Engine misfire detection methods, devices, equipment, engines, and operating machinery

Abstract

This invention relates to the field of engine technology, providing an engine misfire detection method, apparatus, device, engine, and operating machinery. The misfire detection method includes: sampling the running time of each cylinder of the engine within a selected crankshaft angle window; detecting the difference between the running time of the current cylinder and the previous cylinder in the working cycle to determine a first roughness of the engine; determining a second roughness of the engine based on the difference between the running time of the first cylinder before the current cylinder and the running time of the second cylinder after the current cylinder; determining a final roughness of the engine based on the difference between the first and second roughness; and determining whether the current cylinder has misfired based on a comparison between the final roughness and a roughness threshold. This invention solves the problem of high false positive rate in engine misfire detection methods, significantly reducing the false positive rate and thus improving the accuracy of engine misfire detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, and in particular to an engine misfire detection method, device, equipment, engine and working machine. BACKGROUND

[0002] Engine misfire refers to a phenomenon that the mixed gas in the cylinder cannot be combusted or combusted insufficiently due to abnormalities in the ignition system, fuel supply system and the like. Engine misfire can cause engine vibration, excessive emissions and even damage to the catalyst.

[0003] Since engine misfire causes the misfire cylinder to fail to work normally, the engine lacks the normal acceleration process, and the speed fluctuation is large, therefore, whether misfire failure occurs can be diagnosed by analyzing the irregularity of the speed fluctuation through the crankshaft position sensor, and the misfire cylinder can be determined by combining the camshaft position sensor in the related art.

[0004] This engine misfire detection method is simple and easy to use, and is widely used by most vehicle models, but the judgment condition of the engine misfire is relatively harsh, when the engine is accelerating or decelerating, since the speed of each cylinder of the engine is changing in a large range at this time, the traditional engine misfire detection method is easy to misjudge the normal work of the engine as misfire, resulting in high misjudgment rate of engine misfire detection. SUMMARY

[0005] The present application provides an engine misfire detection method, device, equipment, engine and working machine, to solve the problem of high misjudgment rate of engine misfire detection in the related art, and realizes accurate detection of engine misfire.

[0006] The present application provides an engine misfire detection method, comprising:

[0007] Sampling the running time of each cylinder of the engine in the selected crankshaft angle window;

[0008] Performing a misfire detection step for each cylinder; the misfire detection step comprises:

[0009] Based on the difference between the running time of the previous cylinder and the current cylinder in the working cycle of the detected current cylinder, determining the first roughness of the engine, and based on the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder, determining the second roughness of the engine, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles;

[0010] Based on the difference between the first roughness and the second roughness, determining the final roughness of the engine;

[0011] determine whether the current cylinder misfires based on a comparison result of the final roughness of the engine and a roughness threshold.

[0012] According to the engine misfire detection method provided by the application, the difference between the running time of the previous cylinder and the current cylinder in the working cycle is determined as the first roughness of the engine, and the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder is determined as the second roughness of the engine.

[0013] The difference between the running time of the previous cylinder and the current cylinder in the working cycle is determined as the first roughness of the engine.

[0014] The difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder is divided by the number of cylinders to obtain the second roughness of the engine.

[0015] According to the engine misfire detection method provided by the application, the difference between the running time of the previous cylinder and the current cylinder in the working cycle is determined as the first roughness of the engine, and the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder is determined as the second roughness of the engine.

[0016] The difference between the running time of the previous cylinder and the current cylinder in the working cycle is multiplied by the number of cylinders to obtain the first roughness of the engine.

[0017] The difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder is determined as the second roughness of the engine.

[0018] According to the engine misfire detection method provided by the application, the number of cylinders experienced between the first cylinder and the current cylinder is equal to the number of cylinders experienced between the second cylinder and the current cylinder.

[0019] According to the engine misfire detection method provided by the application, the starting point of the crank angle window is M degrees of crank angle after the cylinder compression top dead center, and the value of M is greater than 0.

[0020] According to the engine misfire detection method provided by the application, the running time of each cylinder of the engine in the selected crank angle window is sampled, which comprises:

[0021] sampling a running time length of each cylinder of the engine within a selected crank angle window when the engine meets a misfire detection condition;

[0022] The method further comprises:

[0023] determining the roughness threshold based on a rotational speed, a load and a water temperature corresponding to the current cylinder in a first working cycle of the current cylinder;

[0024] performing the misfire detection step on the current cylinder in a second working cycle of the current cylinder, the first working cycle and the second working cycle being two adjacent working cycles.

[0025] According to the engine misfire detection method provided by the application, the method further comprises:

[0026] determining a number of misfires of each cylinder in a statistical period;

[0027] determining a misfire rate based on the statistical result and a total number of working strokes in the statistical period.

[0028] The application further provides an engine misfire detection device, comprising:

[0029] a sampling module configured to sample a running time length of each cylinder of the engine within a selected crank angle window;

[0030] a detection module configured to perform a misfire detection step on each cylinder, the misfire detection step comprising:

[0031] determining a first roughness of the engine based on a difference between a running time length of a previous cylinder and a current cylinder of the current cylinder in a working cycle, and determining a second roughness of the engine based on a difference between the running time length of a first cylinder experienced by the current cylinder before and the running time length of a second cylinder experienced by the current cylinder after, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles;

[0032] determining a final roughness of the engine based on a difference between the first roughness and the second roughness;

[0033] determining whether the current cylinder misfires based on a comparison result between the final roughness of the engine and a roughness threshold.

[0034] The application further provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of any of the above engine misfire detection methods when executing the program.

[0035] The application further provides an engine for executing any of the engine misfire detection methods, or comprising any of the engine misfire detection devices, or comprising any of the electronic devices.

