A method and device for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle

Abstract

The present application discloses a method and device for confirming abnormal air pressure in the air path of a dual-fuel nozzle, relating to the field of automotive technology. The method comprises the following steps: obtaining the current oil-air pressure differential of the engine; if the current oil-air pressure differential of the engine is greater than a first preset oil-air pressure differential of the engine, obtaining the speed roughness of each cylinder of the engine; and determining the position of the cylinder with abnormal air pressure based on the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold. By obtaining the speed roughness of each cylinder and determining the position of the cylinder with abnormal air pressure based on the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold, the abnormal cylinder is locked, thereby improving the reliability of the engine. The speed roughness of the cylinder is based on the crankshaft angular acceleration corresponding to the power stroke of each cylinder obtained from the engine crankshaft speed signal. Based on the deviation between the crankshaft angular acceleration corresponding to the power stroke of each cylinder and the speed roughness threshold, it can be determined whether the current cylinder has an abnormal air pressure.

Description

Technical Field

[0001] The present application relates to the field of automobile technology, and in particular to a method and device for confirming abnormal air pressure in the air path of a dual-fuel nozzle. Background Art

[0002] Engine alternative fuel technologies, dual-fuel injection, and hybrid technologies are maturing. Dual-fuel direct injection combustion is a key development direction, encompassing a variety of technical solutions, including diesel + natural gas, diesel + ammonia, and diesel + alcohol. This approach offers improved fuel economy and emissions while maintaining the same power and reliability as diesel engines on the same platform. As a key component in this approach, dual-fuel nozzles, with their superior performance and reliability, along with comprehensive fault warning and control mechanisms, are fundamental to ensuring optimal engine performance.

[0003] Since the engine has multiple dual-fuel nozzles, it is difficult to determine the location of the abnormality. The dual-fuel nozzles may have various problems such as oil leakage failure in the air path, which may cause deterioration of engine performance, uneven combustion in each cylinder, coking and blockage of the nozzle orifices, and other more serious failures, affecting their use. Summary of the Invention

[0004] The present application provides a method and device for confirming air pressure anomalies in the air path of a dual-fuel nozzle, so as to improve the existing problems such as difficulty in determining the abnormal location, deterioration of engine performance caused by oil cross-flow failure in the air path, uneven combustion in each cylinder, coking and blockage of the nozzle orifice, and other more serious failures.

[0005] In a first aspect, the present application provides a method for controlling the air pressure of an air path of a dual-fuel nozzle, comprising the following steps:

[0006] Get the current oil-gas pressure difference of the engine;

[0007] If the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine, obtaining the speed roughness of each cylinder of the engine;

[0008] The position of the cylinder with abnormal air pressure is determined according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold.

[0009] Because dual-fuel nozzles typically feature a coaxial dual-valve design, with both oil and gas fuels sharing a single nozzle for injection control, a clearance is created between the oil and gas chambers within the nozzle for pressure sealing, lubrication, and heat dissipation requirements of the jet needle valve, as well as for safety considerations. Common rail systems typically have a higher oil pressure than air pressure. Due to this small clearance (approximately 5μm) between the oil and gas chambers within dual-fuel nozzles, a small amount of fuel can leak into the air path during normal operation, where the oil pressure is higher than the air pressure (10 to 20 bar). This small amount of fuel leaking into the air path facilitates lubrication and heat dissipation of the jet needle valve, extending the life of the nozzle.

[0010] The amount of oil leakage in the dual-fuel nozzle air path changes linearly with the pressure difference between oil and gas. The greater the oil-gas pressure difference, the greater the oil leakage. If the oil-gas pressure difference is too large or the dual-fuel nozzle fails, the amount of oil leakage into the air path will increase, and even the fuel will leak back into the air rail, which will cause the engine combustion to deteriorate, the consistency of each cylinder to deteriorate, the nozzle hole to coke and clog, and other problems, seriously affecting the vehicle's performance and driving experience.

[0011] Taking into account pipeline pressure drop, the engine's gas inlet pressure is typically lower than the gas pressure at the outlet of the engine's oil-gas balance valve. If the engine's gas inlet pressure is higher than the gas pressure at the outlet of the engine's oil-gas balance valve, it's considered abnormal rail pressure and a risk of oil crossover. When the oil-gas pressure difference is caused by excessive oil crossover, often due to nozzle needle valve wear, the fault must be located and promptly corrected.

[0012] This application obtains the speed roughness of each cylinder and, based on the deviation between the speed roughness of each cylinder and a speed roughness threshold, locates the cylinder with abnormal air pressure, thereby improving engine reliability. The speed roughness of each cylinder is derived from the crankshaft angular acceleration corresponding to the power stroke of each cylinder, derived from the engine crankshaft speed signal. The deviation between the crankshaft angular acceleration corresponding to the power stroke of each cylinder and the speed roughness threshold can be used to determine whether the current cylinder has abnormal air pressure. The speed roughness threshold can be determined by using a standard map of speed roughness thresholds for each cylinder under different operating conditions and pre-calibrated in the control system. When the engine is operating normally, the injection and combustion performance of each cylinder is highly consistent, resulting in the same crankshaft angular acceleration during power generation in each cylinder. If an injection or combustion anomaly occurs in a cylinder, the combustion performance in that cylinder will differ significantly from that of other cylinders, resulting in an abnormal crankshaft angular acceleration during power generation in that cylinder. When the threshold exceeds a pre-calibrated threshold at which the engine maintains normal operation at that operating point, the cylinder is confirmed to be operating abnormally. If the whole engine air rail pressure is abnormal at the same time, it can be confirmed that the air path of the cylinder is abnormal. The first preset oil-air pressure difference of the engine can be calibrated according to the actual working conditions, or it can be a fixed value set, such as 20~40bar.

