Urea injection quantity control method, device, electronic device and computer storage medium

Abstract

The present invention relates to a urea injection amount control method, device, electronic device, and computer storage medium, belonging to the technical field of engine exhaust purification. The method comprises: obtaining a first nitrogen oxide measurement value at an SCR system inlet, a second nitrogen oxide measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet; calculating a calculated nitrogen oxide concentration value at the SCR system outlet based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and calculating a nitrogen oxide conversion efficiency based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value; calculating a urea injection amount correction factor and a nitrogen oxide conversion efficiency correction factor based on the calculated ammonia concentration value at the SCR outlet, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and adjusting the urea injection amount. The present invention can improve the accuracy of the final urea injection control, reduce nitrogen oxide emissions, and reduce ammonia leakage.

Description

Technical Field

[0001] The present invention relates to the technical field of engine exhaust purification, and in particular to a urea injection amount control method, device, electronic equipment and computer storage medium. Background Art

[0002] With the implementation of the National VI emission regulations, the requirements for vehicle exhaust emissions are becoming increasingly higher. Commercial vehicles all use SCR (Selective Catalytic Reduction Technology) systems to treat exhaust gases.

[0003] In existing SCR systems, when urea is used to treat exhaust gas, the urea injection amount needs to be corrected according to exhaust emissions. Usually, only nitrogen oxide emission corrections are considered. The nitrogen oxide emission target is calculated based on the correspondence between the urea injection amount and the target conversion efficiency. The target conversion efficiency correspondence is obtained through bench test calibration. The actual vehicle operation process is a transient process. As a result, the nitrogen oxide emission target result obtained based on the target conversion efficiency calculation relationship is inaccurate and cannot be adjusted in real time, and thus cannot guarantee the accurate correction of the urea injection amount.

[0004] This shows that the existing SCR system cannot accurately correct the urea injection amount. Summary of the Invention

[0005] In view of this, it is necessary to provide a urea injection amount control method, device, electronic equipment and computer storage medium to solve the problem that the existing SCR system cannot accurately correct the urea injection amount.

[0006] In order to solve the above problems, the present invention provides a urea injection amount control method, comprising:

[0007] Obtaining a first nitrogen oxide concentration measurement value at an SCR system inlet, a second nitrogen oxide concentration measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet;

[0008] calculating a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and calculating a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value;

[0009] A urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0010] In a possible implementation, the calculating the calculated nitrogen oxide concentration value at the outlet of the SCR system based on the second nitrogen oxide concentration measured value and the calculated ammonia concentration value includes:

[0011] The nitrogen oxide concentration calculation value is calculated using the nitrogen oxide calculation formula, which is:

[0012]

[0013] in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor.

[0014] In a possible implementation, the calculating the nitrogen oxide conversion efficiency calculated value based on the first nitrogen oxide concentration measurement value and the nitrogen oxide concentration calculated value includes:

[0015] The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency. The nitrogen oxide conversion efficiency calculation formula is:

[0016]

[0017] in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

[0018] In one possible implementation, the calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value includes:

[0019] When the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then reducing the nitrogen oxide conversion efficiency correction coefficient; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then reducing the urea injection amount correction coefficient;

[0020] When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, the nitrogen oxide conversion efficiency correction coefficient is increased.

[0021] In one possible implementation, the calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value includes:

[0022] Calculating a nitrogen oxide conversion efficiency deviation value based on the nitrogen oxide conversion efficiency calculation value and the nitrogen oxide conversion efficiency target value;

[0023] Calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the nitrogen oxide conversion efficiency calculation value;

[0024] A urea injection amount correction coefficient is calculated based on the calculated ammonia concentration value and the nitrogen oxide conversion efficiency correction coefficient.

[0025] In a possible implementation, adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient includes:

[0026] The target urea injection amount is calculated using a target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is:

[0027]

[0028] in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia gas, is the urea injection amount correction factor.

[0029] In a possible implementation manner, when adjusting the urea injection amount, the method further includes:

[0030] determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of the SCR system;

[0031] The urea injection amount is controlled to be within the urea injection amount range.

[0032] The present invention also provides a urea injection amount control device, comprising:

[0033] a data acquisition module, configured to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at the outlet of the SCR system;

[0034] a conversion efficiency calculation module, configured to calculate a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and to calculate a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value;

[0035] and a regulating module, configured to calculate a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency, and a preset nitrogen oxide conversion efficiency target value, and to regulate the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0036] The present invention also provides an electronic device, comprising a memory and a processor, wherein:

[0037] The memory is used to store programs;

[0038] The processor is coupled to the memory and is configured to execute the program stored in the memory to implement the steps of the urea injection amount control method described in any one of the above embodiments.

