engine further includes: the rotational speed and the load of the engine of the gasoline engine are adjusted to target values.
Based on the same idea, the present invention further provides an electronic device comprising a processor and a memory, wherein the memory stores a computer program, and the computer program, when executed by the processor, implements the method as described above.
Based on the same idea, the present invention further provides a readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the computer program implements the method as described above.
In the method for testing the gasoline engine catalyst window, the electronic device and the readable storage medium provided by the invention, firstly, the air-fuel ratio is roughly adjusted, the air-fuel ratio is gradually increased or decreased in a mode of gradually changing the correction amount of the air-fuel ratio until the air-fuel ratio correspondingly reaches a first preset boundary or a second preset boundary, then an initial interval can be created according to the last two air-fuel ratio correction amounts, then fine adjustment is carried out, the optimal target air-fuel ratio is obtained by using the concept of dichotomy, namely, the midpoint value of the initial interval is obtained, whether the corresponding air-fuel ratio exceeds the first preset boundary or the second preset boundary or not is judged when the air-fuel ratio is increased or decreased according to the midpoint value, and the midpoint value is further judged to be used as the upper boundary or the lower boundary of a new interval until the difference value between the midpoint value and the lower boundary of the final new interval is smaller than the preset minimum step length, thereby forming the catalytic converter window of the gasoline engine. Thus, compared with the prior art, the method can abandon the test of a large number of invalid points, thereby greatly saving the test time of the catalyst window and laboratory resources.
Drawings
FIG. 1 is a flow chart of a method for testing a catalyst window of a gasoline engine according to an embodiment of the present invention;
FIG. 2 is a flow chart of coarse catalyst window adjustment in an embodiment of the present invention;
FIG. 3 is a flowchart illustrating fine adjustment of the air/fuel ratio reduction performed by the catalyst window in an embodiment of the present invention;
FIG. 4 is a flowchart illustrating fine adjustment of the air-fuel ratio decrease/increase in the catalyst window according to the embodiment of the present invention.
Detailed Description
The following describes a method for testing a catalyst window of a gasoline engine, an electronic device and a readable storage medium in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.
As shown in FIG. 1, the embodiment of the invention provides a method for testing a catalyst window of a gasoline engine, which comprises the following steps:
step S1, testing the initial working condition of the theoretical air-fuel ratio to judge whether the air-fuel ratio exceeds a first preset boundary, if so, executing step S2, and if not, executing step S3;
step S2, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, decreasing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches a second preset boundary, executing step S4, and further executing step S5;
step S3, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, increasing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches the first preset boundary, recording the last two air-fuel ratio correction amounts, then executing step S4, and further executing step S6;
step S4, recording the last two air-fuel ratio correction amounts;
step S5, creating an initial interval according to the last two air-fuel ratio correction amounts, judging whether the reduced air-fuel ratio exceeds the second preset boundary when the air-fuel ratio is reduced according to the midpoint value of the initial interval, if so, taking the midpoint value as the lower boundary of a new interval, if not, taking the midpoint value as the upper boundary of the new interval until the difference value between the final midpoint value and the lower boundary of the new interval is smaller than a preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window;
and step S6, creating an initial interval according to the last two air-fuel ratio correction amounts, judging whether the increased air-fuel ratio exceeds the first preset boundary when the air-fuel ratio is increased according to the midpoint value of the initial interval, if so, taking the midpoint value as the upper boundary of a new interval, if not, taking the midpoint value as the lower boundary of the new interval until the difference between the final midpoint value and the lower boundary of the new interval is smaller than a preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window.