[0013] After confirming that the current cylinder gas circuit is abnormal, the following measures can be taken: report the abnormal oil leakage related faults in the gas circuit to remind the driver to go to the station for processing as soon as possible; according to the actual platform needs, limit the engine torque after reporting the fault to ensure safety; correct and limit the injection amount of the faulty cylinder, for example, control the fuel injection and jet of the dual-fuel nozzle of the faulty cylinder according to the minimum safe oil amount of the nozzle to prevent fuel flooding in the cylinder.

[0014] In some embodiments, determining the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold includes:

[0015] Comparing the absolute value of the difference between the speed roughness of each cylinder and the speed roughness of a preset cylinder with the size of the preset difference;

[0016] If the absolute value of the difference between the rotational speed roughness in the cylinder and the rotational speed roughness of the preset cylinder is greater than the preset difference, the cylinder is determined to be a cylinder with abnormal gas path pressure.

[0017] When the vehicle is running normally, the engine cylinders perform combustion and work in the normal ignition sequence of 1-5-3-6-2-4. The air volume, injection volume and combustion work of each cylinder are relatively consistent, and the overall operation of the engine is relatively smooth. Therefore, when there is no gas path fault, the speed roughness of each cylinder of the engine is at the same level, and the speed roughness of each cylinder operates within the speed roughness range of the preset cylinder. The speed roughness of the preset cylinder can be set in advance according to the working conditions, for example, it can be 30~100r / s 2 Range. When the air path of some cylinders is abnormal, the speed roughness of the abnormal cylinder will deviate from the speed roughness of the preset cylinder. By comparing the absolute value of the difference between the speed roughness in each cylinder and the speed roughness of the preset cylinder with the preset difference, it can be determined whether the cylinder has abnormal air path pressure. Usually, when the absolute value of the difference between the speed roughness and the speed roughness of the preset cylinder is greater than 30% of the speed roughness of the preset cylinder, the cylinder is considered to have abnormal air path pressure. It should be noted that the number of cylinders with abnormal air path pressure can be one or more. As long as the absolute value of the difference between the speed roughness in the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, it is considered to be abnormal.

[0018] In some embodiments, if the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of a preset cylinder is greater than the preset difference, determining that the cylinder is a cylinder with abnormal gas path pressure includes:

[0019] If the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, compare the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders;

[0020] If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds a preset ratio range, the cylinder is determined to be a cylinder with abnormal gas path pressure.

[0021] In order to improve the accuracy of fault diagnosis and eliminate the influence of cylinder dispersion on the judgment, after the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders is further compared. If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds the preset ratio range, the cylinder is judged to be a cylinder with abnormal gas path pressure. It should be noted that the other cylinders here refer to cylinders whose absolute value of the difference between the speed roughness and the speed roughness of the preset cylinder is less than or equal to the preset difference, that is, they are defaulted to normal cylinders. When the speed roughness ratio of the suspected abnormal cylinder is further compared with the default normal cylinder, it can be further confirmed that the suspected abnormal cylinder is an abnormal cylinder, reducing the influence of cylinder dispersion. Usually, the preset ratio range can be 1.15~1.25.

[0022] In some embodiments, if the current oil-air pressure difference of the engine is greater than the first preset oil-air pressure difference of the engine, the speed roughness of each cylinder of the engine is obtained, and the speed roughness of the cylinder is α1, which satisfies:

[0023] α1=d(2π*N) / dt;

[0024] Wherein, N is the engine speed;

[0025] t is time.

[0026] The speed roughness of the cylinder is the crankshaft angular acceleration of the cylinder, which is the derivative of the crankshaft speed of the cylinder with respect to time. The crankshaft speed of the cylinder is related to the speed. The speed roughness of the cylinder can be obtained through the speed and time.

[0027] In some embodiments, after obtaining the current oil-air pressure difference of the engine, the method further includes:

[0028] If the engine's oil-gas pressure difference is greater than the second preset engine's oil-gas pressure difference and less than the first preset engine's oil-gas pressure difference, adjust the fuel pressure so that the degree of deviation between the oil-gas pressure difference and the target pressure difference is less than or equal to the oil-gas pressure difference deviation degree threshold.

[0029] Existing methods for controlling fuel blowby in dual-fuel nozzles primarily rely on nozzle clearance and the differential pressure between the fuel and air, achieving this goal from a design perspective. This approach fails to account for variations in the differential pressure during actual operation, such as insufficient air pressure from a deflated cylinder and increased needle valve clearance due to nozzle needle wear. These factors can increase fuel blowby, negatively impacting engine performance and reliability.

[0030] If the engine's oil-gas pressure differential is greater than the second preset engine's oil-gas pressure differential and less than the first preset engine's oil-gas pressure differential, the first preset engine's oil-gas pressure differential is an abnormally dangerous pressure differential value, and the second preset engine's oil-gas pressure differential is an abnormally warning pressure differential value. That is, if the engine's oil-gas pressure differential deviates from the normal range but has not yet reached a dangerous level, the fuel pressure can be adjusted to keep the oil-gas pressure differential within the preset range and within the abnormally warning pressure differential value, thereby stabilizing the oil-gas pressure differential and reducing oil blowby. The first preset engine's oil-gas pressure differential is greater than the second preset engine's oil-gas pressure differential. The second preset engine's oil-gas pressure differential can be calibrated based on actual operating conditions or can be a fixed value, such as 10 to 20 bar. The first preset engine's oil-gas pressure differential can be calibrated based on actual operating conditions or can be a fixed value, such as 20 to 40 bar.

