Method and device for controlling urea injection quantity of scr system, electronic control unit and medium

Abstract

The application discloses a kind of control method, device and electric control unit of SCR system urea injection quantity and medium.The control method is applied to SCR system, and SCR system includes urea injection quantity measuring device, upstream NOx sensor, downstream NOx sensor and control module.The control method includes: by obtaining urea injection flow rate;Obtain the difference between the gas concentration of upstream and downstream NOx;According to urea injection flow rate and the difference between the gas concentration of upstream and downstream NOx, control the change of urea injection flow rate;And according to the gas concentration of downstream NOx and the gas concentration of preset downstream NOx, correct urea injection flow rate, realize the accurate control of urea injection flow rate, solve the problem that urea injection flow rate cannot be accurately controlled in prior art.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to SCR technology, and particularly relate to a control method and device for urea injection of an SCR system, an electronic control unit, and a medium. BACKGROUND

[0002] SCR (Selective Catalytic Reduction) exhaust treatment system is one of the main aftertreatment technologies for eliminating nitrogen oxides NOx in diesel engine exhaust. In the working process of the SCR, urea solution is sprayed through a pre-set urea nozzle by a urea injection system, and ammonia NH3 is released when the urea solution is hydrolyzed. Under the action of a catalyst, NH3 is used to convert NOx in engine exhaust into N2, thereby avoiding the pollution of NOx gas to the atmosphere. X

[0003] Currently, the SCR technology mainly faces the difficulty of maintaining high NOx conversion efficiency and low NH3 leakage under various road spectra and environments, and therefore it is necessary to precisely control the injection of the urea injection amount of the SCR system.

[0004] In the prior art, in the control process of the urea injection amount, there is a certain deviation in the detection of the ammonia storage level by the sensor in the system, so that the calculated ammonia storage level is not accurate, and thus the target injection flow cannot be obtained accurately. Meanwhile, there is a certain interference and delay in the detection by the sensor in the system, so that the real-time ammonia storage level in the SCR cannot be accurately obtained, and thus the urea injection flow cannot be controlled. SUMMARY

[0005] The present application provides a control method and device for the urea injection amount of an SCR system, an electronic control unit, and a medium, and realizes accurate control of the urea injection flow.

[0006] In a first aspect, embodiments of the present application provide a control method for the urea injection amount of an SCR system, which is applied to the SCR system; the SCR system includes a urea injection amount metering device, an upstream NOx sensor, a downstream NOx sensor, and a control module; the urea injection amount metering device is used to detect the urea injection flow and send the urea injection flow to the control module; the upstream NOx sensor is used to detect the gas concentration of upstream NOx and send the gas concentration of upstream NOx to the control module; the downstream NOx sensor is used to detect the gas concentration of downstream NOx and send the gas concentration of downstream NOx to the control module;

[0007] The control method includes:

[0008] obtaining the urea injection flow;

[0009] ​obtaining a difference between the upstream NOx gas concentration and the downstream NOx gas concentration;

[0010] controlling a change in the urea injection flow rate according to the urea injection flow rate and the difference between the upstream NOx gas concentration and the downstream NOx gas concentration;

[0011] correcting the urea injection flow rate according to the downstream NOx gas concentration and a preset downstream NOx gas concentration.

[0012] Optionally, the controlling the change in the urea injection flow rate according to the urea injection flow rate and the difference between the upstream NOx gas concentration and the downstream NOx gas concentration comprises:

[0013] determining a ratio of the urea injection flow rate and the difference between the upstream NOx gas concentration and the downstream NOx gas concentration;

[0014] when the ratio is less than a preset threshold, controlling to reduce the urea injection flow rate;

[0015] when the ratio is greater than the preset threshold, controlling to increase the urea injection flow rate.

[0016] Optionally, the determining the ratio of the urea injection flow rate and the difference between the upstream NOx gas concentration and the downstream NOx gas concentration comprises:

[0017]

[0018] wherein, is the upstream NOx gas concentration; is the downstream NOx gas concentration; k urea is a urea hydrolysis rate; dm urea is the urea injection flow rate; is an Arrhenius reaction coefficient.

