Fault diagnosis method, device, system and storage medium for gas-driven urea injection system

Abstract

The present invention discloses a fault diagnosis method, device, system and storage medium for a gas-driven urea injection system. The method comprises: when the urea nozzle is in a non-injection state, obtaining the pressure value in the urea tank and the pressure value in the urea pipeline and determining the pressure difference, and judging whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference; when the urea nozzle is in an injection state, obtaining the maximum pressure drop between the pressure value in the urea tank and the pressure value in the urea pipeline in each statistical cycle of the target cycle number; determining the pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes the pressure drop abnormality rate of excessively high pressure drop and the pressure drop abnormality rate of excessively low pressure drop; determining the fault type of the gas-driven urea injection system according to the pressure drop abnormality rate and the nitrogen oxide conversion rate. The technical scheme of the embodiment of the present invention can effectively improve the accuracy and efficiency of fault diagnosis of the gas-driven urea injection system.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of vehicle exhaust aftertreatment, and in particular to a method, device, system and storage medium for diagnosing faults in a gas-driven urea injection system. Background Art

[0002] Since June 22, 2018, the country has issued the sixth phase of motor vehicle pollution emission standards. Heavy-duty diesel vehicles need to be equipped with a selective catalytic reduction (SCR) system to meet the emission requirements for nitrogen oxides (NOx) in the emission standards.

[0003] In the prior art, a dual-pressure sensor type gas-driven urea injection system is used to convert nitrogen oxides in exhaust gas to meet emission requirements. However, when fault detection is performed on the injection system, only judging the fault by the pressure build-up time or the pressure drop may result in low accuracy in determining the fault type, which may easily lead to misjudgment or missed judgment, resulting in vehicle exhaust gas not meeting emission standards and affecting vehicle use. Summary of the invention

[0004] The present invention provides a method, a device, a system and a storage medium for diagnosing a fault of a gas-driven urea injection system, so as to improve the accuracy of diagnosing a fault of a gas-driven urea injection system and improve the diagnosis efficiency.

[0005] According to one aspect of the present invention, a fault diagnosis method for a gas-driven urea injection system is provided, comprising:

[0006] When the urea nozzle is in a non-spraying state, the pressure value in the urea tank and the pressure value in the urea pipeline are obtained, a pressure difference is determined according to the pressure value in the urea tank and the pressure value in the urea pipeline, and it is judged according to the pressure difference whether there is a leakage fault in the urea nozzle or the urea pipeline; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in a spraying state, and the diagnostic data in the spraying state is continuously recorded;

[0007] When the urea nozzle is in a spraying state, obtaining a maximum pressure drop between a pressure value in the urea tank and a pressure value in the urea pipeline in each statistical cycle of a target number of cycles;

[0008] Determine a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes an excessively high pressure drop abnormality rate and an excessively low pressure drop abnormality rate;

[0009] The fault type of the gas-driven urea injection system is determined according to the abnormal pressure drop rate in combination with the nitrogen oxide conversion rate.

[0010] Optionally, the statistical period includes: at least one injection period counted starting from the third injection period among at least three consecutive injection periods that meet the preset rule; wherein the same preset time interval exists between two adjacent injection periods;

[0011] The preset rule includes: the opening time of the urea nozzle in at least three consecutive injection cycles is between a first time threshold and a second time threshold.

[0012] Optionally, determining the pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference includes:

[0013] Determining a pressure drop deviation rate between a pressure value of the urea nozzle and a pressure value of the urea pipeline according to the maximum pressure drop, the pressure difference and the standard pressure drop within the statistical period;

[0014] The pressure drop abnormality rate is determined according to the pressure drop deviation rate.

[0015] Optionally, determining the pressure drop abnormality rate according to the pressure drop deviation rate includes:

[0016] If the voltage drop deviation rate of a statistical period is greater than the maximum deviation threshold, the number of periods of excessive voltage drop is increased by 1;

[0017] If the voltage drop deviation rate of a statistical period is less than the minimum deviation threshold, the number of periods of low voltage drop is increased by 1;

[0018] Determining an abnormal rate of excessive pressure drop according to the number of cycles of excessive pressure drop and the target number of cycles;

[0019] The excessively low pressure drop abnormality rate is determined according to the excessively low pressure drop cycle number and the target cycle number.

[0020] Optionally, determining the fault type of the gas-driven urea injection system according to the abnormal pressure drop rate in combination with the nitrogen oxide conversion rate includes:

[0021] If the pressure drop too low abnormal rate is greater than the pressure drop too low abnormal rate threshold, the fault type is determined to be the urea nozzle blockage;

[0022] If the excessive pressure drop abnormal rate is greater than the excessive pressure drop abnormal rate threshold, the fault type is determined in combination with the nitrogen oxide conversion rate.

[0023] Optionally, if the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, determining the fault type in combination with the nitrogen oxide conversion rate includes:

[0024] If the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, and the nitrogen oxide conversion rate is significantly less than the conversion rate threshold range, the fault type is determined to be urea filter blockage;

[0025] If the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, and the nitrogen oxide conversion rate is within the conversion rate threshold range, the fault type is determined to be the urea nozzle overspray.

