JP2010024903A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a misfire detecting device for an internal combustion engine capable of accurately detecting misfire in distinction from irregular combustion. <P>SOLUTION: A first correction rotation speed OMGMA(i)is calculated by a 720 degree filter process, a second correction rotation speed OMGMB(i) is calculated by a 1440 degree filter process, and first and second determination parameters MFPARAMA(k), MFPARAMB(k) are calculated by using the first and second correction rotation speeds OMGMA(i), OMGMB(i). When it is determined that possibility of a misfire is high by the first determination parameter MFPARAMA(k), and the engine 1 is in warm-up idling state right after a cold start, misfire determination is carried out by the second determination parameter MFPARAMB(k). If the engine 1 is not in the warm-up idling state, a determination result by the first determination parameter MFPARAMA(k) is adopted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a misfire detection device for an internal combustion engine, and more particularly to a device for determining the presence or absence of misfire based on a rotation speed parameter indicating an engine rotation speed.

  Patent Document 1 discloses a misfire detection apparatus that performs misfire determination based on a rotation speed parameter. In this device, the deviation between the reference rotational speed parameter detected when the piston of the cylinder to be determined is located near the top dead center and the rotational speed parameter detected every predetermined crank angle (6 degrees) is calculated. The integrated value calculated by integration is used as a determination parameter, and the presence or absence of misfire is determined from the comparison result between the determination parameter and the determination threshold.

JP 2007-198368 A

  In the apparatus disclosed in Patent Document 1, for example, in order to cancel the increase / decrease in the rotational speed parameter at the time of acceleration or deceleration of the engine, a filter process (in accordance with the amount of change in the rotational speed parameter during one engine operation cycle) ( 720 degree filter processing) is performed on the detected rotational speed parameter. According to this 720 degree filter processing, it is sufficiently compared with the TDC period (the period of the timing at which the piston of any cylinder of the engine is positioned at the compression top dead center, for example, the crank angle corresponds to 120 degrees in a six-cylinder engine). Changes in the rotation speed parameter over a long period can be offset.

  However, in an operating state in which a difference in combustion torque is likely to occur between cylinders (for example, an operating state immediately after the engine is cold-started), if the determination parameter is calculated based on the rotation speed parameter after the 720 degree filter processing, it suddenly occurs. There is a problem that it is not possible to distinguish between misfire that occurs and the misfire that occurs (combustion state in which the in-cylinder pressure is not sufficiently high but the generated torque is small) although misfire has not occurred.

  FIG. 8A is a diagram showing a transition of the determination parameter MFPARAM calculated by the conventional method in a state where the irregular combustion and misfire are randomly generated, and the value when the black circle misfires is shown. A white circle indicates a value when irregular combustion occurs. From this figure, it can be confirmed that it is difficult for the conventional technique to distinguish between misfire and irregular combustion.

  In the case of irregular combustion, the increase in the amount of hydrocarbons in the exhaust gas is small, but in the case of misfire, the amount of hydrocarbons increases significantly, so it is important to distinguish between the two.

  The present invention has been made paying attention to this point, and an object thereof is to provide a misfire detection device for an internal combustion engine that can accurately detect misfire as distinguished from irregular combustion.

  In order to achieve the above object, the invention described in claim 1 is provided with a rotational speed parameter detecting means for detecting a rotational speed parameter (OMG) indicating the rotational speed of the internal combustion engine, and is based on the detected rotational speed parameter (OMG). In the misfire detection apparatus for an internal combustion engine that detects misfire of the engine, an average change amount (DELTAOMGTDCA / 4π) of the rotational speed parameter (OMG) in a first predetermined period (period corresponding to a crank angle of 720 degrees) and the engine By calculating the inertia speed change component (OMGI) accompanying rotation of the motor and correcting the rotation speed parameter (OMG) according to the average change amount and the inertia speed change component, the first corrected rotation speed parameter (OMGMA) is obtained. The first predetermined period (crank angle) of the first correction means to be calculated and the rotation speed parameter (OMG) An average change amount (DELTAOMGTDCB / 8π) in a second predetermined period (period corresponding to a crank angle of 1440 degrees) longer than a period corresponding to 20 degrees) and an inertia speed change component (OMGI) accompanying the rotation of the engine; Second correction means for calculating a second corrected rotation speed parameter (OMGMB) by correcting the rotation speed parameter (OMG) according to the average change amount and the inertia speed change component, and a cylinder that is subject to misfire determination The difference (OMGREFA) between the first corrected rotational speed parameter (OMGMMATDC) corresponding to the rotational speed parameter detected when the piston is near the compression top dead center and the first corrected rotational speed parameter (OMGMA) A first relative speed parameter calculating unit that calculates a first relative speed parameter (OMGREFMA) in response to the request. A second corrected rotational speed parameter (OMGMBTDC) corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is in the vicinity of compression top dead center, and the second corrected rotational speed parameter ( Second relative speed parameter calculating means for calculating a second relative speed parameter (OMGREFMB) according to a deviation (OMGREFB) from the OMGMB), and the first relative speed parameter (OMGREFMA) is set to a crank angle 720 / N (N is the A first determination parameter calculation means for calculating a first determination parameter (MFPARAMA) by integrating over a period of the number of cylinders of the engine), and a second relative speed parameter (OMGREFMB) of a crank angle of 720 / N degrees. By integrating over the period, the second determination parameter (MFPARA) B) second determination parameter calculation means for calculating, and when the engine is in a predetermined operating state (FCSTA = 1), misfire determination is performed based on the second determination parameter (MFPARAMB), and the engine is in the predetermined operating state. And determining means for performing misfire determination based on the first determination parameter (MFPARAMA) when in an operating state other than the above.