[0019] Optionally, the controlling the change in the urea injection flow rate according to the urea injection flow rate and the difference between the upstream NOx gas concentration and the downstream NOx gas concentration comprises:

[0020] determining a correlation coefficient of a change amount of the urea injection flow rate and a change amount of the difference between the upstream NOx gas concentration and the downstream NOx gas concentration;

[0021] when the correlation coefficient is a negative correlation coefficient, controlling to reduce the urea injection flow rate;

[0022] when the correlation coefficient is a positive correlation coefficient, controlling to increase the urea injection flow rate.

[0023] Optionally, the determining the correlation coefficient of the change amount of the urea injection flow rate and the change amount of the difference between the upstream NOx gas concentration and the downstream NOx gas concentration comprises:

[0024]

[0025] Wherein, X is the variation array of the urea injection flow; Y is the variation array of the difference between the upstream and downstream NOx gas concentrations; Cov(X, Y) is the covariance of X and Y; Var[] is the variance.

[0026] Optionally, the urea injection flow is corrected according to the difference between the downstream NOx gas concentration and the preset downstream NOx gas concentration, including:

[0027] The urea injection flow is corrected according to the difference between the downstream NOx gas concentration and the preset downstream NOx gas concentration and the ratio.

[0028] Optionally, the urea injection flow is corrected according to the difference between the downstream NOx gas concentration and the preset downstream NOx gas concentration, including:

[0029] The urea injection flow is corrected according to the difference between the downstream NOx gas concentration and the preset downstream NOx gas concentration and the correlation coefficient.

[0030] Optionally, when the correlation coefficient is a negative correlation coefficient, the control of reducing the urea injection amount includes:

[0031] When the urea injection flow increases and the difference between the upstream and downstream NOx gas concentrations decreases, it is judged that the ammonia storage reaches a preset value to control the reduction of the urea injection amount.

[0032] When the urea injection flow decreases and the difference between the upstream and downstream NOx gas concentrations increases, it is judged that the ammonia storage reaches a preset value to control the reduction of the urea injection amount.

[0033] Optionally, when the correlation coefficient is a positive correlation coefficient, the control of increasing the urea injection amount includes:

[0034] When the urea injection flow increases and the difference between the upstream and downstream NOx gas concentrations increases, it is judged that the ammonia storage does not reach a preset value to control the increase of the urea injection amount.

[0035] When the urea injection flow decreases and the difference between the upstream and downstream NOx gas concentrations decreases, it is judged that the ammonia storage does not reach a preset value to control the increase of the urea injection amount.

[0036] In a second aspect, the embodiments of the present application also provide a control device for the urea injection amount of an SCR system, which comprises:

[0037] A urea injection flow acquisition module is configured to acquire the urea injection flow.

[0038] A NOx gas concentration acquisition module is configured to acquire the difference between the upstream and downstream NOx gas concentrations.

[0039] a flow variation control module configured to control variation of the urea injection flow according to the urea injection flow and the difference between the upstream and downstream NOx gas concentrations;

[0040] a correction module configured to correct the urea injection flow according to the downstream NOx gas concentration and a preset downstream NOx gas concentration.

[0041] In a third aspect, an embodiment of the present application further provides an electronic control unit, which comprises:

[0042] one or more processors;

[0043] a storage device configured to store one or more programs,

[0044] when the one or more programs are executed by the one or more processors, the one or more processors implement the control method of the urea injection flow of the SCR system according to any one of the first aspect.

[0045] In a fourth aspect, an embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to implement the control method of the urea injection flow of the SCR system according to any one of the first aspect.