That is, the method for testing the catalyst window of the gasoline engine provided by the embodiment of the invention firstly carries out rough adjustment on the air-fuel ratio, by gradually increasing the air-fuel ratio or decreasing the air-fuel ratio in such a manner that the air-fuel ratio correction amount is gradually changed until the air-fuel ratio reaches a first preset boundary or a second preset boundary, respectively, it is possible to create an initial interval based on the last two air-fuel ratio correction amounts, then fine adjustment is carried out, the optimal target air-fuel ratio is obtained by using the dichotomy idea, the midpoint value of the initial interval is obtained, whether the air-fuel ratio exceeds a first preset boundary or a second preset boundary correspondingly or not is judged when the air-fuel ratio is increased or decreased according to the midpoint value, and further judging to use the midpoint value as the upper boundary or the lower boundary of the new interval until the difference between the midpoint value and the lower boundary of the final new interval is smaller than the preset minimum step length, and further forming a gasoline engine catalyst window. Thus, compared with the prior art, the method can abandon the test of a large number of invalid points, thereby greatly saving the test time of the catalyst window and laboratory resources.
As described above, when the air-fuel ratio is larger, the CO and HC conversion efficiency is higher, whereas when the air-fuel ratio is smaller, NO is higherXThe conversion efficiency is high, but the CO and HC conversion efficiency is low, and the air-fuel ratio also affects the post-oxygen sensor voltage of the engine, and generally the lower the air-fuel ratio, the higher the post-oxygen voltage. Calibrating the catalyst window essentially calibrates the target air-fuel ratio which gives consideration to emission and optimal post-oxygen voltage under different working conditions, and NO is usedXIs more sensitive to changes in air-fuel ratio, and therefore, NO needs to be prioritized when optimizing the catalyst windowXTherefore, it is preferable that when the coarse adjustment is performed in step S1, the target air-fuel ratio is sought to be as small as possible without affecting NOXBoundary operating point of discharge. The rough adjustment operation of step S1 first determines whether the air-fuel ratio exceeds a first preset boundary, and then determines whether to gradually increase the air-fuel ratio or gradually decrease the air-fuel ratio. Wherein the first predetermined boundary is defined by NOXIs defined by the value of the post-oxygen voltage, and the second predetermined boundary is defined by the value of the CO, HC or post-oxygen voltageThe rows are defined.
Specifically, the first preset boundary is determined under the following conditions: NOX is currently≥NOXLimitAnd UAt present≤UminAt least one of which is satisfied, wherein NOX is currentlyRepresents NOXCurrent value, NOXLimitIndicating preset NOXMaximum allowable value of, UAt presentRepresents the current value of the post-oxygen voltage, UminRepresenting a preset lower limit of post-oxygen voltage.
The second preset boundary is judged under the conditions that: CO 2At present≥COLimit、HCAt present≥HCLimitAnd UAt present≥UmaxAt least one of which is satisfied, wherein, COAt presentRepresenting the current value of CO, COLimitRepresenting a preset maximum allowable value of CO, HCAt presentIndicates the current value of HC, HCLimitRepresents a preset maximum allowable value, U, of HCAt presentRepresents the current value of the post-oxygen voltage, UmaxRepresenting a preset upper limit of post-oxygen voltage.
The steps of the method for testing the gasoline engine catalyst window provided by the invention are explained in detail below by combining the setting of the above judgment conditions.
