JP2018127969A - Misfire detection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that the determination accuracy of a misfire is affected by the detection accuracy of a rotational speed at a gear change device 34 side.SOLUTION: A CPU 62 calculates an instantaneous rotational speed of a crankshaft 12 on the basis of a crank signal Scr outputted by a crank angle sensor 70, and calculates an instantaneous rotational speed of an NT rotor 40 on the basis of an NT signal St outputted by an NT sensor. Then, the CPU 62 removes a resonance component from the instantaneous rotational speed of the crankshaft 12 on the basis of a difference between the instantaneous rotational speeds. The CPU 62 learns an angle variation of a tooth part 42 of the NT rotor 40 during a fuel cut. The CPU 62 detects a misfire on the basis of a comparison of a determination value which is corrected according to a result of the variation, and a rotation variation value based on the instantaneous rotational speed which is removed in the resonance component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine misfire detection apparatus applied to an internal combustion engine having a plurality of cylinders and having a transmission connected to a crankshaft.

  For example, in Patent Document 1, a power distribution and integration mechanism (transmission device) capable of changing the ratio between the rotational speed of the crankshaft and the rotational speed of the drive wheel is connected to the crankshaft of the internal combustion engine via a damper. Is described. In this document, based on the difference between the rotational speed on the transmission side and the rotational speed of the crankshaft, the resonance component caused by the torsion of the damper in the rotational speed of the crankshaft is calculated, and the rotational speed of the crankshaft is calculated. Describes an apparatus for executing the process of removing the resonance component from the apparatus. This device calculates a rotational fluctuation value that quantifies the difference between the instantaneous rotational speeds resulting from the combustion of each cylinder from the rotational speed from which the resonance component has been removed, and determines the presence or absence of misfire based on the rotational fluctuation value. ing. This is in view of the fact that misfire cannot be accurately identified by using a rotational speed including a resonance component.

JP 2008-248877 A

  The apparatus uses the rotational speed on the transmission side in order to remove the influence of the resonance component from the rotational fluctuation value. In this case, since the detection accuracy of the rotational speed on the transmission side greatly affects the calculation accuracy of the rotation fluctuation value, the detection accuracy of misfire is greatly influenced by the detection accuracy of the rotational speed on the transmission side.

  In order to solve the above-described problem, a misfire detection device for an internal combustion engine is applied to an internal combustion engine having a plurality of cylinders and having a transmission connected to a crankshaft, and connecting the rotation shaft of the transmission and the crankshaft. In a state, based on the angle detection signal and the crank angle signal of the rotating shaft, a torsion component that calculates a value obtained by removing a rotating speed component due to the twisting of the crank shaft and the rotating shaft from the instantaneous rotating speed of the crank shaft A rotational fluctuation calculation process for calculating a rotational fluctuation value that is time-series data indicating the magnitudes of rotational speeds according to the combustion stroke in each cylinder based on the output value of the removal process and the torsional component removal process; and the rotational fluctuation The misfire detection process for detecting misfire of the internal combustion engine based on the magnitude comparison between the value and the determination value, and the angle detection signal once during the fuel cut process of the internal combustion engine. Learning process for learning the detection error of the rotation axis angle based on the rotation frequency component corresponding to the above, and the determination value is smaller when the detection error learned by the learning process is large Also, the difference between the rotational speeds that do not cause the misfire is increased.

  When the detection error is large, the rotational fluctuation value tends to indicate a value where the difference between the rotational speeds is larger than when the rotational error is small. Therefore, in the above configuration, when determining the presence or absence of misfire by comparing the magnitude of the rotation fluctuation value and the determination value, the determination value is larger as the difference between the rotation speeds than when the detection error is large and smaller. Let the value be an acceptable value. For this reason, it is possible to suppress the influence of the rotational speed detection accuracy on the transmission side on the misfire detection accuracy.

The figure which shows one Embodiment and the drive system of a misfire detection apparatus. The block diagram which shows the misfire detection process concerning the embodiment. The figure which shows the change of the rotation waveform by the resonance concerning the embodiment. The block diagram which shows the process of the twist component exclusion process part concerning the embodiment. The time chart which shows the dispersion | variation in NT signal concerning the embodiment. The time chart which shows the process of the learning process part concerning the embodiment. The time chart which shows the process of the misfire detection process part concerning the embodiment. The figure which shows the effect of the same embodiment.

Hereinafter, an embodiment of a misfire detection device will be described with reference to the drawings.
As shown in FIG. 1, the internal combustion engine 10 is a four-stroke engine having six cylinders. In the following, cylinders # 1, # 2, # 3, # 4, # 5, and # 6 are defined according to the appearance order of compression top dead center. That is, the cylinder in which the compression top dead center appears next to the first cylinder # 1 is the second cylinder # 2.

