CN112761789B - Engine misfire diagnostic method and misfire diagnostic device - Google Patents
Engine misfire diagnostic method and misfire diagnostic device Download PDFInfo
- Publication number
- CN112761789B CN112761789B CN202110152639.1A CN202110152639A CN112761789B CN 112761789 B CN112761789 B CN 112761789B CN 202110152639 A CN202110152639 A CN 202110152639A CN 112761789 B CN112761789 B CN 112761789B
- Authority
- CN
- China
- Prior art keywords
- engine
- window
- cylinder
- segmented
- cycle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B77/00—Component parts, details or accessories, not otherwise provided for
- F02B77/08—Safety, indicating or supervising devices
- F02B77/085—Safety, indicating or supervising devices with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame
- F02B77/086—Sensor arrangements in the exhaust, e.g. for temperature, misfire, air/fuel ratio, oxygen sensors
Abstract
The invention provides an engine misfire diagnostic method and a misfire diagnostic apparatus, wherein the engine misfire diagnostic method comprises the following steps: firstly, selecting a window with the same crankshaft rotation angle in each working cycle as a segmented window; secondly, measuring the time occupied by the segmented window in each working cycle; then, calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles; and finally, judging whether the cylinder of the engine is on fire according to the difference m of the average angular accelerations of the segmented windows in two adjacent or spaced working cycles. The engine fire diagnosis method provided by the invention does not have the problem of inaccurate angle division caused by the manufacturing deviation of the signal wheel, and can solve the problems of misjudgment and missed judgment in the fire diagnosis of the engine, particularly the asymmetric two-cylinder engine.
Description
Technical Field
The invention relates to the field of engine detection and diagnosis, in particular to an engine misfire diagnosis method and an engine misfire diagnosis device.
Background
With the increasing tightening of emission regulations, the OBDII (second generation on-board diagnostic system) for motorcycles also puts a mandatory requirement for misfire diagnosis. The motorcycle mainly uses a single-cylinder or double-cylinder engine, wherein the inside of the double cylinders is divided into synchronous double cylinders and asynchronous double cylinders (including V-shaped double cylinders). Although the misfire diagnosis based on the rotating speed roughness is already well applied to the multi-cylinder engine of the automobile, the difference between the operation rule of the motorcycle engine (especially an asynchronous double-cylinder engine) and the multi-cylinder engine of the automobile is large due to the difference between the number of cylinders of the engine and the acting interval rule. The original method adopted by the multi-cylinder engine of the automobile is that the whole working cycle is uniformly segmented according to the phase of a crankshaft according to the number of cylinders, the phase continuous angle of each segment corresponds to the acting performance of one cylinder, and because the acting is uniformly distributed, each segmentation time also corresponds to each cylinder; when the fire is not fired, because the work of each cylinder is basically consistent, each subsection time is basically close, and the average angular acceleration of each subsection can be calculated according to the subsection time, and is basically 0; when a certain cylinder catches fire, the subsection time of the cylinder is reduced because the working capacity is seriously reduced, the speed is reduced, and the subsection time is prolonged; the angular acceleration of the misfiring section is calculated at this time to have a relatively significant deceleration, from which it is possible to identify which cylinder is misfiring. For an asynchronous two-cylinder machine, the acting force between the two cylinders has unequal phase difference; this results in angular acceleration obtained by uniform segmentation, even when the engine is not in fire in normal operation, the engine itself has a large roughness, and the value of the roughness varies with specific working conditions, which brings challenges to the original fire identification method, and the direct use of the original method can result in erroneous judgment or missed judgment.
Disclosure of Invention
The invention aims to provide an engine misfire diagnostic method and an engine misfire diagnostic device, which are used for solving the problems of misjudgment and missed judgment in the engine misfire diagnosis of an engine, particularly an asymmetric two-cylinder engine.
In order to solve the technical problem, the invention provides an engine misfire diagnosis method, which comprises the following steps:
step S1: selecting a window with the same crankshaft rotation angle in each working cycle as a sectional window of an engine cylinder, wherein the sectional window comprises a power stroke of the cylinder;
step S2: measuring the time occupied by the segmented window in each working cycle;
step S3: calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
step S4: and judging whether the cylinder of the engine misfires according to the difference m of the average angular accelerations of the segmented windows in two adjacent or spaced working cycles, wherein m is a constant.
Optionally, in the engine misfire diagnostic method, the engine includes a single cylinder engine and a double cylinder engine with any angle.
Optionally, in the engine misfire diagnostic method, when the engine is a dual-cylinder engine, the same cylinder of the engine selects a window of the same crank angle as a segment window of the cylinder in each working cycle, and the windows of the crank angles corresponding to the segment windows of different cylinders are equal or unequal.
Optionally, in the engine misfire diagnostic method, a continuation angle of the segment window is not higher than 360 degrees.
Optionally, in the engine misfire diagnostic method, a phase shift range of the segment window is not higher than 180 degrees.