[0031] In some embodiments, if the engine fuel-gas pressure differential is greater than a second preset engine fuel-gas pressure differential and less than a first preset engine fuel-gas pressure differential, adjusting the fuel pressure so that the degree of deviation between the fuel-gas pressure differential and the target pressure differential is less than or equal to a fuel-gas pressure differential deviation threshold includes:

[0032] If the engine oil-air differential pressure is greater than the second preset engine oil-air differential pressure and less than the first preset engine oil-air differential pressure, obtaining an engine oil-air differential pressure correction value based on a degree of deviation between the current engine oil-air differential pressure and a target engine pressure differential;

[0033] The fuel pressure at the fuel inlet of the engine is corrected according to the engine oil-gas pressure difference correction value so that the deviation degree between the current engine oil-gas pressure difference and the target pressure difference of the engine is less than or equal to the engine oil-gas pressure difference deviation degree threshold.

[0034] By monitoring the common rail oil pressure (i.e., the engine inlet oil pressure) and the outlet pressure of the engine's oil-gas balance valve, the system monitors the current differential pressure of the engine in real time. The current differential pressure is compared with the target pressure. If the current differential pressure deviates too much from the target, it is considered excessive. The differential pressure is then corrected to obtain a correction value. The fuel pressure at the engine's fuel inlet is then corrected based on the correction value, ensuring that the deviation between the current differential pressure and the target pressure is less than or equal to a deviation threshold. This maintains the differential pressure within a dynamically stable range, ensuring it remains within a safe range. This reduces blowby and improves issues such as deteriorating engine performance, uneven combustion among cylinders, and coking and clogging of nozzles. The target differential pressure for an engine is typically 10-15 bar.

[0035] It's important to note that before achieving steady-state balance in the fuel-gas pressure differential, closed-loop control of the cylinder gas supply boost pressure is required to ensure that the actual gas supply pressure is consistent with the target supply pressure. Normal cylinder supply pressure indicates normal engine gas supply pressure. Normal engine gas supply pressure is typically determined based on the actual gas supply pressure and the minimum gas supply pressure. If the actual gas supply pressure is ≤ the minimum gas supply pressure, a low cylinder supply pressure fault is reported. If the minimum gas supply pressure is < the actual gas supply pressure and ≤ the actual fuel rail pressure, the gas supply pressure is considered normal.

[0036] If the degree of deviation between the current oil-gas pressure differential of the engine and the target pressure differential of the engine is greater than the deviation degree threshold, that is, the current oil-gas pressure differential of the engine is too large, the current oil-gas pressure differential of the engine is corrected. The difference between the target pressure differential of the engine and the current oil-gas pressure differential of the engine is the oil-gas pressure differential correction value of the engine. It should be noted that under different operating conditions, the target pressure differential of the engine may be different. For example, under certain operating conditions, the target pressure differential of the engine is 10 bar, under certain operating conditions, the target pressure differential of the engine is 12 bar, and under certain operating conditions, the target pressure differential of the engine is 15 bar. The selection can be made based on actual conditions. By correcting the current oil-gas pressure differential of the engine, the current oil-gas pressure differential of the engine can be made closer to the target pressure differential, stabilizing the oil-gas pressure differential of the engine within a safe range of dynamic balance, thereby reducing the situation of large amounts of oil blowby in the gas path and improving engine performance.

[0037] In some embodiments, the actual fuel pressure at the fuel inlet of the engine is P1, the actual fuel pressure at the outlet of the engine's oil-gas balance valve is P2, the corrected fuel pressure of the engine is P3, the current fuel-gas pressure difference of the engine is ΔP1, the target pressure difference of the engine is ΔP, and the corrected fuel-gas pressure difference of the engine is ΔP2, satisfying:

[0038] △P1=P1-P2;

[0039] △P2=△P-△P1;

[0040] △P=P3-P2;

[0041] P3=P1+△P2.

[0042] By adding the engine oil-gas pressure differential correction value to the fuel pressure at the engine's fuel inlet, the fuel pressure at the engine's fuel inlet is corrected, and the corrected oil-gas pressure differential can be made closer to the target oil-gas pressure differential, dynamically stabilizing the engine's oil-gas pressure differential. It should be noted that at the end of the gas tank's life, due to insufficient gas in the gas tank, the gas pressure differential cannot be controlled to increase. At this time, only the fuel pressure at the engine's fuel inlet can be controlled. By adding the difference to the fuel pressure at the engine's fuel inlet, the oil-gas pressure differential is controlled, and the current engine oil-gas pressure differential can be made closer to the target pressure differential, stabilizing the engine's oil-gas pressure differential within a safe range of dynamic balance, thereby reducing the occurrence of large amounts of oil blowby in the gas circuit and improving engine performance.

[0043] In some embodiments, if the engine fuel-gas pressure differential is greater than a second preset engine fuel-gas pressure differential and less than a first preset engine fuel-gas pressure differential, adjusting the fuel pressure so that the degree of deviation between the fuel-gas pressure differential and the target pressure differential is less than or equal to a fuel-gas pressure differential deviation threshold includes:

[0044] If the oil-gas pressure difference of the engine is greater than the second preset oil-gas pressure difference of the engine and less than the first preset oil-gas pressure difference of the engine, obtaining the oil-gas pressure difference of each cylinder of the engine;

[0045] If the oil-gas pressure difference of the cylinder is greater than the second preset oil-gas pressure difference of the cylinder and less than the first preset oil-gas pressure difference of the cylinder, a cylinder oil-gas pressure difference correction value is obtained according to the degree of deviation between the current oil-gas pressure difference of the cylinder and the target pressure difference of the cylinder;

[0046] The fuel pressure of the cylinder is corrected according to the cylinder fuel-gas pressure difference correction value so that the deviation degree between the current fuel-gas pressure difference of the cylinder and the target pressure difference of the cylinder is less than or equal to the cylinder fuel-gas pressure difference deviation degree threshold.

