Detection Method, Detection Device, Processor and Vehicle for Urea Consumption Deviation Fault

Abstract

The present application provides a detection method, a detection device, a processor and a vehicle for urea consumption deviation failure, including: when the injection amount condition and the stable operating condition are satisfied, controlling the SCR system to reduce the ammonia storage to 0, where the ammonia storage is the molar concentration of ammonia in the SCR system; adjusting the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculating the ammonia coverage of the SCR catalyst in real time, the first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage; determining the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount; when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, determining that there is a urea consumption deviation failure, where the urea consumption deviation failure is a failure in which the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition, thus solving the problem of poor user experience in the existing urea consumption deviation detection method.

Description

Technical Field

[0001] The present invention relates to the field of urea consumption deviation diagnosis, and in particular, to a detection method, a detection device, a computer-readable storage medium, a processor, and a vehicle for urea consumption deviation faults. Background Art

[0002] The SCR (Selective Catalytic Reduction) system further improves the conversion efficiency of the SCR system, which is beneficial to meeting the requirements of higher conversion efficiency and to the engine for reducing NO x emission levels and reducing fuel consumption. However, at the same time, there are higher requirements for the control accuracy of the SCR system. The operation of the SCR model will be affected by factors such as sensor accuracy and injection system accuracy, which will cause the SCR model calculation to deviate. At the same time, due to the cross-sensitivity of the NO x sensor, it is not easy to distinguish whether the leaked substance is NO x or NH3. These reasons will all lead to urea consumption deviation.

[0003] Currently, for the monitoring of urea consumption deviation, the mainstream solution is to judge whether there is a consumption deviation by detecting the urea tank liquid level, or to monitor the flow characteristics at the nozzle by using a pressure sensor.

[0004] However, the method using the urea tank liquid level is affected by the different shapes of urea tanks of each manufacturer and requires calibration of the conversion between the urea liquid level and the sensor voltage, resulting in poor versatility. The solution of using a pressure sensor to monitor the nozzle flow characteristics generally requires stopping the urea injection, which will affect the emissions and lead to a poor user experience. Summary of the Invention

[0005] The main purpose of the present application is to provide a detection method, a detection device, a computer-readable storage medium, a processor, and a vehicle for urea consumption deviation faults, so as to at least solve the problem of poor user experience in the existing urea consumption deviation detection method.

[0006] To achieve the above object, according to one aspect of the present application, a detection method for urea consumption deviation faults is provided, including: when the injection amount condition and the stable operating condition are met, controlling the SCR system to reduce the ammonia storage to 0, where the ammonia storage is the molar concentration of ammonia in the SCR system, the injection amount condition includes that the current urea consumption is greater than a predetermined consumption, and the stable operating condition includes that the temperature and the temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rate of the exhaust gas and the NO x mass flow rate are respectively within corresponding predetermined ranges, and the NO xThe change rate of the mass flow rate is within a corresponding predetermined range; adjust the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration to the NO x concentration in the SCR system; determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1. When the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, it is determined that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage through experimental calibration under the conditions of meeting the injection amount condition and the stable operating condition. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0007] Optionally, controlling the SCR system to reduce the ammonia storage to 0 includes: adjusting the ammonia-nitrogen ratio of the SCR system to a second ammonia-nitrogen ratio, where the second ammonia-nitrogen ratio is less than 1; when the SCR conversion efficiency remains unchanged within a first predetermined time, it is determined that the SCR system has reduced the ammonia storage to 0.

[0008] Optionally, before determining that the SCR system has reduced the ammonia storage to 0 when the SCR conversion efficiency remains unchanged within a first predetermined time, the method includes: obtaining a first NO x concentration and a second NO x concentration. The first NO x concentration is the NO x concentration of the tail gas at the inlet of the SCR system, and the second NO x concentration is the NO x concentration of the tail gas at the outlet of the SCR system; calculate the ratio of the second NO x concentration to the first NO x concentration to obtain an unpurified ratio; calculate the SCR conversion efficiency based on the unpurified ratio, where SCR conversion efficiency = 1 - unpurified ratio.

[0009] Optionally, after adjusting the ammonia-nitrogen ratio of the SCR system to the first ammonia-nitrogen ratio, the method further includes: calculating the SCR conversion efficiency in real time; when the first condition and the second condition are met, it is determined that ammonia leakage has occurred. The first condition is that the SCR conversion efficiency rises to a first conversion efficiency and then drops to a second conversion efficiency, and the second condition is that the SCR conversion efficiency remains at the second conversion efficiency for a second predetermined time. The first conversion efficiency is the maximum value of the SCR conversion efficiency during the reaction process.

[0010] Optionally, the ammonia coverage of the SCR catalyst is calculated in real time, including: calculating the reaction rate of each catalytic reaction according to the reaction kinetic equation of the catalytic reaction of the SCR system; calculating the ammonia coverage of the SCR catalyst according to the reaction rate of each catalytic reaction, the maximum value of the ammonia storage, and the reaction time.

[0011] Optionally, before calculating the ammonia coverage of the SCR catalyst according to the reaction rate of each catalytic reaction, the maximum value of the ammonia storage, and the reaction time, the method includes: obtaining the current temperature of the SCR system; looking up the maximum value of the corresponding ammonia storage in the maximum ammonia storage table according to the current temperature, where the maximum ammonia storage table is a comparison table of the maximum value of the ammonia storage and the temperature of the SCR system.

[0012] Optionally, after adjusting the ammonia-nitrogen ratio of the SCR system to the first ammonia-nitrogen ratio and calculating the ammonia coverage of the SCR catalyst in real time, the method further includes: when the urea injection speed is a predetermined speed and remains unchanged, determining the urea injection time at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection time; when the ratio of the target urea injection time to the calibrated injection time is greater than the predetermined threshold, determining that there is a urea consumption deviation fault, where the calibrated injection time is the injection time when the SCR system reaches the maximum value of the ammonia storage under the experimental calibration under the conditions of meeting the injection amount condition and the stable working condition.

[0013] According to another aspect of the present application, there is provided a detection device for urea consumption deviation fault, including: a control unit for controlling the SCR system to reduce the ammonia storage to 0 under the conditions of meeting the injection amount condition and the stable working condition, where the ammonia storage is the molar concentration of ammonia in the SCR system, the injection amount condition includes that the current urea consumption is greater than the predetermined consumption, and the stable working condition includes that the temperature and the temperature change rate of the SCR system are respectively within the corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within the corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within the corresponding predetermined range; a first calculation unit for adjusting the ammonia-nitrogen ratio of the SCR system to the first ammonia-nitrogen ratio and calculating the ammonia coverage of the SCR catalyst in real time, where the first ammonia-nitrogen ratio is greater than 1, the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage, and the ammonia-nitrogen ratio is the ratio of the ammonia concentration in the SCR system to NO xThe ratio of the concentration; a first determination unit for determining the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount; a second determination unit for determining that there is a urea consumption deviation fault when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, where the calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the experimental calibration under the injection amount condition and the stable operating condition, and the urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0014] According to another aspect of the present application, there is provided a computer-readable storage medium, the computer-readable storage medium including a stored program, wherein when the program runs, it controls the device where the computer-readable storage medium is located to execute any one of the above methods.

[0015] According to yet another aspect of the present application, there is provided a processor for running a program, wherein when the program runs, it executes any one of the above methods.

[0016] According to still another aspect of the present application, there is provided a vehicle including: an SCR system, one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include those for executing any one of the above methods.

