Device and method for diagnosing diesel engine cylinder misfire based on instantaneous speed

Abstract

The present invention discloses a device and method for diagnosing misfire in a diesel engine cylinder based on instantaneous speed. The method includes the following steps: collecting instantaneous speed signals and top dead center signals of each cylinder of the diesel engine; performing array shifting on the instantaneous speed measurement values ​​of the diesel engine cycle, performing average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array to obtain instantaneous speed measurement values, and obtaining instantaneous speed data segments corresponding to each cylinder of the diesel engine; calculating the upper quartile of the maximum characteristic value of the instantaneous speed of each cylinder under actual operating conditions in each b array, and determining that the corresponding cylinder has misfired when the upper quartile of the maximum instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold. The present application achieves the division of the instantaneous speed of each cylinder by top dead center calibration through instantaneous speed, and eliminates the influence on the instantaneous speed measurement by dimensionless processing of the instantaneous speed, thereby reducing the influence of cyclic fluctuations on the instantaneous speed and improving the accuracy of diesel engine cylinder misfire fault detection.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent diagnosis of ship power systems, and in particular to a device and method for diagnosing misfire in a diesel engine cylinder based on instantaneous rotational speed. Background Art

[0002] As a critical component of a ship's propulsion system, diesel engine health directly impacts its safe operation. Failures often result in equipment downtime, ship suspension, and even casualties, leading to significant economic losses. Real-time assessment and fault diagnosis of diesel engine operating status are essential. A misfire, when the engine fails to burn or undergoes poor combustion due to factors such as insufficient fuel supply and poor cylinder sealing, can reduce engine power and fuel economy.

[0003] Conventional misfire diagnosis methods include those based on vibration signals, cylinder pressure signals, and instantaneous speed signals. Vibration-based misfire diagnosis methods typically require a vibration sensor installed on each cylinder head to diagnose and locate the faulty cylinder. By detecting cylinder head vibration, extracting characteristic parameters such as combustion impact energy or vibration energy per unit angle, and comparing them with normal firing conditions, the engine can determine whether a misfire has occurred. However, due to the numerous moving parts and complex vibration excitation in diesel engines, coupled vibration signals from each cylinder can lead to inaccurate misfire diagnosis. Cylinder pressure-based misfire diagnosis methods require a cylinder pressure sensor installed on each cylinder head to diagnose and locate the faulty cylinder. By detecting in-cylinder pressure, extracting characteristic parameters such as burst pressure and pressure rise rate, and comparing them with normal firing conditions, the engine can determine whether a misfire has occurred. Instantaneous speed-based misfire diagnosis methods utilize a crankshaft speed sensor and add a top dead center sensor to achieve both misfire diagnosis and faulty cylinder location. By detecting characteristic parameters such as the maximum, minimum and peak-to-peak values ​​of the instantaneous speed and comparing them with the characteristic parameter thresholds, it is possible to determine whether the diesel engine has misfired.

[0004] However, for multi-cylinder diesel engines, the overlap between cylinders during operation is significant, resulting in complex fluctuations in instantaneous speed. Furthermore, due to engine speed load changes, cycle fluctuations, and uneven combustion, the instantaneous speeds of each cycle are inconsistent. If the instantaneous speed of a single cycle is used for diagnosis, misjudgment may occur. Summary of the Invention

[0005] The present invention provides a device and method for diagnosing diesel engine cylinder misfire based on instantaneous speed, which is used to solve the problem that the instantaneous speed of each cycle of a multi-cylinder engine is inconsistent and only the instantaneous speed of a single cycle is selected for diagnosis, which easily leads to misjudgment.

[0006] To achieve the above objectives, according to one aspect of the present invention, a device for diagnosing in-cylinder misfire in a diesel engine based on instantaneous speed is provided, comprising: an acquisition module, configured to acquire instantaneous speed signals and top dead center signals of each cylinder of the diesel engine; a processing module, connected to the acquisition module, configured to perform top dead center calibration to divide the instantaneous speed measurement values ​​of the diesel engine, perform array shifting on the instantaneous speed measurement values ​​of each diesel engine cycle, and perform average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array, where a is a positive integer, to obtain instantaneous speed measurement values; the processing module is configured to averagely segment the instantaneous speed to obtain instantaneous speed data segments corresponding to each cylinder of the diesel engine; and an output module, connected to the processing module, configured to calculate, based on the instantaneous speed data segments, the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder in each b array under actual operating conditions. The output module is configured to determine that misfire has occurred in the corresponding cylinder when the upper quartile of the maximum eigenvalue of the instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, where b is a positive integer.

[0007] In some embodiments, the output module is used to calculate the lower quartile of the maximum instantaneous speed of each cylinder of the diesel engine under normal operating conditions to obtain the preset threshold.

