CN114704394B - Oxygen storage control method of three-way catalyst - Google Patents
Oxygen storage control method of three-way catalyst Download PDFInfo
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- CN114704394B CN114704394B CN202210494038.3A CN202210494038A CN114704394B CN 114704394 B CN114704394 B CN 114704394B CN 202210494038 A CN202210494038 A CN 202210494038A CN 114704394 B CN114704394 B CN 114704394B
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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
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0047—Controlling exhaust gas recirculation [EGR]
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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
- F02D41/021—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
- F02D41/0295—Control according to the amount of oxygen that is stored on the exhaust gas treating 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
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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
- 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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- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1409—Introducing closed-loop corrections characterised by the control or regulation method using at least a proportional, integral or derivative controller
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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
Abstract
The invention discloses a three-way catalyst oxygen storage control method, which comprises the steps of acquiring initial oxygen storage amount of a previous driving cycle in the running process of a vehicle; determining a target fuel-air ratio and a disturbance fuel-air ratio; calculating an EGR feedforward fuel-air ratio correction amount and a post-oxygen sensor fuel-air ratio correction amount; determining a current fuel-air ratio demand value based on the target fuel-air ratio, the disturbance fuel-air ratio, the EGR feedforward fuel-air ratio correction amount and the post-oxygen sensor fuel-air ratio correction amount; and calculating a fuel-air ratio deviation according to the fuel-air ratio demand value, determining whether an oxygen storage request is satisfied according to the fuel-air ratio deviation, if so, calculating the current demand oxygen storage amount according to the initial oxygen storage amount, the fuel-air ratio deviation and the oxygen quality in the exhaust gas under the current working condition, and performing oxygen storage control according to the demand oxygen storage amount. According to the invention, the disturbance fuel-air ratio is updated in real time according to the working condition and the state of the three-way catalyst, so that the conversion efficiency of the three-way catalyst is improved.
Description
Technical Field
The invention belongs to the technical field of engine tail gas purification treatment, and particularly relates to an oxygen storage control method of a three-way catalyst.
Background
Patent No. CN112664342A discloses a method and a system for controlling a three-way catalyst, which are used for obtaining theoretical maximum and minimum oxygen storage amounts of the three-way catalyst according to the types and specifications of the three-way catalyst, taking an average value of the theoretical maximum and minimum oxygen storage amounts as a theoretical oxygen content set value of an inlet of the three-way catalyst; obtaining an actual oxygen content value of the three-way catalyst inlet through a front oxygen sensor; and then the actual oxygen storage amount reaches the theoretical oxygen storage amount by adjusting the air-fuel ratio, so that the efficiency of the three-way catalyst is improved.
In addition, in other conventional technologies, control of the oxygen storage amount is mostly achieved by control of the fuel-air ratio, which mainly includes: setting a target fuel-air ratio, setting a disturbance fuel-air ratio, and performing feedback control on a post-oxygen voltage.
The above prior art has the following disadvantages:
1) In the prior art, only fixed disturbance is adopted in the disturbance fuel-air ratio setting, and the difference of disturbance of the requirements of the three-way catalyst in different states and different working conditions is not considered, so that the conversion efficiency of the three-way catalyst is directly influenced;
2) In the prior art, only the feedback control of the post-oxygen voltage is adopted, and the responsiveness requirement of oxygen storage control on a high-capacity three-way catalyst is difficult to meet;
3) The prior art ignores the influence of the aging degree of the three-way catalyst on the conversion efficiency of the three-way catalyst, and can reduce the accuracy of oxygen storage amount calculation.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides the three-way catalyst oxygen storage control method which is used for controlling the oxygen storage amount in the three-way catalyst in real time and accurately so that the oxidation and reduction reactions are performed efficiently and the conversion efficiency of the three-way catalyst is improved.