Optionally, in the engine misfire diagnostic method, in step S2, a sensor is used to measure a time taken by the segment window in each operating cycle, and the sensor is connected to a crankshaft of the engine.
Optionally, in the engine misfire diagnostic method, an average angular acceleration α (k) of the segment window in the kth operation cycle is calculated from the time the segment window occupies in the kth operation cycle and the (k + n) th operation cycle, where α (k) ═ a [ ts (k) -ts (k + n) ]]/ts3(k) Wherein A is a constant, n ≠ 0, and k is a positive integer.
Optionally, in the engine misfire diagnostic method, the segment window further includes all or part of the crank angle in the compression stroke and the exhaust stroke adjacent to the power stroke of the cylinder.
Optionally, in the engine misfire diagnostic method, in step S4, where m is an average angular acceleration in a k-th operation cycle to an average angular acceleration in a k + n-th operation cycle, and when an absolute value of the difference m does not exceed a calibrated threshold value, a state of a cylinder of the engine in the k-th operation cycle and the k + n-th operation cycle is the same; and when the absolute value of the difference m exceeds a calibrated threshold value, the cylinder of the engine has misfire in the k working cycle or the k + n working cycle.
In order to achieve the above and other related objects, the present invention also provides an engine misfire diagnostic apparatus comprising: a segment window selecting unit, a measuring unit, an average angular acceleration calculating unit and a judging unit, wherein,
the segmented window selecting unit is used for selecting a window with the same crankshaft rotation angle in each working cycle as a segmented window of an engine cylinder;
the measuring unit is used for measuring the time occupied by the segmented window in each working cycle;
the average angular acceleration calculating unit is used for calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
the judging unit is used for judging whether a cylinder of the engine catches fire according to the difference m of the average angular accelerations of the segmented windows in two adjacent or spaced working cycles, wherein m is a constant.
In summary, the engine misfire diagnostic method provided by the invention selects the window with the same crank angle in each working cycle as the segmented window of the engine cylinder, and judges whether the engine misfire or not according to the difference value of the average angular acceleration of the segmented windows in different working cycles. Namely, the phase and the continuous angle of the segmented window selected by the cylinder in each working cycle are the same and correspond to the same tooth segment position of the signal wheel, so that the problem of inaccurate angle division caused by manufacturing deviation of the signal wheel does not exist, the hidden danger that the high-rotating-speed working condition possibly judges wrongly caused by inaccurate segmented angle is eliminated, and complicated angle deviation learning can not be used. And whether the engine catches fire can be judged through the difference value of the average angular acceleration of the segmented windows in different working cycles, so that whether the engine catches fire or not can be diagnosed, and the problems of misjudgment and missed judgment in fire diagnosis of the engine, particularly an asymmetric two-cylinder engine, can be solved.
Drawings
FIG. 1 is a flow chart of an engine misfire diagnostic method in an embodiment of the present invention;
FIG. 2 is a schematic illustration of a segmented window selection for a single cylinder engine;
FIG. 3 is a schematic diagram of segment window selection for a synchronous twin engine;
FIG. 4 is a schematic diagram of segment window selection for an asynchronous twin-cylinder engine;
FIG. 5 is a sectional window selection diagram of a V-twin engine;
in fig. 1 to 5:
1-segmentation window.
Detailed Description
The engine misfire diagnostic method proposed by the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description.
The existing multi-cylinder machine adopts a method that the whole working cycle is uniformly segmented according to the phase of a crankshaft according to the number of cylinders, and the phase continuous angle of each segment corresponds to the acting performance of one cylinder; because the work is uniformly distributed, each subsection time corresponds to each cylinder, the angular acceleration of each subsection is calculated according to each subsection time, whether the engine catches fire or not is judged by comparing the angular accelerations of different subsections, and further which cylinder of the engine catches fire can be judged. However, for asynchronous two-cylinder machines, the work done between the two cylinders has unequal phase difference, which can result in angular acceleration obtained by uniform segmentation, even when the engine normally works and no fire occurs, the engine has large roughness, and the value of the roughness also changes with specific working conditions, which brings challenges to the original fire identification method. Therefore, for asynchronous two-cylinder engines, direct use of existing engine misfire diagnostic methods can lead to false or missed determinations.
Therefore, the core idea of the invention is to provide an engine misfire diagnosis method, which can accurately judge whether the engine misfire and which cylinder misfire through comparing the angular acceleration of the segmented windows of each cylinder in two working cycles, thereby solving the problems of erroneous judgment and missed judgment in the misfire diagnosis of the engine, especially an asymmetric two-cylinder engine.
Referring to FIG. 1, the engine misfire diagnostic method includes the steps of:
step S1: selecting a window with the same crankshaft rotation angle in each working cycle as a sectional window of an engine cylinder, wherein the sectional window comprises a power stroke of the cylinder;
step S2: measuring the time occupied by the segmented window in each working cycle;
step S3: calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
step S4: and judging whether the cylinder of the engine misfires according to the difference m of the average angular accelerations of the segmented windows in two adjacent or spaced working cycles, wherein m is a constant.
