Engine misfire detection method, system, storage medium and vehicle

Abstract

The present invention belongs to the technical field of on-board diagnostic systems, and specifically relates to an engine misfire detection method, system, storage medium, and vehicle. The system of the present invention includes: an acceleration detection module configured to detect acceleration acce in real time; a first misfire detection module configured to detect flfexsn signals in real time and perform engine misfire detection via the flfexsn signals; a second misfire detection module configured to detect lfexsn signals in real time and perform engine misfire detection via the lfexsn signals; and a control unit configured to determine, through specific logic, whether the first misfire detection module or the second misfire detection module performs engine misfire detection. The present invention also provides a method for performing misfire detection using the above-mentioned system. The present invention can avoid the situation where misfires are missed and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of on-board diagnostic systems, and in particular relates to an engine misfire detection method, system, storage medium and vehicle. Background Art

[0002] A vehicle engine misfire occurs when one or more cylinders of the engine fail to burn properly or burn incompletely during operation. A persistent misfire occurs when one or more cylinders continue to misfire during engine operation. Continuous misfires can lead to reduced power, poor fuel economy, excessive exhaust emissions, and damage to the catalytic converter.

[0003] Vehicle misfire detection refers to the monitoring and identification of engine misfires. The method mainly determines whether a misfire occurs by monitoring parameters related to the engine speed during operation. In the prior art, the method of misfire detection is: after the self-learning of the gear tooth deviation and combustion deviation of the misfire signal is completed, misfire detection is performed through the lfexsn signal (related to the engine speed fluctuation) or the flfexsn signal at the time of misfire. When the lfexsn signal>lfex_w (threshold) or flfexsn>flfex_w (threshold), the corresponding flag bit Misfire_F is set and misfire is detected. According to the experience of the prior art, continuous misfires are better detected by the flfexsn signal, and the lfexsn signal serves as a supplement to the detection of continuous misfires. The detection diagram of single misfire and continuous misfire is shown in the figure below. Figure 1 shown.

[0004] When a vehicle is traveling on a rough road, its speed can fluctuate dramatically. This can cause the engine speed to fluctuate through the transmission system, potentially causing the misfire detection signal (lfexsn) to exceed a threshold, leading to a misfire detection error. To address this issue, ABS typically uses wheel speed signals to sense changes in wheel speed and calculate acceleration (acce). When acce exceeds threshold F (facce), indicating a rough road surface, the misfire detection module disables detection, preventing misfire detection errors.

[0005] However, when some models misfire continuously, the vehicle shakes and the speed fluctuates violently, causing the acceleration signal acce to jump very high and exceed the threshold F. As a result, the misfire phenomenon is recognized as the vehicle is driving on a bad road, and the misfire detection function is turned off. Figure 2 ,When misfire continues, acce>facce_w, a bad path is detected, and misfire detection will be suppressed. ,According to the diagnostic logic, the continuous misfire signal will be assigned to 0, and the misfire detection ,function will be turned off, which will result in missed misfire detection.

[0006] In view of the above problems, it is still necessary to optimize the misfire detection algorithm in this field to avoid vehicle shaking causing misfire detection failure, thereby resulting in missed fire detection. Summary of the Invention

[0007] In view of the problems in the prior art, the present invention provides an engine misfire detection method, system, storage medium and vehicle.

[0008] An engine misfire detection system comprising:

[0009] The acceleration detection module is configured to detect acceleration acce in real time;

[0010] The first misfire detection module is configured to detect the flfexsn signal in real time and perform engine misfire detection based on the flfexsn signal;

[0011] The second misfire detection module is configured to detect the lfexsn signal in real time and perform engine misfire detection based on the lfexsn signal;

[0012] The control unit is configured to determine whether the first misfire detection module or the second misfire detection module performs engine misfire detection according to the following logic:

[0013] When the acceleration acce is less than or equal to the threshold F, engine misfire detection is performed through the flfexsn signal;