(1) Coarse adjustment of catalyst window
As shown in fig. 2, step S1 is first executed to test an initial condition (air-fuel ratio correction amount Δ λ is 0) of the stoichiometric air-fuel ratio, and determine whether the air-fuel ratio exceeds a first preset boundary, that is, to test whether NO is satisfied under the initial conditionX＜NOXLimitAnd the post-oxygen voltage U is more than UminIf not, the air-fuel ratio at this time is considered to have reached the first preset boundary, so step S2 is executed; if so, the air-fuel ratio at this time is considered to have not reached the first preset boundary and has the potential to increase, so step S3 is executed;
s2, roughly adjusting the air-fuel ratio in a reducing way, and gradually reducing the air-fuel ratio until reaching a second preset boundary; wherein, once CO is presentAt present≥COLimitOr HCAt present≥HCLimitOr UAt present≥UmaxThen it is considered that the air-fuel ratio at this time has reached the second preset valueA boundary;
s3, roughly adjusting the air-fuel ratio, and gradually increasing the air-fuel ratio until reaching a first preset boundary; wherein, once NO isX is currently≥NOXLimitOr UAt present≤UminThen the air-fuel ratio at that time is considered to have reached the first preset boundary
S4, recording the last two times air-fuel ratio correction quantity delta lambda in the step S2 or the step S3aAnd Δ λb。
In steps S2 and S3, coarse adjustment is performed by gradually changing the air-fuel ratio, so that the window accuracy can be improved. Preferably, each step is started, the test is carried out according to the working condition, if the air-fuel ratio is gradually reduced, each step is started, whether the current air-fuel ratio reaches a second preset boundary is judged, if the air-fuel ratio is gradually increased, each step is started, whether the current air-fuel ratio reaches a first preset boundary is judged, and therefore invalid points are prevented from being collected. Furthermore, the air-fuel ratio correction quantity can be adjusted according to the actual working condition, so that the closer to the boundary, the smaller the air-fuel ratio correction quantity is, and the testing precision is further improved. For example, in the present embodiment, the method of adjusting the air-fuel ratio correction amount according to the current level of the pre-post oxygen voltage may specifically include: inquiring in a preset step length curve according to the current oxygen voltage and the current oxygen voltage to obtain a step length; if the air-fuel ratio is to be decreased, the air-fuel ratio correction amount is decreased according to the obtained step size, and if the air-fuel ratio is to be increased, the air-fuel ratio correction amount is increased according to the obtained step size. Wherein, the preset step curve is a curve of the absolute value of the step about the difference value of the average value of the upper limit and the lower limit of the post-oxygen voltage: x ═ uAt present-(umin+umax) And/2, wherein x is the step size step. Based on the step length curve, the current oxygen voltage deviates (u)min+umax) The larger the/2, the larger the value of the step size.
Therefore, specifically, as shown in fig. 2, step S2 includes the following steps:
s21, under the current air-fuel ratio working condition, judging whether CO is satisfiedAt present＜COLimitAnd HCAt present＜
HCLimitAnd U isAt present＜UmaxIf yes, go to step S22;
s22, further adjusting the air-fuel ratio correction amount according to the current oxygen voltage query step, where the adjusted air-fuel ratio correction amount Δ λ ═ Δ λ -step, and decreasing the current air-fuel ratio λ according to Δ λ ', to obtain a decreased air-fuel ratio λ ═ λ + Δ λ ', and then executing step S21 under the condition that the air-fuel ratio is λ ';
similarly, as shown in fig. 2, step S3 includes the following steps:
s31, judging whether NO is satisfied under the working condition of the current air-fuel ratioX is currently＜NOXLimitAnd U isAt present＞
UminIf yes, go to step S32;
s32 is executed step S31 under the condition that the air-fuel ratio is λ ', after adjusting the air-fuel ratio correction amount Δ λ ' ═ Δ λ + step and increasing the current air-fuel ratio λ according to Δ λ ', and obtaining the increased air-fuel ratio λ ' ═ λ + Δ λ ', based on the current oxygen voltage query step.
In step S22, Δ λ is a negative value, and in step S32, Δ λ is a positive value. For the air-fuel ratio reduction coarse tuning test, the closer the post oxygen voltage (U) as the air-fuel ratio is reducedmin+Umax) The corresponding step size step decreases accordingly, so the air-fuel ratio correction amount Δ λ decreases gradually, resulting in the air-fuel ratio decreasing speed becoming gradually slow. For the air-fuel ratio increase coarse tuning test, the post oxygen voltage is closer (U) as the air-fuel ratio increasesmin+Umax) The corresponding step size decreases accordingly, so that the increasing speed of the air-fuel ratio correction amount Δ λ becomes gradually slower, resulting in the gradually slower increasing speed of the air-fuel ratio, and the test accuracy can be improved.
(2) Catalyst window fine tuning
The fine adjustment of the catalyst window obtains the optimal target air-fuel ratio by using the dichotomy idea, if the coarse adjustment of the catalyst window is carried out, the initial interval is obtained by gradually reducing the air-fuel ratio, and the fine adjustment is continuously carried out by reducing the air-fuel ratio; if the initial interval is obtained by gradually increasing the air-fuel ratio when the catalyst window is finely adjusted, the coarse adjustment is continued by increasing the air-fuel ratio.