[0047] When the needle valve clearance increases due to wear of a cylinder nozzle needle valve, it affects the fuel pressure differential of the current cylinder but does not affect the fuel pressure differentials of other cylinders. In this case, adjustments can be made to each cylinder. When the fuel pressure differential of a cylinder is greater than a second preset fuel pressure differential of a cylinder and less than a first preset fuel pressure differential of a cylinder, the first preset fuel pressure differential of the cylinder is at a dangerous value, typically indicating a serious abnormality such as damage or malfunction, while the second preset fuel pressure differential of the cylinder is at a warning value, typically indicating a natural condition such as wear of the cylinder nozzle needle valve. Therefore, the cylinder's fuel pressure is corrected within the dangerous value, ensuring that the deviation between the cylinder's current fuel pressure differential and the target fuel pressure differential is less than or equal to the fuel pressure differential deviation threshold. This stabilizes the fuel pressure differential of the abnormal cylinder while not affecting the operation of other cylinders, reducing excessive oil blowby and improving engine performance. The first preset fuel pressure differential of the cylinder is greater than the second preset fuel pressure differential of the cylinder. The specific values ​​can be pre-calibrated based on actual operating conditions.

[0048] In some embodiments, the fuel pressure of the cylinder is P4, the gas pressure of the cylinder is P5, the corrected fuel pressure of the cylinder is P6, the oil-gas pressure difference of the cylinder is ΔP3, the target pressure difference of the cylinder is ΔP', and the corrected oil-gas pressure difference of the cylinder is ΔP4, satisfying:

[0049] △P3=P4-P5;

[0050] △P4=△P'-△P3;

[0051] △P'=P6-P5;

[0052] P6=P4+△P4.

[0053] Due to abnormal air circuit, the air pressure is difficult to adjust. The oil pressure difference of the cylinder can be controlled within the appropriate range by correcting the oil pressure.

[0054] In a second aspect, the present application provides a device for confirming abnormal gas pressure in a dual-fuel nozzle gas path, comprising:

[0055] A first acquiring unit is used to acquire the current oil-gas pressure difference of the engine;

[0056] a second acquiring unit, configured to acquire the speed roughness of each cylinder of the engine if the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine; and

[0057] The execution unit is used to determine the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold.

[0058] By acquiring the speed roughness of each cylinder and determining the deviation between the speed roughness of each cylinder and the speed roughness threshold, the cylinder with abnormal air pressure is located and targeted, improving engine reliability. The speed roughness of each cylinder is derived from the crankshaft angular acceleration corresponding to each cylinder's power stroke, derived from the engine crankshaft speed signal. The deviation between the crankshaft angular acceleration corresponding to each cylinder's power stroke and the speed roughness threshold is used to determine whether the current cylinder has abnormal air pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0060] Figure 1 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0061] Figure 2 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0062] Figure 3 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0063] Figure 4 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0064] Figure 5 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0065] Figure 6 This is a flow chart of a method for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application.

[0066] Figure 7 Schematic diagram of a device for confirming abnormal gas pressure in a gas path of a dual-fuel nozzle according to an embodiment of the present application. DETAILED DESCRIPTION

[0067] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of this application without making any creative efforts shall fall within the scope of protection of this application.

[0068] With the implementation of the National VI emission regulations and the future industry development trend of carbon peak and carbon neutrality, engine alternative fuel technology, dual-fuel injection technology, hybrid technology, etc. are also becoming more mature. Among them, engine dual-fuel direct injection combustion in the cylinder is an important development direction, mainly including various technical solutions such as diesel + natural gas, diesel + ammonia, diesel + alcohol, etc. This technical route can maintain the same power and reliability as the diesel engine on the same platform, while having better economy and emission performance. As a key component of this technical route, the dual-fuel nozzle has good performance and reliability, and a complete fault warning and control mechanism, which is the main basis for ensuring good engine performance.

[0069] Dual-fuel nozzles have various problems such as deterioration of engine performance caused by oil blowby failure in the air path, uneven combustion in each cylinder, coking and blockage of the nozzle orifices, and other more serious failures, which affect their use.

[0070] In view of this, the present application provides a method and device for confirming abnormal air pressure in the air path of a dual-fuel nozzle, so as to improve various problems such as the difficulty in confirming the existing fault location, the deterioration of engine performance caused by oil leakage in the air path, uneven combustion in each cylinder, coking and blockage of the nozzle orifice, and the occurrence of other more serious faults.

[0071] First, as Figure 1 As shown, the present application provides a method for controlling the air pressure of an air path of a dual-fuel nozzle, comprising the following steps:

[0072] S100, obtaining the current oil-gas pressure difference of the engine;

[0073] S200: If the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine, obtaining the speed roughness of each cylinder of the engine;

[0074] S300 : Determine the position of the cylinder with abnormal air pressure based on the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold.

[0075] Because dual-fuel nozzles typically feature a coaxial dual-valve design, with both oil and gas fuels sharing a single nozzle for injection control, a clearance is created between the oil and gas chambers within the nozzle for pressure sealing, lubrication, and heat dissipation requirements of the jet needle valve, as well as for safety considerations. Common rail systems typically have a higher oil pressure than air pressure. Due to this small clearance (approximately 5μm) between the oil and gas chambers within dual-fuel nozzles, a small amount of fuel can leak into the air path during normal operation, where the oil pressure is higher than the air pressure (10 to 20 bar). This small amount of fuel leaking into the air path facilitates lubrication and heat dissipation of the jet needle valve, extending the life of the nozzle.