  An input shaft 36 of a transmission 34 can be connected to the crankshaft 12 of the internal combustion engine 10 via a torque converter 30. The torque converter 30 includes a lockup clutch 32, and the crankshaft 12 and the input shaft 36 are connected when the lockup clutch 32 is in an engaged state. Drive wheels 50 are mechanically connected to the output shaft 38 of the transmission 34.

  Coupled to the crankshaft 12 is a crank rotor 20 provided with tooth portions 22 each indicating a plurality of rotation angles of the crankshaft 12. The crank rotor 20 is basically provided with tooth portions 22 at intervals of 10 ° CA, but has one missing tooth portion 24 where the interval between adjacent tooth portions 22 is 30 ° CA. Is provided. This is to indicate the rotation angle that serves as a reference for the crankshaft 12.

  Coupled to the input shaft 36 is an NT rotor 40 provided with a tooth portion 42 indicating each of a plurality of rotation angles of the input shaft 36. The NT rotor 40 is provided with tooth portions 42 at intervals of 12 °.

  The control device 60 operates various actuators such as a fuel injection valve in order to control the control amount (torque, exhaust component) of the internal combustion engine 10. The control device 60 controls the crank signal Scr of the crank angle sensor 70 that detects the rotation angle of the crankshaft 12 by detecting the tooth portion 22 of the crank rotor 20 when executing control amount control and various diagnostic processes, and the input shaft. Reference is made to the NT signal St of the input shaft angle sensor 72 for detecting the rotation angle 36 and the intake air amount Ga detected by the air flow meter 74. The control device 60 includes a CPU 62, a ROM 64, and an electrically rewritable nonvolatile memory 66, and the CPU 62 executes a program stored in the ROM 64, thereby executing control of the control amount and diagnosis.

  FIG. 2 shows a misfire detection process in particular among the diagnosis processes executed by the control device 60. The processing shown in FIG. 2 is realized by the CPU 62 executing a program stored in the ROM 64.

  Based on the crank signal Scr, the EG speed calculation processing unit M10 averages the instantaneous rotational speed ωNE, which is the rotational speed of the crankshaft 12 in the rotational angle region of 30 ° CA, and the rotational period in the angular region larger than 30 ° CA. A simple rotational speed NE is calculated. Based on the NT signal St, the NT speed calculation processing unit M12 calculates an instantaneous rotational speed ωNT that is a rotational speed in the rotation angle region of 24 ° of the input shaft 36.

  The torsion component removal processing unit M14 executes processing for removing the drive system resonance component caused by the torsion between the crankshaft 12 and the input shaft 36 from the instantaneous rotational speed ωNE. This will be described below.

  As shown in FIG. 3, the internal combustion engine 10 and the transmission 34 can be modeled as being connected via a damper. Here, in the internal combustion engine 10, when misfire continuously occurs in a specific cylinder, the rotational fluctuation of the crankshaft 12 caused by the misfire becomes a vibration source, and resonance occurs in the drive system including the internal combustion engine 10 and the transmission 34. Sometimes. In that case, the rotational fluctuation of the crankshaft 12 is a composite waveform of the rotational fluctuation waveform caused by misfire and the waveform in which the rotational fluctuation returns from the transmission 34. For this reason, there is a problem that misfire detection cannot be performed or a misfire cylinder cannot be specified depending on the composite waveform. The torsion component removal processing unit M14 executes a process for restoring the rotational fluctuation waveform caused by misfire by removing the resonance component from the combined waveform.

FIG. 4 shows processing of the twist component removal processing unit M14.
The deviation calculation processing unit M14a calculates the damper speed ωdmp by subtracting the instantaneous rotational speed ωNT of the input shaft 36 from the instantaneous rotational speed ωNE of the crankshaft 12. The integration element M14b calculates the torsion angle θdmp by integrating the damper speed ωdmp. The torsional acceleration calculation processing unit M14c calculates an acceleration component due to the torsion between the crankshaft 12 and the input shaft 36 by multiplying the torsion angle θdmp by a constant “K / I”. That is, when the torque constant K is used, the torque applied to the crankshaft 12 due to torsion between the crankshaft 12 and the input shaft 36 is “K · θdmp”. Here, when the inertia moment I is used, the acceleration caused by the twist becomes “K · θdmp / I”. The integration element M14d calculates the speed ωtw resulting from torsion by integrating the acceleration. The removal processing unit M14e calculates the rotational speed ωex obtained by subtracting the speed ωtw from the instantaneous rotational speed ωNE to remove the speed component due to the twist from the instantaneous rotational speed ωNE.