In step S1, the engine may be a single cylinder engine or a twin cylinder engine, and the twin cylinder engine includes a twin cylinder engine with any angle. The engine preferably has four strokes, including an intake stroke, a compression stroke, a power stroke, and an exhaust stroke, and the crankshaft of the engine completes one working cycle in two revolutions.
And selecting a window with the same crankshaft angle in each working cycle as a segmented window of the engine cylinder, namely, the phase and the continuous angle of the segmented window selected by the cylinder in each working cycle are the same and correspond to the same tooth segment position of the signal wheel. The method for selecting the same crank angle in each working cycle comprises the following steps: in each working cycle, a starting phase at the same position and an ending phase at the same position are selected on a signal wheel of a sensor connected to a crankshaft of the engine. For example, when the continuous angle of the segment window is 180 degrees, for a 60-2 tooth rpm signal wheel, determining 180 degrees is a method of checking that the rpm signal wheel rotates by 30 teeth, and in each working cycle, the segment window takes the kth tooth as a starting phase and the (k + 30) th tooth as an ending phase, so that in each working cycle, the starting phase and the ending phase corresponding to the segment window are the same, that is, the segment window corresponds to the same tooth position of the signal wheel in each working cycle, and the problem of inaccurate angle division caused by manufacturing deviation of the signal wheel does not exist, the potential problem that the high rpm condition may be judged incorrectly due to inaccurate segment angle is eliminated, and complicated angle deviation learning can not be used.
When the engine is a dual-cylinder engine, the same cylinder of the engine selects the window of the same crankshaft angle as the subsection window of the cylinder in each working cycle, and the windows of the crankshaft angles corresponding to the subsection windows of different cylinders are equal or unequal, that is, the phase and the continuous angle of the subsection window selected by the first cylinder in the dual-cylinder engine can be the same as or different from those of the second cylinder.
The power stroke included in the segmented window may be a part of the power stroke or the whole process of the power stroke. In addition, the segmented window may also include part or all of the intake stroke, the compression stroke and/or the exhaust stroke, that is, the segmented window may include only the power stroke, or may include other strokes at the same time, and therefore, the segmented window does not necessarily correspond to the power stroke completely, and may be varied within a certain range according to actual requirements. The selection principle of the segmented window is that the performance of the window section is obviously influenced by the working degree of the cylinder as much as possible, and the segmented window can be adjusted according to the performance condition of the correlation between the actual segmented window and the rotating speed fluctuation, so that the proportion of the working stroke in the segmented window is as large as possible.
The continuous angle range of the segmented window is less than 720 degrees, further, the continuous angle of the segmented window can be adjusted according to the number of cylinders of the engine and the law of work doing intervals, for example, when the engine is a single cylinder engine, the segmented window can be any continuous angle not exceeding 720 degrees; when the engine is a double-cylinder engine, in order to reduce the mutual influence of two cylinders caused by angle overlapping, the continuous angle of the segmented window does not exceed 360 degrees.
The segment window can be phase-shifted within a certain range, that is, the phase of the segment window can be shifted within a certain range, and the shift range does not exceed 180 degrees, mainly because: the phase is moved too much, the ratio of the power stroke in the segmented window is too small, the correlation between the segmented window and the rotation speed fluctuation is poor, the average angular acceleration of the segmented window is not changed obviously when the cylinder is on fire, and erroneous judgment and missed judgment are easily caused.
In step S2, the specific method for measuring the time ts occupied by the segment window in each duty cycle is as follows: and measuring time points corresponding to the starting phase and the ending phase of the signal wheel corresponding to the segmented window in each working cycle by adopting a sensor, wherein the sensor is connected with a crankshaft of the engine.