[0017] Applying the technical solution of the present application, in the above method for detecting the urea consumption deviation fault, first, under the conditions of meeting the injection amount condition and the stable operating condition, the SCR system is controlled to reduce the ammonia storage to 0, where the ammonia storage is the molar concentration of ammonia in the SCR system, the injection amount condition includes that the current urea consumption is greater than a predetermined consumption, and the stable operating condition includes that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within the corresponding predetermined range; then, under the conditions of meeting the injection amount condition and the stable operating condition, the SCR system is controlled to reduce the ammonia storage to 0, where the ammonia storage is the molar concentration of ammonia in the SCR system, the injection amount condition is that the current urea consumption is greater than a predetermined consumption, and the stable operating condition is that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO xThe change rate of the mass flow rate is within the corresponding predetermined range; then, the urea injection amount at the moment when the ammonia coverage of the above SCR catalyst reaches 1 is determined as the target urea injection amount; finally, when the ratio of the above target urea injection amount to the calibrated injection amount is greater than the predetermined threshold, it is determined that there is a urea consumption deviation fault. The above calibrated injection amount is the injection amount at which the above SCR system reaches the maximum value of the above ammonia storage under the above injection amount conditions and the above stable operating conditions during experimental calibration. The above urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition. By controlling the SCR system to empty the ammonia storage and then adjusting the ammonia-nitrogen ratio of the SCR system to above 1 to increase the ammonia storage of the SCR system, this method calculates the ammonia coverage of the SCR catalyst in real time until the ammonia coverage of the SCR catalyst equals 1, that is, the ammonia storage of the SCR system reaches the maximum value, and the current urea injection amount is the target urea injection amount. Comparing with the calibrated injection amount, when the ratio of the target urea injection amount to the calibrated injection amount is greater than the predetermined threshold, that is, the target urea injection amount exceeds the injection amount at which the maximum value of the above ammonia storage is reached during experimental calibration by a large amount, there is a urea consumption deviation fault. For example, the injection pipeline is blocked, and various urea tanks can be used interchangeably without calibrating the conversion of urea liquid level and sensor voltage, and there is no need to stop injecting urea, ensuring compliance with emissions standards and solving the problem of poor user experience in the existing urea consumption deviation detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. shows a hardware structure block diagram of a mobile terminal for performing a detection method for urea consumption deviation fault provided in an embodiment of the present application;

[0019] Figure 2 FIG. shows a schematic flowchart of a detection method for urea consumption deviation fault provided in an embodiment of the present application;

[0020] Figure 3 FIG. shows a schematic flowchart of a determination method for determining that the ammonia storage drops to 0 provided in an embodiment of the present application;

[0021] Figure 4 FIG. shows a schematic flowchart of an SCR conversion efficiency calculation method provided in an embodiment of the present application;

[0022] Figure 5 FIG. shows a schematic diagram of an SCR system provided in an embodiment of the present application;

[0023] Figure 6 FIG. shows a schematic flowchart of an ammonia leakage determination method provided in an embodiment of the present application;

[0024] Figure 7The flowchart shows a method for calculating the ammonia coverage of an SCR catalyst provided according to an embodiment of the present application;

[0025] Figure 8 The flowchart shows a method for determining the maximum value of ammonia storage provided according to an embodiment of the present application;

[0026] Figure 9 The flowchart shows a method for determining a urea consumption deviation fault provided according to an embodiment of the present application;

[0027] Figure 10 The flowchart shows a method for detecting another urea consumption deviation fault provided according to an embodiment of the present application;

[0028] Figure 11 The block diagram shows a detection device for a urea consumption deviation fault provided according to an embodiment of the present application;

[0029] Among them, the above-mentioned drawings include the following reference numerals:

[0030] 10, SCR system; 20, first NO x sensor; 30, second NO x sensor; 40, temperature sensor; 50, urea nozzle; 60, mixer. Detailed implementation manners

[0031] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0033] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of this application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so as to implement the embodiments of this application described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] For the convenience of description, some nouns or terms related to the embodiments of this application are described below:

[0035] SCR: Selective Catalytic Reduction. Urea is injected before the SCR to reduce nitrogen oxides in the exhaust gas emissions;

[0036] DPF: Diesel Particulate Filter, which is used to trap particulate matter in the exhaust gas. When the mass of the trapped particulate matter reaches a certain level, passive regeneration or active regeneration is required to restore the particulate matter trapping ability of the DPF;

[0037] DOC: Diesel Oxide Catalyst, which is installed in front of the DPF and is used to convert NO in the exhaust gas into NO2, while increasing the exhaust gas temperature to assist the normal operation of the DPF and SCR;

[0038] ASC: Ammonia Slip Catalyst, which is used to oxidize excess ammonia;

[0039] SCR model: A mathematical model established based on the principles of chemical reaction kinetics, which is used for urea injection control and diagnosis.

[0040] As introduced in the background art, the existing urea consumption deviation detection method has a poor user experience. To solve this problem, the embodiments of this application provide a detection method, a detection device, a computer-readable storage medium, a processor and a vehicle for urea consumption deviation faults.

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0042] The method embodiments provided in the embodiments of this application can be executed on a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1It is a hardware block diagram of a mobile terminal for a detection method of urea consumption deviation fault according to an embodiment of the present invention. As Figure 1 shown, the mobile terminal may include one or more ( Figure 1 only one is shown in the figure) processors 102 (the processor 102 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data. Among them, the above mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those of ordinary skill in the art can understand that Figure 1 the structure shown is only schematic and does not limit the structure of the above mobile terminal. For example, the mobile terminal may further include more or fewer components than Figure 1 shown in the figure, or have a different configuration from Figure 1 shown in the figure.

[0043] The memory 104 can be used to store computer programs. For example, software programs and modules of application software, such as the computer program corresponding to the display method of device information in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, implements the above method. The memory 104 may include a high-speed random access memory, and may further include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some instances, the memory 104 may further include a memory remotely set relative to the processor 102, and these remote memories can be connected to the mobile terminal through a network. Examples of the above network include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the above network may include a wireless network provided by a communication provider of the mobile terminal. In one instance, the transmission device 106 includes a network adapter (Network Interface Controller, abbreviated as NIC), which can be connected to other network devices through a base station and thus can communicate with the Internet. In one instance, the transmission device 106 may be a radio frequency (Radio Frequency, abbreviated as RF) module, which is used to communicate with the Internet wirelessly.

[0044] In this embodiment, a detection method of urea consumption deviation fault running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And, although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from here.

[0045] Figure 2 is a flowchart of a method for detecting a urea consumption deviation fault according to an embodiment of the present application. As Figure 2 shown, the method includes the following steps:

[0046] Step S201, when the injection amount condition and the stable operating condition are satisfied, control the SCR system to reduce the ammonia storage to 0. The above ammonia storage is the molar concentration of ammonia gas in the SCR system. The above injection amount condition includes that the current urea consumption is greater than a predetermined consumption, and the above stable operating condition includes that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rate of the exhaust gas and the NO x mass flow rate are respectively within corresponding predetermined ranges, and the change rate of the NO x mass flow rate is within a corresponding predetermined range;

[0047] Specifically, for the stable operating condition, that is, select an interval with a relatively stable operating condition and a higher post-treatment temperature. The main judgment conditions include that the SCR temperature is within a certain range, the SCR temperature change rate is within a certain range, the exhaust gas mass flow rate is within a certain range, the upstream NO x mass flow rate is within a certain range, the upstream NO x mass flow rate change rate is within a certain range, etc. The injection amount condition, that is, the current urea consumption is greater than the predetermined consumption. The specific judgment condition is that the urea consumption in the current driving cycle is greater than a certain value, or the current urea consumption is greater than a certain value from the urea consumption of the last valid diagnosis. Meeting the stable operating condition can avoid the influence of the operating condition on the urea consumption deviation diagnosis, and meeting the injection amount condition can avoid the influence of gas in the urea pipeline on the measurement of urea consumption. Reducing the ammonia storage of the SCR system to 0 can avoid the influence of the remaining ammonia gas in the SCR system on the calculation of ammonia consumption, so as to ensure the accuracy of the urea consumption deviation fault. Among them, the certain value corresponding to the urea consumption is determined according to historical experience, and only need to ensure that there are no bubbles in the urea injection pipeline to affect the urea consumption test. The certain range corresponding to the SCR temperature is the SCR optimal reaction temperature determined according to historical data, and the certain range corresponding to the upstream NO x mass flow rate is the NO x mass flow rate range corresponding to the exhaust gas discharged from the engine during full combustion.

[0048] Step S202, adjust the ammonia-nitrogen ratio of the above SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The above first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The above ammonia-nitrogen ratio is the ratio of the ammonia gas concentration in the SCR system to the concentration of NO x ;

[0049] Specifically, first, urea is sprayed to adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio, that is, the ammonia-nitrogen ratio ANR is selected to be greater than 1, and 1.2 or 1.4 can be selected, which is specifically determined according to the requirements of the emission experiment. Then, the ammonia coverage of the SCR catalyst can be calculated based on the real-time catalytic reduction reaction.

[0050] Step S203: Determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the above SCR catalyst reaches 1.