[0046] According to the embodiment of the present application, the urea injection flow and the difference between the upstream and downstream NOx gas concentrations are obtained, the variation of the urea injection flow is controlled according to the urea injection flow and the difference between the upstream and downstream NOx gas concentrations, and the urea injection flow is corrected according to the downstream NOx gas concentration and a preset downstream NOx gas concentration, so that the urea injection flow is accurately controlled, and the problem that the urea injection flow cannot be accurately controlled in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 a flow chart of the control method of the urea injection flow of the SCR system according to the first embodiment of the present application;

[0048] Figure 2 a flow chart of another control method of the urea injection flow of the SCR system according to the first embodiment of the present application;

[0049] Figure 3 a flow chart of another control method of the urea injection flow of the SCR system according to the first embodiment of the present application;

[0050] Figure 4 a structural schematic diagram of the control device of the urea injection flow of the SCR system according to the second embodiment of the present application;

[0051] Figure 5A structure schematic diagram of an electronic control unit provided for the third embodiment of the present application. DETAILED DESCRIPTION

[0052] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are intended to be merely illustrative of the present application and not in limitation thereof. It should also be noted that, for the purpose of description, only the parts related to the present application are shown in the drawings rather than all the parts.

[0053] Embodiment One

[0054] Figure 1 A flow chart of a control method of urea injection amount of an SCR system provided for the first embodiment of the present application. The present embodiment can be applied to the urea injection amount of an SCR system. The method can be executed by a control device of urea injection amount of an SCR system. The method specifically comprises the following steps:

[0055] S110, obtaining urea injection flow rate;

[0056] S120, obtaining the difference between upstream and downstream NOx gas concentration;

[0057] The control method is applied to an SCR system. The SCR system comprises a urea injection amount measuring device, an upstream NOx sensor, a downstream NOx sensor and a control module. In the actual working process of the SCR system, urea solution is sprayed through a urea nozzle. Ammonia is released when the urea solution is hydrolyzed. Then, under the action of a catalyst, NH3 is used to convert NOx in engine exhaust (usually some unreacted NOx will flow into the downstream) into N2, thereby avoiding NO X polluting the atmosphere. It should be understood that ammonia is released when the urea solution is hydrolyzed, that is, the urea injection flow rate is the mass of NH3 entering the SCR system; and the difference between the upstream and downstream NOx gas concentrations is the mass of NH3 participating in the catalytic reduction reaction. In the urea injection control process of the SCR system, the urea injection amount measuring device detects the urea injection flow rate and sends the urea injection flow rate to the control module; the upstream NOx sensor detects the upstream NOx gas concentration and sends the upstream NOx gas concentration to the control module; and the control module controls the change of the urea injection flow rate according to the obtained urea injection flow rate and the difference between the upstream and downstream NOx gas concentrations, that is, according to the mass of NH3 entering the SCR system and the mass of NH3 participating in the catalytic reduction reaction to control the change of the urea injection flow rate.

[0058] S130, controlling the change of the urea injection flow rate according to the urea injection flow rate and the difference between the upstream and downstream NOx gas concentrations;

[0059] Wherein, since the urea injection flow can reflect the mass of NH3 entering the SCR system; the difference between the upstream and downstream NOx gas concentrations can reflect the mass of NH3 participating in catalytic reduction reaction, the change of urea injection flow is controlled by using the ratio of urea injection flow and the difference between the upstream and downstream NOx gas concentrations or by using the change trend of both urea injection flow and the difference between the upstream and downstream NOx gas concentrations. For example, when the ratio of the difference between the upstream and downstream NOx gas concentrations and urea injection flow is less than a preset ratio, at this time, the ratio of NH3 participating in catalytic reduction reaction is low, at this time, the ammonia storage level is high, the risk of ammonia leakage is large, at this time, the urea injection flow is reduced to avoid ammonia leakage. Or when the difference between the upstream and downstream NOx gas concentrations gradually decreases and the urea injection flow gradually increases, at this time, ammonia leakage has occurred, at this time, the urea injection flow is reduced.

[0060] S140, correcting the urea injection flow according to the difference between the downstream NOx gas concentration detected by the downstream NOx sensor and the preset downstream NOx gas concentration.

[0061] Wherein, on the basis of the above control of the change of urea injection flow, the preset downstream NOx gas concentration is obtained by looking up a table according to the parameters in the engine system, and then the urea injection flow is accurately corrected according to the difference between the downstream NOx gas concentration detected by the downstream NOx sensor and the preset downstream NOx gas concentration, so as to completely eliminate the system deviation and achieve accurate control of the urea injection flow, solving the problem that the urea injection flow cannot be accurately controlled in the prior art.