  According to a second aspect of the present invention, there is provided a rotational speed parameter detecting means for detecting a rotational speed parameter (OMG) indicating the rotational speed of the internal combustion engine. In the misfire detection device for an internal combustion engine to be detected, an average change amount (DELTAOMGTDCA / 4π) in a predetermined period (period corresponding to a crank angle of 720 degrees) of the rotational speed parameter (OMG) and an inertia speed change component accompanying the rotation of the engine (OMGI) and a first correction means for calculating a first corrected rotational speed parameter (OMGMA) by correcting the rotational speed parameter (OMG) according to the average change amount and the inertial speed change component; An inertia speed change component (OMGI) accompanying the rotation of the engine is calculated, and the engine speed is changed according to the inertia speed change component. Detected when the second correction means for calculating the second corrected rotational speed parameter (OMMGC) by correcting the speed parameter (OMG) and the piston of the cylinder subject to misfire determination are near the compression top dead center. A first relative speed parameter (OMGREFMA) is calculated in accordance with a deviation (OMGREFA) between the first corrected rotational speed parameter (OMGMMATDC) corresponding to the rotational speed parameter and the first corrected rotational speed parameter (OMGMA). 1 relative speed parameter calculation means, a second corrected rotational speed parameter (OMGMCTDC) corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is in the vicinity of compression top dead center, 2 Second according to the deviation (OMGREFC) from the corrected rotation speed parameter (OMMGC) The second relative speed parameter calculating means for calculating the relative speed parameter (OMGREFMC) and the first relative speed parameter (OMGREFMA) are integrated over a period of a crank angle of 720 / N (N is the number of cylinders of the engine) degrees. Thus, the first determination parameter calculating means for calculating the first determination parameter (MFPARAMA) and the second relative speed parameter (OMGREMC) are integrated over the period of the crank angle of 720 / N degrees to thereby obtain the second determination parameter ( Second determination parameter calculation means for calculating MFPARAMC), and when the engine is in a predetermined operation state (FCSTA = 1), misfire determination is performed based on the second determination parameter (MFPALAC), and the engine is in the predetermined operation state. The first determination parameter (MFP Characterized in that it comprises a determining means for performing a misfire determination based on the RAMA).

  The invention according to claim 3 is the misfire detection apparatus for an internal combustion engine according to claim 1 or 2, wherein the predetermined operation state is a warm-up operation state immediately after a cold start of the engine. .

  According to the first aspect of the present invention, the first corrected rotation speed is corrected by correcting the rotation speed parameter according to the average change amount and the inertia speed change component of the rotation speed parameter indicating the engine rotation speed in the first predetermined period. The speed parameter is calculated, and the second corrected rotational speed parameter is calculated by correcting the rotational speed parameter according to the average change amount and the inertial speed change component in the second predetermined period longer than the first predetermined period. Is done. A first corrected rotational speed parameter, a second corrected rotational speed parameter corresponding to a rotational speed parameter detected when the piston of the cylinder subject to misfire determination is in the vicinity of compression top dead center, a first corrected rotational speed parameter, and A first relative speed parameter and a second relative speed parameter are calculated in accordance with the deviation from the second corrected rotational speed parameter, and the first relative speed parameter is integrated over a period of a crank angle of 720 / N degrees. One determination parameter is calculated, and the second determination parameter is calculated by integrating the second relative speed parameter over a period of a crank angle of 720 / N degrees. Misfire determination is performed based on the second determination parameter when the engine is in a predetermined operation state, and misfire determination is performed based on the first determination parameter when the engine is in an operation state other than the predetermined operation state. The second corrected rotational speed parameter corrected in accordance with the average change amount in the relatively long second predetermined period is less susceptible to the irregular combustion for the cylinders other than the cylinder in which the irregular combustion has suddenly occurred. By using the second determination parameter, misfire can be accurately determined by distinguishing from irregular combustion in an operation state (predetermined operation state) in which irregular combustion is likely to occur. In an operating state other than the predetermined operating state, the determination is performed using the first determination parameter based on the first corrected rotational speed parameter corrected according to the average change amount in the normal first predetermined period, for example, the engine Accurate misfire determination can be performed even in a transient operation state.