[0036] The application further provides a working machine for executing any of the engine misfire detection methods, or comprising any of the engine misfire detection devices, or comprising any of the electronic devices, or comprising any of the engines.

[0037] The engine misfire detection method provided by the embodiment of the application can sample the running time of each cylinder of the engine in a selected crank angle window, and perform a misfire detection step for each cylinder. When performing the misfire detection, the first roughness of the engine can be determined based on the difference between the running time of the previous cylinder and the current cylinder in the working cycle of the detected current cylinder, the second roughness of the engine can be determined based on the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after, the second roughness can reflect the effect of the angular acceleration of the acceleration and deceleration operation of the engine on the roughness of the engine, the final roughness of the engine can be determined based on the difference between the first roughness and the second roughness, thus the part of the effect of the acceleration and deceleration operation of the engine in the first roughness can be eliminated, and whether the current cylinder misfires can be determined based on the comparison result between the final roughness of the engine and the roughness threshold, the influence of the acceleration and deceleration operation of the engine on the engine misfire detection can be reduced, the misjudgment rate of the engine misfire detection can be greatly reduced, and the accuracy of the engine misfire detection can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor,

[0039] Figure 1 is one of the flowcharts of the engine misfire detection method provided by the application;

[0040] Figure 2 is a schematic diagram of the crank angle window provided by the application;

[0041] Figure 3 is a schematic diagram of the sampling sequence provided by the application;

[0042] Figure 4 is a schematic diagram of the cylinder misfire provided by the application;

[0043] Figure 5 FIG. 2 is a flowchart of a second engine misfire detection method according to the present application;

[0044] Figure 6 FIG. 3 is a flowchart of a third engine misfire detection method according to the present application;

[0045] Figure 7 FIG. 4 is a schematic diagram of engine roughness with a misfire point during engine operation according to the present application;

[0046] Figure 8 FIG. 5 is a schematic diagram of an engine misfire detection device according to the present application;

[0047] Figure 9 FIG. 6 is a schematic diagram of an electronic device according to the present application. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the present application will be described below in connection with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0049] One engine misfire detection method in the related art uses a crankshaft speed fluctuation method. According to the number of cylinders, the entire working cycle is evenly segmented according to the crank angle. Each crankshaft duration (for example, 180 degrees for a 4-cylinder engine and 120 degrees for a 6-cylinder engine) corresponds to the work performance of one cylinder. Because the work is evenly distributed, the segmentation time also corresponds to the cylinder. When the engine is working normally, because the work of each cylinder is basically consistent, each segmentation time is basically close, and the angular acceleration is basically 0 at this time. When a cylinder misfires, the work capacity of the cylinder decreases, the speed decreases, and the segmentation time becomes longer. At this time, the angular acceleration of the misfire section will have a relatively obvious negative value, and the misfire event and the misfire cylinder can be identified accordingly.

[0050] However, the above-mentioned crankshaft speed fluctuation method is only suitable for misfire detection when the angular acceleration of the engine is basically 0 (the engine is uniform speed). Once the engine starts to accelerate or decelerate, the segmentation time of each cylinder in the engine will change. In this case, the normal operation of the engine can be easily misjudged as misfire, and there is a problem of high misjudgment rate of engine misfire detection.

[0051] Therefore, the present application provides an engine misfire detection method to improve the accuracy of engine misfire detection. The engine misfire detection method according to the present application will be described below in connection with Figures 1 to 7 The engine misfire detection method according to the present application will be described below in connection with

[0052] AsFigure 1 As shown, the embodiment of the present application provides a method for detecting engine misfire, which can be executed by an engine misfire detection device, and the method comprises the following steps:

[0053] Step 110: Sampling the running time of each cylinder of the engine in the selected crank angle window.

[0054] In actual application, the working cycle of an engine comprises: intake stroke, compression stroke, power stroke and exhaust stroke. Based on this, in one working cycle, the crankshaft of the engine rotates twice, i.e. 720°, and the piston moves up and down four times, passing through the top dead center four times.

[0055] One rotation of the crankshaft of the engine is 360 degrees, which is generally taken as 0 degree when the piston moves to the top dead center.

[0056] In the embodiment, the same crank angle section is selected as the crank angle window of each cylinder of the engine, and the crank angle window of each cylinder comprises the power stroke of the cylinder. The power stroke included in the crank angle window can be most of the power stroke or the entire process of the power stroke. It can be understood that the crank angle window can be set according to actual requirements.

[0057] For example, the start point of the crank angle window is M degrees of crank angle after the compression top dead center (TDC) of the cylinder, and the value of M is greater than 0. The duration angle of the crank angle window is 720 / cylinder number. The engine can comprise four cylinders, i.e. a four-cylinder engine, or six cylinders, i.e. a six-cylinder engine, etc.

[0058] The value of M can be set according to the actual situation of the engine. For example, the value of M is 42 degrees of crank angle. Taking a four-cylinder engine as an example, as shown in the figure, Figure 2 As shown, the start point of the crank angle window of the cylinder is 42 degrees of crank angle after the TDC, the end point is 222 degrees of crank angle after the compression top dead center of the cylinder, and the duration angle of the crank angle window is 180 degrees.

[0059] Because the influence of the cylinder combustion and power of the engine on the rotational speed angle acceleration starts to be reflected at M degrees of crank angle after the compression top dead center, based on this, the selected crank angle window is more consistent with the power situation of the engine in actual operation. By selecting the crank angle window corresponding to the power process which can best reflect the effect of the crank angle acceleration of the engine, the engine misfire can be accurately detected.

[0060] In the implementation, the time occupied by each cylinder in each working cycle in the crank angle window, i.e. the running time, is sampled and recorded, which is denoted as T_SEG.