[0008] In some embodiments, the acquisition module includes a first speed sensor and a first signal conditioning module, the processing module includes a signal acquisition module, the first speed sensor is arranged on the flywheel sprocket of the diesel engine, the first speed sensor and the signal acquisition module are respectively connected to the first signal conditioning module, the first speed sensor is used to collect the diesel engine flywheel rotation signal and convert it into a sinusoidal signal, the first signal conditioning module is used to convert the sinusoidal signal into a first square wave signal, the signal acquisition module is used to convert the first square wave signal into an instantaneous speed signal, the signal acquisition module is connected to the industrial computer, and the industrial computer is used to receive the instantaneous speed signal to calibrate the top dead center.

[0009] In some embodiments, the acquisition module includes a second speed sensor and a second signal conditioning module. The second speed sensor is arranged on the flywheel sprocket of the diesel engine. The second speed sensor and the signal acquisition module are respectively connected to the second signal conditioning module. The second speed sensor is used to collect the top dead center signal. The second signal conditioning module is used to convert the top dead center signal into a second square wave signal. The signal acquisition module is used to convert the second square wave signal into a top dead center signal.

[0010] In some embodiments, the instantaneous speed measurement value IAS_INI between two teeth of the diesel engine gear plate satisfies:

[0011] IAS_INI=60 / (N*Δt),

[0012] Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of the instantaneous speed.

[0013] In some embodiments, the processing module is used to divide the continuous instantaneous speed measurement values ​​of the diesel engine into arrays with a number of arrays of 2N according to the number of teeth N of the diesel engine gear disc, as the instantaneous speed measurement values ​​of one cycle of the diesel engine; the processing module is used to perform array translation on the instantaneous speed measurement values ​​of each diesel engine cycle, and to filter the average value of the instantaneous speed measurement values ​​of each a array, and divide the filtered instantaneous speed measurement value by the average speed of the diesel engine to obtain the instantaneous speed value, so as to complete the dimensionless processing.

[0014] In some embodiments, the processing module is used to divide the dimensionless instantaneous speed value into num_cyl segments on average according to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine, so as to obtain the instantaneous speed value data segments corresponding to each cylinder of the diesel engine; the output module is used to extract the maximum eigenvalue of the instantaneous speed data segment of a cylinder of the diesel engine according to the instantaneous speed value data segments, so as to calculate the upper quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of each b array under actual working conditions, and the output module is used to calculate the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of the diesel engine under normal working conditions.

[0015] The present application also provides a method for diagnosing diesel engine cylinder misfire based on instantaneous speed, comprising the steps of:

[0016] Obtain the instantaneous speed signal and top dead center signal of each cylinder of the diesel engine;

[0017] Obtain instantaneous speed measurement values ​​of a cycle of the diesel engine, perform array translation on the instantaneous speed measurement values ​​of the diesel engine cycle, perform average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array, where a is a positive integer, to obtain instantaneous speed measurement values; averagely segment the instantaneous speed to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine;

[0018] Based on the instantaneous speed data segments, the upper quartile of the maximum instantaneous speed of each cylinder under actual operating conditions in each of the b arrays is calculated. When the upper quartile of the maximum instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, it is determined that a misfire has occurred in the corresponding cylinder, where b is a positive integer.

[0019] In some embodiments, the preset threshold is obtained by calculating the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal operating conditions.

[0020] In some embodiments, the instantaneous speed measurement value IAS_INI between two teeth of the diesel engine gear plate satisfies:

[0021] IAS_INI=60 / (N*Δt),

[0022] Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of the instantaneous speed.

[0023] In some embodiments, the continuous instantaneous speed measurement values ​​of the diesel engine are divided into 2N arrays according to the number of teeth N of the diesel engine gear plate, to serve as the instantaneous speed measurement values ​​of one cycle of the diesel engine.

[0024] In some embodiments, the dimensionless instantaneous speed value is evenly divided into num_cyl segments according to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine; based on the instantaneous speed value data segments, the maximum eigenvalue of the instantaneous speed data of each cylinder of the diesel engine is extracted, and the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder of each b array under actual working conditions is calculated, and the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of the diesel engine under normal working conditions is calculated.

[0025] In some embodiments, the instantaneous speed value data segment corresponding to a cylinder of the diesel engine is set to IAS, and the maximum characteristic value of the instantaneous speed of the cylinder of the diesel engine is extracted as IAS_max to satisfy:

[0026] IAS_max=max(IAS);

[0027] The upper quartile IAS_max_Q3 of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder under actual working conditions satisfies:

[0028] IAS_max_Q3=quantile(IAS_max, 0.75, 1);

[0029] The lower quartile of the maximum instantaneous speed of the corresponding cylinder under normal operating conditions, IAS_max_Q1_normal, satisfies:

[0030] IAS_max_Q1=quantile(IAS_max,0.25,1).