In step S3: calculating the average angular acceleration alpha of the segmentation window in the current work cycle by the time occupied by the segmentation window in the work cycle adjacent to or spaced from the current work cycle, namely calculating the average angular acceleration alpha (k) of the segmentation window in the k-th work cycle by the time occupied by the segmentation window in the k-th work cycle and the k + n-th work cycle, wherein the alpha (k) is A [ ts (k) -ts (k + n)]/ts3(k) Wherein A is a constant, n ≠ 0, and k is a positive integer. For example, the average angular acceleration α (k) ═ a [ ts (k) — ts (k +1) of the segment window at the kth cycle is calculated from the time of the segment window at the kth cycle and the (k +1) th cycle adjacent thereto]/ts3(k) In that respect Calculating the average angular acceleration alpha (k-1) ═ A [ ts (k-1) -ts (k) } of the segment window in the k-1 working cycle according to the occupied time of the segment window in the k-1 working cycle and the k working cycle adjacent to the k working cycle]/ts3(k-1). And alpha (k) and alpha (k-1) are respectively expressed as the average angular acceleration of the segmentation window in the k-th working cycle and the k-1-th working cycle, and ts (k-1), ts (k) and ts (k +1) are respectively expressed as the time occupied by the segmentation window in the k-1-th working cycle, the k-th working cycle and the k + 1-th working cycle. The average angular acceleration α ═ dw/dt can be obtained by a general method for deducing the average angular acceleration, and the average angular acceleration is in a direct proportion relation with a function formed by the time occupied by the segmented window, namely dw/dt ═ n 2(k+1)-n2(k)∝1/[ts2(k+1)]-1/[ts2(k)]∝[ts(k)-ts(k+1)]/ts3(k) Thus, the α (k) · oc [ ts (k) — ts (k +1)]/ts3(k) I.e. said α (k) ═ a [ ts (k) — ts (k +1)]/ts3(k)。
In step S4, it is determined whether a cylinder of the engine misfires according to the difference m between the average angular accelerations of the segment windows in two adjacent or spaced working cycles. The difference m is the average angular acceleration of the segment window in the kth operating cycle — the average angular acceleration of the segment window in the (k + n) th operating cycle. For example, the difference m is the average angular acceleration of the segmentation window in the kth cycle — the average angular acceleration of the segmentation window in the kth cycle-1, i.e., the difference m is α (k) - α (k-1). And when the absolute value of the difference m does not exceed a calibrated threshold value, the cylinder of the engine has the same state in the kth working cycle and the kth-1 st working cycle, and is normal or misfires, and the calibrated threshold value is a preset reference value and can be adjusted according to process requirements. Further, whether the cylinder is in fire in the k-th working cycle and the k-1-th working cycle can be judged according to a comparison parameter (the time occupied by the segmented window when the cylinder is not in fire), and if the time occupied by the segmented window in the k-th working cycle and the k-1-th working cycle is not similar to the comparison parameter, the cylinder is in fire in the k-th working cycle and the k-1-th working cycle. When the absolute value of the difference m exceeds a calibrated threshold value, a cylinder of the engine is subjected to misfire in the k-th working cycle or the k-1 st working cycle, wherein when the difference m is a positive value, the cylinder of the engine is subjected to misfire in the k-1 st working cycle; and when the difference value m is a negative value, the cylinder of the engine is subjected to misfire in the k working cycle. When the cylinder catches fire, the working capacity of the cylinder is seriously reduced, the speed is reduced, the time occupied by the subsection window is prolonged, the calculated average angular acceleration of the fire-breaking section has a value with obvious deceleration, and the value is lower than the average angular acceleration value of the subsection window in the last working cycle, so that the difference value m has a larger positive value, namely when the difference value m has a positive value exceeding a specified threshold value, the cylinder of the engine catches fire in the k-1 working cycle. Similarly, when the difference m has a positive value and its absolute value exceeds a prescribed threshold, the engine misfire occurs in the k-1 th operating cycle, and the average angular acceleration of the k-th operating cycle is restored, i.e., the k-th operating cycle is not misfired. Therefore, the engine misfire diagnostic method may enable diagnosis of intermittent misfire. When the absolute value of the difference m does not exceed a specified threshold value, the state of the cylinder of the engine in the k working cycle and the state of the cylinder of the engine in the k-1 working cycle are the same, namely the cylinder of the engine misfires in the k working cycle, and then the cylinder of the engine misfires in the k-1 working cycle; the cylinder of the engine is not misfired in the k-th operating cycle, and is not misfired in the k-1 st operating cycle.
When the engine is a double-cylinder engine, two cylinders of the engine are respectively subjected to misfire judgment. For example, the two-cylinder engine comprises a first cylinder and a second cylinder, and the first cylinder selects a window with the same crankshaft rotation angle in each working cycle as a segmented window of the cylinder; then, measuring the time ts occupied by the segmented window of the cylinder in each working cycle; next, calculating the average angular acceleration of the segmented window of the cylinder in each working cycle according to the time occupied by the segmented window of the cylinder in two adjacent or spaced working cycles; finally, judging whether the cylinder has a misfire according to the difference m of the average angular acceleration of the segmented window of the cylinder in two adjacent or spaced working cycles, and judging in which working cycle the misfire occurs, namely the misfire diagnostic method of the first cylinder can refer to the misfire diagnostic method of the single cylinder engine. As above, the misfire determination of the second cylinder may refer to a method of a single cylinder engine. Therefore, in the fire diagnosis of the double-cylinder engine, particularly the asymmetrical double-cylinder engine, the problem that the work between the two cylinders has unequal phase difference to generate larger roughness so as to cause error judgment or missing judgment does not exist. And because the segmented window selected by the same cylinder in each working cycle corresponds to the same tooth segment position of the signal wheel, namely the segmented window of the same cylinder comprises the same stroke in each working cycle, the difference of the average angular acceleration in the two working cycles is not influenced by the change of the working condition.