[0061] The running time of each cylinder in the crank angle window in each working cycle is sampled according to the cylinder working sequence to form a sampling sequence.

[0062] As shown in Figure 3 Taking a 4-cylinder engine as an example, the 4 cylinders in the engine are numbered respectively, and the cylinder numbers can be set as A cylinder, B cylinder, C cylinder and D cylinder, each cylinder corresponds to the same crank angle window, and is numbered as 0, 1, 2 and 3 respectively, see the segmented number shown in Figure 3 The working sequence of all cylinders in the sampling sequence is: … A cylinder-B cylinder-C cylinder-D cylinder-A cylinder… The time occupied by each cylinder in the crank angle window in each working cycle, i.e. the running time, is sampled and recorded to obtain a sampling sequence. The running time of the cylinder sampled by the nth sampling point in the sampling sequence is T_SEGn. For example, the cylinder sampled by the nth sampling point is A cylinder, then the sampling points corresponding to A cylinder are n-4, n, n+4 and so on. Correspondingly, the sampling points corresponding to B cylinder are n-3, n+1, n+5 and so on, and so on, C cylinder and D cylinder also have their own corresponding multiple sampling points.

[0063] Step 120: performing misfire detection on each cylinder; the misfire detection step includes:

[0064] Based on the difference between the running time of the last cylinder and the current cylinder in the working cycle of the detected current cylinder, the first roughness of the engine is determined, and based on the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after, the second roughness of the engine is determined, and the first cylinder and the second cylinder are the same cylinder in two adjacent working cycles.

[0065] Based on the difference between the first roughness and the second roughness, the final roughness of the engine is determined.

[0066] Based on the comparison result of the final roughness of the engine and the roughness threshold, it is determined whether the current cylinder misfires.

[0067] Wherein, the current cylinder is the cylinder that needs to be detected for misfire at present, and the last cylinder of the current cylinder is the last cylinder adjacent to the current cylinder which needs to complete work before the current cylinder works according to the working sequence in the working cycle.

[0068] Specifically, after sampling the running time length of the current cylinder in the crank angle window and sampling the running time length of the last cylinder of the current cylinder in the crank angle window, the first roughness of the engine can be determined based on the difference between the running time length of the last cylinder of the current cylinder in the working cycle and the running time length of the current cylinder in the crank angle window, which directly reflects the actual running condition of the engine. In the actual running process, it may include the acceleration and deceleration in normal running, the deceleration caused by engine misfire, and the uniform running in normal running. Based on this, the first roughness of the engine is the result of the comprehensive action of various conditions, which is referred to as the static part of the engine roughness here.

[0069] It should be noted that the difference between the running time length of the last cylinder of the current cylinder in the working cycle and the running time length of the current cylinder can be the running time length of the last cylinder of the current cylinder in the working cycle minus the running time length of the current cylinder, or the running time length of the current cylinder minus the running time length of the last cylinder of the current cylinder in the working cycle.

[0070] When the engine runs at a constant speed, the work of each cylinder is basically the same, the difference between the running time length of the last cylinder of the current cylinder in the working cycle and the running time length of the current cylinder in the same crank angle window is basically 0, that is, the value of the static part of the engine roughness is basically zero. If a cylinder in the engine misfires at this time, the cylinder will obviously decelerate, and the specific misfire cylinder can be accurately detected accordingly, as shown in FIG. 4. Figure 4 As shown in FIG. 4, when the B cylinder of the 4-cylinder engine misfires, the running time length of the B cylinder in the crank angle window is obviously longer. However, when the engine runs at an acceleration and deceleration, the engine has an angular acceleration, and the speed of all cylinders in the engine changes accordingly. The value of the static part of the engine roughness also changes greatly due to the angular acceleration of the engine running at acceleration and deceleration. At this time, the cylinder speed and the static part of the engine roughness both change greatly, resulting in a significantly higher misjudgment rate of engine misfire detection. In the process of implementing the present application, the inventors found that the effect of the angular acceleration of the engine running at acceleration and deceleration on the engine roughness can be eliminated first, and the remaining part is the effect of the engine running at a constant speed on the engine roughness. Based on this, if a cylinder in the engine misfires and decelerates obviously, it can be accurately detected.

[0071] In the embodiment, the second roughness of the engine is determined based on a difference between the running time length of the first cylinder experienced by the current cylinder and the running time length of the second cylinder experienced by the current cylinder, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles. The same cylinder just experiences one cycle from one working cycle to the adjacent next working cycle, and in the process, if the engine is accelerated or decelerated, the acceleration or deceleration of the current cylinder can be reflected by the change of the running time length of the same cylinder. Therefore, the second roughness of the engine can be determined by the difference of the running time length of the same cylinder, and the second roughness is the angular acceleration of the engine acceleration or deceleration on the engine roughness, also known as the dynamic part of the engine roughness.

[0072] Based on this, in the embodiment, the dynamic part of the engine roughness is introduced to correct the static part of the engine roughness, that is, the final roughness of the engine is determined based on the difference between the first roughness and the second roughness. In this way, the difference between the static part and the dynamic part of the engine roughness is used to determine the final roughness of the engine corresponding to the current cylinder, and the final roughness is the roughness after eliminating the effect of the engine acceleration or deceleration. Based on the comparison result of the final roughness of the engine and the roughness threshold, it is determined whether the current cylinder misfires, which can greatly reduce the misjudgment rate of engine misfire detection.

[0073] The difference between the first roughness and the second roughness can be the first roughness minus the second roughness, or the second roughness minus the first roughness.