[0014] When the acceleration acce is greater than the threshold F, the engine misfire detection is performed through the lfexsn signal, and the following operations are performed according to the identification result of the lfexsn signal:

[0015] If no continuous misfire is identified, the engine misfire detection is maintained using the lfexsn signal;

[0016] If continuous misfire is detected, the set value of threshold F is increased to obtain an updated threshold F1, and the relative size of acceleration acce and threshold F1 is determined. When acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed through the flfexsn signal. When acceleration acce is greater than the updated threshold F1, it indicates that the high misfire signal is caused by driving on a bad road, and misfire detection is immediately interrupted; until acceleration acce returns to less than or equal to threshold F1 and greater than F, engine misfire detection continues through the lfexsn signal (this detection is currently only used to determine whether it is a continuous misfire).

[0017] Preferably, the first misfire detection module identifies an engine misfire as follows: when a cylinder is ignited, after detecting that the flfexsn signal of the cylinder is higher than a preset threshold, the misfire count of the cylinder is increased by 1.

[0018] Preferably, the second misfire detection module identifies an engine misfire as follows: when a cylinder is ignited, after detecting that the lfexsn signal of the cylinder is higher than a preset threshold, the misfire count of the cylinder is increased by 1.

[0019] Preferably, the criterion for determining continuous misfire is: within one ignition cycle, the number of misfires in a certain cylinder is greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders.

[0020] Preferably, the updating formula of the threshold F1 is: F1=F+k, and the value of k is calibrated according to actual test results.

[0021] Preferably, the value of k is 10 m / s 2 .

[0022] The present invention also provides an engine misfire detection method, comprising the following steps:

[0023] Real-time detection of acceleration acce, flfexsn signal and lfexsn signal;

[0024] When the acceleration acce is less than or equal to the threshold F, engine misfire detection is performed through the flfexsn signal;

[0025] When the acceleration acce is greater than the threshold F, the engine misfire detection is performed through the lfexsn signal, and the following operations are performed according to the identification result of the lfexsn signal:

[0026] If no continuous misfire is detected, the engine misfire detection is continued using the lfexsn signal until the acceleration acce returns to a value less than or equal to the threshold F;

[0027] If continuous misfire is identified, the set value of threshold F is increased to obtain an updated threshold F1, and the relative size of acceleration acce and threshold F1 is determined. When acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed through the flfexsn signal; when acceleration acce is greater than the updated threshold F1, engine misfire detection is performed through the lfexsn signal; until acceleration acce returns to less than or equal to threshold F.

[0028] Preferably, when performing engine misfire detection through the flfexsn signal, after detecting that the flfexsn signal of a cylinder is higher than a preset threshold, the misfire count of the cylinder is increased by 1;

[0029] When performing engine misfire detection through the lfexsn signal, if the lfexsn signal of a cylinder is detected to be higher than the preset threshold, the misfire count of the cylinder is increased by 1;

[0030] The criteria for determining continuous misfires are: The criteria for determining continuous misfires are: within one ignition cycle, the number of misfires in a cylinder is greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders;

[0031] The updating formula of the threshold F1 is: F1=F+k, and the value of k is calibrated according to the actual test results.

[0032] The present invention also provides a vehicle, which is driven by an engine and further includes the above-mentioned engine misfire detection system, and the engine performs engine misfire detection through the engine misfire detection system.

[0033] The present invention also provides a computer-readable storage medium storing: a computer program for implementing the above-mentioned engine misfire detection system, or a computer program for implementing the above-mentioned engine misfire detection method.

[0034] In the present invention, the relevant parameters are defined as follows:

[0035] lfexsn signal: When misfire occurs, it causes the engine angular acceleration to change. The difference between the change in angular acceleration and the square of the speed is: n 2(k) -n 2(k+1) The squared difference in speed can be used to represent the engine's operating roughness. Because engine speed n is proportional to the inverse of the split time, 1 / ts, the squared difference in the inverse of the split time can be used to represent the engine's operating roughness signal, lfexsn. The split time is the time it takes for the speed signal to rotate 180 degrees.

