SCR fault diagnosis method and device

A fault diagnosis and detection technology, which is applied in the diagnosis device of exhaust treatment device, electronic control of exhaust treatment device, complex mathematical operation, etc., can solve the problems of easy false alarm and no alarm, etc. Diagnosis accuracy and accuracy, and the effect of improving user experience

Pending Publication Date: 2021-12-10

WEICHAI POWER CO LTD

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This SCR fault diagnosis method is easy to report false alarms (the SCR is a good part but...

Abstract

The invention provides an SCR fault diagnosis method and device. The method comprises the following steps: inputting a conversion efficiency calculation parameter of a to-be-detected SCR into an SCR conversion efficiency calculation function to obtain conversion efficiency values of the to-be-detected SCR corresponding to N information acquisition time windows; inputting the conversion efficiency value of the to-be-detected SCR into the probability density function of the SCR conversion efficiency to obtain a probability value that the to-be-detected SCR corresponding to each information acquisition window is a degraded part; inputting N probability values, corresponding to the N information acquisition time windows, of the to-be-detected SCR as the degraded part into a probability factor calculation function of the SCR as the degraded part to obtain a probability factor of the SCR as the degraded part; and when the probability factor that the SCR is the degraded part is greater than a preset probability factor, determining that the SCR has a fault. According to the method, the accuracy of SCR fault diagnosis can be improved.

Application Domain

Internal combustion piston enginesChemical processes analysis/design +3

Technology Topic

Real-time computingInformation acquisition +4

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Example Embodiment

[0045] Exemplary embodiments will be described in detail herein, and examples are illustrated in the drawings. The following description is related to the drawings, unless otherwise indicated, the same figures in the different drawings represent the same or similar elements. The embodiments described in the exemplary embodiments described below do not represent all embodiments consistent with the present disclosure. Instead, they are only examples of apparatus and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0046] The diesel engine during operation can produce nuisance nitrogen oxides (NO X ), To meet statutory requirements of diesel emissions, the conventional diesel engine aftertreatment system are mostly selective catalytic reduction unit (SelectiveCatalystic Reduction, SCR) installed. The selective catalytic reduction unit by reducing the nitrogen oxides to nitrogen pollution to the catalyst installed in the exhaust line of a diesel engine injected urea aqueous solution.

[0047] According to regulations, a diesel engine control (Engine control Unit, referred to as ECU) of the diesel engine requires the SCR NO X Switch nitrogen efficiency (i.e., as good if the SCR element) real-time diagnosis, and upon detecting a predetermined NO X When the emissions exceed preset limits, a warning SCR requires a low transformation efficiency fault occurs (i.e., degradation of SCR member). Existing fault diagnosis method just SCR SCR conversion efficiency in a single information acquisition time window is calculated, and then calculating a simple determination result to determine whether the SCR failure. This method is easy to SCR fault diagnosis reported false alarm (SCR to SCR failure alarms but good member), or no alarm when the real fault SCR.

[0048] Specifically, the conventional SCR fault diagnosis depends on only a single information acquisition time window, and determining whether the fault SCR SCR by the environment, deterioration SCR, a sensor for gas concentration detection error of the SCR, the SCR control deviation and other aspects interference factors, SCR conversion efficiency in the use of a single information acquisition time window is determined whether or SCR failure, is easy because the effects of these interfering factors and false alarm or no alarm situation occurs. For example, by the SCR conversion efficiency of the SCR benign member of the environment, deterioration SCR, a sensor error factors like gas concentrations detected in the SCR, degradation of SCR misdiagnosis member. SCR is a case where the alarm has not deteriorated member failed SCR SCR conversion efficiency due to deterioration member adapted to their environment SCR, degradation of SCR, sensor error factor for gas concentration detection like the SCR, the SCR conversion efficiency results in compliance with regulatory requirements.

[0049] Therefore, the diagnosis of the existing conversion efficiency SCR (SCR whether the deterioration of the piece) output diagnostic methods are not accurate, how to improve the conversion efficiency SCR (SCR whether the deterioration pieces) diagnostic results, is still a serious problem.