[0074] The first cylinder and the second cylinder can be other cylinders except the current cylinder. For example, the setting condition of the first cylinder and the second cylinder can be that the number of cylinders experienced between the first cylinder and the current cylinder is equal to the number of cylinders experienced between the second cylinder and the current cylinder. In this way, the current cylinder is located between the first cylinder and the second cylinder, and the first cylinder to the current cylinder is half a cycle of the working cycle, and the current cylinder to the second cylinder is half a cycle of the working cycle. The first cylinder and the second cylinder are the same cylinder, so the first cylinder and the second cylinder are the symmetric cylinders of the current cylinder. In this way, the current cylinder is located between the first cylinder and the second cylinder, which can better reflect the acceleration or deceleration change of the working cycle between the first cylinder and the second cylinder, and is beneficial to accurately determine the second roughness.

[0075] Still taking the 4-cylinder engine as an example, referring to Figure 3, if the current cylinder is the A cylinder, and according to the working sequence of the working cycle, if the number of cylinders experienced between the first cylinder and the current cylinder is equal to the number of cylinders experienced between the second cylinder and the current cylinder, then the first cylinder experienced before the current cylinder A cylinder is the C cylinder, and the second cylinder experienced after the current cylinder A cylinder is the C cylinder in the next working cycle of the working cycle in which the first cylinder is located, and there is exactly one working cycle between the first cylinder and the second cylinder.

[0076] After the final roughness of the engine is determined, the final roughness of the engine is compared with the roughness threshold value, and based on the comparison result of the final roughness of the engine and the roughness threshold value, it can be determined whether the current cylinder misfires. Specifically, the final roughness of the engine can be directly compared with the corresponding roughness threshold value, or the absolute value of the final roughness of the engine can be compared with the absolute value of the corresponding roughness threshold value.

[0077] The following is an example of a 4-cylinder engine, still referring to Figure 3 Based on the engine misfire detection method, it is detected whether each cylinder from A cylinder to D cylinder misfires, if the detected current cylinder is the A cylinder, according to the working sequence, the D cylinder is the last cylinder in the working cycle of the current cylinder A cylinder, and the C cylinder is the first cylinder and the second cylinder. Based on the difference between the running time of the D cylinder and the A cylinder in the crank angle window, the first roughness, i.e. the static part of the engine roughness, is determined, and is recorded as Sta ER. Based on the difference between the running time of the C cylinder experienced before the A cylinder and the running time of the C cylinder experienced after the A cylinder in the crank angle window, the second roughness, i.e. the dynamic part of the engine roughness, is determined, and is recorded as Dyn ER. Then, the first roughness of the engine of the detected current cylinder A cylinder at the sampling point n is Sta ERn, which is determined based on the difference between the running time of the D cylinder at the sampling point n-1 and the running time of the A cylinder at the sampling point n. The second roughness of the engine of the detected current cylinder A cylinder at the sampling point n is Dyn ERn, which is determined based on the difference between the running time of the C cylinder at the sampling point n-2 and the running time of the C cylinder at the sampling point n+2.

[0078] The engine misfire detection method provided by the embodiment of the present application can sample the running time of each cylinder of the engine in a selected crank angle window, and perform a misfire detection step for each cylinder. When performing the misfire detection, the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle can be used to determine the first roughness of the engine, and then the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after can be used to determine the second roughness of the engine, which can reflect the effect of the angular acceleration of the engine acceleration and deceleration operation on the roughness of the engine. The difference between the first roughness and the second roughness can be used to determine the final roughness of the engine. In this way, the part of the first roughness affected by the acceleration and deceleration operation of the engine can be eliminated. The comparison result between the final roughness of the engine and the roughness threshold value can be used to determine whether the current cylinder misfires, which can reduce the influence of the acceleration and deceleration operation of the engine on the engine misfire detection, greatly reduce the misjudgment rate of the engine misfire detection, and improve the accuracy of the engine misfire detection.

[0079] There are many specific implementation manners of the first roughness and the second roughness in the above step 120, and some of them are listed below.

[0080] In one possible implementation manner, step 120 can include, as shown in Figure 5 , including:

[0081] Step 510: taking the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle as the first roughness of the engine.

[0082] Step 520: dividing the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after by the number of cylinders to obtain the second roughness of the engine.

[0083] It should be noted that the number of cylinders in step 502 refers to the total number of cylinders included in the engine that needs to perform engine misfire detection. For example, for a 4-cylinder engine, the number of cylinders is 4, for a 6-cylinder engine, the number of cylinders is 6, and for other engines suitable for the engine misfire detection method provided by the embodiment of the present application, they are all within the protection scope of the present application, and will not be described one by one here.

[0084] In the implementation, the difference between the running time of the last cylinder and the current cylinder in the working cycle of the current cylinder can be directly taken as the first roughness of the engine. Each cylinder corresponds to a working process. Since the last cylinder and the current cylinder in the working cycle of the current cylinder only experience one cylinder, only one working process of one cylinder in one working cycle is experienced, while the first cylinder and the second cylinder experience one working cycle, that is, one working process of all cylinders in one working cycle. Based on this, the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after can be divided by the number of cylinders to obtain an average running time, which is taken as the second roughness of the engine. Then, the first roughness of the engine is corrected. In this way, the final roughness of the engine is more accurate. For example, the first roughness of the engine can be subtracted by the second roughness of the engine to obtain the final roughness of the engine.

[0085] Referring to Figure 3 , the number of cylinders is 4, the current cylinder A is detected at the sampling point n, the running time thereof is T_SEGn, the running time of the last cylinder D of the cylinder A in the working cycle is T_SEGn-1, and the first roughness of the cylinder A at the sampling point n is Sta_ERn=T_SEGn-1-T_SEGn. The first cylinder and the second cylinder are C, the first cylinder is at the sampling point n-2, the second cylinder is at the sampling point n+2, the running time of the first cylinder at the sampling point n-2 is T_SEGn-2, the running time of the second cylinder at the sampling point n+2 is T_SEGn+2, and the second roughness of the cylinder A at the sampling point n is Dyn_ERn=(T_SEGn-2-T_SEGn+2) / 4. The final roughness of the engine is ERn=Sta_ERn-Dyn_ERn.