The technical scheme adopted by the invention is as follows: a three-way catalyst oxygen storage control method,
acquiring an initial oxygen storage amount of a previous driving cycle;
determining a target fuel-air ratio and a disturbance fuel-air ratio;
calculating an EGR feedforward fuel-air ratio correction amount and a post-oxygen sensor fuel-air ratio correction amount;
determining a current fuel-air ratio demand value based on the target fuel-air ratio, the disturbance fuel-air ratio, the EGR feedforward fuel-air ratio correction amount and the post-oxygen sensor fuel-air ratio correction amount;
and calculating a fuel-air ratio deviation according to the fuel-air ratio demand value, determining whether an oxygen storage request is satisfied according to the fuel-air ratio deviation, if so, calculating the current demand oxygen storage amount according to the initial oxygen storage amount, the fuel-air ratio deviation and the oxygen quality in the exhaust gas under the current working condition, and performing oxygen storage control according to the demand oxygen storage amount.
Further, the target fuel-air ratio is determined by the following formula:
λ 2 ＝λ 1 *η 1
wherein lambda is 2 Lambda is the target fuel-air ratio 1 For theoretical fuel-air ratio, eta 1 And (3) checking the fuel-air ratio correction coefficient obtained by MAP for the rotation speed and the torque.
Further, the process of determining the disturbance fuel-air ratio is as follows:
obtaining the maximum oxygen storage capacity M under the state by checking the temperature of the first Table through the three-way catalyst 1 Obtaining the minimum oxygen storage capacity M under the state by checking the second Table through the temperature of the three-way catalyst 2 ；
Acquiring a voltage value U of a post-oxygen sensor 1 After that, the voltage value U is passed 1 Obtaining the disturbance fuel-air ratio compensation quantity lambda under the state by checking Table 3 ；
Based on maximum oxygen storage capacity M 1 Minimum oxygen storage capacity M 2 And fuel-air ratio compensation quantity lambda 3 And determining a disturbance fuel-air ratio.
Further, if the minimum oxygen storage capacity M 2 <M int <Maximum oxygen storage capacity M 1 Then the disturbance air-fuel ratio lambda is determined 4 ＝λ 3 ；
If M int Not less than the maximum oxygen storage capacity M 1 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 1 ；
If M int Minimum oxygen storage capacity M 2 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 2 。
Further, the EGR feedforward fuel-air ratio correction amount is calculated by the following formula
λ 7 = (1-EGR rate) ×λ 6 +EGR Rate x lambda 5
Wherein lambda is 7 A feed-forward fuel-air ratio correction amount for EGR; lambda (lambda) 5 When the EGR is fully opened, the MAP is checked by the rotating speed and the torque to obtain a first fuel-air ratio correction quantity under the corresponding working condition; lambda (lambda) 6 And when the EGR is fully closed, checking MAP according to the rotating speed and the torque to obtain a second fuel-air ratio correction quantity under the corresponding working condition.
Further, the process of calculating the fuel-air ratio correction amount of the post-oxygen sensor is as follows:
through the target fuel-air ratio lambda 2 Obtaining the post-oxygen target voltage U under the working condition by checking the characteristic curve of the post-oxygen sensor 2 Based on post oxygen target voltage U 2 And the actual post oxygen voltage U 1 Performing post-oxygen PID feedback control to obtain a PID feedback coefficient;
comparing the PID feedback coefficient with the upper limit value of the post oxygen voltage correction coefficient, and if the PID feedback coefficient is less than or equal to the upper limit value of the post oxygen voltage correction coefficient, setting the fuel-air ratio correction of the post oxygen sensor as the PID feedback coefficient;
if the PID feedback coefficient is larger than the upper limit value of the post-oxygen voltage correction coefficient, the aging degree of the three-way catalyst is calculated, and the fuel-air ratio correction amount of the post-oxygen sensor is determined according to the aging degree.
