JPH0560004A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent misjudgment of misfire in intentional fluctuation of engine torque. CONSTITUTION:Based on a detection result of a revolution number sensor 25 for detecting the revolution number of an engine 1, revolution fluctuation per explosion stroke of each cylinder of the engine 1 is obtained by an engine ECU 30, and when the obtained result is more than a predetermined value, it is considered as misfire at the explosion stroke of the each cylinder, and processing such as lighting of a misfire indicator lamp 12 is carried out in this gasoline engine system. This gasoline engine system is provided with ECTECU 41, TRCECU 42 and an auto drive ECU 44 for commanding intentional revolution fluctuation to the engine according to the driving state of the engine 1. When the command by those ECU 41 to 43 is carried out, misfire judgment by the engine ECU 30 is invalidated so as not to make judgment. By this, when intentional torque fluctuation is generated at the engine 1, judgment of misfire based on revolution fluctuation is not made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection device for detecting a misfire occurring in each cylinder in an internal combustion engine mounted on a vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, when a misfire occurs in a multi-cylinder internal combustion engine, not only the engine torque fluctuates, but unburned fuel is discharged from the misfired cylinder as it is or leaks around the internal combustion engine. It may happen. Therefore, various techniques have been proposed for detecting the occurrence of misfire and notifying the driver, etc. in order to promptly deal with the misfire abnormality of the internal combustion engine.

For example, in Japanese Unexamined Patent Publication No. 61-258955, the rotational fluctuation of the internal combustion engine is detected in synchronization with the explosion stroke of each cylinder, and if the change in the rotational fluctuation is large, it is determined that a misfire has occurred. Was notified to the driver.

[0004]

However, during the control of the internal combustion engine, there are various controls that intentionally reduce the engine torque. For example, an ECT shift torque control delay for reducing a shift shock of a transmission, a traction control delay for smooth start on a snowy road, and an auto for smooth constant speed running. There are retard correction during drive control, fuel cut control in deceleration state, reduction correction when returning to fuel cut, deceleration increase correction, cylinder cutout operation, etc., and these controls include control that intentionally changes the engine torque. It was done.

Therefore, during various control operations as described above,
When the misfire determination as in the prior art is executed, the intentional fluctuation of the engine torque is misfire misjudgment that is determined as abnormal misfire. Therefore, despite the intentional fluctuation of the engine torque, the driver will be notified as a misfire many times, and it is not possible to distinguish between a correct misfire judgment and an erroneous judgment. Was likely to decrease.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a misfire detection device for an internal combustion engine capable of preventing erroneous misfire determination when the engine torque is intentionally changed. It is in.

[0007]

In order to achieve the above object, in the present invention, as shown in FIG. 1, a rotation detecting means M2 for detecting the rotation of an internal combustion engine M1 and a rotation detecting means M2 thereof are provided. Rotational fluctuation indexing means M for indexing the rotational fluctuation for each cylinder explosion stroke of the internal combustion engine M1 based on the detection result.
3 and a misfire determination device M4 that determines misfire in each cylinder explosion stroke when the indexing result of the rotation fluctuation indexing device M3 exceeds a predetermined value. A rotation variation command means M5 for instructing an intentional rotation variation of the internal combustion engine M1 according to an operating state, and a misfire that invalidates the misfire determination by the misfire determination means M4 when the rotation variation command means M5 executes the instruction. The judgment invalidating means M6 is provided.

[0008]

According to the above construction, as shown in FIG. 1, the rotation detecting means M2 detects the rotation of the internal combustion engine M1 during operation, and the rotation variation indexing means M3 detects the rotation based on the detection result. Determine the rotation fluctuation for each. Further, when the rotation fluctuation indexing result exceeds a predetermined value, the misfire determination means M4
Is judged as misfire in each cylinder explosion stroke.

When the rotation fluctuation commanding means M5 executes an intentional rotation fluctuation command of the internal combustion engine M1 according to the operating state of the internal combustion engine M1, the misfire determination invalidating means M6 determines the misfire. The misfire determination by the means M4 is invalidated. Therefore, in the case of causing the internal combustion engine M1 to intentionally rotate, the misfire is not determined.