[0051] Specifically, the moment when the ammonia coverage of the above SCR catalyst reaches 1 is the moment when the actual value of the above ammonia storage reaches the maximum value of the above ammonia storage. At this time, the urea injection amount is the injection amount for the ammonia storage to reach the maximum value from 0.

[0052] Step S204: When the ratio of the above target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, it is determined that there is a urea consumption deviation fault. The above calibrated injection amount is the injection amount calibrated in the experiment for the above SCR system to reach the maximum value of the above ammonia storage under the above injection amount conditions and the above stable operating conditions. The above urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0053] Specifically, when diagnosing the urea consumption deviation, the ammonia storage set value should be reselected according to the current temperature and space velocity. The set value is determined based on experimental verification. The ammonia storage set value should ensure that the actual value that can be reached by additional spraying in a short time may or may not reach the maximum value of the ammonia storage. It can be any ammonia storage set value, that is, the ammonia coverage of the above SCR catalyst can be 80% or 70%, etc. The calibrated injection amount is also the injection amount corresponding to the maximum value of 80% ammonia storage or 70% ammonia storage calibrated in the experiment.

[0054] In the above method for detecting the urea consumption deviation fault, first, under the conditions of meeting the injection amount conditions and the stable operating conditions, the SCR system is controlled to reduce the ammonia storage to 0. The above ammonia storage is the molar concentration of ammonia in the above SCR system. The above injection amount conditions include that the current urea consumption is greater than a predetermined consumption amount. The above stable operating conditions include that the temperature and temperature change rate of the above SCR system are respectively within the corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within the corresponding predetermined ranges, and the mass flow rate of NO xThe change rate of the mass flow rate is within a corresponding predetermined range; then, when the injection amount condition and the stable operating condition are satisfied, the SCR system is controlled to reduce the ammonia storage to 0. The above ammonia storage is the molar concentration of ammonia gas in the above SCR system. The above injection amount condition is that the current urea consumption is greater than the predetermined consumption. The above stable operating condition is that the temperature and the temperature change rate of the above SCR system are respectively within the corresponding predetermined ranges, the mass flow rate of the exhaust gas and NO x The mass flow rates are respectively within the corresponding predetermined ranges and the change rate of the mass flow rate of NO x is within the corresponding predetermined range; after that, the urea injection amount at the moment when the ammonia coverage of the above SCR catalyst reaches 1 is determined as the target urea injection amount; finally, when the ratio of the above target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, it is determined that there is a urea consumption deviation fault. The above calibrated injection amount is the injection amount when the above SCR system reaches the maximum value of the above ammonia storage through experimental calibration under the condition of satisfying the above injection amount condition and the above stable operating condition. The above urea consumption deviation fault is a fault in which the deviation between the theoretical calculated value and the actual consumption value of urea satisfies the alarm condition. By controlling the SCR system to empty the ammonia storage, the ammonia-nitrogen ratio of the SCR system is adjusted to more than 1 to increase the ammonia storage of the SCR system, and the ammonia coverage of the SCR catalyst is calculated in real time until the ammonia coverage of the SCR catalyst is equal to 1, that is, the ammonia storage of the SCR system reaches the maximum value, and the current urea injection amount is the target urea injection amount. Comparing with the calibrated injection amount, the ratio of the target urea injection amount to the calibrated injection amount is greater than the predetermined threshold, that is, the target urea injection amount exceeds the injection amount for reaching the maximum value of the ammonia storage by experimental calibration by a large amount, and there is a urea consumption deviation fault. For example, the injection pipeline is blocked, and various urea tanks can be used interchangeably without calibrating the conversion of the urea liquid level and the sensor voltage, and there is no need to stop injecting urea to ensure emission compliance, solving the problem of poor user experience in the existing urea consumption deviation detection method.

[0055] To ensure the accuracy of the urea consumption deviation fault, in an alternative implementation, as Figure 3 shown, the above step S201 includes:

[0056] Step S2011, adjusting the ammonia-nitrogen ratio of the above SCR system to a second ammonia-nitrogen ratio, and the second ammonia-nitrogen ratio is less than 1;

[0057] Step S2012, when the SCR conversion efficiency remains unchanged within the first predetermined time, it is determined that the above SCR system has reduced the above ammonia storage to 0.

[0058] Specifically, the ammonia-nitrogen ratio of the above SCR system is adjusted to the second ammonia-nitrogen ratio, that is, the set ammonia-nitrogen ratio ANR is less than 1, and ANR = upstream NH3 / upstream NO x, 0.8 or 0.6 can be selected, which is specifically determined according to the requirements of the emission experiment. The SCR conversion efficiency is calculated under stable operating conditions. When the SCR conversion efficiency decreases to a certain value and is less than ANR and remains stable for a certain period of time, it is considered that the above ammonia storage has been reduced to 0 to avoid the influence of the residual ammonia in the SCR system on the ammonia consumption calculation and ensure the accuracy of the urea consumption deviation fault.

[0059] In order to monitor the SCR conversion efficiency in real time, in an alternative implementation, as Figure 4 shown, before the above step S2012, the above method includes:

[0060] Step S301, obtaining the first NO x concentration and the second NO x concentration, where the first NO x concentration is the NO x concentration of the tail gas at the inlet of the above SCR system, and the second NO x concentration is the NO x concentration of the tail gas at the outlet of the above SCR system;

[0061] Step S302, calculating the ratio of the above second NO x concentration to the above first NO x concentration to obtain the unpurified ratio;

[0062] Step S303, calculating the above SCR conversion efficiency according to the above unpurified ratio, where the SCR conversion efficiency = 1 - unpurified ratio.

[0063] Specifically, as Figure 5 shown, a first NO x sensor 20, a temperature sensor 40, a urea nozzle 50, and a mixer 60 are provided upstream of the above SCR system 10. The mixer 60 is used to mix the engine exhaust with the ammonia sprayed by the urea nozzle 50 and introduce it into the SCR system. A second NO x sensor 30 is provided downstream of the above SCR system 10. According to the upstream NO x concentration measured in real time by the first NO x sensor 20 and the downstream NO x concentration measured in real time by the second NO x sensor 30, the SCR conversion efficiency = 1 - second NO x concentration / first NO x concentration can be calculated, and the real-time monitoring of the SCR conversion efficiency can be realized.

[0064] In order to monitor whether ammonia leakage occurs, in an alternative implementation, as Figure 6 shown, after step S202, the above method further includes:

[0065] Step S401, calculate the SCR conversion efficiency in real time;

[0066] Step S402, when the first condition and the second condition are satisfied, it is determined that ammonia leakage has occurred. The above first conversion efficiency is the maximum value of the above SCR conversion efficiency during the reaction process. The above first condition is that the SCR conversion efficiency rises to the first conversion efficiency and then drops to the second conversion efficiency. The above second condition is that the SCR conversion efficiency remains at the second conversion efficiency for a second predetermined time.

[0067] Specifically, calculate the SCR conversion efficiency in real time. Since the first ammonia-nitrogen ratio ANR is less than 1, the SCR efficiency will gradually recover to the maximum value. If it remains near the maximum value afterwards, no ammonia leakage has occurred. If it gradually decreases to a certain value and stabilizes for a certain time afterwards, it is considered that the maximum ammonia storage is reached currently and ammonia leakage has occurred. After detecting ammonia leakage, an alarm is given in time for emergency treatment to ensure safety.

[0068] In order to calculate the ammonia coverage of the SCR catalyst in real time, in an alternative implementation, as Figure 7 shown, the above step S202 includes:

[0069] Step S2021, calculate the reaction rate of each of the above catalytic reactions according to the reaction kinetic equation of the catalytic reaction of the above SCR system;

[0070] Step S2022, calculate the ammonia coverage of the above SCR catalyst according to the reaction rate of each of the above catalytic reactions, the maximum value of the above ammonia storage, and the reaction time.