[0039] The present invention further provides a computer-readable storage medium for storing a computer-readable program or instruction, wherein the program or instruction, when executed by a processor, can implement the steps of the urea injection amount control method described in any of the above embodiments.

[0040] The beneficial effects of the present invention are as follows: the urea injection amount control method provided by the present invention obtains a first nitrogen oxide concentration measurement value at an SCR system inlet, a second nitrogen oxide concentration measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet; calculates a calculated nitrogen oxide concentration value at the SCR system outlet based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value; calculates a nitrogen oxide conversion efficiency calculation value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value; calculates a urea injection amount correction factor and a nitrogen oxide conversion efficiency correction factor based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value; adjusts the urea injection amount based on the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor; adjusts the SCR urea injection amount in real time according to actual engine operating conditions; and simultaneously coordinates and controls the urea injection amount correction and the nitrogen oxide conversion efficiency correction based on the nitrogen oxide conversion efficiency and ammonia leakage as control targets. Finally, the total urea injection amount is coordinated and corrected in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 A schematic flow chart of a urea injection quantity control method provided in an embodiment of the present invention;

[0043] Figure 2 A flowchart of a correction coefficient adjustment method provided by an embodiment of the present invention;

[0044] Figure 3 A flow chart of a correction coefficient control strategy provided by an embodiment of the present invention;

[0045] Figure 4 A schematic flow chart of a correction coefficient calculation method provided in an embodiment of the present invention;

[0046] Figure 5 A schematic flow chart of a method for limiting urea injection amount provided in an embodiment of the present invention;

[0047] Figure 6 A schematic structural diagram of a urea injection quantity control device provided in an embodiment of the present invention;

[0048] Figure 7 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0050] The terms "first," "second," and so on, used in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, technical features designated as "first" or "second" may explicitly or implicitly include at least one such feature.

[0051] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0052] A specific embodiment of the present invention, as Figure 1 As shown, a urea injection amount control method is disclosed, comprising:

[0053] S101, obtaining a first nitrogen oxide concentration measurement value at an SCR system inlet, a second nitrogen oxide concentration measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet;

[0054] S102, calculating a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and calculating a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value;

[0055] S103 , calculating a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency, and a preset nitrogen oxide conversion efficiency target value, and adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0056] In the embodiment of the present invention, the SCR system is widely used in diesel engines. The reducing agent used is urea solution. Urea is decomposed into and The working principle is to spray urea into the exhaust pipe, and the exhaust (nitrogen oxides) and The reaction is reduced to and , thereby reducing harmful components in diesel engine emissions , in order to ensure In order to achieve the reduction effect, excessive urea will generally be injected, resulting in excessive ammonia content in the exhaust gas, waste of urea and urea crystallization problems. Therefore, it is necessary to accurately control the urea injection amount.

[0057] In the embodiment of the present invention, in order to determine The reduction effect needs to be checked at the inlet and outlet of the SCR system. The content can be checked by arranging nitrogen oxide sensors at the inlet and outlet of the SCR system. The nitrogen oxide sensors actually detect the nitrogen oxide concentration in the exhaust gas. Therefore, a first nitrogen oxide concentration measurement value at the inlet of the SCR system and a second nitrogen oxide concentration measurement value at the outlet of the SCR system can be obtained. The calculated ammonia concentration at the outlet of the SCR system can be calculated based on the ammonia emissions under steady-state conditions, the ammonia emissions under transient conditions and the second calculated nitrogen oxide concentration value. The present invention does not impose any restrictions on this.

[0058] Furthermore, a nitrogen oxide concentration measurement value at the outlet of the SCR system is calculated based on the second nitrogen oxide concentration measurement value and the ammonia concentration calculation value, and a nitrogen oxide conversion efficiency calculation value is calculated based on the first nitrogen oxide concentration measurement value and the nitrogen oxide concentration measurement value at the SCR outlet. The specific calculation methods of the above-mentioned nitrogen oxide concentration measurement values ​​and nitrogen oxide conversion efficiency calculation values ​​are described in detail later in the present invention.

