A method for real-time monitoring and fault diagnosis of diesel engine misfire

Abstract

The application discloses a diesel engine under-charge real-time monitoring and fault diagnosis method, which measures the parameters such as cylinder pressure and crank angle signals of the diesel engine by comprehensively applying various sensors, firstly reads or calculates the cylinder pressure at the top dead center, the maximum explosion pressure, the effective power feature and the average effective pressure, respectively, calculates the difference value of the above parameters and the threshold value of the corresponding normal working condition, respectively, and preliminarily diagnoses whether the diesel engine is under-charge; secondly, the fault degree of each parameter is judged by calculating the deviation rate of each parameter; finally, the overall fault degree is comprehensively analyzed according to the above fault degree; according to the fusion of the fault characteristic information, the typical fault characteristics are compared, so that the composite fault diagnosis of the diesel engine is realized, various characteristic information is fully utilized, the diagnosis speed and accuracy are improved, qualitative and quantitative analysis is realized, and the application of the diesel engine fault diagnosis level will be improved.

Description

Technical Field

[0001] This invention relates to the field of diesel engine insufficient air filling fault diagnosis, specifically a method for real-time monitoring and fault diagnosis of insufficient air filling in diesel engines. Background Technology

[0002] During the intake stroke of a diesel engine, due to various reasons, the amount of fresh air drawn into the cylinder may not meet the normal operating requirements, resulting in insufficient air intake. When a diesel engine is under-charged, the amount of air entering the cylinder is reduced, leading to incomplete fuel combustion, which in turn causes severe carbon buildup, increased fuel consumption, and accelerated wear between parts. These adverse consequences shorten the service life of the diesel engine and increase operational risks.

[0003] Currently, research on online diagnosis of insufficient fuel filling in diesel engines is relatively limited, and the technical detection methods are relatively simple. There is a lack of comprehensive analysis of the interactions of various parameters, resulting in long detection cycles and less than ideal accuracy in fault detection. Therefore, developing real-time monitoring and fault diagnosis methods for insufficient fuel filling in diesel engines is of great significance for ensuring the safe and efficient operation of diesel engines. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention discloses a method for real-time monitoring and fault diagnosis of insufficient gas filling in diesel engines, which can diagnose insufficient gas filling faults in diesel engines based on cylinder pressure signal data.

[0005] Input parameters:

[0006] Parameter name unit Cylinder pressure MPa Crankshaft angle ℃A

[0007] Comparison parameters:

[0008] Parameter name numerical values Maximum burst pressure threshold 14.2MPa Mean effective pressure threshold 1.9824MPa Top dead center pressure threshold 6MPa Effective power characteristic threshold 3540

[0009] Fault diagnosis result classification:

[0010] It is divided into four levels: healthy, sub-healthy, general malfunction, and serious malfunction.

[0011] If the cylinder pressure of the equipment varies within the normal range, it is considered healthy. If the overall cylinder pressure of the equipment is lower than the normal value, it is considered sub-healthy. If the overall cylinder pressure of the equipment is significantly lower than the normal value, it is considered a general malfunction. If the cylinder pressure of the equipment is far lower than the normal value, or even if combustion within the cylinder is difficult, it is considered a serious malfunction.

[0012] S1: The cylinder pressure and crankshaft angle signals are read using cylinder pressure sensors and Hall effect sensors to plot the diesel engine's cylinder pressure curve. The maximum burst pressure p is read directly. z And the cylinder pressure p1 when the piston is at top dead center, the effective power characteristic P is obtained by calculating the area under the curve. e The mean effective pressure p is obtained using the following formula.me :

[0013]

[0014] In the formula, P e The effective power characteristic; τ is the number of strokes per cycle, τ=4 for a four-stroke engine and τ=2 for a two-stroke engine; i is the number of cylinders in the diesel engine; n is the crankshaft speed of the diesel engine, in r / min; V s The cylinder working volume, in liters (L), is calculated using the following formula:

[0015]

[0016] In the formula, D is the cylinder diameter, D = 280 mm; S is the piston stroke, S = 290 mm; both parameters are based on the "12PA6 Bench Test Outline".