[0086] In the embodiment, the difference between the running time of the last cylinder and the current cylinder in the working cycle of the current cylinder is directly taken as the first roughness of the engine, and the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after is divided by the number of cylinders to obtain the second roughness of the engine. Based on the difference between the first roughness and the second roughness, the final roughness is determined to be closer to 0. Regardless of whether the engine is actually running at a uniform speed, accelerating or decelerating, since the final roughness is basically 0, it is equivalent to detecting misfire of the engine when the engine is running at a uniform speed. It is more sensitive to deceleration caused by misfire of the engine. In this way, the accuracy of misfire detection of the engine during acceleration and deceleration of the engine can be further improved.

[0087] In another possible implementation, as Figure 6As shown, step 120 can include,

[0088] Step 610, multiply the difference between the last cylinder in the working cycle and the current cylinder of the running time of the current cylinder by the number of the cylinders to obtain the first roughness of the engine;

[0089] Step 620, the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder as the second roughness of the engine.

[0090] In the implementation, the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder can be directly taken as the second roughness of the engine. Each cylinder corresponds to a working process. Since the last cylinder in the working cycle and the current cylinder of the current cylinder only experience one cylinder, only one working process of one cylinder in a working cycle is experienced, while the first cylinder to the second cylinder experiences a working cycle, that is, the working process of all cylinders in a working cycle is experienced. Based on this, the difference between the last cylinder in the working cycle and the running time of the current cylinder of the current cylinder can be multiplied by the number of the cylinders to obtain the first roughness of the engine, and the total running time is obtained. The total running time is taken as the first roughness of the engine, and then the first roughness of the engine is corrected based on the second roughness. In this way, the final roughness of the engine obtained is more accurate. For example, the first roughness of the engine can be subtracted by the second roughness of the engine to obtain the final roughness of the engine.

[0091] Referring to Figure 3 , the number of cylinders is 4, the current cylinder A cylinder is detected at the sampling point n, and the running time is T_SEGn. The running time of the last cylinder D cylinder in the working cycle of the A cylinder is T_SEGn-1. The first roughness of the A cylinder at the sampling point n is Sta_ERn=4*(T_SEGn-1-T_SEGn). The first cylinder is C cylinder, and the second cylinder is C cylinder. The first cylinder is at the sampling point n-2, and the second cylinder is at the sampling point n+2. The running time of the first cylinder at the sampling point n-2 is T_SEGn-2, and the running time of the second cylinder at the sampling point n+2 is T_SEGn+2. The second roughness of the A cylinder at the sampling point n is Dyn_ERn=T_SEGn-2-T_SEGn+2. The final roughness of the engine is ERn=Sta_ERn-Dyn_ERn.

[0092] In the embodiment, the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after is directly taken as the second roughness of the engine, and the difference between the running time of the last cylinder and the current cylinder in the working cycle is multiplied by the number of the cylinders to obtain the first roughness of the engine. Based on the difference between the first roughness and the second roughness, the final roughness determined is more accurate, so that the accuracy of the misfire detection of the engine during acceleration and deceleration operation can be further improved.

[0093] In the example embodiment, the sampling of the running time of each cylinder of the engine in the selected crank angle window includes sampling the running time of each cylinder of the engine in the selected crank angle window when the engine meets the misfire detection condition; the method further includes: in the first working cycle of the current cylinder, determining the roughness threshold based on the corresponding speed, load and water temperature of the cylinder; in the second working cycle of the current cylinder, performing the misfire detection step on the current cylinder, and the first working cycle and the second working cycle are two adjacent working cycles.

[0094] In the implementation, the engine misfire detection can be started when the engine meets the misfire detection condition, at which time the sampling of the running time of each cylinder of the engine in the selected crank angle window can be started. The misfire detection condition can include:

[0095] 1) a preset time (for example, 5 seconds) after starting;

[0096] 2) above zero load;

[0097] 3) above the minimum engine speed (for example, the hot engine idle speed-150 rpm);

[0098] 4) below the calibrated throttle change rate;

[0099] 5) not bad road;

[0100] 6) not crank vibration condition.

[0101] In actual application, engine misfire detection can be performed when the engine runs at a constant speed. If the acceleration or deceleration is great, the influence of other factors that affect the engine roughness can be increased, and thus engine misfire detection is not suitable in this case. The throttle valve change rate can be used as a signal to determine the acceleration or deceleration of the engine. When the throttle valve change rate is lower than a preset calibration value, it is considered that the acceleration or deceleration signal of the engine is small, and engine misfire detection can be performed. Although the engine is accelerating or decelerating, the influence of the acceleration or deceleration of the engine is eliminated in the engine misfire detection provided in the present solution, and thus the misjudgment rate of engine misfire detection can be reduced. In this case, the calibration value corresponding to the throttle valve change rate can be set to be relatively large, and the condition for engine misfire detection is relaxed compared with related technologies.