[0076] The amount of oil leakage in the dual-fuel nozzle air path changes linearly with the pressure difference between oil and gas. The greater the oil-gas pressure difference, the greater the oil leakage. If the oil-gas pressure difference is too large or the dual-fuel nozzle fails, the amount of oil leakage into the air path will increase, and even the fuel will leak back into the air rail, which will cause the engine combustion to deteriorate, the consistency of each cylinder to deteriorate, the nozzle hole to coke and clog, and other problems, seriously affecting the vehicle's performance and driving experience.

[0077] Taking into account pipeline pressure drop, the engine's gas inlet pressure is typically lower than the gas pressure at the outlet of the engine's oil-gas balance valve. If the engine's gas inlet pressure is higher than the gas pressure at the outlet of the engine's oil-gas balance valve, it's considered abnormal rail pressure and a risk of oil crossover. When the oil-gas pressure difference is caused by excessive oil crossover, often due to nozzle needle valve wear, the fault must be located and promptly corrected.

[0078] This application obtains the speed roughness of each cylinder and, based on the deviation between the speed roughness of each cylinder and a speed roughness threshold, locates the cylinder with abnormal air pressure, thereby improving engine reliability. The speed roughness of each cylinder is derived from the crankshaft angular acceleration corresponding to the power stroke of each cylinder, derived from the engine crankshaft speed signal. The deviation between the crankshaft angular acceleration corresponding to the power stroke of each cylinder and the speed roughness threshold can be used to determine whether the current cylinder has abnormal air pressure. The speed roughness threshold can be determined by using a standard map of speed roughness thresholds for each cylinder under different operating conditions and pre-calibrated in the control system. When the engine is operating normally, the injection and combustion performance of each cylinder is highly consistent, resulting in the same crankshaft angular acceleration during power generation in each cylinder. If an injection or combustion anomaly occurs in a cylinder, the combustion performance in that cylinder will differ significantly from that of other cylinders, resulting in an abnormal crankshaft angular acceleration during power generation in that cylinder. When the threshold exceeds a pre-calibrated threshold at which the engine maintains normal operation at that operating point, the cylinder is confirmed to be operating abnormally. If the whole engine air rail pressure is abnormal at the same time, it can be confirmed that the air path of the cylinder is abnormal. The first preset oil-air pressure difference of the engine can be calibrated according to the actual working conditions, or it can be a fixed value set, such as 20~40bar.

[0079] After confirming that the current cylinder gas circuit is abnormal, the following measures can be taken: report the abnormal oil leakage related faults in the gas circuit to remind the driver to go to the station for processing as soon as possible; according to the actual platform needs, limit the engine torque after reporting the fault to ensure safety; correct and limit the injection amount of the faulty cylinder, for example, control the fuel injection and jet of the dual-fuel nozzle of the faulty cylinder according to the minimum safe oil amount of the nozzle to prevent fuel flooding in the cylinder.

[0080] Combined with the first aspect, such as Figure 2 As shown, in some embodiments provided in the present application, determining the cylinder position with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold includes:

[0081] S301, comparing the absolute value of the difference between the speed roughness of each cylinder and the speed roughness of a preset cylinder with the preset difference;

[0082] S302: If the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, the cylinder is determined to have abnormal gas path pressure.

[0083] When the vehicle is running normally, the engine cylinders perform combustion and work in the normal ignition sequence of 1-5-3-6-2-4. The air volume, injection volume and combustion work of each cylinder are relatively consistent, and the overall operation of the engine is relatively smooth. Therefore, when there is no gas path fault, the speed roughness of each cylinder of the engine is at the same level, and the speed roughness of each cylinder operates within the speed roughness range of the preset cylinder. The speed roughness of the preset cylinder can be set in advance according to the working conditions, for example, it can be 30~100r / s 2 Range. When the air path of some cylinders is abnormal, the speed roughness of the abnormal cylinder will deviate from the speed roughness of the preset cylinder. By comparing the absolute value of the difference between the speed roughness in each cylinder and the speed roughness of the preset cylinder with the preset difference, it can be determined whether the cylinder has abnormal air path pressure. Usually, when the absolute value of the difference between the speed roughness and the speed roughness of the preset cylinder is greater than 30% of the speed roughness of the preset cylinder, the cylinder is considered to have abnormal air path pressure. It should be noted that the number of cylinders with abnormal air path pressure can be one or more. As long as the absolute value of the difference between the speed roughness in the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, it is considered to be abnormal.

[0084] Combined with the first aspect, such as Figure 3 As shown, in some embodiments provided in the present application, if the absolute value of the difference between the speed roughness in the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, then determining that the cylinder is a cylinder with abnormal gas path pressure includes:

[0085] S3021: If the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, compare the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders;

[0086] S3022: If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds a preset ratio range, the cylinder is determined to be a cylinder with abnormal gas path pressure.

[0087] In order to improve the accuracy of fault diagnosis and eliminate the influence of cylinder dispersion on the judgment, after the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders is further compared. If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds the preset ratio range, the cylinder is judged to be a cylinder with abnormal gas path pressure. It should be noted that the other cylinders here refer to cylinders whose absolute value of the difference between the speed roughness and the speed roughness of the preset cylinder is less than or equal to the preset difference, that is, they are defaulted to normal cylinders. When the speed roughness ratio of the suspected abnormal cylinder is further compared with the default normal cylinder, it can be further confirmed that the suspected abnormal cylinder is an abnormal cylinder, reducing the influence of cylinder dispersion. Usually, the preset ratio range can be 1.15~1.25.

[0088] In combination with the first aspect, in some embodiments provided herein, if the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine, then in obtaining the speed roughness of each cylinder of the engine, the speed roughness of the cylinder is α1, satisfying:

[0089] α1=d(2π*N) / dt;

[0090] Wherein, N is the engine speed;

[0091] t is time.