The engine misfire diagnosis method provided by the invention judges whether the cylinder of the engine misfires according to the difference value of the average angular acceleration of the segmented window in two working cycles, and the principle of the method is shown in figures 2 to 5. According to the dynamic equation, the angular acceleration of the engine crankshaft rotation is the total torque/moment of inertia (I) of the rotating part of the engine, wherein the total torque experienced is the difference between the power torque and the drag torque, and the power torque mainly comprises: moment of momentum produced by work or expansion; the resistance torque mainly includes: the friction torque generated by the moving element, the resistance torque of the load, the resistance torque of the compression stroke, the resistance torque of the intake stroke, and the resistance torque of the exhaust stroke.
Referring to fig. 2, when the engine is a single cylinder engine, the continuous angle of the segment window is 180 degrees, and the acceleration difference between the adjacent working cycles is used to diagnose whether the single cylinder engine is on fire according to the following principle (the dotted frame in fig. 2 is the selected segment window):
firstly, analyzing the stress relation of the segmented window 1:
the stress relation of the segmented window 1 in the kth working cycle is as follows: t isk total＝Tk work+Tk load resistance+Tk friction force ；
The total torque T of the segment window 1 in the k +1 th working cyclek +1 Total＝Tk +1 doing work+Tk +1 load resistance+Tk +1 friction force。
Wherein, T isxThe signed moment and the equivalent moment that distributes the effect of the moment to the segment window duration angle, X is the total (total moment), work (work moment), load resistance (resistance moment of load), and friction (friction moment).
Secondly, obtaining the angular acceleration of the segmented window according to the stress relation:
the angular acceleration of the segment window 1 for the kth duty cycle is: alpha is alphak＝Tk total/I＝(Tk work+Tk load resistance+Tk friction force)/I；
The angular acceleration of the segment window 1 for the (k + 1) th duty cycle is: alpha is alphak+1＝Tk +1 Total/I＝(Tk +1 doing work
+Tk +1 load resistance+Tk +1 friction force)/I。
Wherein I is the moment of inertia and T iskxAnd Tk+1xIn, except for Tk workAnd Tk +1 doing workOther similar types of T under the same operating conditions, except for a greater difference due to a possible misfirekxAnd Tk+1xAre all substantially close;
finally, the angular accelerations of the two segments are subtracted, and the result after simplification is as follows:
αk-αk+1＝(Tk work-Tk +1 doing work)/I。
It can be seen thatkAnd alphak+1Is only the difference of Tk workAnd Tk +1 doing workIs related to the actual size of the device; when operating in steady state, because of T k workIs substantially equal to Tk +1 doing workSo that αkAnd alphak+1Substantially 0; when the k-th working cycle is normal and the k + 1-th working cycle is in fire, the balance is broken due to Tk +1 doing workIs greatly reduced by akAnd alphak+1Will take a large positive value, and said alphakAnd alphak+1Is greater than or equal to Tk workAnd Tk +1 doing workIs directly related to the size of Tk workAnd Tk +1 doing workAnd is primarily related to engine operating conditions (speed, load, etc.), and thus, according to αkAnd alphak+1The magnitude and sign of the difference value, and referring to a reference value corresponding to the engine working condition, we can identify whether the cylinder has misfired in the k +1 th working cycle; that is, diagnosis of intermittent misfire is achieved.
Referring to fig. 3, the engine may be a synchronous twin cylinder (i.e., a twin cylinder with an ignition interval 360/360) including a first cylinder and a second cylinder, and two pistons of the engine may maintain a synchronous motion state in the first cylinder and the second cylinder, i.e., the pistons may simultaneously ascend and descend. Specifically, when the piston in the first cylinder moves to a bottom dead center to perform an intake stroke (or a power stroke), the piston in the second cylinder also moves to the bottom dead center to perform a power stroke (or an intake stroke); when the piston in the first cylinder moves toward the top dead center to perform a compression stroke (or exhaust stroke), the piston in the second cylinder also moves toward the top dead center to perform an exhaust stroke (or compression stroke). In fig. 3, when the engine is a synchronous two-cylinder engine and the duration angle of the segment window is 180 degrees, the principle that the acceleration difference value in the adjacent working cycles is used for diagnosing whether the synchronous two-cylinder engine misfires is as follows (the dotted frame in fig. 3 is the selected segment window).
Firstly, analyzing the acceleration difference value of a first cylinder in adjacent working cycles to judge the mechanism process of the misfire of the synchronous double-cylinder engine as follows:
the stress relation of the segmented window 1 of the first cylinder in the kth working cycle is as follows: t1k total＝T1k work+T2k air admission+T1k load resistance+T1k friction force；
The stress relation of the segmented window 1 of the first cylinder in the k +1 th working cycle is as follows: t1k +1 Total＝T1k +1 doing work+T2k +1 intake+T1k +1 load resistance+T1k +1 friction force。
Wherein, T isIntake airTo distribute the effect of the resistive torque of the intake stroke to the equivalent torque over the segment window duration angle.