[0102] Specifically, in the first working cycle of the current cylinder, the determination of the roughness threshold value based on the rotation speed, load and water temperature of the cylinder can include the following steps. A threshold value basic value corresponding to the rotation speed and load of the cylinder can be determined based on a preset corresponding relationship among the rotation speed, load and threshold value basic value. A water temperature correction factor corresponding to the water temperature can be determined based on a preset corresponding relationship between the water temperature and the water temperature correction factor. The roughness threshold value can be determined based on the product of the determined threshold value basic value and the water temperature correction factor. For example, thd er = fac tco thd er x thd er bas, where thd er is the roughness threshold value, fac tco thd er is the water temperature correction factor, and thd er bas is the threshold value basic value. For example, when the rotation speed is 1500 rpm and the relative load is 30%, thd er bas =-35 is determined. When the water temperature is 0°C, fac tco thd er = 1.05 is determined. Thus, the roughness threshold value of this operating point (rotation speed 1500 rpm, relative load 30%, water temperature 0°C) is thd er = 1.05 x (-35) =-36.75.

[0103] Still referring to Figure 3 At the sampling point n, the cylinder A is in the current working cycle, i.e., the first working cycle, and the current cylinder A is detected to save the rotation speed, load, water temperature and the like corresponding to the cylinder and calculate the roughness threshold value. At the sampling point n+4, the cylinder A is in the next working cycle, i.e., the second working cycle, of the first working cycle, and the final roughness value ERn = Sta ERn-Dyn ERn of the engine is calculated. The engine roughness and the roughness threshold value are compared to determine whether the cylinder A misfires. When ERn < thd er, the cylinder A misfires, and ERn is negative at this time.

[0104] In the embodiment, misfire detection is performed on the current cylinder through two adjacent working cycles. In the first working cycle of the current cylinder, the roughness threshold is determined based on the rotation speed, load and water temperature corresponding to the cylinder, which dynamically matches the operation of the current cylinder. Based on this, in the second working cycle of the current cylinder, the misfire detection step is performed on the current cylinder, and the detection result is more accurate.

[0105] In an example embodiment, the number of misfires of each cylinder is counted in a statistical period; and based on the counting result and the total number of working strokes in the statistical period, a misfire rate is determined.

[0106] The misfire rate can be a single-cylinder misfire rate. Accordingly, each time a cylinder misfire is detected in the statistical period, a count is performed to obtain the number of misfires of each cylinder. For each cylinder, a single-cylinder misfire rate is determined based on the number of misfires of the cylinder and the total number of working strokes in the statistical period. Each working cycle includes a plurality of working strokes, for example, a 4-cylinder engine can include 4 working strokes.

[0107] The misfire rate can also be a total misfire rate. Accordingly, in the statistical period, the sum of the number of misfires of all cylinders is taken as the total number of misfires, and based on the total number of misfires and the total number of working strokes in the statistical period, a total misfire rate is determined.

[0108] In the implementation, the number of misfires can be recorded by a misfire counter, and the misfire counter is incremented by 1 each time a misfire is detected.

[0109] When the total misfire rate exceeds a misfire rate threshold that causes emissions to exceed a threshold or a misfire rate threshold that causes damage to a catalyst, a corresponding fault is reported and protective measures are taken.

[0110] For example, 1000 engine revolutions are set as a statistical period. For a 4-cylinder engine, the total number of working strokes in the statistical period is 2000, and for a 6-cylinder engine, the total number of working strokes in the statistical period is 3000. Each time a misfire is detected, the misfire counter is incremented by 1. At the end of a statistical period, the total misfire rate in the statistical period is calculated, and the total misfire rate = misfire counter value / total number of working strokes in the period, where the misfire counter value is the total number of misfires.

[0111] In the implementation, a certain misfire rate (such as 3%) can be simulated to make its emissions just exceed the limit value of the on-board diagnostic system (OBD), and the misfire rate is set as the misfire rate threshold that causes emissions to exceed the threshold.

[0112] At the rated power point, a certain misfire rate (for example, 8%) can be actually simulated to make the engine exhaust temperature rise to just reach the catalyst protection temperature, and the misfire rate is set as the misfire rate threshold value causing catalyst damage.

[0113] When the detected total misfire rate is greater than the misfire rate threshold value causing emission exceeding, a misfire fault causing emission exceeding is reported, for example, a fault light can be turned on.

[0114] When the detected misfire rate is greater than the misfire rate threshold value causing catalyst damage, a misfire fault causing catalyst damage is reported, for example, a fault light can be turned on, for a multi-point injection gasoline engine, the fuel closed loop is closed, and the misfire cylinder is cut off; for a single-point injection gasoline engine, a lean burn mode (for example, the target air-fuel ratio is 1.3) is adopted.

[0115] In this embodiment, the misfire rate is determined through the detection and statistics of the number of misfires of the cylinder, so that the user can understand the use of the engine and take appropriate measures in time.

[0116] The engine misfire detection method of this embodiment is described below with a specific application scenario as an example. If the engine speed is 1500 rpm when running at a constant speed, there may be acceleration and deceleration during operation, and there may be misfires, for example, Figure 7 As shown in the figure, there are two misfire points (indicated by two circles in the figure) in the sampling sequence in this scenario. In this process of detecting engine misfire, assuming that the current cylinder to be detected is at the nth sampling point, the first roughness Sta ERn = T SEGn-1-T SEGn, the second roughness Dyn ERn = (T SEGn-2-T SEGn+2) / 4, and the final roughness ERn = Sta ERn-Dyn ERn can be obtained. Compare ERn with the corresponding roughness threshold value, and determine whether the cylinder misfires based on the comparison result. The following takes the two misfire points in the figure as an example.

[0117] Figure 7 The 9th sampling point in the sampling sequence in the figure is the first misfire point, and the 9th sampling point is during the engine running at a constant speed. At the 9th sampling point, the speed of the current detection cylinder is significantly lower than that at the adjacent two sampling points, the first roughness is Sta ER9 = T SEG8-T SEG9, the second roughness is Dyn ER9 = (T SEGn7-T SEG11) / 4, and the final roughness is ER9 = Sta ER9-Dyn ER9. At this time, compare ER9 with the corresponding roughness threshold value, and determine whether the cylinder misfires based on the comparison result.