[0031] The present invention provides an apparatus and method for diagnosing misfire in a diesel engine cylinder based on instantaneous speed. The method comprises the following steps: obtaining an instantaneous speed signal and a top dead center signal of each cylinder of the diesel engine; obtaining an instantaneous speed measurement value for one cycle of the diesel engine, performing array translation on the instantaneous speed measurement value of the diesel engine cycle, and performing average value filtering and dimensionless processing on the instantaneous speed measurement value of each a array to obtain an instantaneous speed measurement value; averaging the instantaneous speed into segments to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine; and calculating, based on the instantaneous speed data segments, the upper quartile of the maximum instantaneous speed of each cylinder in each b array under actual operating conditions. When the upper quartile of the maximum instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, it is determined that misfire has occurred in the corresponding cylinder. The present application can complete the top dead center calibration according to the instantaneous speed, thereby realizing the division of the instantaneous speed of each cylinder. By processing the instantaneous speed in a dimensionless manner, the influence on the instantaneous speed measurement can be eliminated. By calculating and analyzing the maximum eigenvalue, the influence of cyclic fluctuations on the instantaneous speed can be reduced, thereby improving the accuracy of diesel engine cylinder flameout failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0033] Figure 1 This is a system diagram of a device for diagnosing misfire in a diesel engine cylinder based on instantaneous speed in this application;

[0034] Figure 2 This is a data processing flow chart for diagnosing diesel engine cylinder misfire based on instantaneous speed in this application;

[0035] Figure 3 This is a schematic diagram of the calibration of the top dead center signal;

[0036] Figure 4 It is a waveform diagram of the instantaneous speed signal;

[0037] Figure 5 Schematic diagram for misfire fault diagnosis for quartiles;

[0038] The figures are as follows: 100 - acquisition module, 200 - processing module, 1 - first speed sensor, 2 - second speed sensor, 3 - first signal conditioning module, 4 - second signal conditioning module, 5 - signal acquisition module, 6 - industrial computer. DETAILED DESCRIPTION

[0039] The following describes in detail the specific implementation of a device and method for diagnosing diesel engine cylinder misfire based on instantaneous speed in conjunction with the accompanying drawings.

[0040] See also Figure 1The present application provides a device for diagnosing in-cylinder misfire in a diesel engine based on instantaneous speed, comprising: an acquisition module 100, a processing module 200, and an output module, wherein the acquisition module 100 and the output module are respectively connected to the processing module 200; the acquisition module 100 is used to acquire the instantaneous speed signal and the top dead center signal of each cylinder of the diesel engine; the processing module 200 is used to calibrate the top dead center to divide the instantaneous speed measurement value of the diesel engine, and the processing module 200 is used to perform array shifting on the instantaneous speed measurement value of each diesel engine cycle, and the processing module 200 is used to perform average filtering on the instantaneous speed measurement value of each array. and dimensionless processing, and the processing module 200 is used to obtain the instantaneous speed value data segment corresponding to each cylinder of the diesel engine according to the number of diesel engine cylinders and the ignition order of each cylinder of the diesel engine; the output module is used to calculate the upper quartile and the lower quartile of the instantaneous speed maximum value of each cylinder under the actual working condition of each b array, and the upper quartile and the lower quartile of the instantaneous speed maximum value of each cylinder under the normal working condition, and the output module is used to determine that a misfire occurs in the corresponding cylinder when the upper quartile of the instantaneous speed maximum value under the actual working condition of a cylinder is less than the lower quartile of the instantaneous speed maximum value under the normal working condition of the corresponding cylinder, wherein a and b are both positive integers.

[0041] The above-mentioned device for diagnosing misfire in a diesel engine cylinder based on instantaneous speed provided by the present application comprises: an acquisition module 100, a processing module 200 and an output module, wherein the acquisition module 100 and the output module are respectively connected to the processing module 200; the acquisition module 100 is used to acquire the instantaneous speed signal and the top dead center signal of each cylinder of the diesel engine; the processing module 200 is used to calibrate the top dead center and divide the instantaneous speed measurement value of the diesel engine, and the instantaneous speed measurement value of each diesel engine cycle is array-shifted, and the instantaneous speed measurement value of each a value is averaged. Mean filtering and dimensionless processing are performed to obtain the instantaneous speed data segments corresponding to each cylinder of the diesel engine according to the number of diesel engine cylinders and the firing order of each cylinder of the diesel engine. Through the output module, the upper quartile and lower quartile of the instantaneous speed maximum value of each cylinder under actual working conditions of each b array can be calculated, and the upper quartile and lower quartile of the instantaneous speed maximum value of each cylinder under normal working conditions can be calculated. When the upper quartile of the instantaneous speed maximum value of a cylinder under actual working conditions is less than the lower quartile of the instantaneous speed maximum value of the corresponding cylinder under normal working conditions, it is determined that the corresponding cylinder has misfired. Therefore, the above-mentioned device for diagnosing diesel engine misfire in cylinder based on instantaneous speed in the present application can complete the top dead center signal calibration, and can eliminate the influence of speed change on instantaneous speed measurement by processing the instantaneous speed in a dimensionless manner; by calculating and comparing the upper quartile of the maximum instantaneous speed of each cylinder under actual working conditions and the lower quartile of the maximum instantaneous speed under normal working conditions, it is determined whether the corresponding cylinder has misfired, thereby achieving the purpose of reducing the influence of cyclic fluctuations on the instantaneous speed and improving the accuracy of diesel engine cylinder flameout failure.