T of adjacent working cycles before and after steady state operationIntake air、TLoad resistance、TFrictional forceBasically, the angular acceleration difference of the segmented windows of two adjacent work cycles is simplified to be: alpha 1k-α1k+1＝(T1k work－T1k +1 doing work) The misfire identification for the first cylinder may be performed in a manner referred to the single cylinder, in accordance with the calculation result of the formula for the single cylinder.
Secondly, analyzing the acceleration difference value of the second cylinder in the adjacent working cycles to judge the mechanism process of the misfire of the synchronous double-cylinder engine as follows:
and obtaining the angular acceleration of the segmented window of the second cylinder as follows: alpha 2 k＝(T2k work+T1k air admission+Tk loadResistance force+Tk friction force) I; the latter duty cycle being defined as α 2k+1T of adjacent working cycles before and after steady state operationIntake air、TLoad resistance、TFrictional forceBasically, the angular acceleration difference of the segmented windows of two adjacent work cycles is simplified to be: alpha 2k-α2k+1＝(T2k work－T2k +1 doing work) The misfire identification for the second cylinder, which is identical to the calculation result of the formula for the single cylinder, may be performed with reference to the single cylinder.
Referring to fig. 4, the engine is an asynchronous twin cylinder (i.e., a twin cylinder with firing interval 180/540) that includes a first cylinder and a second cylinder, and two pistons in the engine move in opposite directions in the first and second cylinders. In fig. 4, when the engine is an asynchronous two-cylinder engine and the duration angle of the segment window is 180 degrees, the principle that the acceleration difference value in the adjacent working cycles is used for diagnosing whether the asynchronous two-cylinder engine misfires is as follows (the dotted frame in fig. 4 is the selected segment window).
Firstly, the force relationship of the segmented window 1 of the first cylinder in the kth working cycle is as follows: t1k total＝T1k work+T2k compression +T1k load resistance+T1k friction force；
The stress relation of the segmented window 1 of the first cylinder in the k +1 th working cycle is as follows: t1k +1 Total＝T1k +1 doing work+T2k +1 compression+T1k +1 load resistance+T1k +1 friction force。
α1k＝(T1k work+T2k compression+T1k load resistance+T1k friction force)/I；
α1k+1＝(T1k +1 doing work+T2k +1 compression+T1k +1 load resistance+T1k +1 friction force)/I；
Wherein, T isCompressionTo distribute the effect of the resistive torque of the compression stroke to the equivalent torque over the segment window duration angle.
T of adjacent working cycles before and after steady state operationCompression、TLoad resistance、TFrictional forceBasically, the angular acceleration difference of the segmented windows of two adjacent work cycles is simplified to be: alpha 1k-α1k+1＝(T1k work－T1k +1 doing work) The misfire identification for the first cylinder may be performed in a manner referred to the single cylinder, in accordance with the calculation result of the formula for the single cylinder.
Secondly, analyzing the acceleration difference value of the second cylinder in the adjacent working cycles to judge the mechanism process of the fire of the asynchronous double-cylinder engine as follows:
in the same way, the angular acceleration of the segmented window of the second cylinder is obtained as follows: alpha 2k＝(T2k work+T1k compression+Tk load resistance+Tk friction force) I; the latter duty cycle being defined as α 2k+1T of adjacent working cycles before and after steady state operation Intake air、TLoad resistanceAnd TFrictional forceBasically, the angular acceleration difference of the segmented windows of two adjacent work cycles is simplified to be: alpha 2k-α2k+1＝(T2k work－T2k +1 doing work) The above-described method of identifying misfiring of the second cylinder, which is identical to the result of the formula calculation for the single cylinder engine, may be referred to as the single cylinder engine.
Referring to fig. 5, the engine is a V-twin engine, and the angle between the two cylinders is an arbitrary value [ two-cylinder engine of ignition interval T/(720-T) (180< T <360) ]. Compared with the above embodiment, the principle that when the engine is a V-twin engine and the continuous angle of the segment window is 180 degrees, the acceleration difference values in the adjacent working cycles are used for diagnosing whether the asynchronous twin engine is in fire or not is the same as the above method except that the relative relationship of the strokes in each segment window is changed.
The invention provides an engine misfire diagnostic method, which selects a window with the same crank angle in each working cycle as a subsection window of an engine cylinder, and judges whether an engine misfire or not according to the difference value of the average angular acceleration of the subsection window in two adjacent working cycles. I.e. the same start and end phases per working cycle are used for the segmented window of each cylinder, meaning that the signal of the angle sensor uses the same segment tooth position of the signal wheel, there is no problem of inaccurate angle division due to manufacturing variations of the signal wheel (such as when dividing by 180 degrees, the actual two segments can be 179.5 degrees and (360-179.5 degrees), the hidden trouble that the working condition of high rotating speed can be judged wrongly because the segmentation angle is inaccurate is eliminated, and whether the engine is on fire can be judged by the difference of the average angular accelerations of the segment windows in two adjacent working cycles, therefore, whether the engine catches fire or not can be diagnosed, and the problems of misjudgment and missed judgment in the fire diagnosis of the engine, particularly the asymmetrical two-cylinder engine, can also be solved.