[0071] Specifically, the reactions involved in the reaction principle of the SCR technology are as follows: urea hydrolysis to ammonia: (urea injection system) (NH2)2CO + H2O → 2NH3 + CO2, SCR post-treatment reaction: (SCR catalytic converter), NO + NO2 + 2NH3 → 2N2 + 3H2O, 4NO + O2 + 4NH3 → 4N2 + 6H2O, 2NO2 + O2 + 4NH3 → 3N2 + 6H2O, and the reaction kinetic equation involved in the catalytic reduction reaction of the SCR system: r is the reaction rate, mol / m 3 , C nox : NO x gas reactant concentration, mol / m 3 , C NH3 : ammonia reactant concentration, mol / m 3 , k Std : NO x frequency factor of the standard reaction, 1 / s; kAds : Frequency factor of the adsorption reaction, 1 / s; k Des : Frequency factor of the desorption reaction, mol / (m 3 ·s); k Ox : Frequency factor of the oxidation reaction, 1 / s; k Fst : Frequency factor of the fast reaction, 1 / s; E: Activation energy divided by the universal gas constant; T: Temperature, K; θ: Ammonia coverage of the SCR catalyst; ε: Desorption and ammonia storage correlation parameter; θ C : NO x : Ammonia storage adjustment parameter for the reaction. The reaction rates of the above catalytic reactions are calculated according to the above reaction kinetic equations, and are calculated according to ammonia storage conservation Among them, Ω is the maximum value of ammonia storage, mol / m 3 , and thus the ammonia coverage θ of the SCR catalyst is calculated. Of course, the ammonia coverage θ of the SCR catalyst can also be the ratio of the ammonia mass corresponding to the actual value of the above ammonia storage to the ammonia mass corresponding to the maximum value of the above ammonia storage, that is Among them, m NH3,max = Ω * V * 17

[0072] In order to obtain the accurate maximum value of ammonia storage, in an alternative implementation, as Figure 8 shown, before the above step S2022, the above method includes:

[0073] Step S501, obtaining the current temperature of the above SCR system;

[0074] Step S502, looking up the maximum ammonia storage table according to the above current temperature to obtain the corresponding maximum value of the above ammonia storage. The above maximum ammonia storage table is a comparison table of the maximum value of the above ammonia storage and the temperature of the above SCR system

[0075] Specifically, when the current temperature of the above SCR system is different, the upper limit of the ammonia concentration in the above SCR system is different, that is, the maximum value of the above ammonia storage is different. The maximum value of the ammonia storage at the current temperature of the above SCR system is determined by querying the maximum ammonia storage table to further ensure the accuracy of the urea consumption deviation fault. In addition, at different operating temperatures of the SCR system, the maximum value of the ammonia storage of the SCR system is determined through multiple calibration tests, so as to obtain the above maximum ammonia storage table

[0076] In order to simplify the steps of fault judgment, in an alternative implementation, as Figure 9 shown, after the above step S202, the above method further includes:

[0077] Step S601: With the above urea injection rate being a predetermined rate and remaining unchanged, determine the target urea injection time as the moment when the ammonia coverage of the above SCR catalyst reaches 1.

[0078] Step S602: When the ratio of the above target urea injection time to the calibrated injection time is greater than the above predetermined threshold, determine that there is a urea consumption deviation fault. The above calibrated injection time is the injection time when the above SCR system reaches the maximum value of the above ammonia storage under the condition of meeting the above injection volume condition and the above stable operating condition through experimental calibration.

[0079] Specifically, when the above urea injection rate is constant, the injection volume can be determined through the injection time. When additional urea is injected, start timing and accumulate the timing time. When it is determined that the ammonia storage reaches the maximum value of the ammonia storage, complete the time accumulation, and compare the additional injection time with the diagnostic limit value to confirm whether there is a fault, that is, whether the ratio of the above target urea injection time to the calibrated injection time is greater than the above predetermined threshold. If it is a fault, report it, so that there is no need to calculate the injection volume and directly judge through the injection time.

[0080] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the detection method for urea consumption deviation fault of the present application will be described in detail below with specific embodiments.

[0081] This embodiment relates to a specific detection method for urea consumption deviation fault, as Figure 10 shown, including the following steps:

[0082] Step S1: Under the condition of meeting the injection volume condition and the stable operating condition, adjust the ammonia-nitrogen ratio of the above SCR system to a second ammonia-nitrogen ratio, where the second ammonia-nitrogen ratio is less than 1. When the SCR conversion efficiency remains unchanged within the first predetermined time, determine that the above SCR system has reduced the above ammonia storage to 0. The above ammonia storage is the molar concentration of ammonia gas in the above SCR system. The above injection volume condition is that the current urea consumption is greater than the predetermined consumption. The above stable operating condition is that the temperature and temperature change rate of the above SCR system are respectively within the corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within the corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within the corresponding predetermined range;

[0083] Step S2: Adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio. The reaction kinetic equation involved in the catalytic reduction reaction of the SCR system: r is the reaction rate, mol / m 3 ,Cnox : NO x Concentration of gaseous reactant, mol / m 3 , C NH3 : Concentration of ammonia reactant, mol / m 3 , k Std : NO x Frequency factor of standard reaction, 1 / s; k Ads : Frequency factor of adsorption reaction, 1 / s; k Des : Frequency factor of desorption reaction, mol / (m 3 ·s); k Ox : Frequency factor of oxidation reaction, 1 / s; k Fst : Frequency factor of fast reaction, 1 / s; E: Activation energy divided by universal gas constant; T: Temperature, K; θ: Ammonia coverage of SCR catalyst; ε: Desorption and ammonia storage correlation parameter; θ C : NO x Ammonia storage adjustment parameter for reaction, calculate the reaction rate of each of the above catalytic reactions according to the above reaction kinetics equation, and calculate according to ammonia storage conservation Among them, Ω is the maximum value of ammonia storage, mol / m 3 , so as to calculate in real time the ammonia coverage θ of the SCR catalyst. The above first ammonia-nitrogen ratio is greater than 1. The ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration to the nitrogen concentration in the SCR system. The maximum value of the ammonia storage is obtained by looking up the maximum ammonia storage table according to the current temperature of the SCR system. The maximum ammonia storage table is a comparison table of the maximum value of the ammonia storage and the temperature of the SCR system;

[0084] Step S3: Calculate the SCR conversion efficiency in real time. Calculate the SCR conversion efficiency = 1 - second NO x Concentration / first NO x Concentration, the first NO x Concentration is the NO in the tail gas at the inlet of the SCR system x Concentration, the second NO x Concentration is the NO in the tail gas at the outlet of the SCR system x Concentration. When the SCR conversion efficiency rises to the first conversion efficiency and then drops to the second conversion efficiency and the SCR conversion efficiency remains at the second conversion efficiency for the second predetermined time, it is determined that ammonia leakage has occurred. The first conversion efficiency is the maximum value of the SCR conversion efficiency during the reaction process.

[0085] Step S4: Determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1;

[0086] Step S5: With the above urea injection speed being a predetermined speed and remaining unchanged, determine the urea injection time at the moment when the ammonia coverage of the above SCR catalyst reaches 1 as the target urea injection time. If the ratio of the above target urea injection time to the calibrated injection time is greater than the above predetermined threshold, it is determined that there is a urea consumption deviation fault. The above calibrated injection time is the injection time when the above SCR system reaches the maximum value of the above ammonia storage under the conditions of meeting the above injection amount condition and the above stable operating condition through experimental calibration.

[0087] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in a different order than here.

[0088] The embodiment of the present application also provides a detection device for urea consumption deviation fault. It should be noted that the detection device for urea consumption deviation fault in the embodiment of the present application can be used to execute the detection method for urea consumption deviation fault provided in the embodiment of the present application. The device is used to implement the above embodiments and preferred implementation manners, and those that have been described will not be repeated. As used hereinafter, the term "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0089] The following introduces the detection device for urea consumption deviation fault provided in the embodiment of the present application.

[0090] Figure 11 is a schematic diagram of the detection device for urea consumption deviation fault according to the embodiment of the present application. As Figure 11 shown, the device includes:

[0091] A control unit 100, configured to control the SCR system to reduce the ammonia storage to 0 under the conditions of meeting the injection amount condition and the stable operating condition. The above ammonia storage is the molar concentration of ammonia in the above SCR system. The above injection amount condition includes that the current urea consumption is greater than a predetermined consumption. The above stable operating condition includes that the temperature and temperature change rate of the above SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within a corresponding predetermined range;

[0092] Specifically, for stable operating conditions, that is, selecting an interval with a relatively stable operating condition and a relatively high after-treatment temperature, the main judgment conditions include that the SCR temperature is within a certain range, the SCR temperature change rate is within a certain range, the exhaust gas mass flow is within a certain range, the upstream NO x mass flow is within a certain range, and the upstream NO x mass flow change rate is within a certain range, etc. For the injection quantity condition, that is, the current urea consumption is greater than the predetermined consumption. The specific judgment condition is that the urea consumption in the current driving cycle is greater than a certain value, or the current urea consumption is greater than a certain value from the urea consumption that was diagnostically valid last time. Meeting the stable operating conditions can avoid the influence of the operating condition on the urea consumption deviation diagnosis. Meeting the injection quantity condition can avoid the influence of gas in the urea pipeline on the measurement of urea consumption. The SCR system reduces the ammonia storage to 0 to avoid the influence of the residual ammonia in the SCR system on the calculation of ammonia consumption, so as to ensure the accuracy of the urea consumption deviation fault. Among them, the certain value corresponding to the urea consumption is determined according to historical experience. It only needs to ensure that there are no bubbles in the urea injection pipeline to affect the urea consumption test. The certain range corresponding to the SCR temperature is the SCR optimal reaction temperature determined according to historical data. The upstream NO x The certain range corresponding to the mass flow is the NO x mass flow range of the exhaust gas discharged from the engine during full combustion.

