Methods, systems and automobiles for controlling urea injection volume

Abstract

This invention discloses a method, system, and vehicle for controlling urea injection quantity, relating to the field of automotive exhaust gas treatment. The method includes the following steps: under stable engine conditions, determining the NH3 leakage state based on NOx data before and after urea injection, and adjusting the urea injection quantity according to the NH3 leakage state; the stable state refers to the steady-state parameters related to the engine's stable state meeting steady-state conditions. This application can adjust and control the urea injection quantity according to the NH3 leakage state, thereby avoiding or reducing urea over-injection and thus reducing operating costs; particularly for vehicles operating at high speeds for extended periods with relatively stable engine conditions, it can effectively reduce urea consumption.

Description

Technical Field

[0001] This application relates to the field of automotive exhaust treatment, specifically to a method, system, and vehicle for controlling the amount of urea injected. Background Technology

[0002] Urea-SCR (Selective Catalytic Reduction) is a technology used to reduce NOx (nitrogen oxides) emissions from diesel vehicle exhaust. This technology injects an aqueous urea solution (typically 32.5% by mass) into the engine's exhaust system (exhaust pipe) through a urea injection system. The urea decomposes at high temperatures to produce NH3 (ammonia). NH3 reacts with NOx under the action of a catalyst to produce harmless nitrogen and water, thereby reducing NOx emissions.

[0003] Currently, Urea-SCR technology is considered the most effective method for reducing NOx emissions from automotive diesel engines. Through a urea injection system, a 32.5% urea aqueous solution is injected into the exhaust pipe. After passing through processes such as wall collision, evaporation, hydrolysis, and pyrolysis, it is converted into NH3, which then reacts with NO. x This reaction reduces NOx emissions from automotive diesel engines.

[0004] Currently, diesel engine exhaust treatment generally adopts a structure of DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + SCR + ASC (Ammonia Slip Catalyst), and still uses Urea-SCR technology to reduce NO. x emission.

[0005] DOC has three main functions: reducing HC (hydrocarbon) emissions by oxidizing HC in exhaust gas into H2O and CO2; oxidizing NO into NO2 by oxidizing carbon particles captured by the DPF into gaseous CO2; and oxidizing fuel injected into the exhaust pipe by oxidizing diesel fuel, which releases heat and raises the temperature of the DPF, causing carbon in the DPF to react with oxygen to form CO2.

[0006] DPF is mainly used to capture particulates in exhaust gas to meet the requirements for particulate number (PN) in exhaust emissions.

[0007] ASC is mainly used for: eliminating excess or escaped NH3; oxidizing excess NH3 to N2, N2O, NO. x Simultaneously, recatalyze NO x NH3 reacts to produce nitrogen gas (N2).

[0008] With increasingly stringent emission regulations, NO x With emission limits becoming increasingly stringent, more precise urea injection control strategies are needed to achieve the highest possible NO levels. x Conversion efficiency and minimal NH3 leakage.

[0009] Meanwhile, current engine development processes generally use the specified WHTC / WHSC and vehicle PEMS cycles as standard development cycles. These operating conditions include many dynamic conditions with significant variations, causing the catalyst temperature and space velocity to change drastically, thus affecting the catalyst conversion efficiency.

[0010] Based on this, if we always follow NO x A 1:1 equivalent ratio of urea to NH3, controlling the urea injection rate, may result in: some NO x During the rapid increase, the actual urea injection rate cannot keep up with the NO injection rate. x The rate of increase in emissions has led to the emergence of NO x In cases of excessive emissions, the actual injection control is generally based on over-injection.

[0011] According to the statistics of the specified transient cycle WHTC operating conditions, the actual injection volume is compared with the theoretical urea injection volume calculated according to the equivalent ratio of 1. The over-injection coefficient is generally in the range of 1.05 to 1.1. The excess urea (NH3) is oxidized by ASC into N2, H2O, etc.

[0012] Therefore, urea is basically in an over-spraying state under various operating conditions. Although the over-sprayed portion is oxidized by ASC, NO... x The levels are not exceeded, but the urea consumption is high, resulting in higher costs for users. Summary of the Invention

[0013] To address the shortcomings of existing technologies, the technical problem solved by this invention is: how to control the amount of urea injected, thereby avoiding or reducing the occurrence of over-injection of urea, and thus reducing the cost of use.