[0010]

【Example】

(First Embodiment) A first embodiment of the misfire detecting device for an internal combustion engine according to the present invention will be described in detail below with reference to FIGS.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system to which the misfire detection device in this embodiment is applied. Engine 1 as an internal combustion engine mounted on a car
Has an intake passage 2 that constitutes an intake system and an exhaust passage 3 that constitutes an exhaust system. An air cleaner 4 is provided at the inlet of the intake passage 2. A surge tank 5 is provided in the intake passage 2. This surge tank 5
On the downstream side of each of the cylinders of the engine 1 (4 cylinders in this embodiment).
Injectors 6A, 6 for injecting and supplying fuel for each cylinder)
B, 6C and 6D are provided respectively. On the other hand, on the outlet side of the exhaust passage 3, a catalytic converter 7 incorporating a three-way catalyst for purifying the exhaust is provided.

Then, the engine 1 takes in outside air from the air cleaner 4 through the intake passage 2. At the same time when the outside air is taken in, the engine 1 causes the injectors 6A to 6A to
The fuel injected and supplied from D is taken in. Also, engine 1
Explodes and burns the taken-in air-fuel mixture in each combustion chamber to obtain a driving force, and then exhausts the exhaust gas from the exhaust passage 3 to the outside through the catalytic converter 7.

On the upstream side of the surge tank 5, there is provided a throttle valve 8 which opens and closes in conjunction with the operation of an accelerator pedal (not shown). Then, by opening and closing the throttle valve 8, the amount of intake air in the intake passage 2 is adjusted.

A throttle opening sensor 21 for detecting the throttle opening TA is provided near the throttle valve 8. A well-known movable vane type air flow meter 22 for measuring the amount of intake air passing through the intake passage 2 is provided on the downstream side of the air cleaner 4.

An oxygen sensor 23 for detecting the oxygen concentration in the exhaust gas, that is, for detecting the exhaust air-fuel ratio is provided in the middle of the exhaust passage 3 for feedback control of the air-fuel ratio of the engine 1. Further, the engine 1 is provided with a water temperature sensor 24 that detects the temperature of the cooling water (cooling water temperature) THW.

The ignition signal distributed by the distributor 10 is applied to the ignition plugs 9A, 9B, 9C and 9D provided for each cylinder of the engine 1. The distributor 10 synchronizes the high voltage output from the igniter 11 with the crank angle of the engine 1 to each spark plug 9A ...
It is for distribution to 9D. The ignition timing of each of the spark plugs 9A to 9D is determined by the high voltage output timing from the igniter 11.

The distributor 10 incorporates a rotor (not shown) that rotates in association with the rotation of the engine 1. Then, the distributor 10 has a rotation speed N of the engine 1 (engine speed N) based on the rotation of the rotor.
A rotation speed sensor 25 is provided as rotation detection means for detecting E. Similarly, for the distributor 10,
A cylinder discriminating sensor 26 is provided which detects a change in the crank angle CA of the engine 1 at a predetermined rate according to the rotation of the rotor. In this embodiment, the engine 1 is used for one stroke.
, The cylinder discrimination sensor 26
The crank angle is detected at a rate of ° CA. A vehicle speed sensor 27 for detecting the vehicle speed SP is provided in an automatic transmission (not shown) that is drivingly connected to the engine 1.

Further, in this embodiment, the instrument panel in the driver's seat is provided with a misfire indicator lamp 12 for informing the driver of the occurrence of misfire. Then, the injectors 6A to 6D, the igniter 11 and the misfire indicator lamp 12 are provided.
Is electrically connected to an engine electronic control unit (hereinafter simply referred to as “engine ECU”) 30 that constitutes a rotation fluctuation indexing means, a misfire determination means, a misfire determination invalidating means, and a rotation fluctuation command means, and the engine ECU 30 The drive timings of them are controlled by the operation of.

As described above, the engine ECU 30 is a control device that mainly controls the fuel injection control and ignition timing control of the engine 1, and also constitutes a misfire detection device that determines and detects misfire in each cylinder explosion stroke. There is. In addition to this, in this embodiment, as shown in FIG. 2, an electric controlled transmission (ECT) ECU 4
1, a traction control (TRC) ECU 42 and an automatic drive ECU 43 are provided respectively.

In order to reduce the shift shock of the automatic transmission (not shown), the ECT ECU 41 controls the direct coupling clutch control and shift control of the automatic transmission by the torque control delay angle during ECT shift, and intentionally changes the torque of the engine 1. Let Therefore, the ECT ECU 41 inputs a shift position signal indicating the shift position of the automatic transmission. Also, EC
The TECU 41 exchanges signals with the engine ECU 30, and inputs the detection values of the air flow meter 22 and the sensors 21, 23 to 27 from the engine ECU 30 as data signals. Then, the ECT ECU 41 determines a shift pattern according to the shift condition at each time based on various input signals, and outputs a shift control signal for suitably controlling the actuator of the automatic transmission according to the shift pattern.