  Returning to FIG. 2, the filter processing unit M16 is an FIR filter that receives the rotational speed ωex. By filtering the rotational speed ωex, the rotational speeds corresponding to the combustion strokes in the cylinders # 1 to # 6 are determined. The rotational fluctuation value ΔNE, which is time-series data indicating the magnitude of, is calculated. In the present embodiment, the rotation fluctuation value ΔNE indicates that a rotation fluctuation due to misfire occurs when the rotation fluctuation value ΔNE is negative and has a large absolute value. The rotation fluctuation value ΔNE has a speed dimension.

  The determination value setting processing unit M18 sets a determination value to be compared with the rotation fluctuation value. The determination value is a negative value, and when the load KL is the same, the absolute value is smaller when the rotational speed NE is high than when the rotation speed NE is low. This is because the rotational fluctuation of the crankshaft 12 at the time of misfire becomes smaller when the rotational speed NE is high than when the rotational speed NE is low. Further, when the rotational speed NE is the same, the absolute value becomes larger when the load KL is high than when the load KL is low. This is in consideration of the tendency that the rotational fluctuation of the crankshaft 12 at the time of misfire tends to increase as the load KL increases. The load KL is calculated based on the intake air amount Ga and the rotational speed NE, and has a positive correlation with the in-cylinder charged air amount.

  The misfire detection processing unit M20 determines the presence or absence of misfire based on the comparison between the rotation fluctuation value and the determination value. When misfire occurs, the warning lamp 80 shown in FIG. The contents of the abnormality are stored in the memory 66.

  The cycle measurement processing unit M22 measures the length of time (rotation cycle) required for the rotation of the section having the length between the compression top dead centers based on the crank signal Scr, and updates the output of the filter processing unit M16. Provide as periodic information. The period measurement processing unit M22 measures a time T30 required for rotation of 30 ° CA each time based on the crank signal Scr.

  The learning processing unit M24 learns that the time required for the rotation of the angle between the teeth 42 of the NT rotor 40 varies due to an error (variation) from the angle at which the teeth 42 are formed. . Specifically, it is learned that the time required for rotation between the tooth portions 42 every 24 ° varies due to an error (variation) from the angle at which the tooth portions 42 are formed.

  FIG. 5 shows time-series data of the time required for rotation of the region from one to the other of the pair of tooth portions 42 that divides 24 ° when it is assumed that the crankshaft 12 is rotating at a constant speed. In particular, a solid line indicates a case where there is no variation in the region, and a broken line and a one-dot chain line indicate a case where there is a variation.

  FIG. 6 shows processing executed by the learning processing unit M24. The learning processing unit M24 learns the variation during the fuel cut. That is, when the F / C flag indicating that the fuel cut is in progress is on, the rotational frequency component (cycle secondary frequency component) of one rotation of the NT signal is calculated based on the output value of the cycle measurement processing unit M22 (FIG. 2). Middle, described as “filtered waveform of sensor 72 output”). Then, the amplitude of one rotation frequency component is learned as variation. In FIG. 6, the transition of the T / M counter is virtually described by a two-dot chain line. The T / M counter is a counter that measures two rotations of the input shaft 36. However, in the present embodiment, the two rotations of the input shaft 36 are not actually measured. It is considered equal to 2 rotations. The crank counter is a counter calculated based on the output value of the period measurement processing unit M22. Incidentally, since the lockup clutch 32 is released during the fuel cut, there is a difference between the rotational speed of the crankshaft 12 and the rotational speed of the input shaft 36, but this is ignored in this embodiment. Note that the learning processing unit M24 learns the variation for each rotation speed NE and stores the variation in the nonvolatile memory 66.

  Returning to FIG. 2, the determination value correction processing unit M26 corrects the determination value set by the determination value setting processing unit M18 based on the variation learning value. Here, the determination value is corrected by the corresponding learning value based on the rotational speed NE.

Here, the operation of the present embodiment will be described.
The CPU 62 learns the variation of the tooth portion 42 for each rotation speed NE based on the NT signal during the fuel cut process. On the other hand, when the lock-up clutch 32 is in the engaged state, the CPU 62 calculates the rotational fluctuation value ΔNE based on the rotational speed ωex from which the speed component due to the twist between the crankshaft 12 and the input shaft 36 is removed. The CPU 62 sets a determination value based on the rotational speed NE and the load KL, and then corrects the determination value based on the learning value of the variation of the tooth portion 42.