  According to the second aspect of the present invention, the first correction rotational speed parameter is corrected by correcting the rotational speed parameter in accordance with the average change amount and the inertia speed change component of the rotational speed parameter indicating the engine rotational speed in a predetermined period. Is calculated, and the second corrected rotational speed parameter is calculated by correcting the rotational speed parameter according to the inertial speed change component. A first corrected rotational speed parameter, a second corrected rotational speed parameter corresponding to a rotational speed parameter detected when the piston of the cylinder subject to misfire determination is in the vicinity of compression top dead center, a first corrected rotational speed parameter, and A first relative speed parameter and a second relative speed parameter are calculated in accordance with the deviation from the second corrected rotational speed parameter, and the first relative speed parameter is integrated over a period of a crank angle of 720 / N degrees. One determination parameter is calculated, and the second determination parameter is calculated by integrating the second relative speed parameter over a period of a crank angle of 720 / N degrees. Misfire determination is performed based on the second determination parameter when the engine is in a predetermined operation state, and misfire determination is performed based on the first determination parameter when the engine is in an operation state other than the predetermined operation state. The second corrected rotational speed parameter that is not corrected in accordance with the average change amount of the rotational speed parameter is not affected by the irregular combustion for cylinders other than the cylinder that suddenly experienced irregular combustion. By using the two determination parameters, misfiring can be accurately determined by distinguishing from irregular combustion in an operation state (predetermined operation state) in which irregular combustion easily occurs. Further, in an operating state other than the predetermined operating state, the determination is performed using the first determination parameter based on the first corrected rotational speed parameter corrected according to the average change amount in the predetermined period, for example, in the transient operating state of the engine. Can also make an accurate misfire determination.

  According to the third aspect of the present invention, in the warm-up idle operation state immediately after the cold start of the engine, it is possible to accurately determine misfire as distinguished from irregular combustion.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. An internal combustion engine (hereinafter simply referred to as “engine”) 1 has, for example, six cylinders and includes an intake pipe 2 and an exhaust pipe 5. A throttle valve 3 is provided in the intake pipe 2. The exhaust pipe 5 is provided with a catalytic converter 6 for purifying exhaust gas.

  The fuel injection valve 4 is provided for each cylinder between the engine 1 and the throttle valve 3 and slightly upstream of the intake valve (not shown) of the intake pipe 2, and each injection valve is connected to a fuel pump (not shown). At the same time, it is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 20, and the valve opening time of the fuel injection valve 4 is controlled by a control signal from the ECU 20.

An intake pressure sensor 11 for detecting the intake pressure PBA in the intake pipe 2 is provided immediately downstream of the throttle valve 3, and the detection signal is supplied to the ECU 20.
A crank angle position sensor 12 that detects a rotation angle of a crankshaft (not shown) of the engine 1 is connected to the ECU 20, and a signal corresponding to the rotation angle of the crankshaft is supplied to the ECU 20. The crank angle position sensor 12 is a cylinder discrimination sensor that outputs a pulse (hereinafter referred to as “CYL pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1, and relates to a top dead center (TDC) at the start of the intake stroke of each cylinder. A TDC sensor that outputs a TDC pulse at a crank angle position before a predetermined crank angle (every 120 degrees of crank angle in a 6-cylinder engine) and one pulse (hereinafter referred to as “CRK”) with a constant crank angle cycle shorter than the TDC pulse (for example, a cycle of 6 °) The CYL pulse, the TDC pulse, and the CRK pulse are supplied to the ECU 20. These pulses are used for various timing controls such as fuel injection timing and ignition timing, and detection of engine speed (engine speed) NE. Further, the ECU 20 detects misfire in the engine 1 based on the CRK pulse generation time interval (hereinafter referred to as “time parameter”) CRME.

  The CRK sensor includes a pulse wheel that is fixed to the crankshaft and has teeth formed at regular angular intervals on the outer periphery, and a pickup coil that is disposed to face the pulse wheel. An AC signal is generated in the pickup coil by the rotation of the pulse wheel, and the AC signal is converted into a CRK pulse and output.

  The ECU 20 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, a central processing unit (hereinafter referred to as “CPU”). A storage circuit for storing various calculation programs executed by the CPU and calculation results, an output circuit for supplying a control signal to the fuel injection valve 4 and the like. The CPU of the ECU 20 performs misfire detection described below.

  The basic configuration of the misfire determination method in the present embodiment is the same as that described in Patent Document 1 described above, and in this embodiment, determination parameters for performing misfire determination are calculated by two methods. (First and second determination parameters MFPARAMA, MFPARAMB), one of the two determination parameters is appropriately selected according to the operating state of the engine, or misfire determination is performed using both.