[0026] Optionally, when the urea nozzle is in a non-spraying state, before obtaining the pressure value in the urea tank and the pressure value in the urea pipeline, the method further includes:

[0027] After a preset delay time, it is determined whether the gas-driven urea injection system meets the enabling conditions for recording diagnostic data; wherein the enabling conditions include: the engine management system is in a powered-on state, the urea solution and the urea pipeline are in an unfrozen state, the urea liquid level value in the urea tank is greater than the liquid level threshold, and the urea tank pressure and urea pipeline pressure detection devices are both fault-free.

[0028] According to another aspect of the present invention, a fault diagnosis device for a gas-driven urea injection system is provided, the device comprising:

[0029] A non-injection state fault judgment module is used to obtain the pressure value in the urea tank and the pressure value in the urea pipeline when the urea nozzle is in a non-injection state, determine the pressure difference according to the pressure value in the urea tank and the pressure value in the urea pipeline, and judge whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in the injection state, and the diagnostic data in the injection state is continuously recorded;

[0030] a pressure drop determination module, configured to obtain, when the urea nozzle is in a spraying state, a maximum pressure drop between a pressure value in the urea tank and a pressure value in the urea pipeline in each statistical cycle of a target number of cycles;

[0031] A pressure drop abnormality rate determination module is used to determine a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes a pressure drop abnormality rate of too high pressure drop and a pressure drop abnormality rate of too low pressure drop;

[0032] The injection state fault judgment module is used to determine the fault type of the gas-driven urea injection system according to the pressure drop abnormality rate and the nitrogen oxide conversion rate.

[0033] According to another aspect of the present invention, there is also provided an air-driven urea injection system, comprising: a urea tank, a urea filter, a urea nozzle, a urea pipeline, a liquid level float, a urea tank pressure sensor, a urea pipeline pressure sensor and a fault diagnosis device for the air-driven urea injection system according to the second aspect;

[0034] The urea filter is arranged in the urea tank, and the input end of the urea filter is connected to the urea tank, and the urea pipeline is connected between the output end of the urea filter and the urea nozzle; the liquid level float is arranged in the urea tank; the urea tank pressure sensor is arranged in the urea tank, and the urea pipeline pressure sensor is arranged on the urea pipeline;

[0035] The urea nozzle, the urea tank pressure sensor and the urea pipeline pressure sensor are all connected to the fault diagnosis device of the air-driven urea injection system.

[0036] According to another aspect of the present invention, there is further provided a storage medium comprising computer executable instructions, wherein when the computer executable instructions are executed by a computer processor, the computer executable instructions are used to perform the fault diagnosis method for the gas-driven urea injection system as described in the first aspect.

[0037] The technical solution of the embodiment of the present invention is to obtain the pressure value in the urea tank and the pressure value in the urea pipeline when the urea nozzle is in a non-spraying state, determine the pressure difference, and determine whether the urea nozzle or the urea pipeline has a leakage fault according to the pressure difference. If there is no leakage fault, the pressure difference is used as the pressure deviation of the pressure sensor of the urea nozzle in the spraying state. When the urea nozzle is in the spraying state, the maximum pressure drop between the pressure value in the urea tank and the pressure value of the urea pipeline in each statistical cycle of the target number of cycles is obtained, and the pressure drop abnormality rate is determined according to the maximum pressure drop and the pressure difference. The fault type is determined in combination with the pressure drop abnormality rate and the nitrogen oxide conversion rate. The fault diagnosis method provided by the embodiment of the present invention can effectively reduce the deviation of the obtained pressure value and the influence caused by the deviation of the single calculated pressure difference, improve the accuracy of fault diagnosis of the gas-driven urea injection system, effectively distinguish and determine common fault types, and improve diagnostic efficiency.

[0038] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 is a flow chart of a fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0041] Figure 2 is a specific method flow chart of step S130 in a fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0042] Figure 3 is a pressure difference curve diagram of different situations in a fault diagnosis method of a gas-driven urea injection system provided by an embodiment of the present invention;

[0043] Figure 4 is a specific method flow chart of step S1302 in a fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0044] Figure 5 is a schematic diagram of a statistical cycle process in a fault diagnosis method for a gas-driven urea injection system provided in an embodiment of the present invention;

[0045] Figure 6 is a specific method flow chart of step S140 in a fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0046] Figure 7 is a specific method flow chart of step S1402 in a fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0047] Figure 8 is a flow chart of another fault diagnosis method for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0048] Fig. 9 is a structural schematic diagram of a fault diagnosis device for a gas-driven urea injection system provided according to an embodiment of the present invention;

[0049] Fig.10 The figure is a schematic diagram of the structure of a gas-driven urea injection system provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] An embodiment of the present invention provides a fault diagnosis method for a gas-driven urea injection system. Figure 1 The present invention provides a flowchart of a method for diagnosing a fault of a gas-driven urea injection system. The present invention can be applied to the case where a heavy-duty diesel engine vehicle performs fault diagnosis on a gas-driven urea injection system during normal driving. The method can be executed by software and / or hardware, and specifically includes the following steps:

[0053] S110, when the urea nozzle is in a non-spraying state, obtain the pressure value in the urea tank and the pressure value in the urea pipeline, determine the pressure difference according to the pressure value in the urea tank and the pressure value in the urea pipeline, and judge whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference; if not, use the pressure difference as the pressure deviation when the urea nozzle is in the spraying state, and continue to record the diagnostic data in the spraying state.