In FIG. 7, the determination value before correction by the learning value is indicated by a broken line, and the correction value after correction is indicated by a one-dot chain line. The solid line shows the transition of the rotational fluctuation value ΔNE at the time of misfire.
The CPU 62 sets the correction amount to a large positive value so that the absolute value of the determination value is smaller when the variation of the cycle secondary frequency component of the NT signal St is small than when it is large. FIG. 8 shows the judgment value after learning, in particular, the value when the variation of the cycle secondary frequency component is small (C. judgment value) shown by the broken line in FIG. 5, and the one-dot chain line in FIG. In addition, a value (B. determination value) when the variation of the cycle secondary frequency component is large is illustrated. As shown in FIG. 8, by correcting the determination value according to the variation, the normal value and the abnormal value can be appropriately separated for the rotation fluctuation value ΔNE. Thereby, it is possible to detect misfire with high accuracy by eliminating the influence of the error of the NT signal.

According to the embodiment described above, the following effects can be obtained.
(1) By appropriately learning the variation in the rotational speed of the NT rotor 40 according to the variation in the tooth portion 42 for each rotational speed NE, appropriately consider the influence of the rotational speed of the NT rotor 40 on the variation in the tooth portion 42. can do.

  (2) In the learning processing unit M24, the NT signal St is filtered based on the cycle of two rotations of the crankshaft 12. Thereby, based on the NT signal St in which the reference angle cannot be specified, the filter can be configured without constructing a logic for measuring the number of detections of the tooth portion 42 and measuring the rotational speed of the input shaft 36.

<Correspondence>
The correspondence relationship between the items in the above embodiment and the items described in the column “Means for Solving the Problems” is as follows. The rotation axis corresponds to the input shaft 36 of the transmission, the angle detection signal corresponds to the NT signal St, the torsion component removal processing corresponds to the processing of the torsion component removal processing unit M14, and the rotation fluctuation calculation processing Corresponding to the processing of the filter processing unit M16, the misfire detection processing corresponds to the processing of the misfire detection processing unit M20, and the learning processing corresponds to the processing of the learning processing unit M24.

<Other embodiments>
In addition, you may change at least 1 of each matter of the said embodiment as follows.
The rotational fluctuation value ΔNE is not limited to the output data of the FIR filter process that receives the rotational speed ωex. For example, in the case where the internal combustion engine 10 has 6 cylinders, it may be data on the difference between adjacent persons whose compression top dead centers are adjacent in the time T120 required for rotation in the rotation angle region of 30 ATDC to 120 ATDC of each cylinder. In this case, the rotation variation value has a time dimension.

  The calculation method of the rotation frequency component corresponding to one rotation of the input shaft 36 of the NT signal St is not limited to the filter processing corresponding to the two rotations of the crankshaft 12. For example, the time period corresponding to one rotation of the input shaft 36 may be measured by measuring the number of detections of the tooth portion 42 based on the NT signal St, and the filter may be selected based on this.

The angle detection signal of the rotation shaft of the transmission is not limited to the NT signal St, but may be an angle detection signal of the output shaft of the torque converter 30, for example.
The internal combustion engine is not limited to a 6-cylinder engine, and may be a 4-cylinder or 8-cylinder engine, for example.

  The control device is not limited to the one that includes the CPU 62 and the ROM 64 and executes software processing. For example, a dedicated hardware circuit (for example, an ASIC) that performs hardware processing on at least a part of the software processed in the above embodiment may be provided.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Crankshaft, 20 ... Crank rotor, 22 ... Tooth part, 24 ... Missing tooth part, 30 ... Torque converter, 32 ... Lock-up clutch, 34 ... Transmission, 36 ... Input shaft, 38 ... Output Axis, 40 ... NT rotor, 42 ... tooth portion, 50 ... drive wheel, 60 ... control device, 62 ... CPU, 64 ... ROM, 66 ... nonvolatile memory, 70 ... crank angle sensor, 72 ... input shaft angle sensor, 74 ... air flow meter, 80 ... warning light.

Claims (1)

Applied to an internal combustion engine having a plurality of cylinders and a transmission connected to a crankshaft;
Due to the twist between the crankshaft and the rotating shaft from the instantaneous rotational speed of the crankshaft based on the angle detection signal and the crank angle signal of the rotating shaft in the connected state of the rotating shaft and the crankshaft of the transmission Torsional component removal processing for calculating the removed rotational speed component,
A rotation fluctuation calculation process for calculating a rotation fluctuation value which is time-series data indicating the magnitude of the rotation speeds according to the combustion stroke in each cylinder based on the output value of the twist component removal process;
Misfire detection processing for detecting misfire of the internal combustion engine based on a magnitude comparison between the rotational fluctuation value and a determination value;
Performing a learning process of learning an angle detection error of the rotating shaft based on a rotation frequency component corresponding to one rotation of the angle detection signal during the fuel cut process of the internal combustion engine;
A misfire detection apparatus for an internal combustion engine that makes the difference between the rotational speeds that do not cause misfire larger than when the detection value learned by the learning process is large when the determination value is small.

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