  2 and 3 are flowcharts of processing for performing misfire determination based on the time parameter CRME detected by the CRK sensor. This process is executed in synchronization with the TDC pulse by the CPU of the ECU 20. The time parameter CRME (i), which is the generation time interval of the CRK pulse generated every 6 degrees of crank angle, stores the data for the crank angle of 1440 degrees (i = 0 to 240) in the buffer memory in the storage circuit. Has been. Further, if the cylinder identification number in the ignition order is k (= 1 to 6) and the number of data in one TDC period is NTDC (NTDC = 20 in this embodiment), the index parameter i can be obtained by executing this process once. Is calculated from (k-1) NTDC to (kNTDC-1), or from {(k-1) NTDC + 120} to {(kNTDC-1) +120}. For example, when the current process performs an operation corresponding to the first cylinder (k = 1), the index parameter i takes a value from 0 to 19 or a value from 120 to 139, and the current process is the third. When the calculation corresponding to the cylinder (k = 3) is performed, the index parameter i takes a value from 40 to 59 or a value from 160 to 179.

In step S11, the time parameter CRME (i) is converted into the rotational speed OMG (i) [rad / s] by the following equation (1).
OMG (i) = Dθ / CRME (i) (1)
Here, Dθ is an angular interval for measuring the time parameter CRME, and is π / 30 [rad] in the present embodiment.

  In step S12, the rotational speed when the piston of the target cylinder is at the compression top dead center is set as the top dead center rotational speed OMGTDC. Specifically, the top dead center rotational speed OMGTDC is set to OMG {(k−1) NTDC} or OMG {(k−1) NTDC + 120}.

In step S13, a change amount (hereinafter referred to as “first change amount”) DELTAOMGTDCA of the rotational speed OMG (i) in the period of the crank angle of 720 degrees is calculated by the following equation (2). As shown in FIG. 4, the first change amount DELTAOMGTDCA is calculated as a speed change amount in a period of 720 degrees positioned at the center of data corresponding to a crank angle of 1440 degrees.
DELTAOMGTDCA = OMG (180) -OMG (60) (2)

In step S14, a change amount (hereinafter referred to as “second change amount”) DELTAOMGTDCB of the rotational speed OMG (i) in the period of the crank angle of 1440 degrees is calculated by the following equation (3) (see FIG. 4).
DELTAOMGTDCB = OMG (240) −OMG (0) (3)

In step S15, the top dead center rotational speed OMGTDC is applied to the following equation (4) to calculate the inertial force rotational speed OMGI (i). The inertial force rotational speed OMGI (i) is a parameter indicating a speed change component that is inevitably generated by the rotation of the engine 1, and includes the mass of the reciprocating parts (piston and connecting rod) of the engine 1, the length of the connecting rod, It is calculated according to the crank radius and the moment of inertia I of the rotating parts on the load side of the engine 1 such as a crank pulley, torque converter, lockup clutch and the like. In Equation (4), K is a constant set to a predetermined value, and the moment of inertia I is calculated in advance according to the engine specifications. FCR (i) is a combustion correlation function for eliminating the influence of disturbance, and is given by the following equation (5) in this embodiment. A detailed method for calculating the inertial force rotation speed OMGI (i) is disclosed in Patent Document 1.
OMGI (i) = K × OMGTDC × (−2) × FCR (i) / 3I (4)
FCR (i) = {1-cos (N · Dθ · i / 2)} / 2 (5)

In step S16, a 720 degree filter process is executed by the following equation (6), the influence of the inertial force rotation speed OMGI (i) is canceled, and a first corrected rotation speed OMGMA (i) is calculated. The 720 degree filter process is a process for canceling a linear change in a cycle period and extracting a relatively short cycle fluctuation. The 720 degree filter processing is caused by torque applied to the engine 1 from the load side of the engine 1 (torque applied from a tire or an accessory of a vehicle driven by the engine 1 or torque due to friction of sliding parts of the engine 1). This is to remove the rotational fluctuation component. When the index parameter i is 120 or more, the first corrected rotational speed OMGMA (i) is calculated by the following equation (6a).
OMGMA (i) = OMG (i) −DELTAOMGTDCA × Dθ × i / 4π
-OMGI (i) (6)
OMGMA (i) = OMG (i)
-DELTAOMGTDCA × Dθ × (i−120) / 4π
-OMGI (i) (6a)

In step S17, the 1440 degree filter process is executed by the following equation (7), the influence of the inertial force rotational speed OMGI (i) is canceled, and the second corrected rotational speed OMGMB (i) is calculated. The second corrected rotational speed OMGMB (i) is applied to misfire determination in the warm-up idle operation state immediately after the cold start of the engine 1 as will be described later.
OMGMB (i) = OMG (i) −DELTAOMGTDCB × Dθ × i / 8π
-OMGI (i) (7)

In step S18, the first relative rotational speed OMGREFA (i) is calculated by the following equation (8).
OMGREFA (i) = OMGMA (i) -OMGMMATDC (8)

  Here, OMGMATDC is the first reference rotational speed, and corresponds to the first corrected rotational speed when the piston of the cylinder to be determined is at the compression top dead center (the top dead center at which the combustion stroke starts).