[0042] On the other hand, if the device for diagnosing in-cylinder misfire in a diesel engine based on instantaneous speed of the present application lacks at least one of the acquisition module 100, the processing module 200, and the output module, that is, if the acquisition module 100 fails to complete the acquisition of the instantaneous speed signal and the top dead center signal of each cylinder of the diesel engine, or if the processing module 200 fails to calibrate the top dead center and divide the instantaneous speed measurement values ​​of the diesel engine, then it is impossible to perform array shifting on the sequential speed measurement values ​​of each diesel engine cycle, and it is impossible to perform average value filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a value, thereby failing to obtain the instantaneous speed data segments corresponding to each cylinder of the diesel engine; or, if the output module fails to calculate the upper quartile and lower quartile of the instantaneous speed maximum value of each cylinder under normal operating conditions, and fails to calculate the upper quartile and lower quartile of the instantaneous speed maximum value of each cylinder under actual operating conditions, thereby failing to compare the two and determine whether misfire has occurred in the corresponding cylinder. Therefore, the device for diagnosing diesel engine misfire based on instantaneous speed in the present application can avoid misjudgment of the instantaneous speed measurement values ​​of each cylinder of the diesel engine through the above-mentioned acquisition module 100, processing module 200 and output module.

[0043] In an embodiment of the present application, the acquisition module 100 includes a first speed sensor 1, a second speed sensor 2, a first signal conditioning module 3, and a second signal conditioning module 4, and the processing module 200 includes a signal acquisition module 5 and an industrial computer 6; the first speed sensor 1 and the second speed sensor 2 are installed on the diesel engine flywheel sprocket, the first speed sensor 1 is facing the teeth of the sprocket, and the second speed sensor 2 is facing the iron bar on the sprocket surface; the first speed sensor 1 is connected to the first signal conditioning module 3, the signal acquisition module 5 is connected to the first signal conditioning module 3 and the second signal conditioning module 4 respectively, and the signal acquisition module 5 is connected to the industrial computer 6, the first speed sensor 1 is used to collect the diesel engine flywheel rotation signal and convert it into a sinusoidal signal, the first signal conditioning module 3 is used to convert the sinusoidal signal into a square wave signal, the signal acquisition module 5 is used to convert the square wave signal into an instantaneous speed signal, and the industrial computer 6 is used to receive the instantaneous speed signal and to calibrate the top dead center.

[0044] In the embodiment of the present application, the first speed sensor 1 is a magnetoelectric speed sensor, the second speed sensor 2 is a Hall speed sensor, the first signal conditioning module 3 is used to condition the instantaneous speed signal of the diesel engine, and the second signal conditioning module 4 is used to condition the top dead center signal of the diesel engine so that the instantaneous speed signal and the top dead center signal range meet the input requirements of the signal acquisition module 5. The signal acquisition module 5 is used to process the instantaneous speed signal of the diesel engine and transmit the data to the industrial computer 6. The signal acquisition module 5 adopts a counter function, and the industrial computer 6 analyzes the instantaneous speed data and judges the misfire in the diesel engine cylinder based on the instantaneous speed data. The instantaneous speed of the diesel engine adopts the pulse width measurement method.

[0045] In the embodiment of the present application, the instantaneous speed measurement value IAS_INI between two teeth of the diesel engine satisfies:

[0046] IAS_INI=60 / (N*Δt),

[0047] Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of the instantaneous speed.

[0048] In some embodiments, the acquisition module 100 is used to acquire a top dead center signal, and the acquisition module 100 is used to use an edge signal of the top dead center signal as a start trigger condition.

[0049] In some embodiments, as Figure 3 As shown, the processing module 200 is used to perform array shifting on the instantaneous speed measurement value of each diesel engine cycle according to the deviation between the position of the second speed sensor 2 and the actual dead center initial position of the diesel engine reference cylinder, thereby ensuring that the instantaneous speed measurement value of each array starts from the reference cylinder.

[0050] In some embodiments, the processing module 200 is used to perform average filtering on the instantaneous speed measurement values ​​of each array a to eliminate the influence of cyclic fluctuations on the instantaneous speed. The processing module 200 is also used to perform dimensionless processing on the filtered instantaneous speed value. The dimensionless processing is to divide the instantaneous speed measurement value by the average speed of the diesel engine to obtain the instantaneous speed value IAS, eliminating the influence of speed and load changes on the instantaneous speed. The instantaneous speed data after dimensionless processing is as follows: Figure 4 In this embodiment, a is equal to 5.

[0051] The processing module 200 is further configured to divide the filtered and dimensionless instantaneous speed values ​​into num_cyl segments according to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine, thereby forming instantaneous speed value data segments corresponding to each cylinder of the diesel engine. Taking cylinder A1 of the diesel engine as an example, the instantaneous speed value data segment corresponding to cylinder A1 is IAS_A1.