[0054] Specifically, when performing fault diagnosis on the gas-driven urea injection system, firstly perform fault detection on the urea nozzle in the non-injection state. When the pressure building of the gas-driven urea injection system is completed, and the time that the urea nozzle remains in the non-injection state is greater than the first time threshold, obtain the pressure value in the urea tank and the pressure value of the urea pipeline at this time. Among them, the pressure value in the urea tank is obtained by a pressure sensor arranged in the urea tank, and the pressure value of the urea pipeline is obtained by a pressure sensor arranged on the outlet pipeline of the urea tank. The first time threshold is the critical time value that the urea nozzle needs to be stable in the non-injection state, so that the fault diagnosis when the urea nozzle is in the non-injection state is carried out under stable working conditions, ensuring that the fault diagnosis result in the non-injection state has a high accuracy. Exemplarily, the first time threshold can be set by the user according to actual needs, and is not limited here.

[0055] Calculate the pressure difference between the pressure value in the urea tank and the pressure value in the urea pipeline, and compare the absolute value of the pressure difference with the leakage threshold. If the absolute value of the pressure difference is greater than the leakage threshold, it indicates that there is a leakage fault in the urea nozzle or the urea pipeline, and the subsequent gas-driven urea injection system fault diagnosis steps are stopped. If the absolute value of the pressure difference is less than or equal to the leakage threshold, it indicates that the pressure sensor in the urea tank or the pressure sensor installed on the urea pipeline has a certain deviation when collecting pressure data. In the subsequent gas-driven urea injection system fault diagnosis process, the deviation of the pressure sensor is taken into account to improve the accuracy of fault diagnosis.

[0056] S120: When the urea nozzle is in the injection state, the maximum pressure drop between the pressure value in the urea tank and the pressure value in the urea pipeline in each statistical cycle of the target number of cycles is obtained.

[0057] Specifically, when the diagnosis of the urea nozzle in the non-injection state shows that there is no leakage fault, the diagnosis of whether there is a fault when the urea nozzle is in the injection state continues. In order to improve the accuracy of the fault diagnosis result, this embodiment selects a time period of a certain length, and divides the time period into multiple time periods of the target number of cycles, and selects the time period that meets the requirements as the statistical period for data recording. At the end of each statistical period, the pressure drop between the pressure value in the urea tank and the pressure value of the urea pipeline is calculated, multiple data collections are performed, and the maximum pressure drop of the target number of cycles is obtained.

[0058] S130, determining a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes a pressure drop abnormality rate that is too high and a pressure drop abnormality rate that is too low.

[0059] Specifically, the pressure difference is caused by the deviation of the pressure sensor in the urea tank or the pressure sensor in the urea pipeline. The maximum pressure drop and pressure difference are used to determine whether the pressure drop data collected in each statistical period is abnormal, and the ratio of the number of cycles with abnormal pressure drop to the number of target cycles is determined to obtain the pressure drop abnormality rate. Among them, the pressure drop abnormality can include excessive pressure drop and too low pressure drop, so the pressure drop abnormality rate can also include the pressure drop abnormality rate of excessive pressure drop and the pressure drop abnormality rate of too low pressure drop.

[0060] S140: Determine the fault type of the gas-driven urea injection system according to the abnormal pressure drop rate and the nitrogen oxide conversion rate.

[0061] Specifically, the nitrogen oxide conversion rate is the efficiency of the injected urea in converting the nitrogen oxides emitted by the engine. When judging the fault type of the gas-driven urea injection system under the condition of abnormal pressure drop, it is necessary not only to consider the abnormal pressure drop rate, but also to combine the nitrogen oxide conversion rate as a basis for judgment to improve the accuracy of fault diagnosis.

[0062] The technical solution of this embodiment obtains the pressure value in the urea tank and the pressure value of the urea pipeline when the urea nozzle is in a non-spraying state, determines the pressure difference, and determines whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference. If there is no leakage fault, the pressure difference is used as the pressure deviation of the pressure sensor of the urea nozzle in the spraying state. When the urea nozzle is in the spraying state, the maximum pressure drop between the pressure value in the urea tank and the pressure value of the urea pipeline in each statistical cycle of the target number of cycles is obtained, and the pressure drop abnormality rate is determined according to the maximum pressure drop and the pressure difference. The fault type is determined in combination with the pressure drop abnormality rate and the nitrogen oxide conversion rate. The technical solution of this embodiment can effectively reduce the deviation of the obtained pressure value and the influence caused by the deviation of the single calculated pressure difference, improve the accuracy of fault diagnosis of the gas-driven urea injection system, effectively distinguish and determine common fault types, and improve diagnostic efficiency.

[0063] Optionally, based on the above embodiment, the statistical period includes: at least one injection period counted starting from the third injection period among at least three consecutive injection periods that meet the preset rule; wherein there is the same preset time interval between two adjacent injection periods.

[0064] The preset rule includes: the urea nozzle opening time in at least three consecutive injection cycles is between the first time threshold and the second time threshold.