In step S19, the second relative rotational speed OMGREFB (i) is calculated by the following equation (9).
OMGREFB (i) = OMMGB (i) −OMMGBTDC (9)
Here, OMGMBDC is the second reference rotational speed, which corresponds to the second corrected rotational speed when the piston of the cylinder to be determined is at the compression top dead center (the top dead center at which the combustion stroke starts).

In step S20, the first relative rotational speed OMGREFMA (i) and the combustion correlation function FCR (i) (formula (5)) calculated in step S18 are applied to the following formula (10), and the first corrected relative rotational speed OMGREFMA ( i) is calculated.
OMGREFMA (i) = OMGREFA (i) x FCR (i) (10)

In step S21, the second relative rotational speed OMGREFMB (i) and the combustion correlation function FCR (i) calculated in step S19 are applied to the following equation (11) to calculate the second corrected relative rotational speed OMGREFMB (i).
OMGREFMB (i) = OMGREFB (i) × FCR (i) (11)

In step S22, the first corrected relative rotational speed OMGREFMA (i) is applied to the following formula (12) or formula (12a) to calculate the first determination parameter MFPARAMA (k). A calculation for integrating the first corrected relative rotational speed OMGREFMA (i) corresponding to the rotational speed OMG (i) detected during the combustion stroke of the misfire determination target cylinder is performed by Expression (12) and Expression (12a). Expression (12a) is used when the index parameter i takes a value of 120 or more.

In step S23, the second corrected relative rotational speed OMGREFMB (i) is applied to the following formula (13) or formula (13a) to calculate the second determination parameter MFPARAMB (k). A calculation for integrating the second corrected relative rotational speed OMGREFMB (i) corresponding to the rotational speed OMG (i) detected during the combustion stroke of the misfire determination target cylinder is performed by Expression (13) and Expression (13a). Expression (13a) is used when the index parameter i takes a value of 120 or more.

  In the subsequent step S31 (FIG. 3), it is determined whether or not the first determination parameter MFPARAMA (k) is larger than a first determination threshold value MFJUDA (for example, “0”). If the answer is affirmative (YES), it is determined that normal combustion has been performed, and a misfire flag FMF (k) is set to “0” (step S35). On the other hand, when the first determination parameter MFPARAMA (k) ≦ MFJUDA, it is determined whether or not the warm-up operation flag FCSTA is “1” (step S32). The warm-up operation flag FCSTA is set to “1” when the engine 1 is in the warm-up idle operation state immediately after the cold start.

  If FCSTA = 0 in step S32 and the engine 1 is not in the warm-up idle operation state, the cylinder corresponding to the cylinder identification number k (in this embodiment, k = 1, 2, 3, 4, 5, and 6). However, it is determined that misfire has occurred in cylinders # 1, # 5, # 3, # 6, # 2, and # 4, respectively, and the misfire flag FMF (k) is set to “1”. (Step S34).

  When FCSTA = 1 in step S32 and the engine 1 is in the warm-up idle operation state, it is determined whether or not the second determination parameter MFPARAMB (k) is larger than the second determination threshold value MFJUDB (step S33). The second determination threshold value MFJUDB is set to a value smaller than the first determination threshold value MFJUDA. If the answer to step S33 is affirmative (YES), it is determined that normal combustion or irregular combustion has been performed, and the process proceeds to step S35. On the other hand, when MFPARAMB (k) ≦ MFJUDB, it is determined when a misfire has occurred in the cylinder corresponding to the cylinder identification number k, and the process proceeds to step S34.

  In step S36, it is determined whether the cylinder identification number k is equal to the number N of cylinders. If the answer is negative (NO), the cylinder identification number k is incremented by "1" (step S38). If k = N, the cylinder identification number k is returned to “1” (step S37).

  As described above, according to the processing of FIGS. 3 and 4, when the first corrected rotational speed OMGMA (i) is calculated by the conventional 720 degree filter process, the second corrected rotational speed is obtained by the 1440 degree filter process. OMGMB (i) is calculated, the first relative rotational speed OMGREFA (i) is calculated as the difference between the first corrected rotational speed OMGMA (i) and the first reference rotational speed OMGMATDC, and the second corrected rotational speed OMGMB ( The second relative rotational speed OMGREFB (i) is calculated as the difference between i) and the second quasi-rotational speed OMGMBDC. Further, the first and second modified relative rotational speeds OMGREFMA (i) and OMGREFMB (i) are calculated by multiplying the first and second relative rotational speeds OMGREFA (i) and OMGREFB (i) by the combustion correlation function FCR. The first and second corrected relative rotational speeds OMGREFMA (i) and OMGREFMB (i) are integrated over the entire combustion stroke period, whereby the first and second determination parameters MFPARAMA (k) and MFPARAMB (k) are calculated. The