[0118] Figure 7the 29th sampling point in the sampling sequence is a second misfire point, the 29th sampling point is in the engine deceleration operation, at the 29th sampling point, the current detection cylinder speed is obviously too fast compared with the cylinder speed at the previous sampling point, the first roughness is Sta ER29 = T SEG28-T SEG29, the second roughness is Dyn ER29 = (T SEGn27-T SEG31) / 4, and the final roughness is ER29 = Sta ER29-Dyn ER29. At this time, the ER29 is compared with the corresponding roughness threshold value, and based on the comparison result, the cylinder misfire can be determined. In this way, the engine misfire can be accurately detected.

[0119] The engine misfire detection device provided by the application is described below, and the engine misfire detection device described below can be referred to in correspondence with the engine misfire detection method described above.

[0120] The embodiment of the application also provides an engine misfire detection device, as shown in the figure, comprising a sampling module and a detection module. Figure 8

[0121] The sampling module is used for sampling the running time of each cylinder of the engine in a selected crank angle window.

[0122] The detection module is used for performing a misfire detection step for each cylinder; the misfire detection step comprises: determining a first roughness of the engine based on the difference between the running time of the previous cylinder and the current cylinder in the working cycle of the detected current cylinder, determining a second roughness of the engine based on the difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles; determining a final roughness of the engine based on the difference between the first roughness and the second roughness; determining whether the current cylinder misfires based on the comparison result between the final roughness of the engine and the roughness threshold value.

[0123] In the exemplary embodiment, the detection module is specifically used for:

[0124] The difference between the running time of the previous cylinder and the current cylinder in the working cycle of the current cylinder is taken as the first roughness of the engine;

[0125] The difference between the running time of the first cylinder experienced by the current cylinder before and the running time of the second cylinder experienced by the current cylinder after is divided by the number of cylinders to obtain the second roughness of the engine.

[0126] ​In an example embodiment, the detection module is specifically configured to:

[0127] multiply the difference between the runtime length of the previous cylinder and the runtime length of the current cylinder in a working cycle by the number of the cylinders to obtain a first roughness of the engine;

[0128] take the difference between the runtime length of the first cylinder experienced by the current cylinder and the runtime length of the second cylinder experienced by the current cylinder as a second roughness of the engine.

[0129] In an example embodiment, the number of cylinders experienced between the first cylinder and the current cylinder is equal to the number of cylinders experienced between the second cylinder and the current cylinder.

[0130] In an example embodiment, the start point of the crank angle window is M degrees of crank angle after the compression top dead center of the cylinder, and M is greater than 0.

[0131] In an example embodiment, the sampling module is specifically configured to:

[0132] when the engine meets the misfire detection condition, sample the runtime length of each cylinder of the engine in the selected crank angle window;

[0133] The detection module is further configured to:

[0134] in the first working cycle of the current cylinder, determine the roughness threshold based on the corresponding rotation speed, load and water temperature of the cylinder;

[0135] in the second working cycle of the current cylinder, perform the misfire detection step on the current cylinder, and the first working cycle and the second working cycle are two adjacent working cycles.

[0136] In an example embodiment, the detection module is specifically configured to:

[0137] In a statistical period, count the number of misfires of each cylinder determined;

[0138] determine the misfire rate based on the statistical result and the total number of working strokes in the statistical period.

[0139] Figure 9 An example of an electronic device is shown in the structural diagram, such as Figure 9As shown, the electronic device can include a processor 910, a communications interface 920, a memory 930, and a communications bus 940, wherein the processor 910, the communications interface 920, and the memory 930 complete mutual communication through the communications bus 940. The processor 910 can invoke a logic instruction in the memory 930 to execute the engine misfire detection method provided by each of the above embodiments, which includes sampling a running time length of each cylinder of an engine within a selected crank angle window;

[0140] performing a misfire detection step for each cylinder; the misfire detection step includes:

[0141] determining a first roughness of the engine based on a difference between a running time length of a previous cylinder and a current cylinder of the current cylinder in a work cycle, and determining a second roughness of the engine based on a difference between the running time length of a first cylinder experienced before the current cylinder and the running time length of a second cylinder experienced after the current cylinder, the first cylinder and the second cylinder being the same cylinder in two adjacent work cycles;

[0142] determining a final roughness of the engine based on a difference between the first roughness and the second roughness;

[0143] determining whether the current cylinder misfires based on a comparison result between the final roughness of the engine and a roughness threshold.

[0144] In addition, the logic instruction in the memory 930 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or the part of the technical solutions that essentially contribute to the prior art or the part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0145] In another aspect, the present application also provides a computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions that, when executed by a computer, enable the computer to perform the engine misfire detection method provided by any of the above embodiments, the method comprising:

[0146] sampling a running duration of each cylinder of the engine within a selected crank angle window;

[0147] performing a misfire detection step for each cylinder; the misfire detection step comprising:

[0148] determining a first harshness of the engine based on a difference between a running duration of a previous cylinder and a current cylinder of the current cylinder in a work cycle, and determining a second harshness of the engine based on a difference between the running duration of a first cylinder experienced before the current cylinder and the running duration of a second cylinder experienced after the current cylinder, the first cylinder and the second cylinder being the same cylinder in two adjacent work cycles;

[0149] determining a final harshness of the engine based on a difference between the first harshness and the second harshness;

[0150] determining whether the current cylinder misfires based on a comparison result between the final harshness of the engine and a harshness threshold.