[0052] The output module is used to extract the characteristic values ​​of the instantaneous speed data segment of each cylinder of the diesel engine, including the maximum, minimum and peak-to-peak values ​​of the instantaneous speed of each cylinder. Taking the A1 cylinder of the diesel engine as an example, the maximum instantaneous speed of the A1 cylinder IAS_max_A1, the minimum instantaneous speed of the A1 cylinder IAS_min_A1, and the peak-to-peak value of the instantaneous speed of the A1 cylinder IAS_PtoP_A1 are respectively:

[0053] IAS_max_A1=max(IAS_A1);

[0054] IAS_min_A1=min(IAS_A1);

[0055] IAS_PtoP_A1=IAS_max_A1-IAS_min_A1;

[0056] The output module is further used to calculate the upper quartile and the lower quartile of the maximum instantaneous rotational speed of each cylinder in each b array. In this embodiment, b is 100.

[0057] Taking the diesel engine A1 cylinder as an example, the upper quartile IAS_max_A1_Q3 satisfies:

[0058] IAS_max_A1_Q3=quantile(IAS_max_A1,0.75,1);

[0059] The lower quartile IAS_max_A1_Q1 satisfies:

[0060] IAS_max_A1_Q1=quantile(IAS_max_A1,0.25,1);

[0061] The output module is also used to collect the instantaneous speed measurement value of the diesel engine under normal conditions, and to calculate the upper quartile and lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal conditions. Taking the A1 cylinder of the diesel engine as an example, the upper quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal conditions is IAS_max_A1_Q3_normal, and the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal conditions is IAS_max_A1_Q1_normal. The upper quartile IAS_max_A1_Q3_normal and the lower quartile IAS_max_A1_Q1_normal are used as the reference values ​​for judgment.

[0062] The output module is used to compare the upper quartile of the maximum characteristic value of the instantaneous speed of each cylinder during actual operation of the diesel engine with the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder under normal operating conditions of the diesel engine. The output module is used to determine that a cylinder misfire has occurred when the upper quartile of the maximum characteristic value of the instantaneous speed of each cylinder during actual operation is less than the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder under normal operating conditions. Taking cylinder A1 as an example, the output module is used to determine that cylinder A1 may have misfire when IAS_max_A1_Q1 is less than IAS_max_A1_Q3_normal.

[0063] The present application provides a device for diagnosing misfire in a diesel engine cylinder based on instantaneous speed. The acquisition module 100 is used to collect the instantaneous speed and top dead center signal of each cylinder of the diesel engine; the processing module 200 is used to complete the top dead center calibration according to the deviation between the position of the second speed sensor 2 and the actual dead center initial position of the diesel engine reference cylinder, and is used to perform array translation on the instantaneous speed measurement value of each diesel engine cycle. The processing module 200 is used to average the instantaneous speed measurement values ​​of each a array and perform dimensionless processing on the filtered instantaneous speed value; and the processing module 200 is used to obtain the instantaneous speed value data segment corresponding to each cylinder of the diesel engine according to the number of diesel engine cylinders and the ignition order of each cylinder of the diesel engine, where a is a positive integer; the output module is used to calculate each The upper quartile and lower quartile of the maximum eigenvalue of the instantaneous speed of each cylinder of the b arrays are used, and the output module is used to calculate the upper quartile and lower quartile of the maximum eigenvalue of the instantaneous speed of each cylinder under normal operating conditions of the diesel engine. The output module is also used to determine that a misfire has occurred in the corresponding cylinder when the upper quartile of the maximum eigenvalue of the instantaneous speed of a certain cylinder under actual operating conditions is less than the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder under normal operating conditions. In addition, the output module is used to extract the eigenvalues ​​of the instantaneous speed data segments of each cylinder of the diesel engine, the eigenvalues ​​including the maximum eigenvalue of the instantaneous speed of each cylinder, the minimum eigenvalue of the instantaneous speed of each cylinder, and the peak-to-peak eigenvalue of the instantaneous speed of each cylinder. The output module is then used to calculate the upper quartile and lower quartile of the maximum value of the instantaneous speed of each cylinder of each b array.

[0064] See also Figure 2 The present application also provides a method for diagnosing misfire in a diesel engine cylinder based on instantaneous speed, comprising the steps of:

[0065] Step 1: Obtain the instantaneous speed signal and top dead center signal of each cylinder of the diesel engine;

[0066] In this step 1, the first speed sensor 1 is used to collect the diesel engine flywheel rotation signal and convert it into a sinusoidal signal. The first signal conditioning module 3 converts the sinusoidal signal into a square wave signal. The signal acquisition module 5 converts the square wave signal into the instantaneous speed signal of the diesel engine. The signal acquisition module 5 transmits the instantaneous speed signal to the industrial computer 6, thereby completing the step of obtaining the instantaneous speed of the diesel engine in step 1. The first speed sensor 1 is a magnetoelectric speed sensor and is installed on the flywheel sprocket, with the first speed sensor 1 facing the teeth of the sprocket.