[0093] The first calculation unit 200 is used to adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The above first ammonia-nitrogen ratio is greater than 1. The ammonia coverage of the above SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The above ammonia-nitrogen ratio is the ratio of the ammonia concentration in the above SCR system to the concentration of NO x ;

[0094] Specifically, first add spray urea to adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio, that is, select an ammonia-nitrogen ratio ANR greater than 1, which can be 1.2 or 1.4, specifically determined according to the emission experiment requirements. Then, the ammonia coverage of the SCR catalyst can be calculated according to the real-time catalytic reduction reaction.

[0095] The first determination unit 300 is used to determine the urea injection quantity at the moment when the ammonia coverage of the above SCR catalyst reaches 1 as the target urea injection quantity;

[0096] Specifically, the moment when the ammonia coverage of the above SCR catalyst reaches 1 is the moment when the actual value of the above ammonia storage reaches the maximum value of the ammonia storage. The urea injection quantity at this time is the injection quantity for the ammonia storage to reach the maximum value of the ammonia storage from 0.

[0097] A second determination unit 400 is configured to determine that there is a urea consumption deviation fault when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of ammonia storage during experimental calibration under the above-mentioned injection amount conditions and the above-mentioned stable operating conditions. The urea consumption deviation fault is a fault in which the deviation between the theoretical calculated value and the actual consumption value of urea satisfies the alarm condition.

[0098] Specifically, when diagnosing the urea consumption deviation, the ammonia storage set value should be reselected according to the current temperature and space velocity. The set value is determined based on experimental verification. The ammonia storage set value should ensure the actual value that can be achieved by additional injection in a short time, and it may not reach the maximum value of ammonia storage. It can be any ammonia storage set value, that is, the ammonia coverage of the SCR catalyst can be 80% or 70%, etc. The calibrated injection amount is also the injection amount corresponding to the maximum value of 80% ammonia storage or the corresponding injection amount of the maximum value of 70% ammonia storage during experimental calibration.

[0099] In the detection device for the above-mentioned urea consumption deviation fault, when the injection amount condition and the stable operating condition are satisfied, the control unit controls the SCR system to reduce the ammonia storage to 0. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount condition includes that the current urea consumption is greater than a predetermined consumption. The stable operating condition includes that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within the corresponding predetermined range; when the injection amount condition and the stable operating condition are satisfied, the calculation unit controls the SCR system to reduce the ammonia storage to 0. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount condition is that the current urea consumption is greater than a predetermined consumption. The stable operating condition is that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO xThe change rate of the mass flow rate is within the corresponding predetermined range; the first determination unit determines the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount; the second determination unit determines that there is a urea consumption deviation fault when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the above injection amount conditions and the above stable operating conditions through experimental calibration. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition. After the device controls the SCR system to empty the ammonia storage, it adjusts the ammonia-nitrogen ratio of the SCR system to more than 1 to increase the ammonia storage of the SCR system, calculates the ammonia coverage of the SCR catalyst in real time until the ammonia coverage of the SCR catalyst is equal to 1, that is, the ammonia storage of the SCR system reaches the maximum value, and the current urea injection amount is the target urea injection amount. Comparing with the calibrated injection amount, when the ratio of the target urea injection amount to the calibrated injection amount is greater than the predetermined threshold, that is, the target urea injection amount exceeds the injection amount for reaching the maximum value of the ammonia storage by a large margin through experimental calibration, there is a urea consumption deviation fault. For example, the injection pipeline is blocked, and various urea tanks can be used universally without calibrating the conversion between the urea liquid level and the sensor voltage, and there is no need to stop injecting urea to ensure emission compliance, solving the problem of poor user experience in the existing urea consumption deviation detection method.

[0100] To ensure the accuracy of the urea consumption deviation fault, in an alternative implementation, the above control unit includes:

[0101] An adjustment module for adjusting the ammonia-nitrogen ratio of the SCR system to a second ammonia-nitrogen ratio, where the second ammonia-nitrogen ratio is less than 1;

[0102] A determination module for determining that the SCR system has reduced the ammonia storage to 0 when the SCR conversion efficiency remains unchanged within a first predetermined time.

[0103] Specifically, the ammonia-nitrogen ratio of the SCR system is adjusted to the second ammonia-nitrogen ratio, that is, the set ammonia-nitrogen ratio ANR is less than 1, ANR = upstream NH3 / upstream NO x , and 0.8 or 0.6 can be selected, which is specifically determined according to the emission experiment requirements. Calculate the SCR conversion efficiency under stable operating conditions. When the SCR conversion efficiency is reduced to a certain value and is less than ANR and remains stable for a certain time, it is considered that the ammonia storage has been reduced to 0 to avoid the influence of the residual ammonia in the SCR system on the ammonia consumption calculation and ensure the accuracy of the urea consumption deviation fault.

[0104] To monitor the SCR conversion efficiency in real time, in an alternative implementation, the above device includes:

[0105] A third determination unit, configured to obtain a first NO concentration before determining that the ammonia storage in the SCR system has been reduced to 0, when the SCR conversion efficiency remains unchanged within a first predetermined time. x concentration and a second NO x concentration, where the first NO x concentration is the NO concentration of the exhaust gas at the inlet of the SCR system, x and the second NO x concentration is the NO concentration of the exhaust gas at the outlet of the SCR system; x

[0106] A second calculation unit, configured to calculate a ratio of the second NO concentration to the first NO concentration to obtain an unpurified ratio. x concentration and the first NO x concentration, and obtain an unpurified ratio;

[0107] A third calculation unit, configured to calculate the SCR conversion efficiency according to the unpurified ratio, where the SCR conversion efficiency = 1 - unpurified ratio.

[0108] Specifically, as Figure 5 shown, a first NO sensor 20, a temperature sensor 40, a urea nozzle 50, and a mixer 60 are disposed upstream of the SCR system 10. The mixer 60 is configured to mix the engine exhaust gas with the ammonia gas ejected from the urea nozzle 50 and introduce the mixture into the SCR system. A second NO sensor 30 is disposed downstream of the SCR system 10. According to the upstream NO concentration measured in real time by the first NO sensor 20 and the downstream NO concentration measured in real time by the second NO sensor 30, the SCR conversion efficiency can be calculated as SCR conversion efficiency = 1 - second NO concentration / first NO concentration, and the real-time monitoring of the SCR conversion efficiency can be realized. x sensor 20, a temperature sensor 40, a urea nozzle 50, and a mixer 60. The mixer 60 is used to mix the engine exhaust gas with the ammonia gas ejected from the urea nozzle 50 and introduce the mixture into the SCR system. A second NO x sensor 30 is disposed downstream of the SCR system 10. According to the upstream NO x concentration measured in real time by the first NO x sensor 20 and the second NO x concentration measured in real time by the second NO x sensor 30, the SCR conversion efficiency can be calculated as SCR conversion efficiency = 1 - second NO x concentration / first NO x concentration, and the real-time monitoring of the SCR conversion efficiency can be realized.

[0109] In order to monitor whether ammonia leakage occurs, in an optional implementation, after adjusting the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, the device further includes:

[0110] A fourth calculation unit, configured to calculate the SCR conversion efficiency in real time;

[0111] ​A fourth determination unit is configured to determine that ammonia leakage has occurred when the first condition and the second condition are met. The first conversion efficiency is the maximum value of the SCR conversion efficiency during the reaction process. The first condition is that the SCR conversion efficiency rises to the first conversion efficiency and then drops to the second conversion efficiency. The second condition is that the SCR conversion efficiency remains at the second conversion efficiency for a second predetermined time.