[0151] In yet another aspect, the present application also provides a non-transitory computer-readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the engine misfire detection method provided by any of the above embodiments, the method comprising:

[0152] sampling a running duration of each cylinder of the engine within a selected crank angle window;

[0153] performing a misfire detection step for each cylinder; the misfire detection step comprising:

[0154] determining a first harshness of the engine based on a difference between a running duration of a previous cylinder and a current cylinder of the current cylinder in a work cycle, and determining a second harshness of the engine based on a difference between the running duration of a first cylinder experienced before the current cylinder and the running duration of a second cylinder experienced after the current cylinder, the first cylinder and the second cylinder being the same cylinder in two adjacent work cycles;

[0155] determining a final harshness of the engine based on a difference between the first harshness and the second harshness;

[0156] Based on a comparison result of the final roughness of the engine and a roughness threshold, it is determined whether the current cylinder misfires.

[0157] The embodiments of the present application also provide an engine for executing the engine misfire detection method provided by the above-mentioned embodiments, or comprising the engine misfire detection device provided by the above-mentioned embodiments, or comprising the electronic device provided by the above-mentioned embodiments, or comprising the non-transitory computer readable storage medium provided by the above-mentioned embodiments, or comprising the computer program product provided by the above-mentioned embodiments.

[0158] The embodiments of the present application also provide a working machine for executing the engine misfire detection method provided by the above-mentioned embodiments, or comprising the engine misfire detection device provided by the above-mentioned embodiments, or comprising the electronic device provided by the above-mentioned embodiments, or comprising the non-transitory computer readable storage medium provided by the above-mentioned embodiments, or comprising the computer program product provided by the above-mentioned embodiments, or comprising the engine provided by the above-mentioned embodiments.

[0159] Those skilled in the art can clearly understand the technical solutions of the embodiments through the above description of the embodiments, and the technical solutions of the embodiments can be realized by means of software and necessary general hardware platforms, and of course, can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

[0160] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the above-mentioned embodiments have been described in detail, those skilled in the art should understand that: they can still modify the technical solutions recorded in the above-mentioned embodiments, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An engine misfire detection method characterized by, The method comprises: sampling running time of each cylinder of the engine in a selected crank angle window; performing misfire detection on each cylinder; the misfire detection comprises: determining a first roughness of the engine based on a difference between running time of a previous cylinder and a current cylinder of the current cylinder in a working cycle, and determining a second roughness of the engine based on a difference between the running time of a first cylinder experienced before the current cylinder and the running time of a second cylinder experienced after the current cylinder, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles; determining a final roughness of the engine based on a difference between the first roughness and the second roughness; determining whether the current cylinder misfires based on a comparison result between the final roughness of the engine and a roughness threshold.

2. The engine misfire detection method of claim 1, wherein The determination of the first roughness of the engine based on the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle, and the determination of the second roughness of the engine based on the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder, comprise: taking the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle as the first roughness of the engine; dividing the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder by the number of cylinders to obtain the second roughness of the engine.

3. The engine misfire detection method of claim 1, wherein The determination of the first roughness of the engine based on the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle, and the determination of the second roughness of the engine based on the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder, comprise: multiplying the difference between the running time of the previous cylinder and the current cylinder of the current cylinder in the working cycle by the number of cylinders to obtain the first roughness of the engine; taking the difference between the running time of the first cylinder experienced before the current cylinder and the running time of the second cylinder experienced after the current cylinder as the second roughness of the engine.

4. The engine misfire detection method according to any one of claims 1 to 3, characterized by, The number of cylinders experienced between the first cylinder and the current cylinder is equal to the number of cylinders experienced between the second cylinder and the current cylinder.

5. The engine misfire detection method according to any one of claims 1 to 3, characterized by, The start point of the crank angle window is M degrees of crank angle after the compression top dead center of the cylinder, and M is greater than 0.

6. The engine misfire detection method according to any one of claims 1 to 3, characterized by, The sampling of the running time of each cylinder of the engine in the selected crank angle window comprises: sampling the running time of each cylinder of the engine in the selected crank angle window when the engine meets a misfire detection condition; The method further comprises: determining the roughness threshold based on the corresponding speed, load and water temperature of the cylinder in the first working cycle of the current cylinder. In a second working cycle of the current cylinder, the misfire detection step is performed on the current cylinder, the first working cycle and the second working cycle being two adjacent working cycles.

7. The engine misfire detection method according to any one of claims 1 to 3, characterized by, Further comprising: In a statistical cycle, the number of misfires of each of the cylinders is statistically determined; Based on the statistical result and the total number of working strokes in the statistical cycle, a misfire rate is determined.

8. An engine misfire detection apparatus characterized by comprising: Comprising: a sampling module configured to sample the running duration of each cylinder of the engine in a selected crank angle window; a detection module configured to perform a misfire detection step on each cylinder; The misfire detection step comprises: determining a first roughness of the engine based on the difference between the running duration of the previous cylinder and the current cylinder in a working cycle, and determining a second roughness of the engine based on the difference between the running duration of the first cylinder experienced by the current cylinder before and the running duration of the second cylinder experienced by the current cylinder after, the first cylinder and the second cylinder being the same cylinder in two adjacent working cycles; determining a final roughness of the engine based on the difference between the first roughness and the second roughness; determining whether the current cylinder misfires based on the comparison result between the final roughness of the engine and a roughness threshold.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the engine misfire detection method according to any one of claims 1 to 7 when executing the program.

10. An engine characterized by, The electronic device for executing the engine misfire detection method according to any one of claims 1 to 7, or comprising the engine misfire detection apparatus according to claim 8, or comprising the electronic device according to claim 9.

11. A work machine characterized by comprising: The electronic device for executing the engine misfire detection method according to any one of claims 1 to 7, or comprising the engine misfire detection apparatus according to claim 8, or comprising the electronic device according to claim 9, or comprising the engine according to claim 10.

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