[0067] The diesel engine's top dead center signal is acquired using the second speed sensor 2. The second signal conditioning module 4 converts the top dead center signal into a square wave signal. The signal acquisition module 5 uses the square wave signal as the top dead center signal for the acquisition process, thereby completing the acquisition of the top dead center signal in step 1. Second speed sensor 2 is a Hall effect sensor mounted on the flywheel sprocket, directly opposite the rack on the sprocket surface. In this step 1, signal acquisition module 5 utilizes a counter function module and pulse width measurement to acquire the diesel engine's instantaneous speed. The acquisition is triggered in start trigger mode, with the edge of the top dead center signal serving as the start trigger condition.

[0068] Step 2: Divide the instantaneous speed measurement values ​​of the diesel engine, perform array translation on the instantaneous speed measurement values ​​of the diesel engine cycle, perform average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array to obtain the instantaneous speed measurement value, where a is a positive integer; divide the instantaneous speed into segments to obtain the instantaneous speed value data segments corresponding to each cylinder of the diesel engine;

[0069] In step 2, the instantaneous speed measurement value IAS_INI between two teeth of the diesel engine satisfies:

[0070] IAS_INI=60 / (N*Δt),

[0071] Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of instantaneous speed.

[0072] The value of N is generally between 100 and 250, and N is preferably 168; the unit of Δt is seconds. Since the speed of the diesel engine changes and the instantaneous speed changes within the cycle, Δt also changes relatively.

[0073] In this step 2, the continuous instantaneous speed measurement values ​​of the diesel engine are divided into 2N arrays according to the number of teeth N of the diesel engine gear plate, so as to serve as the instantaneous speed measurement values ​​of one cycle of the diesel engine.

[0074] In this step 2, if Figure 3 As shown, based on the initial position deviation between the top dead center sensor position and the actual dead center of the diesel engine reference cylinder, the top dead center sensor position deviation is obtained to perform array translation on the instantaneous speed measurement value of each diesel engine cycle to ensure that the instantaneous speed measurement value of each array starts from the reference cylinder.

[0075] In this step 2, the dimensionless instantaneous speed value is evenly divided into num_cyl segments according to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine, so as to obtain the instantaneous speed value data segment corresponding to each cylinder of the diesel engine.

[0076] Step 3: Based on the instantaneous speed data segments, calculate the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder in each b array under actual operating conditions. When the upper quartile of the maximum eigenvalue of the instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, it is determined that the corresponding cylinder has misfired, where b is a positive integer.

[0077] In this step 3, based on the instantaneous speed value data segment, the maximum eigenvalue of the instantaneous speed data of each cylinder of the diesel engine is extracted, the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder under actual working conditions for each b array is calculated, and the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of the diesel engine under normal working conditions is calculated.

[0078] In step 3, the instantaneous speed value data segment corresponding to a cylinder of the diesel engine is set as IAS, and the maximum characteristic value of the instantaneous speed of a cylinder of the diesel engine is extracted as IAS_max to satisfy:

[0079] IAS_max=max(IAS);

[0080] The upper quartile IAS_max_Q3 of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder under actual working conditions satisfies:

[0081] IAS_max_Q3=quantile(IAS_max, 0.75, 1);

[0082] In step 3, the preset threshold is obtained by calculating the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal operating conditions. The lower quartile of the maximum characteristic value of the instantaneous speed of the corresponding cylinder under normal operating conditions IAS_max_Q1_normal satisfies:

[0083] IAS_max_Q1=quantile(IAS_max,0.25,1).

[0084] That is, the instantaneous speed measurement values ​​of each a array are averaged and filtered, and the filtered instantaneous speed values ​​are dimensionlessly processed to obtain the instantaneous speed value IAS; according to the number of diesel engine cylinders num_cyl, the instantaneous speed is evenly divided into num_cyl segments to obtain the instantaneous speed value data segment IAS_A1 corresponding to each cylinder of the diesel engine.

[0085] In this step 3, it also includes the step of extracting the minimum eigenvalue and peak-to-peak eigenvalue of the instantaneous speed data segment of each cylinder of the diesel engine. Taking cylinder A1 as an example, it includes the maximum eigenvalue IAS_max_A1 of the instantaneous speed of each cylinder, the minimum eigenvalue IAS_min_A1 of the instantaneous speed of each cylinder, and the peak-to-peak eigenvalue IAS_PtoP_A1 of the instantaneous speed of each cylinder.

[0086] In step 3, taking cylinder A1 as an example, the upper quartile IAS_max_A1_Q3 of the maximum eigenvalue of the instantaneous speed of cylinder A1 satisfies:

[0087] IAS_max_A1_Q3=quantile(IAS_max_A1,0.75,1);

[0088] The lower quartile of the maximum eigenvalue of the instantaneous speed of cylinder A1, IAS_max_A1_Q1, satisfies:

[0089] IAS_max_A1_Q1=quantile(IAS_max_A1,0.25,1);

[0090] The quartiles of the maximum eigenvalue of the instantaneous speed of cylinder A1 are IAS_max_A1_Q1_normal and IAS_max_A1_Q3_normal, respectively.