Further, the aging coefficient under the state is obtained by checking MAP through the aging degree and the temperature of the three-way catalyst, and the post-oxygen target voltage U is obtained 2 Multiplying the aging coefficient to obtain a corrected post-oxygen target voltage U 2 Based on post oxygen target voltage U 2 And the actual post oxygen voltage U 1 And performing the post-oxygen PID feedback control to obtain a new PID feedback coefficient, and then setting the fuel-air ratio correction quantity of the post-oxygen sensor as the new PID feedback coefficient.
Further, the current fuel-air ratio demand value is determined by the following formula:
λ 9 ＝λ 2 +λ 4 +λ 7 +λ 8
wherein lambda is 9 Lambda is the current fuel-air ratio demand value 2 Lambda is the target fuel-air ratio 4 To disturb the air-fuel ratio lambda 7 A feed-forward fuel-air ratio correction amount for EGR; lambda (lambda) 8 The fuel-air ratio correction amount is the post-oxygen sensor.
Further, the fuel-air ratio deviation is calculated by the following formula
Δλ＝λ 10 -λ 9
Wherein Deltalambda is the fuel-air ratio deviation, lambda 10 Lambda is the actual fuel air-fuel ratio 9 Is the current fuel-air ratio demand value.
Further, the current required oxygen storage amount is calculated by the following formula
M 4 ＝M 3 *Δλ*η 2 +M int
Wherein M is 4 For the current oxygen storage requirement, M 3 The oxygen quality in the exhaust gas under the current working condition is delta lambda is the fuel-air ratio deviation, eta 2 For oxygen storage efficiency, M int Is the initial oxygen storage amount.
The beneficial effects of the invention are as follows:
1) According to the invention, the disturbance fuel-air ratio is updated in real time according to the working conditions and the state of the three-way catalyst, so that the conversion efficiency of the three-way catalyst is improved;
2) According to the invention, an EGR feedforward control strategy is adopted in the current fuel-air ratio demand value, so that the oxygen storage control efficiency is improved;
3) According to the invention, the influence of the aging degree of the three-way catalyst on the oxygen storage amount is considered in the calculation of the fuel-air ratio correction amount of the oxygen sensor, so that the accuracy of the calculation of the oxygen storage amount is improved.
Drawings
FIG. 1 is a control flow chart of the present invention.
FIG. 2 is a flow chart of oxygen storage control by the three-way catalyst of the present invention.
FIG. 3 is a flow chart of the invention for determining a disturbance fuel-air ratio.
FIG. 4 is a flow chart showing the calculation of the fuel-air ratio correction amount of the post-oxygen sensor according to the present invention.
Detailed Description
The following describes the embodiments of the present invention further with reference to the drawings. The description of these embodiments is provided to assist understanding of the present invention, but is not intended to limit the present invention. In addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The features of the various embodiments of the invention may be combined or spliced with one another, either in part or in whole, and may be implemented in a variety of different configurations as will be well understood by those skilled in the art. Embodiments of the present invention may be performed independently of each other or may be performed together in an interdependent relationship.
As shown in FIG. 1, the invention provides a three-way catalyst oxygen storage control method, which is used for acquiring the initial oxygen storage amount of the previous driving cycle and determining a target fuel-air ratio and a disturbance fuel-air ratio;
calculating an EGR feedforward fuel-air ratio correction amount and a post-oxygen sensor fuel-air ratio correction amount;
determining a current fuel-air ratio demand value based on the target fuel-air ratio, the disturbance fuel-air ratio, the EGR feedforward fuel-air ratio correction amount and the post-oxygen sensor fuel-air ratio correction amount;
calculating a fuel-air ratio deviation according to a fuel-air ratio demand value, determining whether an oxygen storage request is satisfied according to the fuel-air ratio deviation, calculating a current demand oxygen storage amount according to an initial oxygen storage amount, the fuel-air ratio deviation and the oxygen quality in exhaust gas under the current working condition if the oxygen storage request is satisfied, performing oxygen storage control according to the demand oxygen storage amount (namely entering the next driving cycle), and returning to the initial step if the oxygen storage request is not satisfied.