[0092] The speed roughness of the cylinder is the crankshaft angular acceleration of the cylinder, which is the derivative of the crankshaft speed of the cylinder with respect to time. The crankshaft speed of the cylinder is related to the speed. The speed roughness of the cylinder can be obtained through the speed and time.

[0093] Combined with the first aspect, such as Figure 4 As shown, in some embodiments provided in this application, after obtaining the current oil-air pressure difference of the engine, the method further includes:

[0094] S400: If the engine fuel-gas pressure difference is greater than the second preset engine fuel-gas pressure difference and less than the first preset engine fuel-gas pressure difference, adjust the fuel pressure so that the degree of deviation between the fuel-gas pressure difference and the target pressure difference is less than or equal to the fuel-gas pressure difference deviation degree threshold.

[0095] Existing methods for controlling fuel blowby in dual-fuel nozzles primarily rely on nozzle clearance and the differential pressure between the fuel and air, achieving this goal from a design perspective. This approach fails to account for variations in the differential pressure during actual operation, such as insufficient air pressure from a deflated cylinder and increased needle valve clearance due to nozzle needle wear. These factors can increase fuel blowby, negatively impacting engine performance and reliability.

[0096] If the engine's oil-gas pressure differential is greater than the second preset engine's oil-gas pressure differential and less than the first preset engine's oil-gas pressure differential, the first preset engine's oil-gas pressure differential is an abnormally dangerous pressure differential value, and the second preset engine's oil-gas pressure differential is an abnormally warning pressure differential value. That is, if the engine's oil-gas pressure differential deviates from the normal range but has not yet reached a dangerous level, the fuel pressure can be adjusted to keep the oil-gas pressure differential within the preset range and within the abnormally warning pressure differential value, thereby stabilizing the oil-gas pressure differential and reducing oil blowby. The first preset engine's oil-gas pressure differential is greater than the second preset engine's oil-gas pressure differential. The second preset engine's oil-gas pressure differential can be calibrated based on actual operating conditions or can be a fixed value, such as 10 to 20 bar. The first preset engine's oil-gas pressure differential can be calibrated based on actual operating conditions or can be a fixed value, such as 20 to 40 bar.

[0097] Combined with the first aspect, such as Figure 5 As shown, in some embodiments provided herein, if the fuel-air pressure difference of the engine is greater than the second preset fuel-air pressure difference of the engine and less than the first preset fuel-air pressure difference of the engine, adjusting the fuel pressure so that the degree of deviation between the fuel-air pressure difference and the target pressure difference is less than or equal to the fuel-air pressure difference deviation degree threshold includes:

[0098] S401: If the engine oil-air differential pressure is greater than a second preset engine oil-air differential pressure and less than a first preset engine oil-air differential pressure, obtaining an engine oil-air differential pressure correction value based on a degree of deviation between the current engine oil-air differential pressure and a target engine pressure differential;

[0099] S402: Correct the fuel pressure at the fuel inlet of the engine according to the engine oil-gas pressure difference correction value so that the deviation between the current engine oil-gas pressure difference and the target pressure difference of the engine is less than or equal to the engine oil-gas pressure difference deviation threshold.

[0100] By monitoring the common rail oil pressure (i.e., the engine inlet oil pressure) and the outlet pressure of the engine's oil-gas balance valve, the system monitors the current differential pressure of the engine in real time. The current differential pressure is compared with the target pressure. If the current differential pressure deviates too much from the target, it is considered excessive. The differential pressure is then corrected to obtain a correction value. The fuel pressure at the engine's fuel inlet is then corrected based on the correction value, ensuring that the deviation between the current differential pressure and the target pressure is less than or equal to a deviation threshold. This maintains the differential pressure within a dynamically stable range, ensuring it remains within a safe range. This reduces blowby and improves issues such as deteriorating engine performance, uneven combustion among cylinders, and coking and clogging of nozzles. The target differential pressure for an engine is typically 10-15 bar.

[0101] It's important to note that before achieving steady-state balance in the fuel-gas pressure differential, closed-loop control of the cylinder gas supply boost pressure is required to ensure that the actual gas supply pressure is consistent with the target supply pressure. Normal cylinder supply pressure indicates normal engine gas supply pressure. Normal engine gas supply pressure is typically determined based on the actual gas supply pressure and the minimum gas supply pressure. If the actual gas supply pressure is ≤ the minimum gas supply pressure, a low cylinder supply pressure fault is reported. If the minimum gas supply pressure is < the actual gas supply pressure and ≤ the actual fuel rail pressure, the gas supply pressure is considered normal.

[0102] If the degree of deviation between the current oil-gas pressure differential of the engine and the target pressure differential of the engine is greater than the deviation degree threshold, that is, the current oil-gas pressure differential of the engine is too large, the current oil-gas pressure differential of the engine is corrected. The difference between the target pressure differential of the engine and the current oil-gas pressure differential of the engine is the oil-gas pressure differential correction value of the engine. It should be noted that under different operating conditions, the target pressure differential of the engine may be different. For example, under certain operating conditions, the target pressure differential of the engine is 10 bar, under certain operating conditions, the target pressure differential of the engine is 12 bar, and under certain operating conditions, the target pressure differential of the engine is 15 bar. The selection can be made based on actual conditions. By correcting the current oil-gas pressure differential of the engine, the current oil-gas pressure differential of the engine can be made closer to the target pressure differential, stabilizing the oil-gas pressure differential of the engine within a safe range of dynamic balance, thereby reducing the situation of large amounts of oil blowby in the gas path and improving engine performance.