[0091] In this step 3, during actual operation of the diesel engine, the quartiles of the maximum characteristic values ​​of the instantaneous speed of each cylinder are calculated based on the collected instantaneous speed measurement values ​​of the diesel engine. By comparing the relative sizes of the upper quartile IAS_max_A1_Q1 of the maximum instantaneous speed of each cylinder with the lower quartile IAS_max_A1_Q3_normal under normal operating conditions, when the maximum instantaneous speed of cylinder A1 IAS_max_A1_Q1 is less than the lower quartile IAS_max_A1_Q3_normal under normal operating conditions, it is determined that misfire may have occurred in cylinder A1.

[0092] In some specific embodiments of this application, please refer to Figure 5Taking cylinder A1 as an example, the lower quartile of the instantaneous maximum speed of cylinder A1 under normal working conditions is 1.0200, the middle quartile of the instantaneous maximum speed of cylinder A1 under normal working conditions is 1.0206, and the upper quartile of the instantaneous maximum speed of cylinder A1 under normal working conditions is 1.0212; the lower quartile of the instantaneous maximum speed of cylinder A1 under misfire conditions is 1.0084, the middle quartile of the instantaneous maximum speed of cylinder A1 under misfire conditions is 1.0093, and the upper quartile of the instantaneous maximum speed of cylinder A1 under misfire conditions is 1.01011. In addition, taking cylinder B1 as an example, the lower quartile of the instantaneous maximum speed of cylinder B1 under normal working conditions is 1.05433, the middle quartile of the instantaneous maximum speed of cylinder B1 under normal working conditions is 1.05521, and the upper quartile of the instantaneous maximum speed of cylinder B1 under normal working conditions is 1.05594; the lower quartile of the instantaneous maximum speed of cylinder B1 under misfire conditions is 1.04439, the middle quartile of the instantaneous maximum speed of cylinder B1 under misfire conditions is 1.046, and the upper quartile of the instantaneous maximum speed of cylinder B1 under misfire conditions is 1.04735.

[0093] Therefore, the present application provides an apparatus and method for diagnosing in-cylinder misfire in a diesel engine based on instantaneous speed. The method includes the following steps: obtaining an instantaneous speed signal and a top dead center signal for each cylinder of the diesel engine; obtaining instantaneous speed measurement values ​​for one cycle of the diesel engine, performing array shifting on the instantaneous speed measurement values ​​of the diesel engine cycle, and performing average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array to obtain instantaneous speed measurement values; segmenting the instantaneous speed to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine; and calculating the upper quartile of the maximum instantaneous speed of each cylinder under actual operating conditions for each b array based on the instantaneous speed data segments. When the upper quartile of the maximum instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, misfire is determined to have occurred in the corresponding cylinder. The present application can achieve the segmentation of the instantaneous speed of each cylinder. By dimensionlessly processing the instantaneous speed, the influence on the instantaneous speed measurement can be eliminated. By calculating and analyzing the maximum eigenvalue, the influence of cycle fluctuations on the instantaneous speed can be reduced, thereby improving the accuracy of diesel engine cylinder misfire fault detection.

[0094] The above is only a preferred embodiment of the present application. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A device for diagnosing misfire in a diesel engine cylinder based on instantaneous speed, characterized in that: include: A collection module (100), the collection module (100) is used to collect the instantaneous speed signal and top dead center signal of each cylinder of the diesel engine; A processing module (200) is connected to the acquisition module (100), and is used for top dead center calibration to divide the instantaneous speed measurement value of the diesel engine, and performs array translation on the instantaneous speed measurement value of each diesel engine cycle, and performs average value filtering and dimensionless processing on the instantaneous speed measurement value of each a array to obtain the instantaneous speed measurement value, wherein a is a positive integer; the processing module (200) is used to averagely divide the instantaneous speed into segments to obtain the instantaneous speed data segment corresponding to each cylinder of the diesel engine; An output module is connected to the processing module (200), and the output module is used to calculate the upper quartile of the maximum characteristic value of the instantaneous speed of each cylinder in each b array under actual working conditions based on the instantaneous speed data segments, and the output module is used to determine that a misfire occurs in the corresponding cylinder when the upper quartile of the maximum characteristic value of the instantaneous speed of a cylinder under actual working conditions is less than a preset threshold value, wherein b is a positive integer.

2. The device according to claim 1, characterized in that The output module is used to calculate the lower quartile of the maximum instantaneous speed of each cylinder of the diesel engine under normal operating conditions to obtain the preset threshold value.

3. The device according to claim 1, characterized in that The acquisition module (100) includes a first speed sensor (1) and a first signal conditioning module (3); the processing module (200) includes a signal acquisition module (5) and an industrial control computer (6); the first speed sensor (1) is arranged on a flywheel gear of a diesel engine; the first speed sensor (1) and the signal acquisition module (5) are respectively connected to the first signal conditioning module (3); the first speed sensor (1) is used to acquire a diesel engine flywheel rotation signal and convert it into a sinusoidal signal; the first signal conditioning module (3) is used to convert the sinusoidal signal into a first square wave signal; the signal acquisition module (5) is used to convert the first square wave signal into an instantaneous speed signal; the signal acquisition module (5) is connected to the industrial control computer (6); and the industrial control computer (6) is used to receive the instantaneous speed signal to calibrate the top dead center.