The TRCECU 42 intends the torque of the engine 1 by retarding the traction control or the like in order to suppress the wheel spin due to an excessive driving force and secure the directional stability and the driving force of the vehicle at the time of starting acceleration on a snowy road or the like. Fluctuate. Therefore, the TRCECU 42 is connected to the engine ECU 3
Signals to and from the engine ECU 30
From the air flow meter 22 and each sensor 21, 23-2
The detected value of 7 or the like is input as a data signal. And T
The RC ECU 42 determines a target torque amount according to the acceleration state at each time based on various input signals, and a traction communication signal for causing the engine 1 to perform fuel cut or the like in order to perform torque control according to the target torque amount. Is output to the engine ECU 30.

The automatic drive ECU 43 controls the opening of the throttle valve 8 by the retard correction during automatic drive control or the like to control the torque of the engine 1 in order to smoothly drive the vehicle at a constant speed for a long time on a highway or the like. Fluctuate. Therefore, the auto drive ECU 43 operates from a set switch (not shown) operated by the driver.
Input a set signal to instruct auto drive.
Further, the auto drive ECU 43 exchanges signals with the engine ECU 30, and inputs the detection values of the throttle opening sensor 21 and the vehicle speed sensor 27 as data signals from the engine ECU 30. Then, the auto-drive ECU 43 outputs an opening degree control signal to an actuator (not shown) that is driven to control the opening degree of the throttle valve 8 so that the vehicle travels at a speed specified by the driver based on various input signals. To do.

In this embodiment, the ECT ECU described above is used.
41, TRCECU 42 and auto drive ECU 43
Constitutes a rotation fluctuation command means for commanding an intentional rotation fluctuation of the engine 1 in accordance with the operating state of the engine 1.

FIG. 3 is a block diagram illustrating the structure of the engine ECU 30. The engine ECU 30 includes a central processing unit (CPU) 31, a read-only memory (ROM) 32 that stores a predetermined control program and the like in advance, and a random access memory (R) that temporarily stores calculation results of the CPU 31 and the like.
AM) 33, a backup RAM 34 for storing prestored data, and the like, and each unit, an external input circuit 35, an external output circuit 36, and the like are connected by a bus 37 as a logical operation circuit. And the CPU 31
Is an air flow meter 22 and each sensor 21, 23-27
The output signal from is read as an input value through the external input circuit 35. Further, the CPU 31 receives the injectors 6A to 6A through the external output circuit 36 based on these input values.
D, the igniter 11 and the misfire indicator lamp 12 are controlled appropriately. Further, the engine ECU 30 receives the ECT ECU 4 through the external input circuit 35 and the external output circuit 36.
1, the TRCECU 42 and the automatic drive ECU 43, and the air flow meter 22 and the sensors 21, 23.
Data signals such as detection values of 27 to 27 and calculation results are exchanged.

Next, the processing operation for detecting the occurrence of an abnormal cylinder due to a misfire in the misfire detecting device for an internal combustion engine configured as described above will be described with reference to the flow charts of FIGS.

FIGS. 4 to 6 show an abnormal cylinder detection processing routine executed by the engine ECU 30, which is executed by a regular interruption every predetermined time. When the processing shifts to this routine, first, at step 100, the intake air amount Q is calculated from the detection values of the air flow meter 22 and the rotation speed sensor 25.
And engine speed NE etc. are read and ECTE
CU41, TRCECU42 and auto drive ECU
Data signals such as those control signals are read from 43.

Next, in the series of judgment processing of steps 111 to 118, whether or not the abnormal cylinder due to misfire is detected based on the previously read data signal or the like,
That is, it is determined whether to enable or disable the misfire determination.