[0050] Based on this, the present application provides a method and apparatus for SCR fault diagnosis, based on the N information acquisition time window (N is an integer greater than 1) corresponding to SCR SCR determines whether a failure probability factor deterioration member. Only methods to determine values for the SCR conversion efficiency corresponding to a single information acquisition window compared to the prior art SCR whether the fault, using the probability factor provided herein to determine whether a failure of the SCR have further practical operation circumvents the SCR the impact of confounding factors for troubleshooting the SCR. Therefore, you can get a more accurate fault diagnosis on whether SCR, SCR improve the accuracy of fault diagnosis.

[0051] SCR provides fault diagnosis method of the present application is applied to an electronic device, the electronic device such as a diesel controller (Engine control Unit, referred to as ECU). figure 1 Application of an SCR schematic fault diagnosis method of the present application provides, in FIG., The diesel engine is a selective catalytic reduction unit (Selective Catalystic Reduction, SCR) downstream and upstream is provided with a sensor that collected data to the electronic device. The electronic device to capture the concentration of nitrogen oxides upstream and downstream of the SCR, the mass, the mass flow rate sensor data.

[0052] See figure 2 , According to a first embodiment of the present application an SCR fault diagnosis method, the ECU is applied to a diesel engine controller, the method comprising:

[0053] S210, obtaining the selective catalytic reduction unit to be detected SCR conversion efficiency calculation parameters, the conversion efficiency calculation parameters include: the mass flow rate of nitrogen oxides to be detected downstream of the SCR information in the acquisition window of N, N information acquisition window mass flow rate of nitrogen oxides within the SCR to be detected upstream of the start time point N information acquisition time and the end time window; N is an integer greater than 1.

[0054] Information collection time window having a start time point and end time point, it can be understood as the information acquisition time interval. When the information collected during the SCR to be detected, it is graded based on the plurality of acquired information acquisition time window, i.e., the time window for each information collection message to the SCR will collect part of this information collection time window. The SCR information e.g. the concentration of nitrogen oxides SCR described in the above upstream and downstream, mass, mass flow data, information of the SCR varies with time, so that each time the information acquisition window will capture specific values has a difference.

[0055] Preferably, this long acquisition time window information in the embodiment, i.e., a time difference between a start time point and end time point may be ten minutes.

[0056] SCR to be detected upstream of the intake port will be appreciated that the SCR to be detected, which will be understood to be detected downstream of the SCR as the SCR outlet to be detected, the SCR to be detected both upstream and downstream provided with a sensor, the position sensor may be specifically provided according to the actual need to select. Specifically, upstream of the SCR to be detected and the detection sensor to be disposed downstream of the SCR were collected molar concentration of nitrogen oxides and nitrogen oxides the total molar amount of the exhaust gas. The collected molar concentration of nitrogen oxides, nitrogen oxides, and the total molar amount of exhaust nitrogen oxide molar mass can be obtained by multiplying the mass flow of the nitrogen oxides.

[0057] Alternatively, in order to make the conversion efficiency of the SCR parameters to be detected to be more consistent with the affect SCR operation capacity detection itself, and less susceptible to external interference factors obtained, can be detected when the SCR is in a predetermined operating condition obtaining be detected SCR conversion efficiency calculation parameters. The predetermined operating condition comprises at least: the temperature of the exhaust gas upstream of the SCR to be detected within a preset temperature threshold, the SCR to be detected in the preset volume hourly space velocity within the space velocity, the concentration of nitrogen oxides to be detected upstream of the SCR predetermined concentration range. The predetermined temperature threshold value, the predetermined volume of space velocity and the predetermined concentration range can be set according to actual needs, the present application is not limited.

[0058] S220, the conversion efficiency of the SCR to be detected is inputted to the calculation parameter SCR conversion efficiency calculation function, a value obtained conversion efficiency of the SCR to be detected for each of the time windows corresponding to the information collection.

[0059] The ECU stores the SCR conversion efficiency calculation function, the conversion efficiency of the SCR and the SCR probability density function calculated as a function of the probability factor deterioration member.

[0060] Specifically, the conversion efficiency of the SCR calculation function to be used for the detection of nitrogen oxide mass flow downstream of the SCR information in each acquisition window according to the starting time point of each information acquisition time window and the end time point to be calculated detecting nitrogen oxide mass downstream of SCR. The oxygen compound and the nitrogen mass flow upstream of the SCR to be detected within the acquisition time window for each message, a start time point of each information acquisition window in time and an end time point of the nitrogen oxide mass calculated upstream of the SCR is to be detected . The nitrogen oxide mass further downstream of the SCR to be detected for each of the time windows corresponding to the information collection, upstream of the nitrogen oxide mass of each information acquisition window to be detected corresponding to the SCR, the calculated time of each information corresponding to the window to be detected SCR conversion efficiency value.