[0065] Specifically, during the time period for fault diagnosis of the gas-driven urea injection system, multiple injection cycles are included, and the same time interval is maintained between each injection cycle. Exemplarily, the time interval between two injection cycles can be set according to actual diagnostic needs, which is not limited here. Preferably, the same time interval between two injection cycles can be set to 1 second.

[0066] When collecting the pressure value in the urea tank and the pressure value in the urea pipeline, when there are at least three consecutive injection cycles that meet the preset rules, the third injection cycle is taken as the first statistical cycle, and the data is collected at the end of the injection cycle as valid diagnostic data. Exemplarily, if the first, second, third and fourth consecutive injection cycles all meet the preset rules, the third injection cycle is taken as the first statistical cycle, the number of statistical cycles increases by 1, and the diagnostic data is collected and recorded at the end of the injection cycle. If the first to sixth consecutive six injection cycles all meet the preset rules, and the seventh and eighth injection cycles do not meet the preset rules, the third to sixth injection cycles are all statistical cycles, and the number of statistical cycles increases by 4. Afterwards, if the ninth injection cycle meets the preset rules, the ninth injection cycle is taken as the first injection cycle that meets the preset rules in the next statistical cycle count. If at least three consecutive injection cycles meet the preset rules, the count continues from the third injection cycle that meets the preset rules, and the previous four statistical cycles continue to be accumulated. When the accumulated statistical cycle number reaches the target cycle number, the diagnostic data collection stops.

[0067] The preset rule that the injection cycle count must meet as a statistical cycle is: in one injection cycle, the urea nozzle opening time is between the first time threshold and the second time threshold. Exemplarily, the urea nozzle opening time is controlled by the engine controller, and the duration of the opening time is related to the current driving state of the vehicle. For example: if the current vehicle is in a low-speed driving state, the engine controller controls the urea nozzle opening time to be shorter; if the current vehicle is in a high-speed driving state, the engine controller controls the urea nozzle opening time to be longer. The urea nozzle opening time is between the first time threshold and the second time threshold, indicating that the vehicle state in this statistical period is relatively stable during the fault diagnosis time period. Therefore, in order to ensure the accuracy of the fault diagnosis results, the data of the statistical period in which the urea nozzle opening time is relatively stable between the first time threshold and the second time threshold is collected for calculation and judgment.

[0068] Optionally, Figure 2 is a specific method flow chart of step S130 in a fault diagnosis method for a gas-driven urea injection system provided by an embodiment of the present invention, Figure 3 1 is a pressure difference curve diagram of different situations in a fault diagnosis method of a gas-driven urea injection system provided by an embodiment of the present invention. Figure 2 As shown, according to the maximum pressure drop and the pressure difference, the pressure drop abnormality rate of the pressure value of the urea nozzle and the pressure value of the urea pipeline is determined, including:

[0069] S1301. Determine the pressure drop deviation rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop, the pressure difference and the standard pressure drop within a statistical period.

[0070] Specifically, when calculating the maximum pressure drop when the urea nozzle is in the injection state, the deviation of the pressure sensor in the urea tank or the pressure sensor on the urea pipeline is taken into account. Therefore, the maximum pressure drop within the statistical period can be expressed by the following formula:

[0071] p1=p 罐 -p 液 -p diff

[0072] Among them, p1 represents the maximum voltage drop calculated at the end of a statistical period, p 罐 Indicates the pressure value in the urea tank at the end of the statistical period, p 液 Indicates the pressure value of the urea pipeline at the end of the statistical period, p diff Indicates the pressure difference between the pressure value of the urea nozzle and the pressure value of the urea pipeline.

[0073] For each statistical period, there will be a standard pressure drop after the urea nozzle is sprayed. This standard pressure drop is related to the urea nozzle opening time in each statistical period, and there is a mapping relationship between the urea nozzle opening time and the standard pressure drop, that is, different urea nozzle opening times correspond to different standard pressure drops. The standard pressure drop corresponding to the corresponding statistical period can be obtained by looking up the table and performing subsequent calculations.

[0074] Using the maximum pressure drop, pressure difference and standard pressure drop of a statistical cycle, the pressure drop deviation rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline can be calculated. The specific calculation formula can be expressed as:

[0075]

[0076] Among them, p err Indicates the pressure drop deviation rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline, p std Indicates the standard voltage drop in a statistical period.

[0077] S1302. Determine the pressure drop abnormality rate according to the pressure drop deviation rate.

[0078] Specifically, the calculated pressure drop deviation rate of a statistical period is compared with the pressure drop deviation threshold range to determine whether the pressure drop deviation rate of the statistical period belongs to a normal pressure drop situation or an abnormal pressure drop situation. For example, the pressure drop deviation threshold can be set by the user according to actual diagnostic needs, and is not limited here. Among them, the abnormal pressure drop situation also includes the situation where the pressure drop is too low and the situation where the pressure drop is too high. Figure 3, the horizontal line represents the pressure value in the urea tank, the curve represents the pressure value in the urea pipeline, and the vertical difference between the straight line and the curve represents the pressure difference between the pressure value in the urea tank and the pressure value in the urea pipeline. Among them, the pressure difference represented by lines 3 and 4 belongs to the case of normal pressure drop, the pressure difference represented by lines 1 and 2 belongs to the case of too low pressure drop, and the pressure difference represented by lines 5 and 6 belongs to the case of too high pressure drop. According to the above method, it is determined that each statistical period belonging to the abnormal pressure drop situation belongs to the period of too low pressure drop or the period of too high pressure drop, and the abnormal rate of too low pressure drop is calculated according to the number of periods of too low pressure drop, and the abnormal rate of too high pressure drop is calculated according to the number of periods of too high pressure drop.