[0103] In conjunction with the first aspect, in some embodiments provided herein, the actual fuel pressure at the fuel inlet of the engine is P1, the actual fuel pressure at the outlet of the engine's oil-gas balance valve is P2, the corrected fuel pressure of the engine is P3, the current fuel-gas pressure difference of the engine is ΔP1, the target pressure difference of the engine is ΔP, and the corrected fuel-gas pressure difference of the engine is ΔP2, satisfying:

[0104] △P1=P1-P2;

[0105] △P2=△P-△P1;

[0106] △P=P3-P2;

[0107] P3=P1+△P2.

[0108] By adding the engine oil-gas pressure differential correction value to the fuel pressure at the engine's fuel inlet, the fuel pressure at the engine's fuel inlet is corrected, and the corrected oil-gas pressure differential can be made closer to the target oil-gas pressure differential, dynamically stabilizing the engine's oil-gas pressure differential. It should be noted that at the end of the gas tank's life, due to insufficient gas in the gas tank, the gas pressure differential cannot be controlled to increase. At this time, only the fuel pressure at the engine's fuel inlet can be controlled. By adding the difference to the fuel pressure at the engine's fuel inlet, the oil-gas pressure differential is controlled, and the current engine oil-gas pressure differential can be made closer to the target pressure differential, stabilizing the engine's oil-gas pressure differential within a safe range of dynamic balance, thereby reducing the occurrence of large amounts of oil blowby in the gas circuit and improving engine performance.

[0109] Combined with the first aspect, such as Figure 6 As shown, in some embodiments provided herein, if the fuel-air pressure difference of the engine is greater than the second preset fuel-air pressure difference of the engine and less than the first preset fuel-air pressure difference of the engine, adjusting the fuel pressure so that the degree of deviation between the fuel-air pressure difference and the target pressure difference is less than or equal to the fuel-air pressure difference deviation degree threshold includes:

[0110] S403: If the oil-gas pressure difference of the engine is greater than the second preset oil-gas pressure difference of the engine and less than the first preset oil-gas pressure difference of the engine, obtain the oil-gas pressure difference of each cylinder of the engine;

[0111] S404: If the cylinder's oil-gas pressure differential is greater than the second preset cylinder's oil-gas pressure differential and less than the first preset cylinder's oil-gas pressure differential, obtain a cylinder oil-gas pressure differential correction value based on a degree of deviation between the cylinder's current oil-gas pressure differential and the cylinder's target pressure differential.

[0112] S405 , correcting the fuel pressure of the cylinder according to the cylinder fuel-gas pressure difference correction value so that the degree of deviation between the current fuel-gas pressure difference of the cylinder and the target pressure difference of the cylinder is less than or equal to the cylinder fuel-gas pressure difference deviation degree threshold.

[0113] When the needle valve clearance increases due to wear of a cylinder nozzle needle valve, it affects the fuel pressure differential of the current cylinder but does not affect the fuel pressure differentials of other cylinders. In this case, adjustments can be made to each cylinder. When the fuel pressure differential of a cylinder is greater than a second preset fuel pressure differential of a cylinder and less than a first preset fuel pressure differential of a cylinder, the first preset fuel pressure differential of the cylinder is at a dangerous value, typically indicating a serious abnormality such as damage or malfunction, while the second preset fuel pressure differential of the cylinder is at a warning value, typically indicating a natural condition such as wear of the cylinder nozzle needle valve. Therefore, the cylinder's fuel pressure is corrected within the dangerous value, ensuring that the deviation between the cylinder's current fuel pressure differential and the target fuel pressure differential is less than or equal to the fuel pressure differential deviation threshold. This stabilizes the fuel pressure differential of the abnormal cylinder while not affecting the operation of other cylinders, reducing excessive oil blowby and improving engine performance. The first preset fuel pressure differential of the cylinder is greater than the second preset fuel pressure differential of the cylinder. The specific values ​​can be pre-calibrated based on actual operating conditions.

[0114] In conjunction with the first aspect, in some embodiments provided herein, the fuel pressure of the cylinder is P4, the gas pressure of the cylinder is P5, the corrected fuel pressure of the cylinder is P6, the oil-gas pressure difference of the cylinder is ΔP3, the target pressure difference of the cylinder is ΔP', and the corrected oil-gas pressure difference of the cylinder is ΔP4, satisfying:

[0115] △P3=P4-P5;

[0116] △P4=△P'-△P3;

[0117] △P'=P6-P5;

[0118] P6=P4+△P4.

[0119] Due to abnormal air circuit, the air pressure is difficult to adjust. The oil pressure difference of the cylinder can be controlled within the appropriate range by correcting the oil pressure.

[0120] Second, as Figure 7 As shown, the present application provides a device for confirming abnormal gas pressure in a dual-fuel nozzle gas path, comprising:

[0121] A first acquiring unit is used to acquire the current oil-gas pressure difference of the engine;

[0122] a second acquiring unit, configured to acquire the speed roughness of each cylinder of the engine if the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine; and

[0123] The execution unit is used to determine the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold.

[0124] By acquiring the speed roughness of each cylinder and determining the deviation between the speed roughness of each cylinder and the speed roughness threshold, the cylinder with abnormal air pressure is located and targeted, improving engine reliability. The speed roughness of each cylinder is derived from the crankshaft angular acceleration corresponding to each cylinder's power stroke, derived from the engine crankshaft speed signal. The deviation between the crankshaft angular acceleration corresponding to each cylinder's power stroke and the speed roughness threshold is used to determine whether the current cylinder has abnormal air pressure.

[0125] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units inherent to these processes, methods, products or equipment. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0126] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0127] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0128] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0129] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform. 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, or the part that contributes to the existing technology, 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 a number of instructions for enabling a terminal device to execute the methods described in each embodiment of this application.