4. The device according to claim 3, characterized in that The acquisition module (100) comprises a second speed sensor (2) and a second signal conditioning module (4); the second speed sensor (2) is arranged on a flywheel sprocket of a diesel engine; the second speed sensor (2) and the signal acquisition module (5) are respectively connected to the second signal conditioning module (4); the second speed sensor (2) is used to acquire a top dead center signal; the second signal conditioning module (4) is used to convert the top dead center signal into a second square wave signal; and the signal acquisition module (5) is used to convert the second square wave signal into a top dead center signal.

5. The device according to claim 1, characterized in that The instantaneous speed measurement value IAS_INI between two teeth of the diesel engine gear plate satisfies: IAS_INI=60 / (N*Δt), Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of the instantaneous speed.

6. The device according to claim 5, characterized in that The processing module (200) is used to divide the continuous instantaneous speed measurement values ​​of the diesel engine into 2N arrays according to the number of teeth N of the diesel engine gear plate, so as to serve as the instantaneous speed measurement values ​​of one cycle of the diesel engine; The processing module (200) is used to perform array translation on the instantaneous speed measurement value of each diesel engine cycle, and to filter the average value of the instantaneous speed measurement value of each a array, and to divide the filtered instantaneous speed measurement value by the average speed of the diesel engine to obtain the instantaneous speed value, so as to complete the dimensionless processing.

7. The device according to claim 6, characterized in that The processing module (200) is used to divide the dimensionless instantaneous speed value into num_cyl segments according to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine, so as to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine; The output module is used to extract the maximum eigenvalue of the instantaneous speed data segment of a cylinder of the diesel engine based on the instantaneous speed value data segment, so as to calculate the upper quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of each b array under actual working conditions, and the output module is used to calculate the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of the diesel engine under normal working conditions.

8. A method for diagnosing diesel engine cylinder misfire based on instantaneous speed, characterized in that: Including steps: Obtain the instantaneous speed signal and top dead center signal of each cylinder of the diesel engine; Dividing the instantaneous speed measurement values ​​of the diesel engine, performing array shifting on the instantaneous speed measurement values ​​of the diesel engine cycle, performing average filtering and dimensionless processing on the instantaneous speed measurement values ​​of each a array to obtain the instantaneous speed measurement value, where a is a positive integer; and averaging the instantaneous speed into segments to obtain instantaneous speed value data segments corresponding to each cylinder of the diesel engine; Based on the instantaneous speed data segments, the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder under actual operating conditions in each of the b arrays is calculated. When the upper quartile of the maximum eigenvalue of the instantaneous speed of a cylinder under actual operating conditions is less than a preset threshold, it is determined that a misfire has occurred in the corresponding cylinder, where b is a positive integer.

9. The method according to claim 8, characterized in that The preset threshold is obtained by calculating the lower quartile of the maximum characteristic value of the instantaneous speed of each cylinder of the diesel engine under normal operating conditions.

10. The method according to claim 8, characterized in that The instantaneous speed measurement value IAS_INI between two teeth of the diesel engine gear plate satisfies: IAS_INI=60 / (N*Δt), Wherein, N represents the number of teeth of the diesel engine gear plate, Δt represents the time interval between two teeth of the diesel engine gear plate, and Δt represents the time interval between the rising edges of two similar square wave signals of the instantaneous speed.

11. The method according to claim 10, characterized in that According to the number of teeth N of the diesel engine gear plate, the continuous diesel engine instantaneous speed measurement values ​​are divided into arrays with a number of arrays of 2N to serve as the instantaneous speed measurement values ​​of a cycle of the diesel engine.

12. The method according to claim 11, characterized in that According to the number of diesel engine cylinders num_cyl and the firing order of each cylinder of the diesel engine, the dimensionless instantaneous speed value is evenly divided into num_cyl segments to obtain the instantaneous speed value data segments corresponding to each cylinder of the diesel engine; Based on the instantaneous speed value data segment, the maximum eigenvalue of the instantaneous speed data of each cylinder of the diesel engine is extracted, the upper quartile of the maximum eigenvalue of the instantaneous speed of each cylinder under actual operating conditions for each b array is calculated, and the lower quartile of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder of the diesel engine under normal operating conditions is calculated.

13. The method according to claim 12, characterized in that The instantaneous speed data segment corresponding to a cylinder of a diesel engine is set as IAS, and the maximum characteristic value IAS_max of the instantaneous speed of a cylinder of a diesel engine is extracted to meet the following requirements: IAS_max=max(IAS); The upper quartile IAS_max_Q3 of the maximum eigenvalue of the instantaneous speed of the corresponding cylinder under actual working conditions satisfies: IAS_max_Q3=quantile(IAS_max, 0.75, 1); The lower quartile of the maximum instantaneous speed of the corresponding cylinder under normal operating conditions, IAS_max_Q1_normal, satisfies: IAS_max_Q1=quantile(IAS_max,0.25,1).

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