The present invention also provides an engine misfire diagnostic apparatus comprising: a segment window selecting unit, a measuring unit, an average angular acceleration calculating unit and a judging unit, wherein,
the segmented window selecting unit is used for selecting a window with the same crankshaft rotation angle in each working cycle as a segmented window of an engine cylinder;
the measuring unit is used for measuring the occupied time ts of the segmented window in each working cycle;
the average angular acceleration calculating unit is used for calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
the judging unit is used for judging whether a cylinder of the engine catches fire according to the difference m of the average angular accelerations of the segmented windows in two adjacent or spaced working cycles, wherein m is a constant.
In the engine misfire diagnostic apparatus provided by the embodiment of the invention, the segmented window selecting unit selects a window with the same crank angle in each working cycle as a segmented window of an engine cylinder, the measuring unit measures the time ts occupied by the segmented window in each working cycle, the average angular acceleration calculating unit calculates the average angular acceleration alpha (k) of the segmented window from the time occupied by the segmented window in two working cycles, and the judging unit judges whether the engine misfire or not according to the difference of the average angular accelerations of the segmented windows in the two working cycles. Namely, the phase and the continuous angle of the segmented window selected by the segmented window selecting unit in each working cycle are the same and correspond to the same tooth segment position of the signal wheel, so that the problem of inaccurate angle division caused by the manufacturing deviation of the signal wheel does not exist, and the problem of misjudgment and missed judgment in the fire diagnosis of the engine, particularly the asymmetric two-cylinder engine, can be solved by judging whether the engine fires through the judging unit.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (10)
1. An engine misfire diagnostic method characterized by comprising the steps of:
step S1: selecting a window with the same crankshaft rotation angle in each working cycle as a sectional window of an engine cylinder, wherein the sectional window comprises a power stroke of the cylinder;
step S2: measuring the time occupied by the segmented window in each working cycle;
step S3: calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
step S4: and comparing the difference m of the average angular acceleration of the segmented window in two adjacent or spaced working cycles with a calibrated threshold value to judge whether the cylinder of the engine is on fire.
2. The engine misfire diagnostic method as recited in claim 1, wherein the engine comprises a single cylinder engine and a double cylinder engine of any angle.
3. The engine misfire diagnostic method as recited in claim 2, wherein when the engine is a dual engine, the same cylinder of the engine selects a window of the same crank angle as a segment window of the cylinder in each working cycle, and the windows of the crank angles corresponding to the segment windows of different cylinders are equal or unequal.
4. The engine misfire diagnostic method as recited in claim 3, wherein a continuation angle of the segment window is not higher than 360 degrees.
5. The engine misfire diagnostic method as recited in claim 1, wherein a phase shift range of the segment window is not higher than 180 degrees.
6. The engine misfire diagnostic method as recited in claim 1, wherein in step S2, a time taken by the segment window in each operating cycle is measured using a sensor coupled to a crankshaft of the engine.
7. The engine misfire diagnostic method as recited in claim 1, wherein an average angular acceleration α (k) of the segment window in a k-th operation cycle is calculated from a time the segment window takes in the k-th operation cycle and a k + n-th operation cycle, the α (k) -a [ ts (k) -ts (k + n) ] ]/ts3(k) Wherein A is a constant, n ≠ 0, k is a positive integer, and ts is the time occupied by the segmentation window in each working cycle.
8. The engine misfire diagnostic method as recited in claim 1, wherein the segment window further includes all or a portion of crank angle in compression and exhaust strokes adjacent to the power stroke of the cylinder.
9. The engine misfire diagnostic method as recited in claim 7, wherein in step S4, the m is an average angular acceleration in a k-th operation cycle-an average angular acceleration in a k + n-th operation cycle, and when an absolute value of the difference m does not exceed a calibrated threshold value, a state of a cylinder of the engine in the k-th operation cycle and the k + n-th operation cycle is the same; and when the absolute value of the difference m exceeds a calibrated threshold value, the cylinder of the engine has misfire in the k working cycle or the k + n working cycle.