[0062] Optionally, on the basis of the above embodiment, how to control the change of urea injection flow according to urea injection flow and the difference between the upstream and downstream NOx gas concentrations is further refined; Figure 2 is a flow chart of another control method of urea injection flow of an SCR system provided by an embodiment of the present application, as shown in the figure, the method specifically includes the following steps: Figure 2 as shown in the figure, the method specifically includes the following steps:

[0063] S210, obtaining urea injection flow;

[0064] S220, obtaining the difference between the upstream and downstream NOx gas concentrations;

[0065] S230, determining the ratio of urea injection flow and the difference between the upstream and downstream NOx gas concentrations; when the ratio is less than a preset threshold, controlling to reduce the urea injection flow; when the ratio is greater than the preset threshold, controlling to increase the urea injection flow.

[0066] Optionally, the ratio of urea injection flow and the difference between the upstream and downstream NOx gas concentrations is determined, specifically including:

[0067]

[0068] Wherein, is a gas concentration of upstream NOx; is a gas concentration of downstream NOx; k urea is a urea hydrolysis rate; dm urea is a urea injection flow rate; is an Arrhenius reaction coefficient.

[0069] It should be noted that the urea injection flow rate can reflect the mass of NH3 entering the SCR system; the difference between the gas concentrations of upstream and downstream NOx can reflect the mass of NH3 participating in catalytic reduction, when the ratio Fac of the mass of NH3 participating in catalytic reduction to the mass of NH3 entering the SCR system is less than a preset ratio, the ratio of NH3 participating in catalytic reduction is lower, the ammonia storage level is higher, the ammonia leakage risk is greater, and the urea injection flow rate is reduced. Conversely, when the ratio Fac of the mass of NH3 participating in catalytic reduction to the mass of NH3 entering the SCR system is greater than the preset ratio, the ratio of NH3 participating in catalytic reduction is higher, the ammonia storage level is not high, and the urea injection flow rate is normally increased.

[0070] S240, correcting the urea injection flow rate according to the difference and the ratio of the gas concentration of downstream NOx to a preset gas concentration of downstream NOx.

[0071] wherein the preset gas concentration of downstream NOx is obtained according to a lookup table; then the urea injection flow rate is corrected according to the difference between the gas concentration of downstream NOx and the preset gas concentration of downstream NOx, and further corrected in combination with the correction amplitude and correction speed of the urea injection flow rate correction value according to the ratio of the urea injection flow rate and the difference between the gas concentrations of upstream and downstream NOx, so as to ensure the accuracy of the actual urea injection flow rate.

[0072] Optionally, on the basis of the above embodiments, another preferred scheme is provided for how to control the change of the urea injection flow rate according to the urea injection flow rate and the difference between the gas concentrations of upstream and downstream NOx; Figure 3 is a flow chart of another method for controlling the urea injection flow rate of an SCR system according to an embodiment of the present application, as shown in the figure, the method specifically includes the following steps: Figure 3 as shown in the figure, the method specifically includes the following steps:

[0073] S310, obtaining a urea injection flow rate;

[0074] S320, obtaining the difference between the gas concentrations of upstream and downstream NOx;

[0075] S330, determining the correlation coefficient of the change amount of the urea injection flow rate and the change amount of the difference between the gas concentrations of upstream and downstream NOx; when the correlation coefficient is a negative correlation coefficient, the urea injection amount is controlled to be reduced; when the correlation coefficient is a positive correlation coefficient, the urea injection amount is controlled to be increased.

[0076] Optionally, the correlation coefficient of the variation of the urea injection flow and the variation of the difference between the upstream and downstream NOx gas concentrations is determined, and specifically includes:

[0077]

[0078] Wherein, X is the variation array of the urea injection flow; Y is the variation array of the difference between the upstream and downstream NOx gas concentrations; Cov(X, Y) is the covariance of X and Y; Var[] is the variance.