That is, in step 111, ECT
Based on the data signal from the ECU 41, it is determined whether or not the ECT torque control command is being executed. Where EC
If the T-torque control is not being executed, it is determined in step 112 based on the data signal from the auto-drive ECU 43 whether or not the command of the auto-drive torque control is being executed. If the automatic drive torque control is not being performed, then in step 113, TRCECU
Based on the data signal from 42, it is determined whether or not the TRC torque control command is being executed. When the TRC torque control is not being performed, in step 114, the engine 1
It is determined whether or not the deceleration amount is increasing to cause the intentional torque fluctuation. Here, if the deceleration amount is not increasing, it is determined in step 115 whether or not the fuel cut return decreasing amount for similarly causing the intentional torque fluctuation is being executed, that is, the fuel injection is performed to return the fuel injection after the fuel cutting. It is determined whether or not the volume control moderating process is being performed. Then, if the fuel cut return reduction amount is not in progress, it is determined in step 116 whether or not the cylinder is a stopped cylinder by the reduced cylinder operation control for causing intentional torque fluctuation. The reduced-cylinder operation control is to reduce the number of operating cylinders by stopping fuel injection in some cylinders when the engine 1 has a light load, so that the operating load is increased in the operating cylinder even if the engine 1 as a whole has a light load. This is the control for improving the combustion state in the cylinder. Here, if the cylinder is not the stopped cylinder by the reduced-cylinder operation control, it is determined in step 117 whether or not the fuel cut for intentionally causing the torque fluctuation is being performed. And when the fuel cut is not in progress,
In step 118, 2 after the fuel cut is restored.
It is determined whether or not only the control cycle has passed.

Here, if only two control cycles have elapsed after the return of the fuel cut, the routine proceeds to step 130. That is, when the determination at step 118 described above is affirmative, each of the steps 111 to 117 before that is performed.
Since the series of determinations in No. are all negative, and control for intentional torque fluctuation of the engine 1 is not performed, it is determined that abnormal cylinder detection is performed, that is, misfire determination is performed, and the process proceeds to step 130.

On the other hand, the above-mentioned steps 111 to 117
If the determinations in step 1 are positive or the determinations in step 118 are negative, various controls for intentional torque fluctuations of the engine 1 are performed, so abnormal cylinder detection is not performed. That is, that is, the misfire determination is invalidated, the process proceeds to step 120. Then, in the same step 120, each variable used for detecting the abnormal cylinder, that is, the elapsed time CD by the counting of the counter, the number of rotation abnormalities CDINJ in the cylinder number n
n, the number of revolutions NEB (n-
The process of resetting 1) to "0" is performed. Then, the subsequent processing is once ended.

Then, at step 130 after shifting from step 118, whether or not the elapsed time CD from the start of the process of detecting the abnormal cylinder due to the misfire is "0", that is, immediately after the start of the detection process. Or not.

Here, if it is not immediately after the start of the detection process, the process directly proceeds to step 150. If the detection process has just started, in step 140,
After resetting the cylinder number n indicating the number of the cylinder to "0", the process proceeds to step 150. The value of the cylinder number n is a number assigned to each cylinder in the order of the explosion stroke, and is not the actual cylinder number. Further, in this embodiment, since the engine 1 has four cylinders, the cylinder number n takes a value of "1 to 4".

In step 150, it is determined whether or not the count value Ccrnk representing the rotation timing of the crankshaft of the engine 1 is "3, 9". This count value C
As shown in the flowchart of FIG. 7, crnk is a value set by the “30 ° CA interrupt routine” executed by the engine ECU 30. That is, step 152
In, the count value Ccrnk is incremented by "1" every time the crankshaft rotates 30 °. In step 154, it is determined whether the count value Ccrnk has been counted up to "12". Then, when the count value Ccrnk is not counted up to "12", the process is temporarily terminated. On the other hand, when the count value Ccrnk is counted up to “12” in step 154, the count value Ccrnk is counted in step 156.
Is reset to "0", and the subsequent processing is temporarily terminated.

Therefore, the condition that the count value Ccrnk is "3, 9" is that the crank angle is "90 ° CA, 270 ° CA, 4".
50 ° CA, 630 ° CA ”for each crank angle. That is, the judgment becomes affirmative at the timing in the middle of the explosion stroke of each cylinder.

Returning again to the processing routines of FIGS.
In step 150, the count value Ccrnk is "3.
If it is not “9”, the process directly proceeds to step 230. On the other hand, in step 150, the count value Ccrnk
If the value is "3, 9", first, at step 160, the cylinder number n is incremented by "1". Next, in step 170, it is determined whether or not the cylinder number is "5". If the value is not "5", the process directly proceeds to step 190. If the cylinder number n is "5" in step 170, the cylinder number n is set to "1" in step 180 and the process proceeds to step 190. That is, steps 160-18
In the processing of 0, the cylinder number n is incremented by "1" within the range of "1 to 4".

Then, proceeding from steps 170 and 180, in step 190, the current engine speed NE is set to the engine speed NEn of the cylinder of cylinder number n,
Rotational fluctuation amount ΔNE which is the difference between the rotational speed NEn and the rotational speed NEB (n-1) of the previous cylinder number (n-1).
Ask for.