[0017] If the cylinder pressure curve shows that the difference between the cylinder pressure p1 when the piston is at top dead center and the cylinder pressure at top dead center under normal operating conditions exceeds the specified range, the maximum explosion pressure p z It is also much lower than the maximum burst pressure under normal operating conditions, and the effective power P e If the power output is much lower than the rated power of the diesel engine, then the diesel engine can be diagnosed as having insufficient air intake.

[0018] Four physical quantities are defined as follows: top dead center pressure deviation rate ρ_1, maximum burst pressure deviation rate ρ_z, effective power characteristic deviation rate ρ_e, and average effective pressure deviation rate ρ_me. The calculation formulas are as follows:

[0019]

[0020]

[0021]

[0022]

[0023] The judgment rules are as follows:

[0024] Judgment Rule 1 Return value ρ1_danger≤ρ_1<100% Serious Fault ρ1_ab≤ρ_1<ρ1_danger Common Faults ρ1_safe≤ρ_1<ρ1_ab Sub-health other healthy

[0025] The threshold values ​​for the top dead center pressure deviation rate are set as follows: ρ1_save = 10%, ρ1_ab = 20%, ρ1_danger = 30%. These values ​​can be modified in actual engineering and programming.

[0026] Judgment Rule 2 Return value ρz_danger≤ρ_z<100% Serious Fault ρz_ab≤ρ_z<ρz_danger Common Faults ρz_safe≤ρ_z<ρz_ab Sub-health other healthy

[0027] The maximum burst pressure deviation rate threshold is set as follows: ρz_save = 10%, ρz_ab = 20%, ρz_danger = 30%. These values ​​can be modified in actual engineering and program writing.

[0028] Judgment Rule 3 Return value ρe_danger≤ρ_e<100% Serious Fault ρe_ab≤ρ_e<ρe_danger Common Faults ρe_safe≤ρ_e<ρe_ab Sub-health other healthy

[0029] The effective power characteristic deviation rate thresholds are set as follows: ρe_safe = 10%, ρe_ab = 20%, ρe_danger = 30%. These values ​​can be modified in actual engineering and program writing.

[0030]

[0031]

[0032] The average effective pressure deviation rate thresholds are set as follows: ρme_safe = 10%, ρme_ab = 20%, ρme_danger = 30%. These values ​​can be modified in actual engineering and program writing.

[0033]

[0034] Note: The threshold values ​​for the maximum burst pressure deviation rate are set as follows: ρZ_safe = 10%, ρZ_ab = 20%, ρZ_danger = 30%. These values ​​can be modified in actual engineering and program writing. Maximum burst pressure threshold: based on the "12PA6 bench test outline".

[0035] Beneficial effects:

[0036] This invention comprehensively applies various sensors to measure parameters such as cylinder pressure and crankshaft angle signals of a diesel engine. First, it reads or calculates the cylinder pressure at top dead center, maximum combustion pressure, effective power characteristics, and average effective pressure. It then calculates the difference between these parameters and their corresponding threshold values ​​under normal operating conditions to preliminarily diagnose whether the diesel engine is under-charged. Second, it determines the degree of fault by calculating the deviation rate of each parameter. Finally, it comprehensively analyzes the overall fault severity based on the above fault severity. By fusing these fault characteristic information and comparing typical fault characteristics, it achieves composite fault diagnosis of diesel engines. It fully utilizes various characteristic information, improves diagnostic speed and accuracy, achieves complementary advantages, and enables qualitative and quantitative analysis. This invention shows great potential in diesel engine fault diagnosis, and its application will contribute to improving the level of diesel engine fault diagnosis. Attached Figure Description

[0037] Figure 1 This is a flowchart of the fault diagnosis process of the present invention. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1 The present invention will be further described to better illustrate the implementation process of the invention:

[0039] A method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine includes the following steps:

[0040] S1: The cylinder pressure is read by the cylinder pressure sensor, and the crankshaft angle signal is read by the Hall sensor. The cylinder pressure curve of the diesel engine is plotted, and the maximum burst pressure p is read directly. z And the cylinder pressure p1 when the piston is at top dead center, the effective power characteristic P is obtained by calculating the area under the curve. e The mean effective pressure p is obtained using the following formula. me :

[0041]

[0042] Among them, P e For effective power characteristics, τ is the number of strokes per cycle, i is the number of cylinders in the diesel engine, n is the crankshaft speed of the diesel engine, and V is... s This refers to the working volume of the cylinder.