[0061] Specifically, SCR conversion efficiency is calculated as a function Which, η M The representative value of the conversion efficiency of the SCR to be detected in the M-th information corresponding to the time window, Representing the M-th information acquisition time window corresponding to the nitrogen oxide mass flow downstream of the SCR to be detected, Representing the M-th information acquisition time window corresponding to the nitrogen oxide mass flow upstream of the SCR to be detected, Ti represents the starting point of time of the M-th information acquisition time window, Ti + t each information representative of the acquisition window the end point of time, wherein t represents the length of the M-th information acquisition time window; M is greater than 1, and M is less than or equal to N.

[0062] S230, the information acquisition window corresponding to each of the conversion efficiency of the SCR to be detected value of the input to the SCR conversion efficiency of the probability density function to obtain information of each of the acquisition window corresponding to a probability value to be detected is deteriorated SCR element.

[0063] Probability density function is a function of continuous random variable, the output value of the random variable is a description of the function in the possibility of a point close to the value determined. SCR conversion efficiency on the probability density function is a value of SCR conversion efficiency when, as a function of the likelihood of degradation of SCR element, the probability density function of the output of the conversion efficiency of the SCR to be detected value of the SCR is the value of the degradation probability member .

[0064] Alternatively, when the probability of creation of the SCR conversion efficiency density function is already determined to be part of the deterioration of the SCR determined. Specifically, the member acquires deterioration SCR conversion efficiency corresponding to a plurality of information values in acquisition time window, determining the conversion efficiency of these values fall within a frequency interval efficiency value for each set. A plurality of sections set efficiency value of the horizontal axis and values fall in the conversion efficiency of the efficiency values of the frequency setting interval of the vertical axis, to generate two-dimensional map. Frequency values on the two-dimensional graph in the form of markers of these values fall within each of the conversion efficiency of the efficiency of the set interval value, based on the plurality of two-dimensional points marked in FIG fitted curve, then the curve of some calculation processing, it is possible to obtain the conversion efficiency of the SCR probability density function.

[0065] Many ways to create probability density function of the SCR conversion efficiency of the prior art, these are just a. The present application is not limited conversion efficiency of the SCR probability density function creating process to create a long conversion efficiency of the SCR probability density function may be a probability value SCR value output device according to the deterioration of the conversion efficiency.

[0066] S240, the N information corresponding to the acquisition time window for the N SCR to be detected probability values of the input member to the degradation of the SCR is the probability factor calculation function deterioration member, to obtain the probability of deterioration of the SCR element factor.

[0067] Specifically, the deterioration of the SCR is the probability factor calculation function member for: calculating a value to be detected on the N SCR is the probability values respectively corresponding to the deterioration of the member; summing and averaging the N calculated probability values respectively corresponding to the values of the value of the probability factor is deteriorated SCR element.

[0068] This SCR is calculated as a function of the probability factor deterioration member Where g N Representative N information corresponding to the acquisition time window for the deterioration of the SCR element probability factor, P (η M ) Represents the conversion efficiency of the SCR probability density function, η MThe conversion efficiency value of the SCR to be detected in accordance with the Mth information acquisition time window.

[0069] For example, n is equal to 3, g N A probability factor corresponding to the three probability values to be detected by the SCR as the deterioration piece corresponding to the first information acquisition time window to the third information acquisition time window (3 information acquisition time windows) corresponds to the SCR of the SCR to be detected.

[0070] S250 determines the SCR failure when the probability factor of the SCR is greater than the preset probability factor.

[0071] When the probability factor of the SCR is greater than the preset probability factor, it is determined that the SCR fault can be alarm to be alarm to notify the user or the staff to overhaul or replace the deteriorator SCR as soon as possible.

[0072] Further, the electronic device is compared to the probability factor and the preset probability factor of the SCR and the preset probability factor, the output SCR fault diagnosis result is M S M Times, the SCR is a good piece for 0 times, s M Type 1 Times The SCR fault, that is, SCR is a deteriorator.