[0079] It should be noted that the urea injection flow can reflect the mass of NH3 entering the SCR system; the difference between the upstream and downstream NOx gas concentrations can reflect the mass of NH3 participating in the catalytic reduction reaction. In one case, when the correlation coefficient r(X, Y) of the variation of the urea injection flow and the variation of the difference between the upstream and downstream NOx gas concentrations is a negative correlation coefficient, if the urea injection flow gradually increases and the difference between the upstream and downstream NOx gas concentrations gradually decreases, it is determined that ammonia leakage has occurred at this time, so the urea injection amount is appropriately reduced to avoid ammonia leakage. When the urea injection flow gradually decreases and the difference between the upstream and downstream NOx gas concentrations gradually increases, it is determined that the ammonia storage level reaches the preset value, so the urea injection amount is controlled to be reduced.

[0080] In another case, when the correlation coefficient r(X, Y) of the variation of the urea injection flow and the variation of the difference between the upstream and downstream NOx gas concentrations is a positive correlation coefficient, if the urea injection flow gradually increases and the difference between the upstream and downstream NOx gas concentrations increases, it is determined that the ammonia storage has not reached the preset value, so the urea injection amount is controlled to be normally increased; when the urea injection flow decreases and the difference between the upstream and downstream NOx gas concentrations decreases, it is determined that the ammonia storage has not reached the preset value, so the urea injection amount is controlled to be normally increased.

[0081] S340, correcting the urea injection flow according to the deviation of the downstream NOx gas concentration from the preset downstream NOx gas concentration and the correlation coefficient.

[0082] Wherein, the preset downstream NOx gas concentration is obtained according to the lookup table; then the urea injection flow is corrected according to the deviation of the downstream NOx gas concentration from the preset downstream NOx gas concentration, and further combined with the correlation coefficient of the variation of the urea injection flow and the variation of the difference between the upstream and downstream NOx gas concentrations to correct the correction amplitude and correction speed of the urea injection flow correction value, so as to ensure the accuracy of the actual urea injection flow.

[0083] Example Two

[0084] The SCR system urea injection amount control device provided by the embodiment of the present application can execute the SCR system urea injection amount control method provided by any of the embodiments of the present application, and has the function modules and beneficial effects corresponding to the execution method. Figure 4 is a structural schematic diagram of an SCR system urea injection amount control device provided by the second embodiment of the present application; as Figure 4 shown, the SCR system urea injection amount control device comprises:

[0085] a urea injection flow rate acquisition module 10 for acquiring a urea injection flow rate;

[0086] a NOx gas concentration difference acquisition module 20 for acquiring a difference between upstream and downstream NOx gas concentrations;

[0087] a flow rate change control module 30 for controlling a change in the urea injection flow rate according to the urea injection flow rate and the difference between the upstream and downstream NOx gas concentrations;

[0088] a correction module 40 for correcting the urea injection flow rate according to a downstream NOx gas concentration and a preset downstream NOx gas concentration.

[0089] Optionally, the flow rate change control module 30 comprises:

[0090] a ratio determining unit for determining a ratio of the urea injection flow rate and the difference between the upstream and downstream NOx gas concentrations;

[0091] a first flow rate change control unit for controlling to reduce the urea injection amount when the ratio is less than a preset threshold value, and controlling to increase the urea injection amount when the ratio is greater than the preset threshold value.

[0092] Optionally, the ratio determining unit specifically functions as:

[0093]

[0094] wherein, is the upstream NOx gas concentration; is the downstream NOx gas concentration; k urea is a urea hydrolysis rate; dm urea is the urea injection flow rate; is an Arrhenius reaction coefficient.

[0095] Optionally, the flow rate change control module 30 comprises:

[0096] a correlation coefficient determining unit for determining a correlation coefficient of a change amount of the urea injection flow rate and a change amount of the difference between the upstream and downstream NOx gas concentrations;

[0097] The second flow variation control unit is configured to control to decrease the urea injection amount when the correlation coefficient is a negative correlation coefficient, and to control to increase the urea injection amount when the correlation coefficient is a positive correlation coefficient.

[0098] Optionally, the correlation coefficient determination unit is configured to:

[0099]

[0100] wherein X is an array of variation amounts of the urea injection flow, Y is an array of variation amounts of the difference between the upstream and downstream NOx gas concentrations, Cov(X, Y) is a covariance of X and Y, and Var[] is a variance.