[0112] Specifically, the SCR conversion efficiency is calculated in real time. Since the first ammonia-nitrogen ratio ANR is less than 1, the SCR efficiency will gradually recover to the maximum value. If it remains near the maximum value afterwards, no ammonia leakage has occurred. If it gradually decreases to a certain value and stabilizes for a certain time afterwards, it is considered that the maximum ammonia storage is reached currently and ammonia leakage has occurred. After detecting ammonia leakage, an alarm is given in time for emergency treatment to ensure safety.

[0113] In order to calculate the ammonia coverage of the SCR catalyst in real time, in an optional implementation manner, the calculation unit includes:

[0114] A first calculation module is configured to calculate the reaction rate of each of the catalytic reactions according to the reaction kinetic equation of the catalytic reaction of the SCR system;

[0115] A second calculation module is configured to calculate the ammonia coverage of the SCR catalyst according to the reaction rate of each of the catalytic reactions, the maximum value of the ammonia storage, and the reaction time.

[0116] Specifically, the reactions involved in the reaction principle of the SCR technology are as follows: Urea hydrolysis to ammonia: (urea injection system) (NH2)2CO + H2O → 2NH3 + CO2, SCR post-treatment reaction: (SCR catalytic converter), NO + NO2 + 2NH3 → 2N2 + 3H2O, 4NO + O2 + 4NH3 → 4N2 + 6H2O, 2NO2 + O2 + 4NH3 → 3N2 + 6H2O, and the reaction kinetic equation involved in the catalytic reduction reaction of the SCR system: r is the reaction rate, mol / m 3 , C nox : NO x Gas reactant concentration, mol / m 3 , C NH3 : Ammonia reactant concentration, mol / m 3 , k Std : NO x Frequency factor of the standard reaction, 1 / s; k Ads : Frequency factor of the adsorption reaction, 1 / s; k Des : Frequency factor of the desorption reaction, mol / (m 3 ·s); kOx : Frequency factor of the oxidation reaction, 1 / s; k Fst : Frequency factor of the fast reaction, 1 / s; E: Activation energy divided by the universal gas constant; T: Temperature, K; θ: Ammonia coverage of the SCR catalyst; ε: Desorption and ammonia storage correlation parameter; θ C : NO x : Ammonia storage adjustment parameter for the reaction. The reaction rates of the above catalytic reactions are calculated according to the above reaction kinetic equation, and calculated according to ammonia storage conservation Among them, Ω is the maximum value of ammonia storage, mol / m 3 , thus calculating the ammonia coverage θ of the SCR catalyst. Of course, the ammonia coverage θ of the SCR catalyst can also be the ratio of the ammonia mass corresponding to the actual value of the above ammonia storage to the ammonia mass corresponding to the maximum value of the above ammonia storage, that is Among them, m NH3,max =Ω*V*17

[0117] In order to obtain the accurate maximum value of ammonia storage, in an alternative implementation, the above device includes:

[0118] An acquisition unit, configured to acquire the current temperature of the SCR system before calculating the ammonia coverage of the SCR catalyst according to the reaction rates of the above catalytic reactions, the maximum value of the ammonia storage, and the reaction time

[0119] A fifth determination unit, configured to look up the corresponding maximum value of the ammonia storage in the maximum ammonia storage table according to the current temperature. The maximum ammonia storage table is a comparison table of the maximum value of the ammonia storage and the temperature of the SCR system

[0120] Specifically, the current temperature of the SCR system is different, and the upper limit of the ammonia concentration in the SCR system is different, that is, the maximum value of the ammonia storage is different. The maximum value of the ammonia storage at the current temperature of the SCR system is determined by querying the maximum ammonia storage table to further ensure the accuracy of the urea consumption deviation fault. In addition, at different operating temperatures of the SCR system, the maximum value of the ammonia storage of the SCR system is measured through multiple calibration tests, thereby obtaining the above maximum ammonia storage table

[0121] In order to simplify the steps of fault judgment, in an alternative implementation, the above device further includes:

[0122] A sixth determination unit, configured to, after adjusting the ammonia-nitrogen ratio of the SCR system to the first ammonia-nitrogen ratio and calculating the ammonia coverage of the SCR catalyst in real time, determine the urea injection time at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection time when the urea injection speed is a predetermined speed and remains unchanged

[0123] A seventh determination unit is configured to determine that there is a urea consumption deviation fault when the ratio of the target urea injection time to the calibrated injection time is greater than the predetermined threshold. The calibrated injection time is the injection time when the SCR system reaches the maximum value of the ammonia storage through experimental calibration under the condition of meeting the injection amount condition and the stable operating condition.

[0124] Specifically, the urea injection speed is constant, so the injection amount can be determined by the injection time. When urea additional injection is performed, timing starts, and the cumulative timing time is calculated. When it is determined that the ammonia storage reaches the maximum value of the ammonia storage, the time accumulation is completed. The additional injection time is compared with the diagnostic limit value to confirm whether there is a fault, that is, whether the ratio of the target urea injection time to the calibrated injection time is greater than the predetermined threshold. If it is a fault, it is reported, so there is no need to calculate the injection amount, and the judgment can be directly made through the injection time.

[0125] The detection device for the urea consumption deviation fault includes a processor and a memory. The control unit, the first calculation unit, the first determination unit, the second determination unit, etc. are all stored in the memory as program units, and the corresponding functions are realized by the processor executing the program units stored in the memory. The above modules are all located in the same processor; or, the above modules are respectively located in different processors in any combination form.

[0126] The processor contains a kernel, and the kernel retrieves the corresponding program unit from the memory. One or more kernels can be set, and by adjusting the kernel parameters, the problem of poor use experience of the existing urea consumption deviation detection method can be solved.

[0127] The memory may include non-permanent memory in a computer-readable medium, forms such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one storage chip.

[0128] An embodiment of the present invention provides a computer-readable storage medium, and the computer-readable storage medium includes a stored program. When the program runs, the device where the computer-readable storage medium is located is controlled to execute the detection method for the urea consumption deviation fault.

[0129] Specifically, the detection method for the urea consumption deviation fault includes:

[0130] Step S201, under the condition of meeting the injection amount condition and the stable operating condition, control the SCR system to reduce the ammonia storage to 0. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount condition includes that the current urea consumption is greater than the predetermined consumption, and the stable operating condition includes that the temperature and temperature change rate of the SCR system are respectively within the corresponding predetermined ranges, the mass flow rate of the exhaust gas and NOx The mass flow rates are respectively within corresponding predetermined ranges and the change rate of the mass flow rate of NO x is within a corresponding predetermined range;

[0131] Specifically, under stable operating conditions, that is, after selecting a relatively stable operating condition and a range with a relatively high post-treatment temperature, the main judgment conditions include that the SCR temperature is within a certain range, the change rate of the SCR temperature is within a certain range, the exhaust gas mass flow rate is within a certain range, the upstream NO x mass flow rate is within a certain range, the upstream NO x mass flow rate change rate is within a certain range, etc. For the injection amount condition, that is, the current urea consumption is greater than the predetermined consumption. The specific judgment condition is that the urea consumption in the current driving cycle is greater than a certain value, or the current urea consumption is greater than a certain value from the urea consumption in the last valid diagnosis. Meeting the stable operating conditions can avoid the influence of the operating condition on the urea consumption deviation diagnosis, and meeting the injection amount condition can avoid the influence of gas in the urea pipeline on the measurement of urea consumption. Lower the ammonia storage of the SCR system to 0 to avoid the influence of the residual ammonia gas in the SCR system on the calculation of ammonia consumption, so as to ensure the accuracy of the urea consumption deviation fault.

[0132] Step S202: Adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The above first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration to the nitrogen concentration in the above SCR system;

[0133] Specifically, first add urea injection to adjust the ammonia-nitrogen ratio of the above SCR system to the first ammonia-nitrogen ratio, that is, select an ammonia-nitrogen ratio ANR greater than 1, which can be 1.2 or 1.4, specifically determined according to the emission experiment requirements. Then, the ammonia coverage of the SCR catalyst can be calculated according to the real-time catalytic reduction reaction.