[0073] The SCR fault diagnosis method provided herein acquires the conversion efficiency calculation parameters to be detected, and then determine the conversion of the SCR in the N information acquisition time window according to the conversion efficiency of the SCR to be detected. Efficiency value. According to the conversion efficiency value, it is determined that the SCR to be detected is the probability value of the deteriorator, and then determines the probability factor of the corresponding to the corresponding N greetings when the probability factor computing function of the deteriorator is determined according to the probability factor calculation function of the SCR. The probability factor of the deteriorator is determined whether the SCR is faulty according to the probability factor of the deteriorator. The method provided herein does not only rely on a single information acquisition time window to determine if the SCR is faulty, but is determined whether the SCR is faulty according to the probability factor of the SCR corresponding to the N information acquisition time window (N is more than 1 integersion).

[0074] The method of utilizing the probability factor to determine if the SCR is faulty is further acceptor to the SCR's fault method compared to the SCR conversion efficiency value corresponding to the single information acquisition time window. The impact of interference factors for SCR troubleshooting. Therefore, the method provided by the present application increases the accuracy and accuracy of SCR fault diagnosis, and also enhances the use of SCR's use experience.

[0075] See image 3 The second embodiment of the present application provides an SCR fault diagnosis device 10, which is applied to a diesel controller ECU, which includes:

[0076] The module 11 is acquired to obtain the conversion efficiency calculation parameters of the selective catalytic reduction unit SCR to be detected. The conversion efficiency calculation parameter includes: N-information acquisition time windows to be detected by the nitrogen oxyxide mass flow in the downstream of the SCR, n information In the acquisition time window, the nitrogen oxygen quality flow of the SCR is detected, the start time point and end time point of the N information acquisition time window; N is an integer greater than 1;

[0077] Processing module 12, configured to detect the conversion efficiency calculation function of the SCR to be detected to obtain the conversion efficiency value of the SCR to be detected by each information acquisition time window.

[0078] The processing module 12 is further configured to input the conversion efficiency value of the SCR corresponding to the SCR of each information acquisition time window to the probability factor calculation function of the SCR as the deteriorator, resulting in the probability factor input to the SCR for the deteriorator. The probability density function of the conversion efficiency obtains the probability value of the SCR to be detected by each information acquisition window;

[0079] The processing module 12 is further configured to input the N probability factor calculation function corresponding to the N information acquisition time window to the deteriorator of the deteriorator to the SCR as the deteriorator, resulting in the probability factor of the SCR as deterioration. ;

[0080] The determination module 13 determines the SCR failure when the probability factor of the SCR is greater than the preset probability factor.

[0081] The SCR is a probability factor computing function of the deteriorator for: calculating the N probability values corresponding to the SCR to be detected as the deterioration member, respectively, respectively; calculates the sum of the values corresponding to the N probability values, respectively. SCR is the probability factor of deterioration.

[0082] The SCR conversion efficiency calculation function is used to: calculate the start time point and end time point of each information acquisition time window according to the information acquisition time window, and each information acquisition time window is calculated to obtain each of the information acquisition time. The information acquisition time window corresponds to the downstream nitrogen oxide quality of the SCR; according to each information acquisition time window, the nitrogen oxygen mass flow to be detected upstream, each information acquisition time window start time and end The time point is calculated to obtain the upstream nitrogen oxide quality of the SCR corresponding to the SCR of the information acquisition time; the downstream nitrogen oxide quality of the SCR is detected according to the acquisition time window of each information acquisition time, each information collection The time window corresponds to the upstream nitrogen oxynitride quality of the SCR to calculate the conversion efficiency value of the SCR to be detected by each information time window.

[0083] The SCR conversion efficiency calculation function is Among them, η M The conversion efficiency value of the SCR to be detected on behalf of the mth information time window, On behalf of the mth information acquisition time window, the quality flow of the nitrogen oxide downstream of the SCR is detected, On behalf of the mth information acquisition time window, the nitrogen oxygen mass flow to be detected, Ti represents the start time point of the Mth information acquisition time window, and Ti + T represents the acquisition time window of each information. The end time point, where t represents the time length of the Mth information acquisition time window; M is greater than 1, and m is less than or equal to N.