[0079] Optionally, Figure 4 is a specific method flow chart of step S1302 in a fault diagnosis method for a gas-driven urea injection system provided by an embodiment of the present invention, Figure 5 FIG. 1 is a schematic diagram of a statistical cycle process in a fault diagnosis method for a gas-driven urea injection system provided by an embodiment of the present invention. Figure 4 and Figure 5 , according to the pressure drop deviation rate, determine the pressure drop abnormality rate, including:

[0080] S13021. If the voltage drop deviation rate of a statistical period is greater than the maximum deviation threshold, the number of periods of excessive voltage drop is increased by 1.

[0081] Specifically, when determining whether each statistical cycle belongs to a low voltage drop cycle or a high voltage drop cycle, if the voltage drop deviation rate of a statistical cycle is greater than the upper limit of the voltage drop deviation threshold range, that is, the maximum deviation threshold, it means that the statistical cycle belongs to a high voltage drop cycle, and the number of high voltage drop cycles is accumulated by 1. If the voltage drop deviation rate of a statistical cycle is within the voltage drop deviation threshold range, it means that the statistical cycle belongs to a normal voltage drop cycle, and the statistical cycle is not accumulated. For example, see Figure 5 , graph line 11 represents the pressure value in the urea tank, graph line 12 represents the pressure value in the urea pipeline, and the difference between graph line 11 and graph line 12 can represent the pressure difference between the urea tank and the urea pipeline. Graph line 13 represents the total number of statistical cycles, graph line 14 represents the number of cycles with too low pressure drop, and graph line 15 represents the number of cycles with too high pressure drop. The number of statistical cycles can be represented by the rising edge in graph line 13, and the number of rising edges is the number of statistical cycles, and the cycle count is performed at the end of an injection cycle. For example, Figure 5 For example, it includes 4 statistical cycles, wherein the first statistical cycle is a cycle of too low voltage drop, the fourth statistical cycle is a cycle of too high voltage drop, and the second and third statistical cycles are cycles of normal voltage drop.

[0082] S13022. If the voltage drop deviation rate of a statistical period is less than the minimum deviation threshold, the number of periods of low voltage drop is increased by 1.

[0083] Specifically, when determining whether each statistical cycle belongs to a low voltage drop cycle or a high voltage drop cycle, if the voltage drop deviation rate of a statistical cycle is less than the lower limit of the voltage drop deviation threshold range, that is, the minimum deviation threshold, it means that the statistical cycle belongs to a low voltage drop cycle, and the number of low voltage drop cycles is accumulated by 1. For example, see the above Figure 5 The description is not repeated here.

[0084] S13023. Determine the excessive pressure drop abnormality rate based on the number of excessive pressure drop cycles and the target number of cycles.

[0085] Specifically, after comparing and judging the statistical cycles of the target number of cycles, the total number of cycles with excessively high pressure drop is obtained. The excessively high pressure drop abnormality rate can be obtained by calculating the number of cycles with excessively high pressure drop and the target number of cycles. For example, the calculation formula of the excessively high pressure drop abnormality rate can be expressed as:

[0086]

[0087] Among them, p high Indicates the abnormal rate of excessive pressure drop, n e1 Indicates the number of cycles where the voltage drop is too high, n total Indicates the target number of cycles.

[0088] S13024. Determine the abnormal rate of too low pressure drop based on the number of cycles of too low pressure drop and the target number of cycles.

[0089] Specifically, after comparing and judging the statistical cycles of the target number of cycles, the total number of cycles with too low pressure drop is obtained. The abnormal rate of too low pressure drop can be obtained by calculating the number of cycles with too low pressure drop and the target number of cycles. For example, the calculation formula of the abnormal rate of too low pressure drop can be expressed as:

[0090]

[0091] Among them, p low Indicates the abnormal rate of low pressure drop, n e2 Indicates the number of cycles when the voltage drop is too low.

[0092] Optionally, Figure 6 FIG. 1 is a flow chart of a specific method of step S140 in a method for diagnosing a fault of a gas-driven urea injection system provided by an embodiment of the present invention. Figure 6 As shown in the figure, according to the abnormal pressure drop rate and the nitrogen oxide conversion rate, the fault type of the gas-driven urea injection system is determined, including:

[0093] S1401: If the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, the fault type is determined to be urea nozzle blockage.

[0094] Specifically, the fault is judged based on the calculated pressure drop abnormality rate. If the pressure drop abnormality rate is greater than the pressure drop abnormality rate threshold, it can be determined that the gas-driven urea injection system has a urea nozzle blockage fault, resulting in too little urea solution injection, so the pressure drop is too low. Among them, the pressure drop abnormality rate threshold can be set by the user according to the actual needs of the vehicle and is not limited here.