[0043] When the diesel engine is a four-stroke engine, τ = 4; when the diesel engine is a two-stroke engine, τ = 2.

[0044] The formula for calculating Vs is as follows:

[0045]

[0046] Where D is the cylinder diameter, D = 280 mm; S is the piston stroke, S = 290 mm; both parameters are based on the "12PA6 Bench Test Outline".

[0047] S2: Calculate the cylinder pressure p1 when the piston is at top dead center and the maximum burst pressure p1, respectively. z Effective power characteristic P e Mean effective pressure p me The difference between each and the threshold value corresponding to the normal operating condition.

[0048] If the cylinder pressure curve shows that the above differences all exceed the specified range, the preliminary diagnosis is insufficient air intake in the diesel engine.

[0049] S3: The severity of the top dead center pressure failure is determined by the top dead center pressure deviation rate ρ_1, defined as follows:

[0050]

[0051] Where p_1 is the top dead center pressure threshold under normal operating conditions, which is 6 MPa.

[0052] When ρ1_danger≤ρ_1<100%, the return value is "critical fault";

[0053] When ρ1_ab≤ρ_1<ρ1_danger, the return value is "general fault";

[0054] When ρ1_safe≤ρ_1<ρ1_ab, the return value is "sub-healthy";

[0055] When the value of ρ_1 is in other states, the return value is "healthy";

[0056] Among them, ρ1_save=10%, ρ1_ab=20%, and ρ1_danger=30%.

[0057] S4: The severity of the fault at the highest burst pressure is determined by the highest burst pressure deviation rate ρ_z, as defined below:

[0058]

[0059] Where p_z is the highest burst pressure threshold under normal operating conditions, which is 14.2 MPa.

[0060] When ρz_danger≤ρ_z<100%, the return value is "serious fault";

[0061] When ρz_ab≤ρ_z<ρz_danger, the return value is "general fault";

[0062] When ρz_safe≤ρ_z<ρz_ab, the return value is "sub-healthy";

[0063] When the value of ρ_z is in other states, the return value is "healthy";

[0064] ρz_save:=10%, ρz_ab=20%, ρz_danger=30%.

[0065] S5: The severity of faults in the effective power characteristic is determined by the effective power characteristic deviation rate ρ_e, as defined below:

[0066]

[0067] Where p_e is the effective power characteristic threshold under normal operating conditions, which is 3540.

[0068] When ρe_danger≤ρ_e<100%, the return value is "critical fault";

[0069] When ρe_ab≤ρ_e<ρe_danger, the return value is "general fault";

[0070] When ρe_safe≤ρ_e<ρe_ab, the return value is "sub-healthy";

[0071] When the value of ρ_e is in other states, the return value is "healthy";

[0072] Among them, ρe_safe=10%, ρe_ab=20%, and ρe_danger=30%.

[0073] S6: The severity of the fault in the mean effective pressure is determined by the mean effective pressure deviation rate ρ_me, as defined below:

[0074]

[0075] Where p_me is the average effective pressure threshold under normal operating conditions, which is 1.9824 MPa.

[0076] When ρme_danger≤ρ_me<100%, the return value is "critical fault";

[0077] When ρme_ab≤ρ_me<ρme_danger, the return value is "general fault";

[0078] When ρme_safe≤ρ_me<ρme_ab, the return value is "sub-healthy";

[0079] When the value of ρ_me is in other states, the return value is "healthy";

[0080] Among them, ρme_safe=10%, ρme_ab=20%, and ρme_danger=30%.

[0081] S7:

[0082] If the return values ​​calculated in steps S3-S6 include a "serious fault" and all return values ​​are in a fault or dangerous state, the final state is determined to be a serious fault.

[0083] If the return values ​​calculated in steps S3-S6 include "general fault" and none of the return values ​​are "healthy", the final state is determined to be general fault.

[0084] If all the return values ​​calculated in steps S3-S6 are "healthy", the final status is determined to be healthy.