[0101] Optionally, the correction module 40 comprises:

[0102] The first correction unit is configured to correct the urea injection flow according to a deviation of the downstream NOx gas concentration from a preset downstream NOx gas concentration and a ratio.

[0103] Optionally, the correction module 40 further comprises:

[0104] The second correction unit is configured to correct the urea injection flow according to a deviation of the downstream NOx gas concentration from a preset downstream NOx gas concentration and a correlation coefficient.

[0105] Optionally, the first flow variation control unit is particularly configured to control to decrease the urea injection amount when the correlation coefficient is a negative correlation coefficient, and comprises:

[0106] When the urea injection flow is increased and the difference between the upstream and downstream NOx gas concentrations is decreased, it is determined that the ammonia storage reaches a preset value to control to decrease the urea injection amount.

[0107] When the urea injection flow is decreased and the difference between the upstream and downstream NOx gas concentrations is increased, it is determined that the ammonia storage reaches a preset value to control to decrease the urea injection amount.

[0108] Optionally, the first flow variation control unit is particularly configured to control to increase the urea injection amount when the urea injection flow is increased and the difference between the upstream and downstream NOx gas concentrations is increased, and to control to increase the urea injection amount when the urea injection flow is decreased and the difference between the upstream and downstream NOx gas concentrations is decreased.

[0109] When the urea injection flow is decreased and the difference between the upstream and downstream NOx gas concentrations is decreased, it is determined that the ammonia storage reaches a preset value to control to decrease the urea injection amount.

[0110] Embodiment Three

[0111] Figure 5 A structure schematic diagram of an electronic control unit provided for Embodiment Three of the present application is shown in FIG. 3. Figure 5As shown, the device includes a processor 70, a memory 71, an input device 72 and an output device 73; the number of processors 70 in the device can be one or more, Figure 5 The processor 70 in the device is taken as an example in the embodiment; the processor 70, the memory 71, the input device 72 and the output device 73 in the device can be connected through a bus or other means, Figure 5 The connection through the bus is taken as an example in the embodiment.

[0112] The memory 71 is a kind of computer readable storage medium, which can be used to store software programs, computer executable programs and modules, such as program instructions corresponding to the control method of urea injection amount of SCR system in the embodiment of the application. The processor 70 executes the software programs, instructions and modules stored in the memory 71, thereby performing various functional applications and data processing of the device, i.e. realizing the control method of urea injection amount of SCR system described above.

[0113] The memory 71 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system and application programs required by at least one function; the data storage area can store data created according to the use of the terminal and the like. In addition, the memory 71 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some examples, the memory 71 can further include a memory remotely arranged with respect to the processor 70, which can be connected to the device through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0114] The input device 72 can be used to receive input digital or character information, and generate key signal input related to user settings and function control of the device. The output device 73 can include a display device such as a display screen.

[0115] Embodiment four

[0116] The embodiment four of the application further provides a storage medium containing computer executable instructions, which are used to execute a control method of urea injection amount of SCR system when executed by a computer processor, and the method comprises the following steps:

[0117] Obtaining urea injection flow rate;

[0118] Obtaining the difference between upstream and downstream NOx gas concentrations;

[0119] Controlling the change of urea injection flow rate according to the urea injection flow rate and the difference between upstream and downstream NOx gas concentrations;

[0120] Correcting the urea injection flow rate according to the downstream NOx gas concentration and the preset downstream NOx gas concentration.

[0121] Of course, the storage medium provided by the embodiments of the present application contains computer executable instructions, which are not limited to the method operations described above, but can also perform the related operations in the control method of the SCR system urea injection amount provided by any embodiment of the present application.

[0122] Through the above description of the embodiments, those skilled in the art can clearly understand that the present application can be realized by means of software and necessary universal hardware, and of course can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, and the computer software product can be stored in a computer readable storage medium, such as a floppy disk, a read-only memory (ROM), a random access memory (RAM), a FLASH, a hard disk or an optical disk, etc., including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in various embodiments of the present application.