As shown in fig. 2, the specific steps for performing the oxygen storage control are as follows:
1) When the previous driving cycle starts, the controller reads the initial oxygen storage M of the previous driving cycle from the system EEPROM int . ( When the vehicle is just electrified, the oxygen storage amount is the oxygen storage amount at the last power-down time; the oxygen storage amount is the required oxygen storage amount determined in the last driving cycle during driving. )
2) Setting a target fuel-air ratio: theoretical fuel-air ratio lambda 1 According to the three-way catalyst characteristic, the equivalent weight is 1, but the optimal fuel-air ratio in different working conditions fluctuates around 1, so that the target fuel-air ratio needs to be corrected, and the correction coefficient eta in the working conditions is obtained by checking MAP through the rotating speed and the torque 1 Then the target fuel-air ratio lambda 2 The method comprises the following steps: lambda (lambda) 2 ＝λ 1 *η 1 ，
Wherein lambda is 2 Lambda is the target fuel-air ratio 1 For theoretical fuel-air ratio, eta 1 And (3) checking the fuel-air ratio correction coefficient obtained by MAP for the rotation speed and the torque.
3) The disturbance fuel-air ratio is set, as shown in fig. 3, so that the three-way catalyst can store and release oxygen continuously.
A) Obtaining the maximum oxygen storage capacity M under the state by checking Table through the temperature of the three-way catalyst 1 Obtaining the minimum oxygen storage capacity M under the state by checking another Table through the temperature of the three-way catalyst 2 The method comprises the steps of carrying out a first treatment on the surface of the (the temperature of the three-way catalyst is obtained by a temperature sensor at the catalyst inlet).
B) The post-oxygen sensor directly acquires the voltage value U thereof 1 After that, through U 1 Obtaining the disturbance fuel-air ratio compensation quantity lambda under the state by checking Table 3 . Post-sensor voltage value U 1 Above 0.45V, lambda 3 Is negative and used for reducing the lean air-fuel ratio, U 1 The larger lambda 3 The greater the absolute value of (2), the maximum is not more than 0.1; post-sensor voltage value U 1 Lambda is less than 0.45V 3 Positive value for enriching fuel-air ratio, U 1 Smaller lambda 3 Not exceeding 0.1 at maximum; u (U) 1 when=0.45V, λ 3 Is 0.
C) The perturbation settings were as follows:
i) If the minimum oxygen storage capacity M 2 <M int <Maximum oxygen storage capacity M 1 Then the disturbance air-fuel ratio lambda is determined 4 ＝λ 3 ；
ii)M int Not less than the maximum oxygen storage capacity M 1 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 1 ；
iii)M int Minimum oxygen storage capacity M 2 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 2 ；
Wherein C is 1 、C 2 All are standard quantities which are set according to actual demands.
4) Calculation of EGR feed-forward fuel-air ratio correction: the EGR opening determines the oxygen content into the engine, so it is necessary to take account of EGRThe ratio of the current opening of the EGR to the magnitude of the opening range of the EGR may be the EGR rate. When EGR is fully opened, the MAP is checked by the rotation speed and the torque to obtain a first fuel-air ratio correction quantity lambda of the corresponding working condition 5 The method comprises the steps of carrying out a first treatment on the surface of the When the EGR is fully closed, a second fuel-air ratio correction quantity lambda of the corresponding working condition is obtained by checking MAP through the rotation speed and the torque 6 . The EGR feed-forward fuel-air ratio correction amount lambda 7 The calculation is as follows:
λ 7 = (1-EGR rate) ×λ 6 +EGR Rate x lambda 5
Wherein lambda is 7 A feed-forward fuel-air ratio correction amount for EGR; lambda (lambda) 5 When the EGR is fully opened, the MAP is checked by the rotating speed and the torque to obtain a first fuel-air ratio correction quantity under the corresponding working condition; lambda (lambda) 6 And when the EGR is fully closed, checking MAP according to the rotating speed and the torque to obtain a second fuel-air ratio correction quantity under the corresponding working condition.