[0085] If the return value calculated in steps S3-S6 belongs to other states, the final state is determined to be sub-healthy.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine, characterized in that: Includes the following steps: S1: The cylinder pressure is read by the cylinder pressure sensor, and the crankshaft angle signal is read by the Hall sensor. The cylinder pressure curve of the diesel engine is plotted, and the maximum burst pressure p is read directly. z And the cylinder pressure p1 when the piston is at top dead center, the effective power characteristic P is obtained by calculating the area under the curve. e The mean effective pressure p is obtained using the following formula. me : Among them, P e For effective power characteristics, τ is the number of strokes per cycle, i is the number of cylinders in the diesel engine, n is the crankshaft speed of the diesel engine, and V is... s This refers to the working volume of the cylinder. S2: Calculate the cylinder pressure p1 when the piston is at top dead center and the maximum burst pressure p1, respectively. z Effective power characteristic P e Mean effective pressure p me The difference between each and the threshold value corresponding to the normal operating condition. If the above differences all exceed the specified range, the preliminary diagnosis is insufficient air intake in the diesel engine; S3: The severity of the top dead center pressure failure is determined by the top dead center pressure deviation rate ρ_1, defined as follows: Where p_1 is the top dead center pressure threshold under normal operating conditions. When ρ1_danger≤ρ_1<100%, the return value is "critical fault"; When ρ1_ab≤ρ_1<ρ1_danger, the return value is "general fault"; When ρ1_safe≤ρ_1<ρ1_ab, the return value is "sub-healthy"; If the value of ρ_1 is in any other state, the return value is "healthy"; S4: The severity of the fault at the highest burst pressure is determined by the highest burst pressure deviation rate ρ_z, as defined below: Where p_z is the highest burst pressure threshold under normal operating conditions. When ρz_danger≤ρ_z<100%, the return value is "critical fault"; When ρz_ab≤ρ_z<ρz_danger, the return value is "general fault"; When ρz_safe≤ρ_z<ρz_ab, the return value is "sub-healthy"; When the value of ρ_z is in other states, the return value is "healthy"; S5: The severity of faults in the effective power characteristic is determined by the effective power characteristic deviation rate ρ_e, as defined below: Where p_e is the effective power characteristic threshold under normal operating conditions. When ρe_danger≤ρ_e<100%, the return value is "critical fault"; When ρe_ab≤ρ_e<ρe_danger, the return value is "general fault"; When ρe_safe≤ρ_e<ρe_ab, the return value is "sub-healthy"; When the value of ρ_e is in other states, the return value is "healthy"; S6: The severity of the fault in the mean effective pressure is determined by the mean effective pressure deviation rate ρ_me, as defined below: Where p_me is the average effective pressure threshold under normal operating conditions. When ρme_danger≤ρ_me<100%, the return value is "critical fault"; When ρme_ab≤ρ_me<ρme_danger, the return value is "general fault"; When ρme_safe≤ρ_me<ρme_ab, the return value is "sub-healthy"; If the value of ρ_me is in another state, the return value is "healthy"; S7： If the return values ​​calculated in steps S3-S6 include "serious fault" and all return values ​​are faulty or dangerous, the final state is determined to be a serious fault. If the return values ​​calculated in steps S3-S6 include "general fault" and none of the return values ​​are "healthy", the final state is determined to be general fault. If all the return values ​​calculated in steps S3-S6 are "healthy", the final status is determined to be healthy. If the return value calculated in steps S3-S6 belongs to other states, the final state is determined to be sub-healthy.

2. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S1, when the diesel engine is a four-stroke engine, τ = 4; When the diesel engine is a two-stroke engine, τ = 2.

3. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S1, Vs is calculated using the following formula: Where D is the cylinder diameter and S is the piston stroke.

4. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S3, ρ1_save = 10%, ρ1_ab = 20%, and ρ1_danger = 30%.

5. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S4, ρz_save = 10%, ρz_ab = 20%, and ρz_danger = 30%.

6. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S5, ρe_safe = 10%, ρe_ab = 20%, and ρe_danger = 30%.

7. The method for real-time monitoring and fault diagnosis of insufficient air charging in a diesel engine according to claim 1, characterized in that: In step S6, ρme_safe = 10%, ρme_ab = 20%, and ρme_danger = 30%.

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