[0134] Step S203: Determine the target urea injection amount at the moment when the ammonia coverage of the above SCR catalyst reaches 1;

[0135] Specifically, the moment when the ammonia coverage of the above SCR catalyst reaches 1 is the moment when the actual value of the ammonia storage reaches the maximum value of the ammonia storage. At this time, the urea injection amount is the injection amount for the ammonia storage to reach the maximum value of the ammonia storage from 0.

[0136] Step S204: When the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, it is determined that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount at which the SCR system experimentally calibrated reaches the maximum value of the ammonia storage under the above injection amount conditions and the above stable operating conditions. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0137] Specifically, when diagnosing the urea consumption deviation, the ammonia storage set value should be reselected according to the current temperature and space velocity. The set value is determined based on experimental verification. The ammonia storage set value should ensure that the actual value that can be reached by additional injection in a short time may or may not reach the maximum value of the ammonia storage, and can be any ammonia storage set value. That is, the ammonia coverage of the SCR catalyst can be 80% or 70%, etc. The calibrated injection amount is also the injection amount corresponding to the maximum value of the ammonia storage of 80% or the maximum value of the ammonia storage of 70% experimentally calibrated.

[0138] Optionally, step S201 includes: step S2011, adjusting the ammonia-nitrogen ratio of the SCR system to a second ammonia-nitrogen ratio, where the second ammonia-nitrogen ratio is less than 1; step S2012, when the SCR conversion efficiency remains unchanged within a first predetermined time, it is determined that the SCR system has reduced the ammonia storage to 0.

[0139] Optionally, before step S2012, the method includes: step S301, obtaining a first NO x concentration and a second NO x concentration. The first NO x concentration is the NO x concentration of the exhaust gas at the inlet of the SCR system, and the second NO x concentration is the NO x concentration of the exhaust gas at the outlet of the SCR system; step S302, calculating the ratio of the second NO x concentration to the first NO x concentration to obtain an unpurified ratio; step S303, calculating the SCR conversion efficiency based on the unpurified ratio, where the SCR conversion efficiency = 1 - unpurified ratio.

[0140] Optionally, after step S202, the method further includes: step S401, calculating the SCR conversion efficiency in real time; step S402, when the first condition and the second condition are met, it is determined that ammonia leakage has occurred. The first conversion efficiency is the maximum value of the SCR conversion efficiency during the reaction process. The first condition is that the SCR conversion efficiency rises to the first conversion efficiency and then drops to the second conversion efficiency, and the second condition is that the SCR conversion efficiency remains at the second conversion efficiency for a second predetermined time.

[0141] Optionally, the above-mentioned step S202 includes: step S2021, calculating the reaction rate of each of the above-mentioned catalytic reactions according to the reaction kinetic equation of the catalytic reaction of the above-mentioned SCR system; step S2022, calculating the ammonia coverage of the above-mentioned SCR catalyst according to the reaction rate of each of the above-mentioned catalytic reactions, the maximum value of the above-mentioned ammonia storage, and the reaction time.

[0142] Optionally, before the above-mentioned step S2022, the above-mentioned method includes: step S501, obtaining the current temperature of the above-mentioned SCR system; step S502, looking up the maximum value of the above-mentioned ammonia storage corresponding to the current temperature in the maximum ammonia storage table, and the maximum ammonia storage table is a comparison table of the maximum value of the above-mentioned ammonia storage and the temperature of the above-mentioned SCR system.

[0143] Optionally, after the above-mentioned step S202, the above-mentioned method further includes: step S601, when the above-mentioned urea injection speed is a predetermined speed and remains unchanged, determining the urea injection time at the moment when the ammonia coverage of the above-mentioned SCR catalyst reaches 1 as the target urea injection time; step S602, when the ratio of the above-mentioned target urea injection time to the calibrated injection time is greater than the above-mentioned predetermined threshold, determining that there is a urea consumption deviation fault, and the above-mentioned calibrated injection time is the injection time when the above-mentioned SCR system reaches the maximum value of the above-mentioned ammonia storage through experimental calibration under the above-mentioned injection amount condition and the above-mentioned stable operating condition.

[0144] An embodiment of the present invention provides a processor, and the above-mentioned processor is used to run a program, wherein when the above-mentioned program runs, it executes the detection method for the urea consumption deviation fault.

[0145] Specifically, the detection method for the urea consumption deviation fault includes:

[0146] Step S201, under the conditions of meeting the injection amount condition and the stable operating condition, controlling the SCR system to reduce the ammonia storage to 0, and the above-mentioned ammonia storage is the molar concentration of ammonia gas in the above-mentioned SCR system. The above-mentioned injection amount condition includes that the current urea consumption is greater than the predetermined consumption, and the above-mentioned stable operating condition includes that the temperature and the temperature change rate of the above-mentioned SCR system are respectively within the corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within the corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within the corresponding predetermined range;

[0147] Step S202, adjusting the ammonia-nitrogen ratio of the above-mentioned SCR system to a first ammonia-nitrogen ratio, and calculating the ammonia coverage of the SCR catalyst in real time. The above-mentioned first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the above-mentioned ammonia storage to the maximum value of the above-mentioned ammonia storage. The above-mentioned ammonia-nitrogen ratio is the ammonia gas concentration in the above-mentioned SCR system and NOx The ratio of the concentration;

[0148] Step S203, determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1;

[0149] Step S204, when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, determine that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the above injection amount conditions and the above stable operating conditions through experimental calibration. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0150] An embodiment of the present invention provides a vehicle. The device includes an SCR system, a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements at least the following steps:

[0151] Step S201, under the conditions of meeting the injection amount conditions and the stable operating conditions, control the SCR system to reduce the ammonia storage to 0. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount conditions include that the current urea consumption is greater than a predetermined consumption. The stable operating conditions include that the temperature and the temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rate of the exhaust gas and the NO x The mass flow rate of and the mass flow rate of NO x The change rate of the mass flow rate of are respectively within corresponding predetermined ranges;

[0152] Step S202, adjust the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The first ammonia-nitrogen ratio is greater than 1. The ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration in the SCR system to the concentration of NO x The ratio of the concentration;

[0153] Step S203, determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1;

[0154] Step S204, when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, determine that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the above injection amount conditions and the above stable operating conditions through experimental calibration. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

[0155] The present application also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program initialized with at least the following method steps:

[0156] Step S201, when the injection amount condition and the stable operating condition are satisfied, control the SCR system to reduce the ammonia storage to 0. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount condition includes that the current urea consumption is greater than a predetermined consumption, and the stable operating condition includes that the temperature and the temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within a corresponding predetermined range;

[0157] Step S202, adjust the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The first ammonia-nitrogen ratio is greater than 1. The ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration in the SCR system to the concentration of NO x ;

[0158] Step S203, determine the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount;

[0159] Step S204, when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, determine that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount experimentally calibrated for the SCR system to reach the maximum value of the ammonia storage under the injection amount condition and the stable operating condition. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea satisfies the alarm condition.

[0160] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. They can be implemented by program codes executable by the computing device. Thus, they can be stored in a storage device and executed by the computing device. And in some cases, the steps shown or described can be executed in a different order from here, or they can be separately made into individual integrated circuit modules, or multiple modules or steps among them can be made into a single integrated circuit module to implement. In this way, the present invention is not limited to any specific combination of hardware and software.

[0161] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0162] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one or more of the processes Figure 1 or blocks or a combination of blocks.

[0163] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that realize the functions specified in Figure 1 one or more of the processes Figure 1 or blocks or a combination of blocks.

[0164] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in Figure 1 one or more of the processes Figure 1 or blocks or a combination of blocks.

[0165] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0166] The memory may include non-permanent memory in the computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.

[0167] A computer-readable medium includes both permanent and non-permanent, removable and non-removable media and can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassette tapes, magnetic tape magnetic disk storage, or other magnetic storage devices, or any other non-transitory medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media do not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0168] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0169] 1) In the urea consumption deviation fault detection method of the present application, after controlling the SCR system to empty the ammonia storage, the ammonia-nitrogen ratio of the SCR system is adjusted to more than 1 to increase the ammonia storage of the SCR system. The ammonia coverage of the SCR catalyst is calculated in real time until the ammonia coverage of the SCR catalyst is equal to 1, that is, the ammonia storage of the SCR system reaches the maximum value. The current urea injection amount is the target urea injection amount. Comparing with the calibrated injection amount, the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, that is, the target urea injection amount exceeds the injection amount for reaching the maximum value of the ammonia storage calibrated in the experiment by a large amount, indicating a urea consumption deviation fault. For example, the injection pipeline is blocked, and it is applicable to various urea tanks without the need to calibrate the conversion of urea liquid level and sensor voltage, nor to stop injecting urea, ensuring compliance with emissions standards and solving the problem of poor user experience in the existing urea consumption deviation detection method.