[0059] Furthermore, a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient can be calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value. The urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient. The SCR urea injection amount is adjusted in real time according to the actual engine operating condition. At the same time, based on the nitrogen oxide conversion efficiency and the ammonia leakage amount as control targets, the urea injection amount correction and the nitrogen oxide conversion efficiency correction are coordinated and controlled. Finally, the total urea injection amount is coordinated and corrected in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0060] As a possible embodiment of the present invention, in this embodiment, calculating the calculated nitrogen oxide concentration value at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value includes:

[0061] The nitrogen oxide calculation formula is used to calculate the nitrogen oxide concentration. The nitrogen oxide calculation formula is:

[0062] (1)

[0063] in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor.

[0064] In the embodiment of the present invention, the preset sensitivity factor K has a value range of 0.5 to 2, is linearly related to the catalyst bed temperature, generally increases with the increase of the catalyst bed temperature, and can be obtained through calibration.

[0065] Furthermore, the nitrogen oxide conversion efficiency calculation value is calculated based on the first nitrogen oxide concentration measurement value and the SCR outlet nitrogen oxide concentration calculation value, including:

[0066] The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency. The nitrogen oxide conversion rate calculation formula is:

[0067] (2)

[0068] in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

[0069] The embodiment of the present invention calculates the calculated value of nitrogen oxide conversion efficiency through a formula to ensure the accuracy of the calculated value of nitrogen oxide conversion efficiency.

[0070] As a possible embodiment of the present invention, in this embodiment, Figure 2 As shown, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and the preset nitrogen oxide conversion efficiency target value, including:

[0071] S201, when the calculated ammonia concentration value is greater than a preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the target nitrogen oxide conversion efficiency value, then reducing the nitrogen oxide conversion efficiency correction coefficient; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the target nitrogen oxide conversion efficiency value, then reducing the urea injection amount correction coefficient;

[0072] S202: When the calculated ammonia concentration is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency is less than the target nitrogen oxide conversion efficiency, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency is greater than the target nitrogen oxide conversion efficiency, the nitrogen oxide conversion efficiency correction coefficient is decreased.

[0073] In the embodiment of the present invention, the adjustment strategy of the NOx conversion efficiency correction coefficient and the urea injection amount correction coefficient in the urea injection amount control can be determined based on the calculated ammonia concentration value at the outlet of the SCR system, the calculated NOx conversion efficiency value, and the preset NOx conversion efficiency target value in the aforementioned embodiment. Specifically, Figure 3 As shown, after obtaining the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value and the preset nitrogen oxide conversion efficiency target value at the SCR system outlet, it is first determined whether the calculated ammonia concentration value is greater than the preset ammonia concentration threshold.

[0074] When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, determine whether the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value; if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, increase the urea injection amount correction factor; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, increase the nitrogen oxide conversion efficiency correction factor.

[0075] When the calculated ammonia concentration is less than or equal to the preset ammonia concentration threshold, the relationship between the calculated NOx conversion efficiency and the target NOx conversion efficiency is determined. If the calculated NOx conversion efficiency is less than the target NOx conversion efficiency, the urea injection amount correction factor is increased. If the calculated NOx conversion efficiency is greater than the target NOx conversion efficiency, the NOx conversion efficiency correction factor is increased. If the calculated NOx conversion efficiency is equal to the target NOx conversion efficiency, the NOx conversion efficiency correction factor and the urea injection amount correction factor remain unchanged.

[0076] The detailed adjustment strategy of the nitrogen oxide conversion efficiency correction coefficient and the urea injection amount correction coefficient provided by the embodiment of the present invention ensures the accuracy of the adjustment of the nitrogen oxide conversion efficiency correction coefficient and the urea injection amount correction coefficient.

[0077] As a possible embodiment of the present invention, in this embodiment, Figure 4 As shown, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor are calculated based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and the preset nitrogen oxide conversion efficiency target value, including:

[0078] S401, calculating a nitrogen oxide conversion efficiency deviation value based on the nitrogen oxide conversion efficiency calculation value and the nitrogen oxide conversion efficiency target value;

[0079] S402, calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the calculated nitrogen oxide conversion efficiency value;

[0080] S403 : Calculate a urea injection amount correction coefficient based on the calculated ammonia concentration and the nitrogen oxide conversion efficiency correction coefficient.