10. An engine misfire diagnostic apparatus characterized by comprising: a segment window selecting unit, a measuring unit, an average angular acceleration calculating unit and a judging unit, wherein,
the segmented window selecting unit is used for selecting a window with the same crankshaft rotation angle in each working cycle as a segmented window of an engine cylinder;
The measuring unit is used for measuring the time occupied by the segmented window in each working cycle;
the average angular acceleration calculating unit is used for calculating the average angular acceleration of the segmented window in each working cycle according to the time occupied by the segmented window in two adjacent or spaced working cycles;
the judging unit is used for comparing the difference value m of the average angular acceleration of the segmented window in two adjacent or spaced working cycles with a calibrated threshold value so as to judge whether the cylinder of the engine catches fire or not.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110152639.1A CN112761789B (en) | 2021-02-03 | 2021-02-03 | Engine misfire diagnostic method and misfire diagnostic device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110152639.1A CN112761789B (en) | 2021-02-03 | 2021-02-03 | Engine misfire diagnostic method and misfire diagnostic device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112761789A CN112761789A (en) | 2021-05-07 |
| CN112761789B true CN112761789B (en) | 2022-06-28 |
Family
ID=75704841
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110152639.1A Active CN112761789B (en) | 2021-02-03 | 2021-02-03 | Engine misfire diagnostic method and misfire diagnostic device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112761789B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114544186B (en) * | 2022-02-23 | 2024-03-26 | 中国第一汽车股份有限公司 | Engine misfire diagnosis method and vehicle |
| CN114622991B (en) * | 2022-03-18 | 2023-07-18 | 潍柴动力股份有限公司 | Engine misfire judging method, engine and vehicle |
| CN115182813B (en) * | 2022-07-26 | 2023-10-20 | 东风汽车集团股份有限公司 | Engine misfire monitoring method of hybrid electric vehicle |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100578023B1 (en) * | 1999-12-30 | 2006-05-11 | 현대자동차주식회사 | A System and A Way of Detecting Misfire |
| ITBO20030529A1 (en) * | 2003-09-15 | 2005-03-16 | Magneti Marelli Powertrain Spa | METHOD TO DETECT THE ANGULAR ACCELERATION OF ONE |
| CN102072818B (en) * | 2010-11-09 | 2013-06-26 | 联合汽车电子有限公司 | Method for obtaining fire detection signal of cylinder of engine with speed sensor arranged in front |
| CN102980777B (en) * | 2012-12-21 | 2015-05-13 | 潍柴动力股份有限公司 | Method and equipment for detecting misfiring of diesel engine based on single-cylinder angular acceleration |
| CN104929845A (en) * | 2014-03-21 | 2015-09-23 | 北京清研宏达信息科技有限公司 | Fire fault diagnosis method for engine |
| CN112065582B (en) * | 2019-06-11 | 2021-09-28 | 联合汽车电子有限公司 | Method for diagnosing engine misfire in hybrid electric vehicle |
-
2021
- 2021-02-03 CN CN202110152639.1A patent/CN112761789B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN112761789A (en) | 2021-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112761789B (en) | Engine misfire diagnostic method and misfire diagnostic device | |
| US5041980A (en) | Method and apparatus for producing fault signals responsive to malfunctions in individual engine cylinders | |
| JP5099258B2 (en) | Torque estimation device for internal combustion engine | |
| US5915272A (en) | Method of detecting low compression pressure responsive to crankshaft acceleration measurement and apparatus therefor | |
| US5485374A (en) | Combustion-conditon diagnostic system and method for a multicylinder engine | |
| JPH0130098B2 (en) | ||
| JPH0362210B2 (en) | ||
| US10309872B2 (en) | Misfire determination apparatus for internal combustion engine | |
| JP6818127B2 (en) | Tooth error removal method and equipment for engine vehicles and crank pulsar rotors | |
| JP6531222B1 (en) | Engine abnormality detection device | |
| JP2009541629A (en) | Method for detecting misfire and corresponding apparatus | |
| US7540185B2 (en) | System and method for detecting engine misfires | |
| US6212945B1 (en) | Method and apparatus for combustion quality diagnosis and control utilizing synthetic measures of combustion quality | |
| CN112761790B (en) | Misfire diagnostic method and misfire diagnostic device for two-cylinder engine | |
| CN110671203B (en) | Method, device and equipment for determining ignition loss cylinder and computer readable storage medium | |
| CN110529278B (en) | Engine misfire detection method, device and system | |
| US5562082A (en) | Engine cycle identification from engine speed | |
| US5394742A (en) | Method for recognizing abnormal combustions in the cylinder of an internal-combustion engine | |
| KR102163796B1 (en) | Misfire diagnosis method and device of Multi cylinder four-stroke engine | |
| US5503009A (en) | Method for recognizing irregular combustions in a cylinder of an internal combustion engine | |
| KR102213233B1 (en) | Misfire diagnosis system and method for single cylinder engine | |
| JP2831493B2 (en) | Engine combustion condition diagnostic device | |
| KR102202723B1 (en) | Misfire diagnosis method and device of Multi cylinder four-stroke engine | |
| JP2559516B2 (en) | Combustion state detection device for internal combustion engine | |
| KR102119873B1 (en) | Misfire diagnosis method and device of single cylinder four-stroke engine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |