Engine misfire detection method and system, storage medium and carrying tool

Abstract

The invention belongs to the technical field of vehicle-mounted diagnostic systems, and particularly relates to an engine misfire detection method and system, a storage medium and a carrying tool. The system comprises: an acceleration detection module configured to detect an acceleration acce in real time; the first misfire detection module is configured to detect a flfexsn signal in real time and perform engine misfire detection through the flfexsn signal; the second misfire detection module is configured to detect an lfexsn signal in real time and perform engine misfire detection through the lfexsn signal; and the control unit is configured to decide to perform engine misfire detection by the first misfire detection module or the second misfire detection module through specific logic. The invention further provides a method for carrying out misfire detection by applying the system. According to the invention, the situation of missed fire detection can be avoided, and the application prospect is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle diagnostic systems, and particularly relates to a method and system for detecting engine misfires, a storage medium, and a vehicle. Background Art

[0002] Vehicle engine misfire refers to the phenomenon that one or more cylinders of the engine fail to burn properly or incompletely during operation. Continuous engine misfire means that during the operation of the engine, misfires continuously occur in one or some cylinders. Continuous engine misfires may cause hazards such as a decline in power performance, poor fuel economy, excessive exhaust emissions, and damage to the three-way catalytic converter.

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

[0004] When the vehicle is driving on a bad road, the vehicle speed will fluctuate violently, and it will cause the engine speed to fluctuate through the transmission system, resulting in the signal lfexsn used for misfire detection may exceed the threshold, causing misjudgment of misfire detection. In the prior art, to solve this problem, generally, the wheel speed signal of the vehicle is obtained by using the ABS, and by sensing the change of the vehicle wheel speed, the acceleration acce is calculated. When acce exceeds the threshold F (full name facce), it is detected that the vehicle is driving on a bad road surface at this time, and the misfire detection module will turn off the misfire detection to avoid misjudgment of misfire detection.

[0005] However, when some vehicle models have continuous misfires, the vehicle shakes, and the vehicle speed will also fluctuate violently, resulting in the acceleration signal acce also jumping very high and exceeding the threshold F, ultimately resulting in the continuous misfire phenomenon being recognized as the vehicle driving on a bad road at this time, thus turning off the misfire detection function. As Figure 2 shown, during continuous misfires, acce > facce_w, it is detected that it is a bad road, and the misfire detection will be inhibited. According to the diagnostic logic, the continuous misfire signal will be assigned a value of 0, and at the same time, the misfire detection function will be turned off, which will lead to missed detection of misfires.

[0006] In view of the above problems, it is still necessary in the art to optimize the algorithm for misfire detection to avoid the misfire detection failure caused by vehicle jitter, thereby resulting in missed misfire judgments. Summary of the Invention

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

[0008] An engine misfire detection system includes: An acceleration detection module configured to detect the acceleration acce in real time; A first misfire detection module configured to detect the flfexsn signal in real time and perform engine misfire detection through the flfexsn signal; A second misfire detection module configured to detect the lfexsn signal in real time and perform engine misfire detection through the lfexsn signal; A control unit configured to determine, by the following logic, whether to perform engine misfire detection by the first misfire detection module or the second misfire detection module: When the acceleration acce is less than or equal to the threshold F, perform engine misfire detection through the flfexsn signal; When the acceleration acce is greater than the threshold F, perform engine misfire detection through the lfexsn signal, and perform the following operations according to the recognition result through the lfexsn signal: If continuous misfires are not recognized, continue to perform engine misfire detection using the lfexsn signal; If continuous misfires are recognized, increase the set value of the threshold F to obtain an updated threshold F1, and judge the relative magnitude of the acceleration acce and the threshold F1. When the acceleration acce is less than or equal to the updated threshold F1, perform engine misfire detection through the flfexsn signal; when the 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 immediately interrupt the misfire detection; until the acceleration acce returns to less than or equal to the threshold F1 and greater than F, and then continue to perform engine misfire detection through the lfexsn signal (this detection is only used to judge whether there are continuous misfires in the current situation).

[0009] Preferably, the standard for the first misfire detection module to recognize engine misfire is: when a certain cylinder is ignited, after the flfexsn signal of the cylinder is detected to be higher than a preset threshold, the misfire count of the cylinder is increased by 1 time.

[0010] Preferably, the standard for the second misfire detection module to recognize engine misfire is: when a certain cylinder is ignited, after the lfexsn signal of the cylinder is detected to be higher than a preset threshold, the misfire count of the cylinder is increased by 1 time.

[0011] Preferably, the criterion for determining consecutive misfires is that 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 ignition times by the number of cylinders.

[0012] Preferably, the update formula for the threshold F1 is: F1 = F + k, where the value of k is calibrated according to the actual test results.

[0013] Preferably, the value of k is 10 m / s 2 。

[0014] The present invention also provides an engine misfire detection method, including the following steps: Real-time detect the acceleration acce, flfexsn signal, and lfexsn signal; When the acceleration acce is less than or equal to the threshold F, perform engine misfire detection through the flfexsn signal; When the acceleration acce is greater than the threshold F, perform engine misfire detection through the lfexsn signal, and perform the following operations according to the recognition result through the lfexsn signal: If consecutive misfires are not recognized, maintain engine misfire detection using the lfexsn signal until the acceleration acce returns to less than or equal to the threshold F; If consecutive misfires are recognized, increase the set value of the threshold F to obtain the updated threshold F1, judge the relative magnitude of the acceleration acce and the threshold F1. When the acceleration acce is less than or equal to the updated threshold F1, perform engine misfire detection through the flfexsn signal; when the acceleration acce is greater than the updated threshold F1, perform engine misfire detection through the lfexsn signal; until the acceleration acce returns to less than or equal to the threshold F.

[0015] Preferably, when performing engine misfire detection through the flfexsn signal, after detecting that the flfexsn signal of a certain cylinder is higher than the preset threshold, the misfire count of this cylinder increases by 1 time; When performing engine misfire detection through the lfexsn signal, after detecting that the lfexsn signal of a certain cylinder is higher than the preset threshold, the misfire count of this cylinder increases by 1 time; The criterion for determining consecutive misfires is that 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 ignition times by the number of cylinders; The update formula for the threshold F1 is: F1 = F + k, where the value of k is calibrated according to the actual test results.

[0016] The present invention also provides a vehicle, which is driven by an engine and further includes the above engine misfire detection system, and the engine performs engine misfire detection through the engine misfire detection system.

[0017] The present invention also provides a computer-readable storage medium, on which there is stored: a computer program for implementing the above engine misfire detection system, or a computer program for implementing the above engine misfire detection method.

[0018] In the present invention, the relevant parameter definitions are as follows: lfexsn signal: When a misfire occurs, it causes a change in the engine angular acceleration. The change in angular acceleration is proportional to the square difference of the rotational speeds: n 2(k) -n 2(k+1) and can be represented by the square difference of the rotational speeds to represent the roughness level of the engine operation. Since the engine rotational speed n is proportional to the reciprocal of the segmentation time 1 / ts, the square difference of the reciprocal of the segmentation time can be used to represent the lfexsn signal of the engine operation. The segmentation time is the time taken for the rotational speed signal wheel to rotate 180 degrees.

[0019] flfexsn signal: It is obtained by low-pass filtering the lfexsn signals of each cylinder and is mainly used for continuous misfire detection.

[0020] lfex_w: The threshold of the lfexsn signal.

[0021] flfex_w: The threshold of the flfexsn signal.

[0022] Misfire_F: The flag bit for detecting misfire. Detection is performed for each ignition. When a misfire is detected once, this flag bit is TRUE, otherwise it is FALSE.

[0023] Acceleration acce: It is the acceleration calculated by using the wheel speed signal of the vehicle through the Anti-lock Braking System (ABS) of the vehicle and is used for detecting bad roads.

[0024] facce_w: Used to represent the threshold of the acceleration acce, which is equivalent to the threshold F in the present invention.

[0025] B_s: The flag bit for detecting bad roads. When it is detected that the vehicle is traveling on a bad road, it is TRUE, otherwise it is FALSE.

[0026] B_l: The flag bit for suppressing misfire detection. Assigning it to TURE will suppress misfire detection, and assigning it to FALSE will allow normal misfire detection.

[0027] In the present invention, the set values of the thresholds F, lfex_w or flfex_w can be calibrated or set conventionally according to the prior art.

[0028] The present invention improves the method and system for detecting engine misfires. To solve the problem that continuous misfires may be misjudged as a bad road, thus turning off the misfire diagnosis, when the present invention recognizes a bad road and at the same time recognizes that it is a continuous misfire at this time, it increases the threshold for detecting the bad road and restores the misfire diagnosis function, thereby avoiding the vehicle jitter caused by continuous misfires being misjudged as a bad road. The present invention can reduce the missed judgment of misfires, improve the accuracy of engine misfire detection, and has good application prospects.

[0029] Obviously, based on the above content of the present invention, according to the common general knowledge and customary means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions or changes can be made.

[0030] The following is a further detailed description of the above content of the present invention 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. Description of the Drawings

[0031] Figure 1 It is a judgment example diagram for single misfire and continuous misfires; Figure 2 It is an example diagram of detecting a bad road in some cases of normal continuous misfires in the prior art, and the misfire diagnosis function is turned off during continuous misfires; Figure 3 It is an example diagram of detecting a bad road for normal continuous misfires in the prior art, and the misfire diagnosis function is turned off during continuous misfires.

[0032] Figure 4 It is a schematic flowchart of Embodiment 1. Detailed Description of the Specific Embodiment

[0033] It should be particularly noted that the algorithms for the steps of data acquisition, transmission, storage and processing, etc., which are not specifically described in the embodiments, and the hardware structures, circuit connections, etc., which are not specifically described, can all be implemented through the content disclosed in the prior art.

[0034] Embodiment 1 Engine Misfire Detection System and Method An example of misfire detection in the prior art is as Figures 1 - 3 shown: As Figure 1As shown, generally, the wheel speed signal of the vehicle is obtained by using ABS. 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 surface at this time, and the misfire detection module will turn off the misfire detection to avoid misjudgment of misfire detection.

[0035] In some vehicle models during continuous misfire, the vehicle shakes and the vehicle speed also fluctuates violently, resulting in a very high jump in its acceleration signal acce and exceeding the threshold F, ultimately leading to the recognition of the continuous misfire phenomenon as the vehicle driving on a bad road at this time, thus turning off the misfire detection function. For example Figure 1 , during continuous misfire, acce > facce_w, it is detected that it is a bad road, then B_s = True, B_l = True, and the misfire detection will be inhibited. According to the diagnostic logic, the continuous misfire signal fultusk will be assigned a value of 0, and at the same time, the misfire detection function will be turned off, which will lead to missed misfire detection. Figure 2 In some cases of continuous misfire, acce > facce_w, while Figure 3 the misjudgment of continuous misfire as a bad road is more obvious.

[0036] To solve the above problem of missed misfire detection, the present embodiment provides an improved system and method. The system includes: An acceleration detection module configured to detect the acceleration acce in real time; A first misfire detection module configured to detect the flfexsn signal in real time and perform engine misfire detection through the flfexsn signal; A second misfire detection module configured to detect the lfexsn signal in real time and perform engine misfire detection through the lfexsn signal; A control unit configured to determine whether to perform engine misfire detection by the first misfire detection module or the second misfire detection module.

[0037] The method for performing engine misfire detection using the above system is as Figure 4 shown, and specifically includes the following process: Detect the acceleration acce, flfexsn signal, and lfexsn signal in real time; 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: When the acceleration acce is less than or equal to the threshold F, perform engine misfire detection through the flfexsn signal; When the acceleration acce is greater than the threshold F, perform engine misfire detection through the lfexsn signal, and perform the following operations according to the recognition result through the lfexsn signal: If no consecutive misfires are detected, the engine misfire detection using the lfexsn signal is maintained; If consecutive misfires are detected, the set value of threshold F is increased to obtain an updated threshold F1, and the relative magnitudes of the acceleration acce and the threshold F1 are judged. When the acceleration acce is less than or equal to the updated threshold F1, the engine misfire detection is performed through the flfexsn signal; when the 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 the misfire detection is immediately interrupted; until the acceleration acce returns to be less than or equal to the threshold F1 and greater than F, at this time, the engine misfire detection is continued through the lfexsn signal (this detection is only used to judge whether there are consecutive misfires in the current situation).

[0038] The update formula for the threshold F1 is: F1 = F + k, and 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 。

[0039] Among them, the standard for the first misfire detection module to identify engine misfires is: when a certain cylinder is ignited, after the flfexsn signal of this cylinder is detected to be higher than a preset threshold, the misfire count of this cylinder increases by 1 time. The standard for the second misfire detection module to identify engine misfires is: when a certain cylinder is ignited, after the lfexsn signal of this cylinder is detected to be higher than a preset threshold, the misfire count of this cylinder increases by 1 time. The standard for judging consecutive misfires is: within one ignition cycle (preferably 40 or 100 ignitions in this embodiment), the misfire times of a certain cylinder are greater than or equal to 80% of the value obtained by dividing the number of ignitions by the number of cylinders.

[0040] Embodiment 2 A vehicle This embodiment provides a vehicle, which can be any tool driven by an engine to run the wheels, including but not limited to cars, flatbed trucks, tricycles, motorcycles, etc. The control system of the vehicle includes the engine misfire detection system described in Embodiment 1, and the engine performs engine misfire detection through the engine misfire detection system.

[0041] Through the above embodiments and experimental examples, it can be seen that the present invention provides a new method and system for engine misfire detection, which can flexibly adjust the parameter threshold for judging bad roads, avoid suppressing the misfire detection system due to misjudging bad roads when the engine has consecutive misfires, and thus avoid the situation of missed misfire detection. Therefore, the present invention has good application prospects.

Claims

1. An engine misfire detection system, characterized in that, Including: An acceleration detection module configured to detect acceleration acce in real time; A first misfire detection module configured to detect the flfexsn signal in real time and perform engine misfire detection through the flfexsn signal; A second misfire detection module configured to detect the lfexsn signal in real time and perform engine misfire detection through the lfexsn signal; A control unit configured to determine which of the first misfire detection module or the second misfire detection module performs engine misfire detection through the following logic: When the acceleration acce is less than or equal to the threshold F, perform engine misfire detection through the flfexsn signal; When the acceleration acce is greater than the threshold F, perform engine misfire detection through the lfexsn signal, and perform the following operations according to the recognition result through the lfexsn signal: If continuous misfires are not recognized, maintain engine misfire detection using the lfexsn signal; If continuous misfires are recognized, increase the set value of the threshold F to obtain an updated threshold F1, judge the relative magnitude of the acceleration acce and the threshold F1. When the acceleration acce is less than or equal to the updated threshold F1, perform engine misfire detection through the flfexsn signal; when the acceleration acce is greater than the updated threshold F1, interrupt misfire detection until the acceleration acce returns to less than or equal to the threshold F1 and greater than the threshold F, and then continue to perform engine misfire detection through the lfexsn signal.

2. The engine misfire detection system according to claim 1, wherein: The standard for the first misfire detection module to recognize engine misfire is: when a certain cylinder is ignited, after detecting that the flfexsn signal of this cylinder is higher than the preset threshold, the misfire count of this cylinder increases by 1 time.

3. The engine misfire detection system according to claim 1, wherein: The standard for the second misfire detection module to recognize engine misfire is: when a certain cylinder is ignited, after detecting that the lfexsn signal of this cylinder is higher than the preset threshold, the misfire count of this cylinder increases by 1 time.

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

5. The engine misfire detection system according to claim 1, wherein: The update 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, wherein: The value of k is 10 m / s 2 .

7. An engine misfire detection method, characterized in that, Including the following steps: Detect the acceleration acce, flfexsn signal and lfexsn signal in real time; When the acceleration acce is less than or equal to the threshold F, perform engine misfire detection through the flfexsn signal; When the acceleration acce is greater than the threshold F, perform engine misfire detection through the lfexsn signal, and perform the following operations according to the recognition result through the lfexsn signal: If continuous misfires are not recognized, maintain engine misfire detection using the lfexsn signal until the acceleration acce returns to less than or equal to the threshold F; If continuous misfires are detected, the set value of threshold F is increased to obtain an updated threshold F1, and the relative magnitudes of the acceleration acce and the threshold F1 are judged. When the acceleration acce is less than or equal to the updated threshold F1, engine misfire detection is performed through the flfexsn signal; when the acceleration acce is greater than the updated threshold F1, engine misfire detection is performed through the lfexsn signal; until the acceleration acce returns to be less than or equal to the threshold F.

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

9. A vehicle, which is driven by an engine, characterized in that: It further includes the engine misfire detection system according to any one of claims 1-6, and the engine performs engine misfire detection through the engine misfire detection system.

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

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