[0081] In the embodiment of the present invention, if the ammonia leakage is high and The calculated conversion efficiency is less than The calculated value of the conversion efficiency model should reduce the actual ammonia storage The conversion efficiency correction factor (actual ammonia storage increases) reduces the final urea injection amount and further reduces the ammonia leakage at the SCR outlet; if the ammonia leakage is high and The calculated conversion efficiency is equal to The conversion efficiency model calculation value should reduce the correction coefficient of urea injection amount, reduce the final urea injection amount, and further reduce the ammonia leakage at the SCR outlet; if the ammonia leakage is high and The calculated conversion efficiency is greater than The conversion efficiency model calculation value should reduce the correction coefficient of urea injection amount, reduce the final urea injection amount, and further reduce the ammonia leakage at the SCR outlet; if the ammonia leakage is low (the leakage amount is appropriate), and The calculated conversion efficiency is less than The calculated value of the conversion efficiency model should increase the urea injection amount correction coefficient to increase the final urea injection amount and further improve Calculated conversion efficiency; if the ammonia leakage is low and The calculated conversion efficiency is equal to The conversion efficiency model calculates the value, maintaining the urea injection amount and The correction factor of conversion efficiency remains unchanged; if the ammonia leakage is low and The calculated conversion efficiency is greater than The calculated value of the conversion efficiency model should be increased by the actual ammonia storage Conversion efficiency correction factor (actual ammonia storage amount is reduced), increasing the final urea injection amount, further improving Calculated conversion efficiency to achieve the target Conversion efficiency.

[0082] The specific calculation logic for the nitrogen oxide conversion efficiency correction factor and the urea injection amount correction factor is as follows:

[0083] The nitrogen oxide conversion efficiency deviation value is calculated using formula (3):

[0084] (3)

[0085] in, is the nitrogen oxide conversion efficiency deviation value, is the calculated value of nitrogen oxide conversion efficiency, is the calculated value of the nitrogen oxide conversion efficiency model, which can be obtained through model calculation.

[0086] Then, based on the relationship between the calculated value of the NOx conversion efficiency and the value calculated by the NOx conversion efficiency model, a value is assigned to the NOx conversion efficiency correction coefficient. The assigned NOx conversion efficiency correction coefficient can be obtained by calibration based on the NOx conversion efficiency deviation value. The NOx conversion efficiency correction coefficient under different working conditions satisfies formula (4):

[0087] (4)

[0088] in, is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is equal to the target NOx conversion efficiency value, It is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is less than the NOx conversion efficiency target value. It is the NOx conversion efficiency correction factor when the calculated NOx conversion efficiency is greater than the NOx conversion efficiency target value. and The default calculation rules.

[0089] Based on the calculated value of ammonia leakage, the ammonia leakage correction coefficient can be calculated. The assigned ammonia leakage correction coefficient can be calibrated based on the calculated value of ammonia leakage. The ammonia leakage correction coefficient under different working conditions satisfies formula (5):

[0090] (5)

[0091] in, For SCR export Calculated leakage value, for Correction factor for higher leakage, for Correction factor when leakage meets regulatory requirements, The default calculation rules.

[0092] Furthermore, as shown in Table 1, the urea injection amount correction factor and the nitrogen oxide conversion efficiency correction factor can be calculated:

[0093]

[0094] in,

[0095] (6)

[0096] (7)

[0097] (8)

[0098] (9)

[0099] in, and is the urea injection amount correction coefficient, and is the correction factor for the nitrogen oxide conversion efficiency.

[0100] Furthermore, the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient, including:

[0101] The target urea injection amount is calculated using the target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is:

[0102] (10)

[0103] in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia gas, is the urea injection amount correction factor.

[0104] In the embodiment of the present invention, the corresponding corrected urea injection amount can be determined based on the nitrogen oxide conversion efficiency correction coefficient calculated in the above embodiment, and then the target urea injection amount is calculated based on the corrected urea injection amount, the conversion coefficient of urea solution and ammonia, and the urea injection amount correction coefficient, wherein the conversion coefficient of urea solution and ammonia is It is related to the urea concentration. The basic conversion coefficient of 32.5% urea solution to ammonia is 0.174. The actual conversion coefficient can be corrected based on the exhaust temperature.

[0105] The embodiment of the present invention uses both nitrogen oxide conversion efficiency and ammonia leakage as control targets, coordinates and controls the urea injection amount correction and the nitrogen oxide conversion efficiency correction, and ultimately coordinates and corrects the total urea injection amount in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0106] As a possible embodiment of the present invention, in this embodiment, Figure 5 As shown, when adjusting the urea injection amount, it also includes:

[0107] S501, determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of an SCR system;

[0108] S502: Control the urea injection amount to be within a urea injection amount range.