Creation of initial section [ Δ λ ] by step S2a,Δλb]Then, when performing fine adjustment, as shown in fig. 3, step S5 specifically includes the following steps:
s51, obtaining the interval [ Delta lambda ]a,Δλb]Is (Δ λ) ═ valuea+Δλb)/2；
S52, judging the difference value delta lambda-delta lambda between the midpoint value and the lower boundary of the intervalaWhether it is less than the preset minimum stepminOtherwise, go to step S53, if not, end;
s53, judging whether the air-fuel ratio lambda after reduction exceeds the second preset boundary when the air-fuel ratio lambda is reduced according to the midpoint value of the initial interval, namely judging whether the air-fuel ratio lambda' meets CO under the working condition of the air-fuel ratio lambdaAt present＜
COLimitAnd HCAt present＜HCLimitAnd U isAt present＜UmaxIf yes, it indicates that the second preset boundary is not exceeded, then step S54 is executed, otherwise, it indicates that the second preset boundary is exceeded, then step S55 is executed;
s54, storing the delta lambda in the upper boundary delta lambda of the new regionb；
S55, storing the delta lambda in the lower boundary delta lambda of the new regiona；
S51-S55 were repeated.
Creating an initial interval [ Δ λ ] according to step S3a,Δλb]Then, when performing fine adjustment, as shown in fig. 4, step S6 specifically includes the following steps:
s61, obtaining the interval [ Delta lambda ]a,Δλb]Is (Δ λ) ═ valuea+Δλb)/2；
S62, judging the difference value delta lambda-delta lambda between the midpoint value and the lower boundary of the intervalaWhether it is less than the preset minimum stepminIf not, go to step S63,if yes, ending;
s63, judging whether the increased air-fuel ratio lambda' exceeds the first preset boundary when the air-fuel ratio lambda is increased according to the midpoint value of the initial interval, namely judging whether NO is met under the working condition of the air-fuel ratio lambdaX is currently < (R) >NOXLimitAnd UAt present＞UminIf yes, it is determined that the first preset boundary is not exceeded, so step S64 is executed, otherwise, it is determined that the first preset boundary is exceeded, and step S65 is executed;
s64, storing the delta lambda in the lower boundary delta lambda of the new regiona；
S65, storing the delta lambda in the upper boundary delta lambda of the new regionb；
S61-S65 were repeated.
Based on the fine tuning results, the matching engineer can be in the interval [ Δ λ a, Δ λ [ ]b]And a catalyst window which gives consideration to emission and post-oxygen voltage is quickly found.
Note that U ismax、Umin、COLimit、HCLimit、NOXLimit、Umax、UminAnd stepminMay be manually set up before the test begins. And the rough adjustment of the catalyst window and the fine adjustment of the catalyst window can be executed after the rotating speed and the load of the engine are adjusted to the target values, and the testing of the next catalyst window can be carried out by switching the rotating speed and the load of the engine after the catalyst window under the target values is obtained.
From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solution of the present invention may be embodied in the form of a computer program, which may be stored in a readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., or a part thereof that contributes to the prior art. Therefore, an embodiment of the present invention further provides an electronic device, where the electronic device includes a processor and a memory, where the memory stores a computer program, and the computer program, when executed by the processor, implements the method according to the embodiment or some parts of the embodiment of the present invention. Furthermore, the embodiment of the present invention also provides a readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the method according to the embodiment or some parts of the embodiment is performed.