[0036] flfexsn signal: It is obtained by low-pass filtering the lfexsn signal of each cylinder and is mainly used for continuous misfire detection.

[0037] lfex_w: Threshold for lfexsn signal.

[0038] flfex_w: Threshold of flfexsn signal.

[0039] Misfire_F: The flag bit for detecting misfire. The flag bit is detected every time the ignition is turned on. When a misfire is detected, the flag bit is TRUE, otherwise it is FLASE.

[0040] Acceleration acce: It uses the vehicle's anti-lock braking system (ABS) to obtain the vehicle's wheel speed signal. The acceleration calculated by the change in the vehicle's wheel speed is used to detect bad roads.

[0041] facce_w: used to represent the threshold value of acceleration acce, which is equivalent to the threshold value F in the present invention.

[0042] B_s: Bad road detection flag. TRUE if the vehicle is detected on a bad road, otherwise FALSE.

[0043] B_l: The flag for suppressing misfire detection. If it is set to TRUE, misfire detection will be suppressed. If it is set to FALSE, misfire detection can be performed normally.

[0044] The threshold F, lfex_w or the set value of flfex_w in the present invention can be calibrated or conventionally set according to the prior art.

[0045] This invention improves the method and system for engine misfire detection. To address the problem of continuous misfires being misidentified as bad road conditions, which can disable misfire diagnosis, the present invention raises the bad road detection threshold when both a bad road condition and a continuous misfire condition are identified, restoring the misfire diagnosis function. This prevents vehicle vibration caused by continuous misfires from being misidentified as bad road conditions. This invention reduces missed misfire detections, improves the accuracy of engine misfire detection, and has promising application prospects.

[0046] Obviously, based on the above contents of the present invention, according to common technical knowledge and customary means in this field, without departing from the above basic technical ideas of the present invention, other various forms of modifications, replacements or changes can be made.

[0047] The following further describes the above content of the present invention in detail through specific embodiments in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is an example diagram for judging single misfire and continuous misfire;

[0049] Figure 2 This is an example diagram of the prior art in which a bad road is detected in a normal continuous misfire situation, and the misfire diagnosis function is turned off during the continuous misfire;

[0050] Figure 3 This is an example diagram of the prior art in which normal continuous misfires are detected as bad paths and the misfire diagnosis function is disabled during continuous misfires.

[0051] Figure 4 Schematic diagram of the process of Example 1. DETAILED DESCRIPTION

[0052] It should be noted that the algorithms for data collection, transmission, storage and processing steps not specifically described in the embodiments, as well as the hardware structures, circuit connections, etc. not specifically described can all be implemented through the disclosed content of the prior art.

[0053] Example 1 Engine Misfire Detection System and Method

[0054] Examples of prior art fire detection include Figure 1-3 As shown:

[0055] like Figure 1 As shown, ABS is generally used to obtain the vehicle's wheel speed signal. By sensing the change in the vehicle's wheel speed, the acceleration acce is calculated. When acce exceeds the threshold F (facce_w), it is detected that the vehicle is driving on a bad road. The misfire detection module will then turn off the misfire detection to avoid misjudgment of the misfire detection.

[0056] When some models have continuous misfires, the vehicle will shake and the speed will fluctuate violently, causing the acceleration signal acce to jump very high and exceed the threshold F. Ultimately, the continuous misfire phenomenon is identified as the vehicle is driving on a bad road, and the misfire detection function is turned off. Figure 1 When misfire occurs continuously, acce>facce_w, and a bad path is detected, then B_s=True, B_l=True, which will suppress misfire detection. According to the diagnostic logic, the continuous misfire signal fultusk will be assigned a value of 0, and the misfire detection function will be turned off, which will result in missed misfire detection. Figure 2 In the case of continuous misfire, acce>facce_w, and Figure 3 It is more obvious when continuous misfires are misjudged as bad roads.