[0014] To achieve the above objectives, in a first aspect, embodiments of this application provide a method for controlling the amount of urea injection. The method includes the following steps: under the condition that the engine has reached a stable state, determining the leakage state of NH3 based on NOx data before and after urea injection, and adjusting the amount of urea injection based on the leakage state of NH3; the stable state refers to the steady-state parameters related to the engine's stable state meeting the steady-state conditions.

[0015] In conjunction with the first aspect, in one embodiment, the process of determining the NH3 leakage status based on NOx data before and after urea injection, and adjusting the urea injection volume based on the NH3 leakage status, includes: determining the NH3 leakage value based on NOx data before urea injection and NOx data after urea injection at adjacent time points.

[0016] When the NH3 leakage value is non-zero, it indicates that there is an NH3 leakage, and the urea injection amount should be reduced.

[0017] When the NH3 leakage value is 0, it means that there is no NH3 leakage, and the urea injection rate remains unchanged.

[0018] In conjunction with the first aspect, in one embodiment, the method further includes the following steps: under the condition that there is no NH3 leakage, determining the NOx specific emission based on the NOx emission and cumulative work within the NOx emission detection period; adjusting the urea injection amount based on the NOx specific emission; wherein the NOx emission detection period is: the period between the start time of recording cumulative work and the next time when the cumulative work is above the cumulative work threshold at a certain moment.

[0019] In conjunction with the first aspect, in one implementation, the NOx emission ratio is obtained by dividing the NOx emission amount by the cumulative work.

[0020] In conjunction with the first aspect, in one embodiment, the process of adjusting the urea injection volume according to the NOx emission ratio includes:

[0021] When the NOx emission ratio is less than the emission threshold range, reduce the urea injection rate;

[0022] When the NOx emission ratio exceeds the emission threshold, the urea injection rate is increased.

[0023] In conjunction with the first aspect, in one implementation, the process for determining the steady state includes: determining that the engine is in a steady state under the enabling conditions of the engine being in a steady state; the enabling conditions of the steady state are determined based on the engine speed, torque, and environmental parameters.

[0024] In conjunction with the first aspect, in one implementation, the process for determining whether the steady-state parameter meets the steady-state condition includes: determining that the value of the steady-state parameter meets a specified threshold; the process for determining the value of the steady-state parameter includes: determining the average value of the steady-state parameter within a specified period and the actual value of the parameter at the next moment after the specified period; and taking the absolute value of the difference between the average value and the actual value as the value of the steady-state parameter.

[0025] In conjunction with the first aspect, in one implementation, the steady-state parameters include: the change in engine speed, the change in engine torque, and the change in vehicle speed.

[0026] Secondly, embodiments of this application provide a control system for urea injection volume, the system comprising: a controller, a steady-state parameter sampling module, and a urea injection module;

[0027] The controller is used to: execute the process provided in the first aspect of determining the NH3 leakage status based on NOx data before and after urea injection, under the condition that the engine has reached a stable state, and adjusting the urea injection quantity based on the NH3 leakage status;

[0028] The steady-state parameter sampling module is used to: provide the controller with the parameters required for the engine to reach a steady state;

[0029] The urea injection module is used to inject urea according to the controller's instructions.

[0030] Thirdly, embodiments of this application provide an automobile that includes the urea injection quantity control system provided in the second aspect.

[0031] The beneficial effects of the technical solutions provided in this application include:

[0032] (1) This application can determine the NH3 leakage state based on NOx data before and after urea injection when the engine reaches a stable state, and then adjust the urea injection amount accordingly based on the NH3 leakage state. Therefore, compared with the excessive urea injection in the prior art, this application can adjust and control the urea injection amount according to the NH3 leakage state, thereby avoiding or reducing the occurrence of urea over-injection and thus reducing operating costs; especially for vehicles that are in a high-speed operation scenario for a long time and whose engine state is relatively stable, it can effectively reduce urea consumption.

[0033] (2) In addition to adjusting and controlling the urea injection amount according to the leakage state of NH3, this application will further adjust the urea injection amount according to the NOx emission ratio when the cumulative work exceeds the cumulative work threshold, thereby improving the adjustment accuracy of the urea injection amount and further reasonably controlling the cost. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the method for controlling the amount of urea injected in an embodiment of this application.