  When the first determination parameter MFPARAMA (k) determines that the possibility of misfire is high and the engine 1 is in the warm-up idle operation state immediately after the cold start, the second determination parameter MFPARAMB (k) causes misfire. A determination is made. The average change amount (DELTAOOMGTDCB / 8π) calculated using the second change amount DELTAOMTGTDCB in the period of the crank angle 1440 degrees that is longer than the period of the crank angle 720 degrees is less susceptible to sudden irregular combustion. (2) The corrected rotational speed OMGMB (i) is less susceptible to the irregular combustion for cylinders other than the cylinder that suddenly experienced irregular combustion. Therefore, by using the second determination parameter MFPARAMB, misfire can be accurately determined by distinguishing it from irregular combustion in a warm-up idle operation state in which irregular combustion is likely to occur. Further, in an operation state other than the warm-up idle operation state, the first corrected rotation corrected according to the average change amount (DELTAOMGTDCCA / 4π) calculated using the first change amount DELTAOMGTDCCA in the period of the normal crank angle of 720 degrees. By performing the determination using the first determination parameter MFPARAMA based on the speed OMGMA (i), for example, an accurate misfire determination can be performed even in a transient operation state of the engine 1.

  In this embodiment, the second predetermined period (Claim 1) is a period corresponding to the crank angle of 1440 degrees, and the average change amount (DELTAOMGTDCCB /) obtained by averaging the change amount of the rotational speed in the period of 1440 degrees. 8π) is used to calculate the second corrected rotational speed OMGB (i), but the second predetermined period may be longer than 1440 degrees. However, it is desirable that the period be an integer multiple of 720 degrees.

  FIG. 5A shows the transition of the second determination parameter MFPARAMB calculated by performing the 1440 degree filter process in the same operating state as in FIG. 8A, and the black circle shows the value when misfire occurs. A white circle indicates a value when irregular combustion occurs. Although there are still some cases where the value when misfire occurs exceeds the value when irregular combustion occurs, it can be confirmed that the value is considerably improved over the determination parameter MFPARAM shown in FIG.

  FIG. 5B shows the transition of the second determination parameter MFPARAMB ′ when the second predetermined period is further increased to 2880 degrees. As is apparent from this figure, it is possible to more accurately determine misfire and irregular combustion by increasing the second predetermined period.

  In the present embodiment, the crank angle position sensor 12 and the ECU 20 constitute rotational speed parameter detection means, and the ECU 20 includes first correction means, second correction means, first relative speed parameter calculation means, second relative speed parameter, 1 determination parameter calculation means, 2nd determination parameter calculation means, and determination means are comprised. Specifically, steps S13 and S16 in FIG. 2 correspond to the first correction unit, steps S14 and S17 correspond to the second correction unit, step S18 corresponds to the first relative speed parameter calculation unit, and step S19. Corresponds to the second relative speed parameter calculation means, steps S22 and S23 correspond to the first determination parameter calculation means and the second determination parameter calculation means, respectively, and steps S31 to S35 in FIG. 3 correspond to the determination means.

[Second Embodiment]
In the present embodiment, focusing on the fact that the engine speed NE does not change significantly in the warm-up idle operation state of the engine 1, the detected rotational speed OMG (i) is used instead of the second corrected rotational speed OMGMB (i). The third corrected rotational speed OMGMC (i) in which only correction for canceling the influence of the inertial force rotational speed OMGI is performed is used. Except for the points described below, the second embodiment is the same as the first embodiment.

  6 and 7 are flowcharts of misfire determination processing in the present embodiment. In this process, step S14 in FIG. 2 is deleted, and steps S17, S19, S23 and step S33 in FIG. 3 are changed to steps S17a, S19a, S23a and step S33a, respectively.

  In the present embodiment, data (i = 0 to 120) for the crank angle 720 degrees of the time parameter CRME (i) is stored in the buffer memory. Therefore, in the processes of FIGS. 6 and 7, the index parameter i takes a value from “0” to “120”, and the index parameter i is changed from (k−1) NTDC ( Operations up to kNTDC-1) are performed.

In step S17a, the influence of the inertial force rotational speed OMGI (i) is canceled by the following equation (7a), and the third corrected rotational speed OMGMC (i) is calculated. The third corrected rotational speed OMGMC (i) is applied to the misfire determination in the warm-up idle operation state immediately after the cold start of the engine 1.
OMGMC (i) = OMG (i) -OMGI (i) (7a)

In step S19a, the third relative rotational speed OMGREFC (i) is calculated by the following equation (9a).
OMGREFC (i) = OMMGC (i) -OMGMCTDC (9a)
Here, OMGMCTDC is the third reference rotational speed, and corresponds to the third corrected rotational speed when the piston of the cylinder to be determined is at the compression top dead center (the top dead center at which the combustion stroke starts).