[0057] To solve the aforementioned problem of missed fire detection, this embodiment provides an improved system and method, the system comprising:

[0058] The acceleration detection module is configured to detect acceleration acce in real time;

[0059] The first misfire detection module is configured to detect the flfexsn signal in real time and perform engine misfire detection based on the flfexsn signal;

[0060] The second misfire detection module is configured to detect the lfexsn signal in real time and perform engine misfire detection based on the lfexsn signal;

[0061] The control unit is configured to determine whether the first misfire detection module or the second misfire detection module performs engine misfire detection.

[0062] The method for detecting engine misfire using the above system is as follows: Figure 4 As shown, the specific process includes the following:

[0063] Real-time detection of acceleration acce, flfexsn signal and lfexsn signal;

[0064] The control unit determines whether to perform engine misfire detection by the first misfire detection module or the second misfire detection module according to the following logic:

[0065] When the acceleration acce is less than or equal to the threshold F, engine misfire detection is performed through the flfexsn signal;

[0066] When the acceleration acce is greater than the threshold F, the engine misfire detection is performed through the lfexsn signal, and the following operations are performed according to the identification result of the lfexsn signal:

[0067] If no continuous misfire is identified, the engine misfire detection is maintained using the lfexsn signal;

[0068] If continuous misfire is detected, the set value of threshold F is increased to obtain an updated threshold F1, and the relative size of acceleration acce and threshold F1 is determined. When acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed through the flfexsn signal. When acceleration acce is greater than the updated threshold F1, it indicates that the high misfire signal is caused by driving on a bad road, and misfire detection is immediately interrupted; until acceleration acce returns to less than or equal to threshold F1 and greater than F, engine misfire detection continues through the lfexsn signal (this detection is currently only used to determine whether it is a continuous misfire).

[0069] The update formula of threshold F1 is: F1=F+k, where the value of k is calibrated according to the actual test results. In this embodiment, the value of k is preferably 10 m / s 2 .

[0070] The first misfire detection module identifies an engine misfire as follows: when a cylinder is ignited, if the flfexsn signal of that cylinder is detected to be above a preset threshold, the misfire count for that cylinder is incremented by one. The second misfire detection module identifies an engine misfire as follows: when a cylinder is ignited, if the lfexsn signal of that cylinder is detected to be above a preset threshold, the misfire count for that cylinder is incremented by one. A continuous misfire is determined when the number of misfires in a cylinder within an ignition cycle (preferably 40 or 100 ignitions in this embodiment) is greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders.

[0071] Example 2 A vehicle

[0072] This embodiment provides a vehicle, which can be any vehicle driven by an engine, including but not limited to automobiles, flatbed trucks, tricycles, motorcycles, etc. The vehicle's control system includes the engine misfire detection system described in Example 1, and the engine performs engine misfire detection via the engine misfire detection system.

[0073] As can be seen from the above embodiments and experimental examples, the present invention provides a novel engine misfire detection method and system that can flexibly adjust the parameter threshold for determining a faulty circuit. This prevents the misfire detection system from being inhibited due to falsely diagnosing a faulty circuit when the engine misfires continuously, thereby avoiding missed misfire detections. Therefore, the present invention has promising application prospects.