[0109] In an embodiment of the present invention, before urea injection is controlled by a urea injection system based on a calculated urea injection amount correction coefficient, minimum and maximum limits are imposed on the urea injection amount to protect the urea nozzle and prevent urea overspray and crystallization at low temperatures. Specifically, an upper limit for the urea injection amount under current operating conditions is determined based on the catalyst bed temperature and exhaust mass flow rate. When the urea injection amount exceeds the upper limit, the urea injection amount is limited to the upper limit to prevent urea overspray, ammonia leakage, and urea crystallization. When the catalyst bed temperature is below 200°C, the upper limit is set to 0, and urea injection is stopped. When the catalyst bed temperature is above 200°C, the upper limit increases with increasing catalyst bed temperature and exhaust mass flow rate. Furthermore, a lower limit for the urea injection amount under current operating conditions is determined based on the catalyst bed temperature and exhaust mass flow rate. When the urea injection amount is below the limit, urea injection is stopped to prevent damage to the urea nozzle from urea injection at low flow rates.

[0110] The embodiment of the present invention sets upper and lower limits for the urea injection amount to prevent damage to the urea nozzle due to overspray of urea or too low a urea flow rate.

[0111] In order to better implement the urea injection amount control method in the embodiment of the present invention, based on the urea injection amount control method, correspondingly, Figure 6 As shown, an embodiment of the present invention further provides a urea injection amount control device, and the urea injection amount control device 600 includes:

[0112] A data acquisition module 601 is configured to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at an outlet of the SCR system;

[0113] a conversion efficiency calculation module 602, configured to calculate a calculated nitrogen oxide concentration at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and to calculate a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value;

[0114] The adjustment module 603 is configured to calculate a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency, and a preset nitrogen oxide conversion efficiency target value, and to adjust the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0115] The urea injection quantity control device 600 provided in the above embodiment can implement the technical solution described in the above embodiment of the urea injection quantity control method. The specific implementation principles of the above modules or units can be found in the corresponding contents of the above embodiment of the urea injection quantity control method, which will not be repeated here.

[0116] The urea injection quantity control device provided by the present invention simultaneously takes nitrogen oxide conversion efficiency and ammonia leakage as control targets, coordinates and controls the urea injection quantity correction and nitrogen oxide conversion efficiency correction, and ultimately coordinates and corrects the total urea injection quantity in real time, thereby improving the accuracy of the final urea injection control, reducing nitrogen oxide emissions and ammonia leakage.

[0117] like Figure 7 As shown, the present invention also provides an electronic device 700. The electronic device 700 includes a processor 701, a memory 702 and a display 703. Figure 7 Only some of the components of the electronic device 700 are shown, but it should be understood that it is not required to implement all of the shown components, and more or fewer components may be implemented instead.

[0118] In some embodiments, the processor 701 may be a central processing unit (CPU), a microprocessor, or other data processing chip, configured to execute program codes or process data stored in the memory 702 , such as the urea injection quantity control method of the present invention.

[0119] In some embodiments, the processor 701 may be a single server or a server group. The server group may be centralized or distributed.

[0120] In some embodiments, the memory 702 may be an internal storage unit of the electronic device 700, such as a hard disk or memory of the electronic device 700. The memory 702 is used to store application software installed on the electronic device 700 and various data.

[0121] In some embodiments, when the processor 701 executes the urea injection amount control program in the memory 702 , the following steps may be implemented:

[0122] Obtaining a first nitrogen oxide concentration measurement value at an SCR system inlet, a second nitrogen oxide concentration measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet;

[0123] Calculating a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and calculating a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value;

[0124] A urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient are calculated based on the calculated ammonia concentration, the calculated nitrogen oxide conversion efficiency, and a preset nitrogen oxide conversion efficiency target value, and the urea injection amount is adjusted based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient.

[0125] It should be understood that, when the processor 701 executes the urea injection quantity control program in the memory 702 , in addition to the above functions, it can also implement other functions. For details, please refer to the description of the corresponding method embodiment above.

[0126] Accordingly, an embodiment of the present invention further provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the programs or instructions are executed by a processor, the steps or functions of the urea injection quantity control methods provided in the above-mentioned method embodiments can be implemented.

[0127] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for controlling urea injection amount, characterized in that: include: Obtaining a first nitrogen oxide concentration measurement value at an SCR system inlet, a second nitrogen oxide concentration measurement value at an SCR system outlet, and a calculated ammonia concentration value at the SCR system outlet; calculating a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and calculating a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value; calculating a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient; The calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value includes: When the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then reducing the nitrogen oxide conversion efficiency correction coefficient; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then reducing the urea injection amount correction coefficient; When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, the nitrogen oxide conversion efficiency correction coefficient is increased.