[0035] Figure 2 This is a schematic diagram of the hardware structure of the urea injection volume control device involved in the embodiments of this application. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0037] The research and development principle and concept of this application are as follows: After research, the applicant concluded that when the engine is in steady-state operating conditions, the urea injection quantity can be appropriately reduced to reduce the oxidation effect of ASC on urea, thereby appropriately reducing urea consumption while meeting NOx and NH3 emission requirements.

[0038] In a first aspect, embodiments of this application provide a method for controlling the injection quantity of urea (urea aqueous solution). The method includes the following steps: under the condition that the engine reaches a stable state, determining the leakage state of NH3 based on NOx data before and after urea injection, and adjusting the urea injection quantity accordingly based on the leakage state of NH3; the aforementioned stable state refers to the steady-state parameters related to the engine's stable state meeting the steady-state conditions.

[0039] Therefore, this application can determine the NH3 leakage state based on NOx data before and after urea injection, under stable engine conditions, and then adjust the urea injection quantity accordingly. Thus, compared to excessive urea injection in existing technologies, this application can adjust and control the urea injection quantity based on the NH3 leakage state, thereby avoiding or reducing urea over-injection and lowering operating costs. This is particularly effective for vehicles operating at high speeds for extended periods with relatively stable engine conditions, significantly reducing urea consumption.

[0040] In one embodiment, the process for determining the steady state includes: determining that the engine is in a steady state under the enabling conditions of the engine being in a steady state; the enabling conditions of the steady state are determined based on the engine speed, torque and environmental parameters.

[0041] Specifically, the enabling conditions for an engine to reach a steady state include:

[0042] (1) The engine speed, torque, coolant temperature, ambient temperature and ambient pressure are all above their respective set thresholds;

[0043] (2) NOx data can be collected normally (i.e., the front and rear NOx sensors are working normally);

[0044] (3) Urea injection is normal (i.e., the urea injection system is working normally).

[0045] Point (1) specifically includes:

[0046] The engine speed is above the set speed threshold;

[0047] The engine torque is above the torque setting threshold;

[0048] The engine coolant temperature is above the torque setting threshold;

[0049] The engine's ambient temperature is within the temperature threshold range (greater than or equal to the minimum temperature threshold and less than or equal to the maximum temperature threshold);

[0050] The engine's ambient pressure is within the pressure threshold range (greater than or equal to the minimum pressure threshold and less than or equal to the maximum pressure threshold).

[0051] In one embodiment, the aforementioned steady-state parameters include: the change in engine speed, the change in engine torque, and the change in vehicle speed.

[0052] Specifically, the process for determining whether the aforementioned steady-state parameter meets the steady-state condition includes: determining that the value of the steady-state parameter meets a specified threshold (below the specified threshold). The process for determining the value of the steady-state parameter includes: determining the average value of the parameter within a specified period, and the actual value of the parameter at the next moment after the specified period (the precision of the next moment can be in minutes or seconds, and the specific time is not limited); the absolute value of the difference between the average value and the actual value of the parameter is taken as the value of the parameter.

[0053] The following explanation uses the change in vehicle speed as an example.

[0054] If the specified period is 10s and the time accuracy is 1s, then the statistics are started from time T0, and the average vehicle speed from T0 to T9 is calculated. The actual vehicle speed at time T10 is compared with the average vehicle speed, and the absolute value of the difference between the two speeds is calculated. If the absolute value is below the set vehicle speed change threshold, it means that the vehicle speed is stable.

[0055] It should be noted that the above process is a cyclical process, which compares the average vehicle speed in the range of T0 to T9 with the actual vehicle speed at time T10, and also compares the average vehicle speed in the range of T1 to T10 with the actual vehicle speed at time T11, and so on.

[0056] The method for determining whether other steady-state parameters (engine speed change and engine torque change) meet the specified thresholds is the same as the method for determining the vehicle speed change.