[0095] S1402: If the excessive pressure drop abnormality rate is greater than the excessive pressure drop abnormality rate threshold, determine the fault type in combination with the nitrogen oxide conversion rate.

[0096] Specifically, if the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, it may be that the urea nozzle is overspraying, that is, the urea nozzle is spraying too much. However, a large pressure drop abnormal rate may also be caused by other factors. Therefore, it is necessary to further determine the fault type in combination with the nitrogen oxide conversion rate to ensure that the diagnosis result has a high accuracy. Among them, the pressure drop abnormal rate threshold can be set by the user according to the actual needs of the vehicle and is not limited here.

[0097] Optionally, Figure 7 FIG. 1 is a flow chart of a specific method of step S1402 in a method for diagnosing a fault of a gas-driven urea injection system provided by an embodiment of the present invention. Figure 7 As shown, if the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, the fault type is determined in combination with the nitrogen oxide conversion rate, including:

[0098] S14021. If the excessive pressure drop abnormality rate is greater than the excessive pressure drop abnormality rate threshold, and the nitrogen oxide conversion rate is significantly less than the conversion rate threshold range, the fault type is determined to be urea filter blockage.

[0099] Specifically, when the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, if the nitrogen oxide conversion rate is significantly less than the lower limit of the conversion rate threshold range, it means that the nitrogen oxide conversion rate is still low under the premise that the urea nozzle is not blocked, and the fault type can be determined to be the blockage of the urea filter. When the urea filter is blocked, the correct urea solution supply cannot be provided to the urea nozzle. Therefore, even if the urea nozzle is not blocked, the injection amount of the urea solution is still small, resulting in the nitrogen oxide conversion rate being significantly less than the lower limit of the conversion rate threshold range.

[0100] S14022: If the excessive pressure drop abnormality rate is greater than the excessive pressure drop abnormality rate threshold, and the nitrogen oxide conversion rate is within the conversion rate threshold range, the fault type is determined to be urea nozzle overspray.

[0101] Specifically, when the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, if the nitrogen oxide conversion rate is within the conversion rate threshold range, it means that the nitrogen oxide conversion rate is normal, that is, the urea filter is not blocked. Therefore, the high pressure drop phenomenon at this time is caused by overspray of the urea nozzle.

[0102] Optionally, Figure 8 FIG. 1 is a flow chart of another method for diagnosing a fault of a gas-driven urea injection system provided by an embodiment of the present invention. Figure 8 As shown, when the urea nozzle is in a non-spraying state, before obtaining the pressure value in the urea tank and the pressure value in the urea pipeline, the following steps are also included:

[0103] S100, after a preset delay time, determining whether the gas-driven urea injection system meets the enabling conditions for recording diagnostic data; wherein the enabling conditions include: the engine management system is in a powered-on state, the urea solution and the urea pipeline are in an unfrozen state, the urea liquid level value in the urea tank is greater than the liquid level threshold, and the urea tank pressure and urea pipeline pressure detection devices are both fault-free.

[0104] Specifically, before performing fault diagnosis, it is necessary to determine whether the vehicle state meets the requirements for fault diagnosis. When determining the vehicle state, it is necessary to delay for a certain preset time, keep the vehicle in a stable state, obtain various vehicle state parameters, and determine whether the enabling conditions for recording diagnostic data are met, thereby improving the authenticity of the diagnostic data and the accuracy of the fault diagnosis results. For example, the preset time can be set by the user according to the actual situation, and is not limited here.

[0105] Among the enabling conditions that need to be met for vehicle fault diagnosis, the engine management system needs to be in a powered-on state so that the pressure value in the urea tank and the pressure value in the urea pipeline can be collected, and the data can be calculated and the size can be judged. The urea solution and the urea pipeline are in an unfrozen state, so that the urea solution can be normally output from the urea pipeline to the urea nozzle for injection. The remaining amount of urea solution in the urea tank, that is, the urea liquid level value, will affect the pressure building time. Therefore, the urea liquid level value needs to be higher than the liquid level threshold so that the pressure building time remains normal. In the absence of faults, the urea tank pressure detection device and the urea pipeline pressure detection device can ensure the accuracy of the pressure value in the urea tank and the pressure value in the urea pipeline, thereby improving the accuracy of the fault diagnosis results.

[0106] The embodiment of the present invention also provides a fault diagnosis device for a gas-driven urea injection system. Fig. 9 FIG. 1 is a schematic diagram of a fault diagnosis device for a gas-driven urea injection system provided by an embodiment of the present invention. Fig. 9 As shown, the fault diagnosis device 800 of the gas-driven urea injection system includes:

[0107] The non-injection state fault judgment module 10 is used to obtain the pressure value in the urea tank and the pressure value in the urea pipeline when the urea nozzle is in the non-injection state, determine the pressure difference according to the pressure value in the urea tank and the pressure value in the urea pipeline, and judge whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in the injection state, and the diagnostic data in the injection state is continuously recorded;

[0108] The pressure drop determination module 20 is used to obtain the maximum pressure drop between the pressure value in the urea tank and the pressure value in the urea pipeline in each statistical cycle of the target number of cycles when the urea nozzle is in the injection state;

[0109] The pressure drop abnormality determination module 30 is used to determine the pressure drop abnormality of the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality includes the pressure drop abnormality rate of too high pressure drop and the pressure drop abnormality rate of too low pressure drop;

[0110] The injection state fault judgment module 40 is used to determine the fault type of the gas-driven urea injection system according to the pressure drop abnormality rate and the nitrogen oxide conversion rate.