2. The urea injection amount control method according to claim 1, characterized in that: The calculating the calculated value of nitrogen oxide concentration at the outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated value of ammonia concentration includes: The nitrogen oxide concentration calculation value is calculated using the nitrogen oxide calculation formula, which is: in, is the calculated value of nitrogen oxide concentration at the outlet of the SCR system, is the second nitrogen oxide concentration measurement value, is the calculated value of ammonia concentration, K is the preset sensitivity factor.

3. The urea injection amount control method according to claim 2, characterized in that: The calculating of the nitrogen oxide conversion efficiency calculated value based on the first nitrogen oxide concentration measurement value and the nitrogen oxide concentration calculated value includes: The nitrogen oxide conversion efficiency calculation formula is used to calculate the nitrogen oxide conversion efficiency. The nitrogen oxide conversion efficiency calculation formula is: in, is the calculated value of nitrogen oxide conversion efficiency, is the first nitrogen oxide concentration measurement value.

4. The urea injection amount control method according to claim 1, characterized in that: The calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value includes: Calculating a nitrogen oxide conversion efficiency deviation value based on the nitrogen oxide conversion efficiency calculation value and the nitrogen oxide conversion efficiency target value; Calculating a nitrogen oxide conversion efficiency correction coefficient based on the nitrogen oxide conversion efficiency deviation value and the nitrogen oxide conversion efficiency calculation value; A urea injection amount correction coefficient is calculated based on the calculated ammonia concentration value and the nitrogen oxide conversion efficiency correction coefficient.

5. The urea injection amount control method according to claim 1, characterized in that: The adjusting the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient includes: The target urea injection amount is calculated using a target urea injection amount calculation formula, wherein the target urea injection amount calculation formula is: in, is the target urea injection amount, The actual ammonia storage amount of SCR is calculated based on the correction of nitrogen oxide conversion efficiency, and the corresponding urea injection amount is calculated by ammonia storage control. is the conversion coefficient between urea solution and ammonia gas, is the urea injection amount correction factor.

6. The urea injection amount control method according to claim 5, characterized in that: When adjusting the urea injection amount, it also includes: determining a urea injection amount range based on a urea catalyst bed temperature and an exhaust mass flow rate of the SCR system; The urea injection amount is controlled to be within the urea injection amount range.

7. A urea injection amount control device, characterized in that: include: a data acquisition module, configured to acquire a first nitrogen oxide concentration measurement value at an inlet of the SCR system, a second nitrogen oxide concentration measurement value at an outlet of the SCR system, and a calculated ammonia concentration value at the outlet of the SCR system; a conversion efficiency calculation module, configured to calculate a calculated nitrogen oxide concentration value at an outlet of the SCR system based on the second nitrogen oxide concentration measurement value and the calculated ammonia concentration value, and to calculate a calculated nitrogen oxide conversion efficiency value based on the first nitrogen oxide concentration measurement value and the calculated nitrogen oxide concentration value; an adjustment module, configured to calculate a urea injection amount correction coefficient and a nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value, and adjust the urea injection amount based on the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient; The calculating of the urea injection amount correction coefficient and the nitrogen oxide conversion efficiency correction coefficient based on the calculated ammonia concentration value, the calculated nitrogen oxide conversion efficiency value, and a preset nitrogen oxide conversion efficiency target value includes: When the calculated ammonia concentration value is greater than the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, then reducing the nitrogen oxide conversion efficiency correction coefficient; if the calculated nitrogen oxide conversion efficiency value is greater than or equal to the nitrogen oxide conversion efficiency target value, then reducing the urea injection amount correction coefficient; When the calculated ammonia concentration value is less than or equal to the preset ammonia concentration threshold, if the calculated nitrogen oxide conversion efficiency value is less than the nitrogen oxide conversion efficiency target value, the urea injection amount correction coefficient is increased; if the calculated nitrogen oxide conversion efficiency value is greater than the nitrogen oxide conversion efficiency target value, the nitrogen oxide conversion efficiency correction coefficient is increased.

8. An electronic device, characterized in that: comprising a memory and a processor, wherein, The memory is used to store programs; The processor is coupled to the memory and is configured to execute the program stored in the memory to implement the steps of the urea injection amount control method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that It is used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps of the urea injection amount control method according to any one of claims 1 to 6.

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