In conclusion, the testing method, the electronic device and the readable storage medium for the gasoline engine catalyst window provided by the invention improve the testing efficiency of the gasoline engine catalyst window on the premise of not influencing the testing quality.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims (10)

1. A method for testing a gasoline engine catalyst window is characterized by comprising the following steps:
testing an initial working condition of a theoretical air-fuel ratio to judge whether the air-fuel ratio exceeds a first preset boundary;
if the voltage exceeds the preset threshold, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, reducing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches a second preset boundary, and recording the last two air-fuel ratio correction amounts to create an initial interval; when the air-fuel ratio is reduced according to the midpoint value of the initial interval, judging whether the reduced air-fuel ratio exceeds the second preset boundary, if so, taking the midpoint value as the lower boundary of a new interval, if not, taking the midpoint value as the upper boundary of the new interval until the difference value between the midpoint value and the lower boundary of the final new interval is smaller than a preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window;
if the voltage does not exceed the preset limit, gradually adjusting the air-fuel ratio correction amount according to the current oxygen voltage, increasing the air-fuel ratio according to the adjusted air-fuel ratio correction amount until the air-fuel ratio reaches the first preset limit, and recording the last two air-fuel ratio correction amounts to create an initial interval; and judging whether the increased air-fuel ratio exceeds the first preset boundary or not when the air-fuel ratio is increased according to the midpoint value of the initial interval, if so, taking the midpoint value as the upper boundary of a new interval, and if not, taking the midpoint value as the lower boundary of the new interval until the difference between the midpoint value and the lower boundary of the final new interval is smaller than the preset minimum step length, and further taking the final new interval as a gasoline engine catalyst window.
2. The method for testing a catalyst window of a gasoline engine as set forth in claim 1, further comprising:
if the air-fuel ratio is gradually reduced, judging whether the current air-fuel ratio reaches a second preset boundary or not every time one step is started;
and if the air-fuel ratio is gradually increased, judging whether the current air-fuel ratio reaches a first preset boundary or not every beginning step.
3. The method for testing the catalyst window of the gasoline engine as set forth in claim 1 or 2, wherein the first predetermined boundary is determined under the following conditions: NOX is currently≥NOXLimitAnd UAt present≤UminAt least one of which is satisfied, wherein,
NOx is currentlyRepresents NOXCurrent value, NOXLimitRepresents NOXMaximum allowable value, UAt presentRepresents the current value of the post-oxygen voltage, UminRepresents the lower rear oxygen voltage limit.
4. The method for testing the catalyst window of the gasoline engine as set forth in claim 1 or 2, wherein the second predetermined boundary is determined under the following conditions: CO 2At present≥COLimit、HCAt present≥HCLimitAnd UAt present≥UmaxAt least one of which is satisfied, wherein,
COat presentRepresenting the current value of CO, COLimitIndicating the maximum allowable value of CO, HCAt presentWhich represents the current value of HC,HCLimitdenotes the maximum allowable value of HC, UAt presentRepresents the current value of the post-oxygen voltage, UmaxRepresents the upper limit of the post-oxygen voltage.
5. The method for testing a catalyst window of a gasoline engine according to claim 1, wherein the method for adjusting the air-fuel ratio correction amount according to the magnitude of the current front and rear oxygen voltages comprises:
inquiring in a preset step length curve according to the current oxygen voltage and the current oxygen voltage to obtain a step length;
if the air-fuel ratio is to be decreased, the air-fuel ratio correction amount is decreased according to the obtained step size, and if the air-fuel ratio is to be increased, the air-fuel ratio correction amount is increased according to the obtained step size.
6. The method for testing a catalyst window of a gasoline engine as set forth in claim 4, wherein the predetermined step curve is a curve of step with respect to an absolute value of a difference between the rear oxygen voltage and an average of upper and lower limits of the rear oxygen voltage.
7. The method for testing a catalyst window of a gasoline engine as set forth in claim 1, further comprising:
when the air-fuel ratio is decreased or increased, if the air-fuel ratio correction amount is less than or equal to the lower limit of the preset target air-fuel ratio correction amount or greater than or equal to the upper limit of the preset target air-fuel ratio correction amount, the decrease or increase of the air-fuel ratio is stopped.
8. The method for testing a catalyst window of a gasoline engine as claimed in claim 1, wherein before the initial condition when testing the stoichiometric air-fuel ratio, the method for testing a catalyst window of a gasoline engine further comprises: the rotational speed and the load of the engine of the gasoline engine are adjusted to target values.
9. An electronic device comprising a processor and a memory, the memory having stored thereon a computer program which, when executed by the processor, implements the method of any of claims 1 to 8.
10. A readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the method of any one of claims 1 to 8.
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