[0111] The fault diagnosis device for a gas-driven urea injection system provided in an embodiment of the present invention can execute the fault diagnosis method for a gas-driven urea injection system provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0112] The embodiment of the present invention also provides a gas-driven urea injection system. Fig.10 Schematic diagram of the structure of a gas-driven urea injection system provided by an embodiment of the present invention. Fig.10 As shown, the system includes: a urea tank 100, a urea filter 200, a urea nozzle 300, a urea pipeline 400, a liquid level float 500, a urea tank pressure sensor 600, a urea pipeline pressure sensor 700 and a fault diagnosis device 800 for the gas-driven urea injection system as described in any of the above embodiments.

[0113] The urea filter 200 is arranged in the urea tank 100, and the input end of the urea filter 200 is connected to the urea tank 100, and a urea pipeline 400 is connected between the output end of the urea filter 200 and the urea nozzle 300; the liquid level float 500 is arranged in the urea tank 100; the urea tank pressure sensor 600 is arranged in the urea tank 100, and the urea pipeline pressure sensor 700 is arranged on the urea pipeline 400.

[0114] The urea nozzle 300 , the urea tank pressure sensor 600 and the urea pipeline pressure sensor 700 are all connected to the fault diagnosis device 800 of the air-driven urea injection system.

[0115] For example, Fig.10The solid lines in the figure represent the urea pipeline and the gas pipeline, and the dotted lines represent the data communication lines.

[0116] The gas-driven urea injection system provided by the embodiment of the present invention can execute the fault diagnosis method of the gas-driven urea injection system provided by any embodiment of the present invention under the control of the fault diagnosis device 800 of the gas-driven urea injection system, and has the corresponding beneficial effects of the execution method.

[0117] An embodiment of the present invention further provides a storage medium comprising computer executable instructions, wherein the computer executable instructions are used to execute a fault diagnosis method for a gas-driven urea injection system when executed by a computer processor, the method comprising:

[0118] When the urea nozzle is in a non-spraying state, the pressure value in the urea tank and the pressure value in the urea pipeline are obtained, a pressure difference is determined according to the pressure value in the urea tank and the pressure value in the urea pipeline, and it is judged according to the pressure difference whether there is a leakage fault in the urea nozzle or the urea pipeline; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in a spraying state, and the diagnostic data in the spraying state is continuously recorded;

[0119] When the urea nozzle is in a spraying state, obtaining a maximum pressure drop between a pressure value in the urea tank and a pressure value in the urea pipeline in each statistical cycle of a target number of cycles;

[0120] Determine a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes an excessively high pressure drop abnormality rate and an excessively low pressure drop abnormality rate;

[0121] The fault type of the gas-driven urea injection system is determined according to the abnormal pressure drop rate in combination with the nitrogen oxide conversion rate.

[0122] Of course, the computer executable instructions of the storage medium including computer executable instructions provided in the embodiment of the present invention are not limited to the method operations described above, and can also execute related operations in the fault diagnosis method of the gas-driven urea injection system provided in any embodiment of the present invention.

[0123] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include: being implemented in one or more computer programs, which may be executed and / or interpret a method for diagnosing a fault in a gas-driven urea injection system on a programmable system including at least one programmable processor, which may be a dedicated or general programmable processor, which may receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0124] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0125] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0126] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0127] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fault diagnosis method for a gas-driven urea injection system, characterized in that: include: When the urea nozzle is in a non-spraying state, the pressure value in the urea tank and the pressure value in the urea pipeline are obtained, a pressure difference is determined according to the pressure value in the urea tank and the pressure value in the urea pipeline, and it is judged according to the pressure difference whether there is a leakage fault in the urea nozzle or the urea pipeline; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in a spraying state, and the diagnostic data in the spraying state is continuously recorded; When the urea nozzle is in the injection state, a maximum pressure drop between the pressure value in the urea tank and the pressure value in the urea pipeline in each statistical period of a target number of cycles is obtained; the maximum pressure drop represents the difference between the pressure value in the urea tank at the end of the statistical period and the pressure value in the urea pipeline at the end of the statistical period, and the pressure difference between the pressure value of the urea nozzle and the pressure value of the urea pipeline; According to the maximum pressure drop and the pressure difference, a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline is determined; wherein the pressure drop abnormality rate includes an excessively high pressure drop abnormality rate and an excessively low pressure drop abnormality rate; the pressure drop abnormality rate represents a ratio of the number of cycles in which the pressure drop deviation rate is outside the pressure drop deviation threshold range to the target number of cycles, the excessively high pressure drop abnormality rate represents a ratio of the number of cycles in which the pressure drop deviation rate is greater than the upper limit value of the pressure drop deviation threshold range to the target number of cycles, and the excessively low pressure drop abnormality rate represents a ratio of the number of cycles in which the pressure drop deviation rate is less than the lower limit value of the pressure drop deviation threshold range to the target number of cycles; Determining the fault type of the gas-driven urea injection system according to the abnormal pressure drop rate and in combination with the nitrogen oxide conversion rate; Wherein, determining the pressure drop abnormality rate of the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference includes: Determining a pressure drop deviation rate between a pressure value of the urea nozzle and a pressure value of the urea pipeline according to the maximum pressure drop, the pressure difference and the standard pressure drop within the statistical period; Determining the pressure drop abnormality rate according to the pressure drop deviation rate; Wherein, determining the pressure drop abnormality rate according to the pressure drop deviation rate includes: If the voltage drop deviation rate of a statistical period is greater than the maximum deviation threshold, the number of periods of excessive voltage drop is increased by 1; If the voltage drop deviation rate of a statistical period is less than the minimum deviation threshold, the number of periods of low voltage drop is increased by 1; Determining an excessively high voltage drop abnormality rate according to the excessively high voltage drop cycle number and the target cycle number; Determining a too-low pressure drop abnormality rate according to the too-low pressure drop cycle number and the target cycle number; Wherein, determining the fault type of the gas-driven urea injection system according to the abnormal pressure drop rate and in combination with the nitrogen oxide conversion rate includes: If the pressure drop too low abnormal rate is greater than the pressure drop too low abnormal rate threshold, the fault type is determined to be the urea nozzle blockage; If the excessive pressure drop abnormality rate is greater than the excessive pressure drop abnormality rate threshold, the fault type is determined in combination with the nitrogen oxide conversion rate; Wherein, if the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, the fault type is determined in combination with the nitrogen oxide conversion rate, including: If the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, and the nitrogen oxide conversion rate is significantly less than the conversion rate threshold range, the fault type is determined to be urea filter blockage; If the pressure drop abnormal rate is greater than the pressure drop abnormal rate threshold, and the nitrogen oxide conversion rate is within the conversion rate threshold range, the fault type is determined to be the urea nozzle overspray.