[0123] It is worth noting that in the above embodiments of the search device, each unit and module included is only divided according to functional logic, but is not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific name of each functional unit is only for easy mutual distinction, and does not limit the protection scope of the present application.

[0124] Note that the above are only preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A method for controlling the urea injection volume in an SCR system, characterized in that, This technology is applied to an SCR system. The SCR system includes a urea injection rate metering device, an upstream NOx sensor, a downstream NOx sensor, and a control module. The urea injection rate metering device is used to detect the urea injection flow rate and send the urea injection flow rate to the control module. The upstream NOx sensor is used to detect the upstream NOx gas concentration and send the upstream NOx gas concentration to the control module. The downstream NOx sensor is used to detect the downstream NOx gas concentration and send the downstream NOx gas concentration to the control module; The control method includes: Obtain the urea injection flow rate; Obtain the difference in NOx gas concentration between upstream and downstream; The change in urea injection flow rate is controlled based on the correlation coefficient between the change in urea injection flow rate and the change in the difference in NOx gas concentration between upstream and downstream. Controlling the change in urea injection flow rate based on the correlation coefficient between the change in urea injection flow rate and the change in the difference in NOx gas concentration between upstream and downstream includes: Determine the correlation coefficient between the change in urea injection flow rate and the change in the difference between upstream and downstream NOx gas concentrations; Specifically, determining the correlation coefficient between the change in urea injection flow rate and the change in the difference in NOx gas concentration between the upstream and downstream areas includes: in, Y is an array representing the change in urea injection flow rate; Y is an array representing the change in the difference in NOx gas concentration between upstream and downstream; Cov(X,Y) is used to calculate the covariance of X and Y; Var[] is used to calculate the variance; When the correlation coefficient is negative, the amount of urea injected is reduced. Wherein, when the correlation coefficient is a negative correlation coefficient, controlling the reduction of the urea injection amount includes: When the urea injection flow rate increases and the difference in NOx gas concentration between the upstream and downstream decreases, it is determined that the ammonia storage has reached a preset value, so as to control and reduce the urea injection rate. When the urea injection flow rate decreases and the difference in NOx gas concentration between the upstream and downstream increases, it is determined that the ammonia storage has reached a preset value, so the urea injection rate is reduced accordingly. When the correlation coefficient is positive, the amount of urea injected is increased. Wherein, when the correlation coefficient is a positive correlation coefficient, controlling the increase of the urea injection amount includes: When the urea injection flow rate increases and the difference in NOx gas concentration between the upstream and downstream increases, it is determined that the ammonia storage has not reached the preset value, so the urea injection rate is increased. When the urea injection flow rate decreases and the difference in NOx gas concentration between the upstream and downstream decreases, it is determined that the ammonia storage has not reached a preset value, and the urea injection rate is increased accordingly. The urea injection flow rate is adjusted based on the downstream NOx gas concentration and a preset downstream NOx gas concentration.

2. The method for controlling the urea injection volume of an SCR system according to claim 1, characterized in that, The urea injection flow rate is adjusted based on the downstream NOx gas concentration and a preset downstream NOx gas concentration, including: The urea injection flow rate is adjusted based on the deviation between the downstream NOx gas concentration and the preset downstream NOx gas concentration, and the correlation coefficient.

3. A device for controlling the urea injection volume in an SCR system, characterized in that, The method for controlling the urea injection volume of the SCR system according to any one of claims 1-2, wherein the control device comprises: Urea injection flow rate acquisition module: used to acquire urea injection flow rate; NOx gas concentration acquisition module: used to acquire the difference in NOx gas concentration between upstream and downstream; Flow rate change control module: used to control the change of urea injection flow rate based on the correlation coefficient between the change in urea injection flow rate and the change in the difference between upstream and downstream NOx gas concentrations; Correction module: used to correct the urea injection flow rate based on the downstream NOx gas concentration and a preset downstream NOx gas concentration.

4. An electronic control unit, characterized in that, The electronic control unit includes: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the method for controlling the amount of urea injected into the SCR system as described in any one of claims 1-2.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the method for controlling the urea injection volume of the SCR system as described in any one of claims 1-2.

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