In step S21a, the third relative rotation speed OMGREFMC (i) and the combustion correlation function FCR (i) calculated in step S19a are applied to the following equation (11a) to calculate the third corrected relative rotation speed OMGREFMC (i).
OMGREFMC (i) = OMGREFC (i) x FCR (i) (11a)

In step S23a, the third corrected relative rotational speed OMGREFMC (i) is applied to the following equation (13b) to calculate a third determination parameter MFPARAMC (k). According to the equation (13b), a calculation for integrating the third corrected relative rotational speed OMGREFMC (i) corresponding to the rotational speed OMG (i) detected during the combustion stroke of the misfire determination target cylinder is performed.

  In step S33a, it is determined whether or not the third determination parameter MFPARAMC (k) is greater than a third determination threshold value MFJUDC. If the answer is affirmative (YES), it is determined that normal combustion or irregular combustion has been performed, Proceed to step S35. On the other hand, if MFPARAMC (k) ≦ MFJUDC, it is determined when a misfire has occurred in the cylinder corresponding to the cylinder identification number k, and the process proceeds to step S34. The third determination threshold value MFJUDC is set to a value smaller than the first determination threshold value MFJUDA.

  In the present embodiment, the third determination parameter MFPARAMC (k) is calculated using the third corrected rotational speed OMGMC (i) that has not been subjected to the 720 degree filter process, and the misfire determination is performed using the third determination parameter MFPARAMC (k). Done. The third corrected rotational speed OMGMC (i) is not affected by the irregular combustion for the cylinders other than the cylinder in which the irregular combustion suddenly occurs. Therefore, the third correction rotational speed OMGMC (i) is irregular by using the third determination parameter MFPARAMC (k). In a warm-up idle operation state in which combustion is likely to occur, misfire can be accurately determined as distinguished from irregular combustion. Further, in the operation state other than the warm-up idle operation state, the determination is performed by the first determination parameter MFPARAMA (k) calculated using the first corrected rotational speed OMGMA (i) subjected to the normal 720 degree filter processing. For example, an accurate misfire determination can be performed even in a transient operation state of the engine 1.

  FIG. 8B is a diagram showing the transition of the third determination parameter MFPARAMC in a state where irregular combustion and misfire occur at random as in the determination result shown in FIG. By setting to, it can be confirmed that it is possible to distinguish between irregular combustion (white circle) and misfire (black circle).

  In this embodiment, steps S13 and S16 in FIG. 6 correspond to the first correction means, step S17a corresponds to the second correction means, and steps S18 and S19a correspond to the first relative speed parameter calculation means and the second relative speed, respectively. Steps S22 and S23a correspond to the first determination parameter calculation unit and the second determination parameter calculation unit, respectively, and steps S31, S32, S33a, S34, and S35 in FIG. 3 correspond to the determination unit. .

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the misfire determination is performed by converting the time parameter CRME to the rotational speed OMG. However, as shown in Patent Document 1, the misfire determination is performed using the time parameter CRME itself as the rotational speed parameter. You may make it perform.

  In the above-described embodiment, the determination using the second determination parameter MFPARAMB or the third determination parameter MFPARAMC is performed in the warm-up idle operation state immediately after the cold start of the engine 1, but the engine 1 is in the idle operation state. The determination using the second determination parameter MFPARAMB or the third determination parameter MFPARAMC may be performed in the operation state in which the lean burn operation is performed in which the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio.

  Further, the processing shown in FIG. 3 may be modified as shown in FIG. In FIG. 9, first, it is determined whether or not the warm-up operation flag FCSTA is “1”. If FCSTA = 0, determination is made by the first determination parameter MFPARAMA (k) (step S31). When = 1, determination by the second determination parameter MFPARAMB (k) is performed (step S33). Note that the processing of FIG. 7 of the second embodiment can be similarly modified.

  In the embodiment described above, the determination parameters MFPARAMA, MFPARAMB, and MFPARAMC are calculated by integrating the corrected relative rotational speeds OMGREFMA, OMGREFMB, and OMGREFMC obtained by correcting the relative rotational speeds OMGREFA, OMGREFB, and OMGREFC with the combustion correlation function FCR. The determination parameters MFPARAMA, MFPARAMB, and MFPARAMC may be calculated by integrating the relative rotational speeds OMGREFA, OMGREFB, and OMGREFC that are not corrected by the function FCR. In that case, the FCR (i) in the equation (4) for calculating the inertial force rotation speed OMGI (i) is set to a constant value (for example, “1”).

  In the above-described embodiment, the reference rotational speeds used as the reference for calculating the relative rotational speeds OMGREFA, OMGREFB, and OMGREFC are corrected rotational speeds OMGMATDC, OMGMATDC, and OMGMCDC corresponding to the rotational speed at the compression top dead center of each cylinder. However, the sampling timing need not exactly match the compression top dead center, and may be in the vicinity of the compression top dead center (for example, within a range of ± 7.5 degrees). Here, 7.5 degrees corresponds to the case where the sampling period of the rotation speed parameter is 15 degrees. Generally, if the sampling period is θSPL, the rotation sampled within a range of ± θSPL / 2. Speed parameters can be used.