[0057] In one embodiment, the process of determining the NH3 leakage status based on NOx data before and after urea injection and adjusting the urea injection volume based on the NH3 leakage status includes: obtaining the NH3 leakage value based on the NOx data before urea injection (collected by the front NOx sensor) and the NOx data after urea injection (collected by the rear NOx sensor, i.e., the NOx data before and after urea injection at the current time and the previous time, similar to the above, the time accuracy is not limited, generally in minutes or seconds). (Based on the above information disclosure, the specific calculation method of the NH3 leakage result is common knowledge in the art and will not be elaborated here.)

[0058] When the NH3 leakage value is non-zero, it indicates that there is an NH3 leakage, and the urea injection rate should be reduced.

[0059] When the NH3 leakage value is 0, it means that there is no NH3 leakage, and the urea injection rate remains unchanged.

[0060] In one embodiment, the above method further includes the following steps: under the condition that there is no NH3 leakage, determining the NOx specific emission based on the NOx emission and cumulative work within the NOx emission detection period; and adjusting the urea injection rate based on the NOx specific emission. The NOx emission detection period is the period from the start of recording the cumulative work to the next moment when the cumulative work is above the cumulative work threshold at a certain moment (similar to the above, the time accuracy is not limited, generally minutes or seconds).

[0061] For example: Starting from time T0, the cumulative work and NOx emissions are calculated in units of 1 second. If the cumulative work at a certain time is less than the work of the set work base window (cumulative work threshold), but is greater than or equal to the work threshold of the set work base window at the next time, then it is considered to be a work base window; the NOx emissions and cumulative work of the work base window are statistically analyzed.

[0062] It should be noted that, similar to the process for determining steady-state parameters that meet steady-state conditions, the adjustment of urea injection based on NOx ratio emissions after determination is also a polling process. This results in multiple work base windows with different time periods, such as T0 to T10, where T0 is the start time for recording accumulated work, and T10 is the next time the accumulated work exceeds the accumulated work threshold; similarly, T1 to T11, where T1 is the start time for recording accumulated work, and T11 is the next time the accumulated work exceeds the accumulated work threshold, and so on. The urea injection rate is adjusted after each determination of NOx ratio emissions.

[0063] Therefore, this application, in addition to adjusting and controlling the urea injection volume according to the leakage state of NH3, will further adjust the urea injection volume according to the NOx emission ratio when the cumulative work exceeds the cumulative work threshold, thereby improving the adjustment accuracy of the urea injection volume and further reasonably controlling the cost.

[0064] Specifically, NOx emissions are calculated by dividing NOx emissions by cumulative work.

[0065] Meanwhile, the above process for adjusting urea injection volume based on NOx emission ratio includes:

[0066] When the NOx emission ratio is less than the emission threshold range (i.e., less than the lower emission limit threshold), it indicates that the urea injection volume is too high, and the urea injection volume should be reduced in this case.

[0067] When the NOx emission ratio is greater than the emission threshold range (i.e., greater than the upper emission limit threshold), it indicates that the urea injection quantity is too low, and the urea injection quantity should be increased.

[0068] When NOx emissions fall within the emission threshold range (i.e., greater than or equal to the lower emission threshold and less than or equal to the upper emission threshold), it indicates that the urea injection rate is appropriate, and the urea injection rate should be kept constant.

[0069] See below. Figure 1 As shown, the above method is illustrated from a timing perspective through an embodiment.

[0070] S1: Perform urea injection according to the initially calibrated urea injection quantity (i.e., set the injection correction factor to 1).

[0071] S2: Determine whether the engine is in a steady state (see the corresponding section above for details). If so, set the engine state determination enable to TRUE and proceed to S3; otherwise, set it to FALSE and end.

[0072] S3: Determine if the engine is in a stable state (see the corresponding section above for details). If yes, proceed to S4; otherwise, end.

[0073] S4: Determine if there is an NH3 leak (see the corresponding section above for details). If so, reduce the urea injection volume and re-execute S4; otherwise, proceed to S5.

[0074] S5: The cycle determines the NOx emission ratio based on the NOx emission and cumulative work during the NOx emission detection cycle; the urea injection volume is adjusted based on the NOx emission ratio.

[0075] If the engine's stable state changes during the execution of S1 to S5 (exits stable state or regeneration occurs), it will return to S1.

[0076] Secondly, embodiments of this application also provide a control system for urea injection volume, including: a controller, a steady-state parameter sampling module, and a urea injection module.