2. The fault diagnosis method of the gas-driven urea injection system according to claim 1, characterized in that: The statistical cycle includes: at least one injection cycle counted from the third injection cycle among at least three consecutive injection cycles that meet the preset rules; wherein the same preset time interval exists between two adjacent injection cycles; The preset rule includes: the opening time of the urea nozzle in at least three consecutive injection cycles is between a first time threshold and a second time threshold.

3. The fault diagnosis method of the gas-driven urea injection system according to claim 1, characterized in that: Before obtaining the pressure value in the urea tank and the pressure value in the urea pipeline when the urea nozzle is in a non-spraying state, the method further includes: After a preset delay time, it is determined whether the gas-driven urea injection system meets the enabling conditions for recording diagnostic data; wherein the enabling conditions include: the engine management system is in a powered-on state, the urea solution and the urea pipeline are in an unfrozen state, the urea liquid level value in the urea tank is greater than the liquid level threshold, and the urea tank pressure and urea pipeline pressure detection devices are both fault-free.

4. A fault diagnosis device for a gas-driven urea injection system, characterized in that: Used to perform the fault diagnosis method of the gas-driven urea injection system according to any one of claims 1 to 3; The fault diagnosis device of the gas-driven urea injection system comprises: A non-injection state fault judgment module is used to obtain the pressure value in the urea tank and the pressure value in the urea pipeline when the urea nozzle is in a non-injection state, determine the pressure difference according to the pressure value in the urea tank and the pressure value in the urea pipeline, and judge whether there is a leakage fault in the urea nozzle or the urea pipeline according to the pressure difference; if not, the pressure difference is used as the pressure deviation when the urea nozzle is in the injection state, and the diagnostic data in the injection state is continuously recorded; a pressure drop determination module, configured to obtain, when the urea nozzle is in a spraying state, a maximum pressure drop between a pressure value in the urea tank and a pressure value in the urea pipeline in each statistical cycle of a target number of cycles; A pressure drop abnormality rate determination module is used to determine a pressure drop abnormality rate between the pressure value of the urea nozzle and the pressure value of the urea pipeline according to the maximum pressure drop and the pressure difference; wherein the pressure drop abnormality rate includes a pressure drop abnormality rate of too high pressure drop and a pressure drop abnormality rate of too low pressure drop; The injection state fault judgment module is used to determine the fault type of the gas-driven urea injection system according to the pressure drop abnormality rate and the nitrogen oxide conversion rate.

5. A gas-driven urea injection system, characterized in that: include: A urea tank, a urea filter, a urea nozzle, a urea pipeline, a liquid level float, a urea tank pressure sensor, a urea pipeline pressure sensor, and a fault diagnosis device for an air-driven urea injection system as claimed in claim 4; The urea filter is arranged in the urea tank, and the input end of the urea filter is connected to the urea tank, and the urea pipeline is connected between the output end of the urea filter and the urea nozzle; the liquid level float is arranged in the urea tank; the urea tank pressure sensor is arranged in the urea tank, and the urea pipeline pressure sensor is arranged on the urea pipeline; The urea nozzle, the urea tank pressure sensor and the urea pipeline pressure sensor are all connected to the fault diagnosis device of the air-driven urea injection system.

6. A storage medium comprising computer executable instructions, wherein the computer executable instructions are used to execute the fault diagnosis method for the gas-driven urea injection system according to any one of claims 1 to 3 when executed by a computer processor.

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