5) The calculation of the post-oxygen sensor fuel-air ratio correction amount is shown in fig. 4:
a. post-oxygen PID feedback compensation: through the post-oxidation target fuel-air ratio lambda 2 Obtaining the post-oxygen target voltage U under the working condition by checking the characteristic curve of the post-oxygen sensor 2 ；
b. Based on post oxygen target voltage U 2 And the actual post oxygen voltage U 1 Performing post-oxygen PID feedback compensation control to obtain a PID feedback coefficient;
c. comparing the PID feedback coefficient with the upper limit value of the post oxygen voltage correction coefficient, and checking MAP through the rotating speed and the torque to obtain the upper limit value of the post oxygen voltage correction coefficient under the working condition (the maximum PID correction coefficient of the fresh three-way catalyst under each working condition);
d. if the PID feedback coefficient is less than or equal to the upper limit value of the post oxygen voltage correction coefficient, the fuel-air ratio correction amount of the post oxygen sensor is the PID feedback coefficient;
e. if PID feedback coefficient is greater than upper limit value of post oxygen voltage correction coefficient, three-way catalyst is considered to be aged, theoretical target air-fuel ratio is deviated after three-way catalyst is aged, and post oxygen target fuel-air ratio lambda 2 With a consequent change, the post-oxygen target voltage U needs to be redetermined 2 。
f. Calculating the aging degree (the ratio of PID feedback coefficient to the upper limit value of the post-oxygen voltage correction coefficient) of the three-way catalyst as the aging processDegree), obtaining the aging coefficient under the state by checking MAP through the aging degree and the temperature of the three-way catalyst, and obtaining the post-oxygen target voltage U 2 Multiplying the aging coefficient to obtain a corrected post-oxygen target voltage U 2 Based on the corrected oxygen target voltage U 2 And the actual post oxygen voltage U 1 And performing the post-oxygen PID feedback control again to obtain a new PID feedback coefficient, and then setting the fuel-air ratio correction quantity of the post-oxygen sensor as the new PID feedback coefficient.
6) Calculating a current fuel-air ratio demand value: obtaining a current fuel-air ratio demand value lambda based on the target fuel-air ratio, the disturbance fuel-air ratio, the EGR feedforward fuel-air ratio correction amount and the post-oxygen sensor fuel-air ratio correction amount 9 The method comprises the following steps:
λ 9 ＝λ 2 +λ 4 +λ 7 +λ 8
wherein lambda is 2 Lambda is the target fuel-air ratio 4 To disturb the air-fuel ratio lambda 7 A feed-forward fuel-air ratio correction amount for EGR; lambda (lambda) 8 The fuel-air ratio correction amount is the post-oxygen sensor.
7) Calculating the fuel-air ratio deviation: if the actual fuel air-fuel ratio measured by the oxygen sensor before the current working condition is lambda 10 The fuel-air ratio deviation Δλ under this condition is:
Δλ＝λ 10 -λ 9
if the absolute value of the fuel-air ratio deviation delta lambda is smaller than or equal to a set value (preferably 0.08), the three-way catalyst does not need to perform oxygen storage control; if the absolute value of the fuel-air ratio deviation delta lambda is larger than a set value (preferably 0.08), the three-way catalyst is required to perform oxygen storage control currently, and the required oxygen storage amount is calculated.
8) And (5) calculating the required oxygen storage amount.
i) Mass M of oxygen in exhaust gas of current working condition 3 And (3) calculating: single cylinder exhaust volume V, single cylinder exhaust density ρ, oxygen content ε, then:
M 3 ＝V*ρ*ε
ii) calculating the oxygen storage efficiency under the current working condition: obtaining the current oxygen storage efficiency eta through checking Table by the deviation value delta lambda of the fuel-air ratio 2 Currently demanded oxygen storage amount M 4 The method comprises the following steps:
M 4 ＝M 3 *Δλ*η 2 +M int
wherein M is 4 For the current oxygen storage requirement, M 3 The oxygen quality in the exhaust gas under the current working condition is delta lambda is the fuel-air ratio deviation, eta 2 For oxygen storage efficiency, M int Is the initial oxygen storage amount.
iii) Performing fuel-air ratio control based on the required oxygen storage amount, entering the next driving cycle, updating the disturbance fuel-air ratio of the next driving cycle, and the initial oxygen storage amount M of the next cycle int The current calculated required oxygen storage amount is obtained.