[0077] The controller is used to: determine the NH3 leakage status based on NOx data before and after urea injection after the engine has reached a stable state, and control the urea injection module to adjust the urea injection quantity accordingly based on the NH3 leakage status; specifically:

[0078] The process for determining the steady state includes: determining that the engine is in a steady state under the enabling conditions of steady state; the enabling conditions of steady state are determined based on the engine speed, torque and environmental parameters.

[0079] Specifically, the enabling conditions for an engine to reach a steady state include:

[0080] (1) The engine speed, torque, coolant temperature, ambient temperature and ambient pressure are all above their respective set thresholds;

[0081] (2) NOx data can be collected normally (i.e., the front and rear NOx sensors are working normally);

[0082] (3) Urea injection is normal (i.e., the urea injection system is working normally).

[0083] Steady-state parameters include: changes in engine speed, changes in engine torque, and changes in vehicle speed.

[0084] The process for determining whether a steady-state parameter meets the steady-state condition includes: determining that the value of the steady-state parameter meets a specified threshold (below the specified threshold). The process for determining the value of the steady-state parameter includes: determining the average value of the parameter within a specified period, and the actual value of the parameter at the next moment after the specified period (the precision of the next moment can be in minutes or seconds, and the specific time is not limited); the absolute value of the difference between the average value and the actual value of the parameter is taken as the value of the parameter.

[0085] The process of determining the NH3 leakage status based on NOx data before and after urea injection, and adjusting the urea injection volume based on the NH3 leakage status, includes: obtaining the NH3 leakage value based on the NOx data before urea injection (collected by the front NOx sensor) and the NOx data after urea injection (collected by the rear NOx sensor, i.e., the NOx data before and after urea injection at the current time and the previous time, similar to the above, with no limitation on the time accuracy, generally in minutes or seconds).

[0086] When the NH3 leakage value is non-zero, it indicates that there is an NH3 leakage, and the urea injection rate should be reduced.

[0087] When the NH3 leakage value is 0, it means that there is no NH3 leakage, and the urea injection rate remains unchanged.

[0088] The controller is also used to: determine the NOx emission ratio based on the NOx emission and cumulative work during the NOx emission detection cycle, under the condition that there is no NH3 leakage; and adjust the urea injection volume based on the NOx emission ratio. The NOx emission detection cycle is the period from the start of recording the cumulative work to the next moment when the cumulative work is above the cumulative work threshold at a certain moment (similar to the above, the time accuracy is not limited, generally minutes or seconds).

[0089] NOx emissions are calculated by dividing NOx emissions by cumulative work.

[0090] The process for adjusting urea injection volume based on NOx emission ratio includes:

[0091] When the NOx emission ratio is less than the emission threshold range (i.e., less than the lower emission limit threshold), it indicates that the urea injection volume is too high, and the urea injection volume should be reduced in this case.

[0092] When the NOx emission ratio is greater than the emission threshold range (i.e., greater than the upper emission limit threshold), it indicates that the urea injection quantity is too low, and the urea injection quantity should be increased.

[0093] When NOx emissions fall within the emission threshold range (i.e., greater than or equal to the lower emission threshold and less than or equal to the upper emission threshold), it indicates that the urea injection rate is appropriate, and the urea injection rate should be kept constant.

[0094] The steady-state parameter sampling module is used to provide the controller with the parameters required for the engine to reach a steady state. Specifically, the steady-state parameter sampling module includes acquisition devices for acquiring the steady-state parameters mentioned above and the enabling conditions for the engine to be in a steady state, such as front and rear NOx sensors, vehicle speed sensor, and speed sensor.

[0095] The urea injection module is used to inject urea according to the controller's instructions.

[0096] Thirdly, embodiments of this application provide an automobile that includes a control system for the amount of urea injection mentioned in the second aspect.

[0097] Fourthly, embodiments of this application provide a device for controlling the amount of urea injected. The device for controlling the amount of urea injected can be a personal computer (PC), a laptop computer, a server, or other device with data processing capabilities.

[0098] Reference Figure 2 , Figure 2This is a schematic diagram of the hardware structure of the urea injection volume control device involved in the embodiments of this application. In the embodiments of this application, the urea injection volume control device may include a processor, a memory, a communication interface, and a communication bus.