Claims

1. An engine misfire detection system, characterized in that: include: The acceleration detection module is configured to detect acceleration acce in real time; The first misfire detection module is configured to detect the flfexsn signal in real time and perform engine misfire detection based on the flfexsn signal; The second misfire detection module is configured to detect the lfexsn signal in real time and perform engine misfire detection based on the lfexsn signal; The control unit is configured to determine whether the first misfire detection module or the second misfire detection module performs engine misfire detection according to the following logic: When the acceleration acce is less than or equal to the threshold F, engine misfire detection is performed through the flfexsn signal; When the acceleration acce is greater than the threshold F, the engine misfire detection is performed through the lfexsn signal, and the following operations are performed according to the identification result of the lfexsn signal: If no continuous misfire is identified, the engine misfire detection is maintained using the lfexsn signal; If continuous misfire is detected, the threshold F is increased to obtain an updated threshold F1. The relative magnitude of acceleration acce and threshold F1 is determined. When acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed via the flfexsn signal. When acceleration acce is greater than the updated threshold F1, misfire detection is interrupted until acceleration acce returns to a value less than or equal to threshold F1 and greater than threshold F, at which point engine misfire detection is resumed via the lfexsn signal. The lfexsn signal is a roughness of engine operation represented by the inverse square difference of segmented time; the flfexsn signal is obtained by low-pass filtering the lfexsn signal of each cylinder.

2. The engine misfire detection system according to claim 1, characterized in that: The first misfire detection module identifies engine misfires according to the following criteria: when a cylinder is ignited, if the flfexsn signal of the cylinder is detected to be higher than a preset threshold, the misfire count of the cylinder is increased by one.

3. The engine misfire detection system according to claim 1, characterized in that: The second misfire detection module identifies engine misfires according to the following criteria: when a cylinder is ignited, if the lfexsn signal of the cylinder is detected to be higher than a preset threshold, the misfire count of the cylinder is increased by one.

4. The engine misfire detection system according to claim 2 or 3, characterized in that: The standard for judging continuous misfire is: within one ignition cycle, the number of misfires in a cylinder is greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders.

5. The engine misfire detection system according to claim 1, characterized in that: The updating formula of the threshold F1 is: F1=F+k, and the value of k is calibrated according to the actual test results.

6. The engine misfire detection system according to claim 5, characterized in that: The value of k is 10 m / s 2 .

7. An engine misfire detection method, characterized in that: The steps include: Real-time detection of acceleration acce, flfexsn signal and lfexsn signal; When the acceleration acce is less than or equal to the threshold F, engine misfire detection is performed through the flfexsn signal; When the acceleration acce is greater than the threshold F, the engine misfire detection is performed through the lfexsn signal, and the following operations are performed according to the identification result of the lfexsn signal: If no continuous misfire is detected, the engine misfire detection is continued using the lfexsn signal until the acceleration acce returns to a value less than or equal to the threshold F; If continuous misfire is detected, the threshold F is increased to obtain an updated threshold F1. The relative magnitude of acceleration acce and threshold F1 is determined. When acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed through the flfexsn signal. When acceleration acce is greater than the updated threshold F1, engine misfire detection is performed through the lfexsn signal. This continues until acceleration acce returns to a value less than or equal to threshold F. The lfexsn signal is a roughness of engine operation represented by the inverse square difference of segmented time; the flfexsn signal is obtained by low-pass filtering the lfexsn signal of each cylinder.

8. The engine misfire detection method according to claim 7, characterized in that: When performing engine misfire detection through the flfexsn signal, if the flfexsn signal of a cylinder is detected to be higher than the preset threshold, the misfire count of the cylinder is increased by 1; When performing engine misfire detection through the lfexsn signal, if the lfexsn signal of a cylinder is detected to be higher than the preset threshold, the misfire count of the cylinder is increased by 1; The criteria for determining continuous misfires are: The criteria for determining continuous misfires are: within one ignition cycle, the number of misfires in a cylinder is greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders; The updating formula of the threshold F1 is: F1=F+k, and the value of k is calibrated according to the actual test results.

9. A vehicle driven by an engine, characterized in that: The invention further comprises the engine misfire detection system according to any one of claims 1 to 6, wherein the engine misfire detection is performed on the engine through the engine misfire detection system.

10. A computer-readable storage medium, characterized in that Stored thereon is: a computer program for implementing the engine misfire detection system according to any one of claims 1 to 6, or a computer program for implementing the engine misfire detection method according to claim 7 or 8.

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