[0084] The acquisition module 11 is specifically configured to obtain a conversion efficiency calculation parameter to be detected when the SCR to be detected is in a preset operating condition; the preset operating condition includes at least: the upstream exhaust temperature of the SCR is in the preset temperature threshold. Inside, the volume vacant in the SCR is in the preset volume of vacant velocity, which is in the preset concentration range in the preset volume.

[0085] The implementation method of the SCR fault diagnosis device 10 coincides with the SCR fault diagnosis method in the first embodiment, and details are not described herein again.

[0086] See Figure 4 According to the present application, the fourth embodiment further provides an electronic device 20, including: a processor 21, a memory 22 communicating with the processor 21, which stores a computer execution instruction; the processor 21 performs the memory 22 stored. The computer executes instructions to implement the SCR fault diagnosis method as described in Example.

[0087] The present application also provides a computer readable storage medium that stores a computer execution instruction in the computer readable storage medium, and when the instruction is executed, the computer execution instruction is performed for implementation of any one of the embodiments. The SCR fault diagnosis method is provided.

[0088] It should be noted that the above-described computer readable storage medium can be a read only memory (ROM), a programmable read-only memory (Programmable Read-Only Memory, PROM), can erasable programmable read only memory (EraSable Programmable) Read-Only Memory, EPROM, Electroless Eraseable Programmable Read-Only Memory, EEPROM, Magnetic Random Access Memory, FRAM, Flash Memory , Magnetic surface memory, optical disk, or memory such as Compact Disc Read-Only Memory, CD-ROM. Various electronic devices including one or any combination of the above memory, such as mobile phones, computers, tablet devices, personal digital assistants, and the like.

[0089] It should be noted that the terms "including", "include" or any other variable admissibility thereof is intended to cover non-exclusive contained, such that the process, method, article, or device including a series of elements, not only those elements, Also included, other elements that are not explicitly listed, or include elements inherent to such processes, methods, articles, or devices. In the absence of more restrictions, the elements defined by the statement "include a ...", and there is no additional same elements in the process, method, article, or device including the element.

[0090] The above application example sequence number is only for describing, does not represent the advantages and disadvantages of the embodiment.

[0091] Through the description of the above embodiments, those skilled in the art will clearly understand that the above-described embodiment method can be implemented by means of software plus necessary general hardware platforms, of course, can also pass hardware, but in many cases, the former is better. Embodiment. Based on this understanding, the technical solutions of the present application essentially or to contribute to prior art can be embodied in the form of software products, the computer software product stores in a storage medium (such as ROM / RAM, disks, In an optical disc, a number of instructions are included to enable a terminal device (can be a mobile phone, computer, server, air conditioner, or network device, etc.) to perform the methods described in the various embodiments of the present application.

[0092] The present application is described with reference to the method, device (system), and flowcharts and / or block diagrams of the computer program product, in accordance with the present application embodiment. It should be understood that each of the flowcharts and / or blocks in the flowchart and / or block diagram can be implemented by a computer program command, and the binding of the flow and / or box in the flowchart and / or block diagram. These computer program instructions can be provided to generic computers, dedicated computers, embedded processes, or other programmable data processing devices to generate a machine such that instructions executed by the processor of the computer or other programmable data processing device. Implementation in the process Figure one Process or multiple processes and / or boxes Figure one Apparatus specified in a plurality of boxes or multiple boxes.

[0093] These computer program instructions can also be stored in a computer readable memory capable of booting a computer or other programmable data processing device in a particular manner, making the instructions stored in the computer readable memory generate a manufacturing product of the instruction device, which Device is implemented in the process Figure one Process or multiple processes and / or boxes Figure one The function specified in the box or multiple boxes.

[0094] These computer program instructions can also be loaded on a computer or other programmable data processing device such that a series of steps are performed on a computer or other programmable device to generate a computer implemented process, thereby executing on a computer or other programmable device. The instruction is provided for implementation Figure one Process or multiple processes and / or boxes Figure one The step of the function specified in multiple boxes or multiple boxes.

[0095]The above is only the preferred embodiments of the present application, and it is not limited to the patent scope of the present application, and an equivalent structure or equivalent process transform is used to use the present application and the drawings, or use it directly or indirectly in other related technical fields.All of them are included within the scope of the patent protection of the present application.

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