[0099] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0100] The communication interface includes input / output (I / O) interfaces, physical interfaces, and logical interfaces used for interconnecting internal components of the urea injection control device, as well as interfaces used for interconnecting the urea injection control device with other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0101] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0102] The processor can be a general-purpose processor, which can call the urea injection quantity control program stored in the memory and execute the urea injection quantity control method provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the urea injection quantity control program is called can be referred to in the various embodiments of the urea injection quantity control method of this application, and will not be repeated here.

[0103] Those skilled in the art will understand that Figure 2 The hardware structure shown does not constitute a limitation of this application and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0104] Fifthly, embodiments of this application also provide a computer-readable storage medium.

[0105] The present application has a computer-readable storage medium storing a control program for urea injection volume, wherein when the control program for urea injection volume is executed by a processor, the steps of the urea injection volume control method described above are implemented.

[0106] The method implemented when the urea injection quantity control procedure is executed can be referred to in various embodiments of the urea injection quantity control method of this application, and will not be repeated here.

[0107] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0108] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0109] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0110] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0111] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0112] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0113] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0114] The above are merely specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling the amount of urea injected, characterized in that, The method includes the following steps: under the condition that the engine reaches a stable state, the leakage state of NH3 is determined based on the NOx data before and after urea injection, and the urea injection quantity is adjusted according to the leakage state of NH3; the stable state refers to the steady-state parameters related to the engine's stable state meeting the steady-state conditions. The process for determining whether a steady-state parameter meets steady-state conditions includes: determining that the value of the steady-state parameter meets a specified threshold; the process for determining the value of the steady-state parameter includes: determining the average value of the steady-state parameter within a specified period and the actual value of the parameter at the next moment after the specified period; and taking the absolute value of the difference between the average value and the actual value as the value of the steady-state parameter.

2. The method for controlling the amount of urea injected as described in claim 1, characterized in that, The process of determining the NH3 leakage status based on NOx data before and after urea injection, and adjusting the urea injection volume based on the NH3 leakage status, includes: determining the NH3 leakage value based on NOx data before and after urea injection at adjacent time points. When the NH3 leakage value is non-zero, it indicates that there is an NH3 leakage, and the urea injection amount should be reduced. When the NH3 leakage value is 0, it means that there is no NH3 leakage, and the urea injection rate remains unchanged.

3. The method for controlling the amount of urea injected as described in claim 2, characterized in that, The method further includes the following steps: under the condition that there is no NH3 leakage, determining the NOx specific emission based on the NOx emission and cumulative work during the NOx emission detection period; adjusting the urea injection amount based on the NOx specific emission; the NOx emission detection period is: the period between the start time of recording cumulative work and the next time when the cumulative work is above the cumulative work threshold at a certain moment.

4. The method for controlling the amount of urea injected as described in claim 3, characterized in that: The NOx emission ratio is obtained by dividing the NOx emission amount by the cumulative work.

5. The method for controlling the urea injection volume as described in claim 3, characterized in that, The process of adjusting the urea injection volume based on the NOx emission ratio includes: When the NOx emission ratio is less than the emission threshold range, reduce the urea injection rate; When the NOx emission ratio exceeds the emission threshold, the urea injection rate is increased.

6. The method for controlling the urea injection volume as described in any one of claims 1 to 5, characterized in that, The process for determining the steady state includes: determining that the engine is in a steady state under the enabling conditions of the engine being in a steady state; the enabling conditions of the steady state are determined based on the engine speed, torque and environmental parameters.

7. The method for controlling the amount of urea injected as described in any one of claims 1 to 5, characterized in that: The steady-state parameters include: changes in engine speed, changes in engine torque, and changes in vehicle speed.

8. A control system for urea injection volume, characterized in that, The system includes: a controller, a steady-state parameter sampling module, and a urea injection module; The controller is used to: execute the process described in any one of claims 1 to 7, under the condition that the engine has reached a stable state, to determine the leakage state of NH3 based on NOx data before and after urea injection, and to adjust the urea injection quantity based on the leakage state of NH3. The steady-state parameter sampling module is used to: provide the controller with the parameters required for the engine to reach a steady state; The urea injection module is used to inject urea according to the controller's instructions.

9. A car, characterized in that: The vehicle includes a control system for the amount of urea injection as described in claim 8.

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