It should be understood that the specific order or hierarchy of steps in the processes disclosed are examples of exemplary approaches. Based on design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
The foregoing description of the embodiments and specific examples of the present invention has been presented for purposes of illustration and description; this is not the only form of practicing or implementing the invention as embodied. The description covers the features of the embodiments and the method steps and sequences for constructing and operating the embodiments. However, other embodiments may be utilized to achieve the same or equivalent functions and sequences of steps.
In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment of this invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. As will be apparent to those skilled in the art; various modifications to these embodiments will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, as used in the specification or claims, the term "comprising" is intended to be inclusive in a manner similar to the term "comprising," as interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean "non-exclusive or".
The foregoing description is only of the preferred embodiments of the invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements, combinations, and substitutions can be made by those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims. What is not described in detail in this specification is prior art known to those skilled in the art.
Claims (8)
1. A three-way catalyst oxygen storage control method is characterized in that:
acquiring an initial oxygen storage amount of the previous driving cycle in the running process of the vehicle;
determining a target fuel-air ratio and a disturbance fuel-air ratio;
calculating an EGR feedforward fuel-air ratio correction amount and a post-oxygen sensor fuel-air ratio correction amount;
determining a current fuel-air ratio demand value based on the target fuel-air ratio, the disturbance fuel-air ratio, the EGR feedforward fuel-air ratio correction amount and the post-oxygen sensor fuel-air ratio correction amount;
calculating a fuel-air ratio deviation according to a fuel-air ratio demand value, determining whether an oxygen storage request is met according to the fuel-air ratio deviation, if so, calculating a current demand oxygen storage amount according to an initial oxygen storage amount, the fuel-air ratio deviation and the oxygen quality in exhaust under the current working condition, and performing oxygen storage control according to the demand oxygen storage amount;
the current fuel-air ratio demand value is determined by the following formula:
λ 9 ＝λ 2 +λ 4 +λ 7 +λ 8
wherein lambda is 9 Lambda is the current fuel-air ratio demand value 2 Lambda is the target fuel-air ratio 4 To disturb the air-fuel ratio lambda 7 A feed-forward fuel-air ratio correction amount for EGR; lambda (lambda) 8 A fuel-air ratio correction amount for the post-oxygen sensor;
the current required oxygen storage amount is calculated by the following formula
M 4 ＝M 3 *Δλ*η 2 +M int
Wherein M is 4 For the current oxygen storage requirement, M 3 The oxygen quality in the exhaust gas under the current working condition is delta lambda is the fuel-air ratio deviation, eta 2 For oxygen storage efficiency, M int Is the initial oxygen storage amount.
2. The three-way catalyst oxygen storage control method according to claim 1, characterized in that: the target fuel-air ratio is determined by the following formula:
λ 2 ＝λ 1 *η 1
wherein lambda is 2 For the target fuel-air ratio，λ 1 For theoretical fuel-air ratio, eta 1 And (3) checking the fuel-air ratio correction coefficient obtained by MAP for the rotation speed and the torque.