[0130] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle, characterized in that: The following steps are involved: Obtain the current fuel-gas pressure differential of the engine, which is the difference between the actual fuel pressure at the fuel inlet of the engine and the actual fuel pressure at the outlet of the fuel-gas balance valve of the engine; If the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine, obtaining the speed roughness of each cylinder of the engine; Determining the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold; The step of determining the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold comprises: Comparing the absolute value of the difference between the speed roughness of each cylinder and the speed roughness of a preset cylinder with the size of the preset difference; If the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, compare the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders; If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds a preset ratio range, the cylinder is determined to be a cylinder with abnormal gas path pressure.

2. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 1, characterized in that: If the current oil-gas pressure difference of the engine is greater than the first preset oil-gas pressure difference of the engine, the speed roughness of each cylinder of the engine is obtained, and the speed roughness of the cylinder is α1, which satisfies: α1=d(2π*N) / dt; Wherein, N is the engine speed; t is time.

3. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 1, characterized in that: After obtaining the current oil-gas pressure difference of the engine, the method further includes: If the engine's oil-gas pressure difference is greater than the second preset engine's oil-gas pressure difference and less than the first preset engine's oil-gas pressure difference, adjust the fuel pressure so that the degree of deviation between the oil-gas pressure difference and the target pressure difference is less than or equal to the oil-gas pressure difference deviation degree threshold.

4. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 3, characterized in that: If the fuel-gas pressure difference of the engine is greater than the second preset fuel-gas pressure difference of the engine and less than the first preset fuel-gas pressure difference of the engine, adjusting the fuel pressure so that the degree of deviation between the fuel-gas pressure difference and the target pressure difference is less than or equal to the fuel-gas pressure difference deviation degree threshold includes: If the engine oil-air differential pressure is greater than the second preset engine oil-air differential pressure and less than the first preset engine oil-air differential pressure, obtaining an engine oil-air differential pressure correction value based on a degree of deviation between the current engine oil-air differential pressure and a target engine pressure differential; The fuel pressure at the fuel inlet of the engine is corrected according to the engine oil-gas pressure difference correction value so that the deviation degree between the current engine oil-gas pressure difference and the target pressure difference of the engine is less than or equal to the engine oil-gas pressure difference deviation degree threshold.

5. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 4, characterized in that: The actual fuel pressure at the engine's fuel inlet is P1, the actual fuel pressure at the engine's oil-gas balance valve outlet is P2, the corrected fuel pressure of the engine is P3, the engine's current oil-gas pressure difference is △P1, the engine's target pressure difference is △P, and the engine's oil-gas pressure difference correction value is △P2, satisfying: △P1=P1-P2; △P2=△P-△P1; △P=P3-P2; P3=P1+△P2.

6. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 3, characterized in that: If the fuel-gas pressure difference of the engine is greater than the second preset fuel-gas pressure difference of the engine and less than the first preset fuel-gas pressure difference of the engine, adjusting the fuel pressure so that the degree of deviation between the fuel-gas pressure difference and the target pressure difference is less than or equal to the fuel-gas pressure difference deviation degree threshold includes: If the oil-gas pressure difference of the engine is greater than the second preset oil-gas pressure difference of the engine and less than the first preset oil-gas pressure difference of the engine, obtaining the oil-gas pressure difference of each cylinder of the engine; If the oil-gas pressure difference of the cylinder is greater than the second preset oil-gas pressure difference of the cylinder and less than the first preset oil-gas pressure difference of the cylinder, a cylinder oil-gas pressure difference correction value is obtained according to the degree of deviation between the current oil-gas pressure difference of the cylinder and the target pressure difference of the cylinder; The fuel pressure of the cylinder is corrected according to the cylinder fuel-gas pressure difference correction value so that the deviation degree between the current fuel-gas pressure difference of the cylinder and the target pressure difference of the cylinder is less than or equal to the cylinder fuel-gas pressure difference deviation degree threshold.

7. The method for confirming abnormal gas pressure in the gas path of a dual-fuel nozzle according to claim 6, characterized in that: The fuel pressure of the cylinder is P4, the gas pressure of the cylinder is P5, the corrected fuel pressure of the cylinder is P6, the oil-gas pressure difference of the cylinder is △P3, the target pressure difference of the cylinder is △P', and the correction value of the oil-gas pressure difference of the cylinder is △P4, which satisfies: △P3=P4-P5; △P4=△P'-△P3; △P'=P6-P5; P6=P4+△P4.

8. A device for confirming abnormal gas pressure in a dual-fuel nozzle, characterized in that: include: A first acquisition unit is used to acquire the current oil-gas pressure difference of the engine, where the oil-gas pressure difference is the difference between the actual fuel pressure at the fuel inlet of the engine and the actual gas pressure at the outlet of the oil-gas balance valve of the engine; a second acquiring unit, configured to acquire the speed roughness of each cylinder of the engine if the current oil-air pressure difference of the engine is greater than a first preset oil-air pressure difference of the engine; as well as an execution unit, configured to determine a cylinder position having abnormal air pressure according to a deviation between a speed roughness of each cylinder of the engine and a speed roughness threshold; The step of determining the position of the cylinder with abnormal air pressure according to the deviation between the speed roughness of each cylinder of the engine and the speed roughness threshold comprises: Comparing the absolute value of the difference between the speed roughness of each cylinder and the speed roughness of a preset cylinder with the size of the preset difference; If the absolute value of the difference between the speed roughness of the cylinder and the speed roughness of the preset cylinder is greater than the preset difference, compare the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders; If the ratio of the speed roughness of the cylinder to the speed roughness of other normal cylinders exceeds a preset ratio range, the cylinder is determined to be a cylinder with abnormal gas path pressure.

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