  In the above-described embodiment, an example in which the present invention is applied to a six-cylinder engine is shown, but the present invention can be applied regardless of the number of cylinders. The present invention can also be applied to misfire determination of a gasoline engine or a diesel engine that directly injects fuel into a combustion chamber. Furthermore, the present invention can be applied to misfire determination of a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a flowchart of the process (1st Embodiment) which performs misfire determination. It is a flowchart of the process (1st Embodiment) which performs misfire determination. It is a time chart for demonstrating the process of FIG.2 and FIG.3. It is a time chart for demonstrating the improvement effect in 1st Embodiment. It is a flowchart of the process (2nd Embodiment) which performs misfire determination. It is a flowchart of the process (2nd Embodiment) which performs misfire determination. It is a time chart for demonstrating the problem of the conventional method and the improvement effect of 2nd Embodiment. It is a flowchart of the modification of the process shown in FIG.

Explanation of symbols

1 Internal combustion engine 12 Crank angle position sensor (rotational speed parameter detection means)
20 electronic control unit (rotation speed parameter detection means, first correction means, second correction means, first relative speed parameter calculation means, second relative speed parameter, first determination parameter calculation means, second determination parameter calculation means, determination means)

Claims (3)

In a misfire detection apparatus for an internal combustion engine, comprising a rotation speed parameter detection means for detecting a rotation speed parameter indicating a rotation speed of the internal combustion engine, and detecting misfire of the engine based on the detected rotation speed parameter.
By calculating an average change amount of the rotation speed parameter in a first predetermined period and an inertia speed change component accompanying the rotation of the engine, and correcting the rotation speed parameter according to the average change amount and the inertia speed change component, First correction means for calculating a first correction rotation speed parameter;
An average change amount of the rotation speed parameter in a second predetermined period longer than the first predetermined period and an inertia speed change component accompanying the rotation of the engine are calculated, and the rotation according to the average change amount and the inertia speed change component Second correction means for calculating a second corrected rotation speed parameter by correcting the speed parameter;
According to the deviation between the first corrected rotational speed parameter corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is near the compression top dead center and the first corrected rotational speed parameter. First relative speed parameter calculating means for calculating a first relative speed parameter;
According to the deviation between the second corrected rotational speed parameter corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is near the compression top dead center and the second corrected rotational speed parameter. Second relative speed parameter calculating means for calculating a second relative speed parameter;
First determination parameter calculating means for calculating the first determination parameter by integrating the first relative speed parameter over a period of a crank angle of 720 / N (N is the number of cylinders of the engine);
A second determination parameter calculating means for calculating a second determination parameter by integrating the second relative speed parameter over a period of a crank angle of 720 / N degrees; and the second determination when the engine is in a predetermined operating state. A misfire detection of an internal combustion engine, comprising: determination means for performing misfire determination based on a parameter and performing misfire determination based on the first determination parameter when the engine is in an operation state other than the predetermined operation state apparatus. In a misfire detection apparatus for an internal combustion engine, comprising a rotation speed parameter detection means for detecting a rotation speed parameter indicating a rotation speed of the internal combustion engine, and detecting misfire of the engine based on the detected rotation speed parameter.
By calculating an average change amount of the rotation speed parameter in a predetermined period and an inertia speed change component accompanying the rotation of the engine, and correcting the rotation speed parameter according to the average change amount and the inertia speed change component, the first First correction means for calculating a corrected rotation speed parameter;
Second correction means for calculating a second corrected rotation speed parameter by calculating an inertia speed change component accompanying rotation of the engine and correcting the rotation speed parameter according to the inertia speed change component;
According to the deviation between the first corrected rotational speed parameter corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is near the compression top dead center and the first corrected rotational speed parameter. First relative speed parameter calculating means for calculating a first relative speed parameter;
According to the deviation between the second corrected rotational speed parameter corresponding to the rotational speed parameter detected when the piston of the cylinder subject to misfire determination is near the compression top dead center and the second corrected rotational speed parameter. Second relative speed parameter calculating means for calculating a second relative speed parameter;
First determination parameter calculating means for calculating the first determination parameter by integrating the first relative speed parameter over a period of a crank angle of 720 / N (N is the number of cylinders of the engine);
Second determination parameter calculation means for calculating a second determination parameter by integrating the second relative speed parameter over a period of a crank angle of 720 / N degrees;
Determination means for performing misfire determination based on the second determination parameter when the engine is in a predetermined operation state, and performing misfire determination based on the first determination parameter when the engine is in an operation state other than the predetermined operation state And a misfire detection device for an internal combustion engine.   The internal combustion engine misfire detection apparatus according to claim 1 or 2, wherein the predetermined operation state is a warm-up idle operation state immediately after a cold start of the engine.

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