3. The three-way catalyst oxygen storage control method according to claim 1, characterized in that: the process for determining the disturbance fuel-air ratio comprises the following steps:
obtaining the maximum oxygen storage capacity M under the state by checking the temperature of the first Table through the three-way catalyst 1 Obtaining the minimum oxygen storage capacity M under the state by checking the second Table through the temperature of the three-way catalyst 2 ；
Acquiring a voltage value of a post-oxygen sensor as an actual post-oxygen voltage U 1 After that, the voltage value U is passed 1 Obtaining the disturbance fuel-air ratio compensation quantity lambda under the state by checking Table 3 ；
Based on maximum oxygen storage capacity M 1 Minimum oxygen storage capacity M 2 And fuel-air ratio compensation quantity lambda 3 And determining a disturbance fuel-air ratio.
4. The three-way catalyst oxygen storage control method according to claim 3, characterized in that:
if the minimum oxygen storage capacity M 2 <M int <Maximum oxygen storage capacity M 1 Then the disturbance air-fuel ratio lambda is determined 4 ＝λ 3 ；
If M int Not less than the maximum oxygen storage capacity M 1 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 1 ；
If M int Minimum oxygen storage capacity M 2 Then the disturbance fuel-air ratio lambda is determined 4 Is of constant value C 2 ；
M int Is the initial oxygen storage amount of the last driving cycle.
5. The three-way catalyst oxygen storage control method according to claim 1, characterized in that: calculating an EGR feed-forward fuel-air ratio correction by the following equation
λ 7 = (1-EGR rate) ×λ 6 +EGR Rate x lambda 5
Wherein lambda is 7 Is EG (EG)R is a feedforward fuel-air ratio correction amount; lambda (lambda) 5 When the EGR is fully opened, the MAP is checked by the rotating speed and the torque to obtain a first fuel-air ratio correction quantity under the corresponding working condition; lambda (lambda) 6 And when the EGR is fully closed, checking MAP according to the rotating speed and the torque to obtain a second fuel-air ratio correction quantity under the corresponding working condition.
6. The three-way catalyst oxygen storage control method according to claim 1, characterized in that: the process of calculating the fuel-air ratio correction amount of the oxygen sensor is as follows:
through the target fuel-air ratio lambda 2 Obtaining the post-oxygen target voltage U under the working condition by checking the characteristic curve of the post-oxygen sensor 2 Based on post oxygen target voltage U 2 And the actual post oxygen voltage U 1 Performing post-oxygen PID feedback control to obtain a PID feedback coefficient;
comparing the PID feedback coefficient with the upper limit value of the post oxygen voltage correction coefficient;
if the PID feedback coefficient is less than or equal to the upper limit value of the post oxygen voltage correction coefficient, the fuel-air ratio correction amount of the post oxygen sensor is the PID feedback coefficient;
if the PID feedback coefficient is larger than the upper limit value of the post-oxygen voltage correction coefficient, the aging degree of the three-way catalyst is calculated, and the fuel-air ratio correction amount of the post-oxygen sensor is determined according to the aging degree.
7. The three-way catalyst oxygen storage control method according to claim 6, characterized in that: the aging coefficient under the state is obtained by checking MAP through the aging degree and the temperature of the three-way catalyst, and the post-oxygen target voltage U is obtained 2 Multiplying the aging coefficient to obtain a corrected post-oxygen target voltage U 2 Based on post oxygen target voltage U 2 And the actual post oxygen voltage U 1 And performing the post-oxygen PID feedback control to obtain a new PID feedback coefficient, and then setting the fuel-air ratio correction quantity of the post-oxygen sensor as the new PID feedback coefficient.
8. The three-way catalyst oxygen storage control method according to claim 1, characterized in that: calculating the fuel-air ratio deviation by the following formula
Δλ＝λ 10 -λ 9
Wherein Deltalambda is the fuel-air ratio deviation, lambda 10 Lambda is the actual fuel air-fuel ratio 9 Is the current fuel-air ratio demand value.
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| JP3939026B2 (en) * | 1998-06-17 | 2007-06-27 | 株式会社日立製作所 | Three-way catalyst oxygen storage control device |
| JP3963130B2 (en) * | 2002-06-27 | 2007-08-22 | トヨタ自動車株式会社 | Catalyst deterioration judgment device |
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