[0170] 2) In the urea consumption deviation fault detection device of the present application, when the injection amount condition and the stable operating condition are met, the control unit controls the SCR system to reduce the ammonia storage to 0. The above ammonia storage is the molar concentration of ammonia in the above SCR system. The above injection amount condition includes that the current urea consumption is greater than a predetermined consumption. The above stable operating condition includes that the temperature and temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rate of the exhaust gas and the NO x of the mass flow rate are respectively within corresponding predetermined ranges, and the NO xThe change rate of the mass flow rate is within a corresponding predetermined range; when the injection amount condition and the stable operating condition are satisfied, the calculation unit controls the SCR system to reduce the ammonia storage to 0, where the ammonia storage is the molar concentration of ammonia in the SCR system, the injection amount condition is that the current urea consumption is greater than a predetermined consumption, and the stable operating condition is that the temperature and the temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rate of the exhaust gas and NO x The mass flow rates are respectively within corresponding predetermined ranges and NO x The change rate of the mass flow rate is within a corresponding predetermined range; the first determination unit determines the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount; the second determination unit determines that there is a urea consumption deviation fault when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, where the calibrated injection amount is the injection amount when the SCR system reaches the maximum value of the ammonia storage under the condition of satisfying the injection amount condition and the stable operating condition through experimental calibration, and the urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition. After the device controls the SCR system to empty the ammonia storage, it adjusts the ammonia-nitrogen ratio of the SCR system to more than 1 to increase the ammonia storage of the SCR system, calculates the ammonia coverage of the SCR catalyst in real time until the ammonia coverage of the SCR catalyst is equal to 1, that is, the ammonia storage of the SCR system reaches the maximum value, and the current urea injection amount is the target urea injection amount. Comparing with the calibrated injection amount, when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, that is, the target urea injection amount exceeds the injection amount for reaching the maximum value of the ammonia storage calibrated by the experiment by a large amount, there is a urea consumption deviation fault. For example, the injection pipeline is blocked, and various urea tanks can be used interchangeably without calibrating the conversion between the urea liquid level and the sensor voltage, and there is no need to stop injecting urea to ensure compliance with emissions, solving the problem of poor user experience in the existing urea consumption deviation detection method.

[0171] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A detection method for urea consumption deviation fault, characterized in that, Including: Under the condition of satisfying the injection quantity condition and the stable working condition condition, the SCR system is controlled to reduce the ammonia storage to 0, wherein the ammonia storage is the molar concentration of ammonia in the SCR system, the injection quantity condition includes that the current urea consumption is greater than the predetermined consumption, and the stable working condition includes that the temperature and the temperature change rate of the SCR system are respectively within the corresponding predetermined ranges, the mass flow rate of the exhaust gas and the NO x The mass flow rates of NO x The rate of change of the mass flow rate is within a corresponding predetermined range; Adjust the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of ammonia storage to the maximum value of ammonia storage. The ammonia-nitrogen ratio is the ratio of the ammonia concentration to the NO x concentration in the SCR system; Determine the target urea injection amount as the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1; When the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, it is determined that there is a urea consumption deviation fault. The calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the conditions of meeting the injection amount condition and the stable operating condition through experimental calibration. The urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

2. The method according to claim 1, wherein Controlling the SCR system to reduce the ammonia storage to 0 includes: Adjusting the ammonia-nitrogen ratio of the SCR system to a second ammonia-nitrogen ratio, where the second ammonia-nitrogen ratio is less than 1; When the SCR conversion efficiency remains unchanged within a first predetermined time, it is determined that the SCR system has reduced the ammonia storage to 0.

3. The method according to claim 2, wherein Before determining that the SCR system has reduced the ammonia storage to 0 when the SCR conversion efficiency remains unchanged within a first predetermined time, the method includes: Obtain the first NO x concentration and the second NO x concentration, where the first NO x concentration is the NO of the exhaust gas at the inlet of the SCR system x concentration, and the second NO x concentration is the NO of the exhaust gas at the outlet of the SCR system x concentration; Calculate the second NO x concentration and the first NO x concentration ratio to obtain the unpurified ratio; Calculating the SCR conversion efficiency according to the unpurified ratio, where SCR conversion efficiency = 1 - unpurified ratio.

4. The method according to claim 1, wherein After adjusting the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, the method further includes: Calculating the SCR conversion efficiency in real time; When the first condition and the second condition are met, it is determined that ammonia leakage has occurred. The first condition is that the SCR conversion efficiency rises to a first conversion efficiency and then drops to a second conversion efficiency, and the second condition is that the SCR conversion efficiency remains at the second conversion efficiency for a second predetermined time. The first conversion efficiency is the maximum value of the SCR conversion efficiency during the reaction process.

5. The method according to claim 1, characterized in that, Calculating the ammonia coverage of the SCR catalyst in real time includes: Calculating the reaction rate of each catalytic reaction according to the reaction kinetic equation of the catalytic reaction of the SCR system; Calculating the ammonia coverage of the SCR catalyst according to the reaction rate of each catalytic reaction, the maximum value of the ammonia storage, and the reaction time.

6. The method according to claim 5, wherein Before calculating the ammonia coverage of the SCR catalyst according to the reaction rate of each catalytic reaction, the maximum value of the ammonia storage, and the reaction time, the method includes: Obtaining the current temperature of the SCR system; Looking up the maximum value of the corresponding ammonia storage in the maximum ammonia storage table according to the current temperature. The maximum ammonia storage table is a comparison table of the maximum value of the ammonia storage and the temperature of the SCR system.

7. The method according to any one of claims 1 to 6, characterized in that, After adjusting the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio and calculating the ammonia coverage of the SCR catalyst in real time, the method further includes: When the urea injection speed is a predetermined speed and remains unchanged, determining the urea injection time at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection time; When the ratio of the target urea injection time to the calibrated injection time is greater than the predetermined threshold, it is determined that there is a urea consumption deviation fault. The calibrated injection time is the injection time at which the SCR system reaches the maximum value of the ammonia storage under the conditions of meeting the injection amount condition and the stable operating condition through experimental calibration.

8. A detection device for urea consumption deviation fault, characterized in that Including: A control unit is configured to control the SCR system to reduce the ammonia storage to 0 when the injection amount condition and the stable operating condition are satisfied. The ammonia storage is the molar concentration of ammonia in the SCR system. The injection amount condition includes that the current urea consumption is greater than a predetermined consumption. The stable operating condition includes that the temperature and the temperature change rate of the SCR system are respectively within corresponding predetermined ranges, the mass flow rates of the exhaust gas and NO x are respectively within corresponding predetermined ranges, and the change rate of the mass flow rate of NO x is within a corresponding predetermined range; The first calculation unit is configured to adjust the ammonia-nitrogen ratio of the SCR system to a first ammonia-nitrogen ratio, and calculate the ammonia coverage of the SCR catalyst in real time. The first ammonia-nitrogen ratio is greater than 1, and the ammonia coverage of the SCR catalyst is the ratio of the actual value of the ammonia storage to the maximum value of the ammonia storage. The ammonia-nitrogen ratio is the ratio of the concentration of NO x in the SCR system to the nitrogen concentration; A first determination unit, configured to determine the urea injection amount at the moment when the ammonia coverage of the SCR catalyst reaches 1 as the target urea injection amount; A second determination unit, configured to determine that there is a urea consumption deviation fault when the ratio of the target urea injection amount to the calibrated injection amount is greater than a predetermined threshold, where the calibrated injection amount is the injection amount at which the SCR system reaches the maximum value of the ammonia storage under the condition of meeting the injection amount condition and the stable operating condition during experimental calibration, and the urea consumption deviation fault is a fault where the deviation between the theoretical calculated value and the actual consumption value of urea meets the alarm condition.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein when the program runs, it controls the device where the computer-readable storage medium is located to execute the method according to any one of claims 1 to 7.

10. A vehicle, characterized in that, Comprising: An SCR system, one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include methods for executing the method according to any one of claims 1 to 7.

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