Then, in step 200, the magnitude of the rotation fluctuation amount ΔNE is determined. This rotation fluctuation amount ΔNE
Becomes smaller when there is no abnormal cylinder due to misfire. When the engine misfires for some reason, the rotational speed NEn of the misfiring cylinder decreases and the rotational fluctuation amount Δ which is the difference from the rotational speed NEB (n-1) of the previous cylinder.
NE increases.

Therefore, in step 200, when the rotational fluctuation amount ΔNE is larger than the predetermined reference value X, in step 210, it is determined that the rotational speed NEn of the cylinder is abnormal, and the rotational abnormality of the cylinder of the cylinder number n is abnormal. The number of times CDINJn is increased by the value A. Furthermore,
The value obtained by adding the reference value X to the rotational speed NEn of the current cylinder is used as the rotational speed NEB of the previous cylinder in the process of the next cylinder.
Update as (n-1). As a result, the rotation fluctuation amount ΔN in the determination regarding the abnormal cylinder is not only caused when the irregular misfire does not occur but also when the irregular misfire occurs.
E is detected as a large value.

On the other hand, when the rotation fluctuation amount ΔNE is smaller than the predetermined reference value Y in step 200, it is determined in step 220 that the rotation speed NEn of the cylinder is normal, and the number of abnormal rotations CDINJn is equal to the value B. Reduce. Further, the rotational speed NEn of the cylinder this time is directly changed to the rotational speed NE of the previous cylinder in the process of the next cylinder.
Update as B (n-1).

If the rotation fluctuation amount ΔNE exceeds the value Y and is less than the reference value X in step 200, the number of abnormal rotations CDINJn is not increased or decreased in step 225, and the rotation speed NEB in the previous cylinder is not increased. (N-
Only update 1). As a result, the number of abnormal rotations CDINJn is correctly increased according to the abnormal cylinder.

Then, step 210 and step 22
0, the process proceeds from step 225 or step 150, and in step 230, it is determined whether or not "1 second" has elapsed since the processing of this routine was started. Here, if "1 second" has not elapsed, the process directly proceeds to step 250. On the other hand, when "1 second" has elapsed, in step 240, the elapsed time CD is incremented by "1" and then the process proceeds to step 250.

In step 250, the elapsed time CD
Is greater than or equal to a predetermined value L (“25 seconds” in this embodiment) or not. Here, when the elapsed time CD is not equal to or greater than the predetermined value L, it is determined that the data that can be used to determine the abnormality of each cylinder is normal in a state where the data is not collected, and the subsequent processing is temporarily terminated.

On the other hand, if the elapsed time CD is greater than or equal to the predetermined value L in step 250, the number of abnormal rotations CDINJn in the cylinder number n is greater than or equal to the predetermined value M ("100 times" in this embodiment) in step 260. Or not. Here, the number of times CDINJn is a predetermined value M
If not, the number of times CDINJn has not reached the number at which it can be determined to be abnormal. Therefore, the subsequent processing is temporarily terminated as it is.

In step 260, the number of times CDI
If NJn is equal to or greater than the predetermined value M, it is determined that the cylinder with the cylinder number n has abnormal rotation, that is, misfire is determined, and in step 270, a misfire determination signal is output and a misfire indicator lamp in the driver's seat. Processing for turning on 12 is performed.
At the same time, the misfire determination signal is stored in the backup RAM 34 as diagnosis data, and the subsequent processing is once terminated.

As described above, according to the misfire detecting device for the internal combustion engine in this embodiment, steps 111 to 11 are executed prior to the abnormal cylinder detection, that is, the misfire determination.
In 8, it is determined whether or not to invalidate the misfire determination depending on whether or not the control for intentional torque fluctuation of the engine 1 is performed. And the ECT ECU 41,
When the TRCECU 42, the automatic drive ECU 43, or the engine ECU 30 performs various controls for intentional torque fluctuations of the engine 1, the misfire determination is invalidated. That is, the misfire determination is not performed.

Therefore, while various controls for intentional torque fluctuation of the engine 1 are being performed, even if the engine 1 fluctuates in rotation, it is determined that each cylinder is abnormal due to misfire. It is possible to prevent erroneous determination of misfire in advance. Therefore, the misfire indication lamp 12 is prevented from being turned on by the misjudgment of misfire, and the driver is not informed of the result of the misjudgment. At the same time, the result of the erroneous determination is prevented from being stored in the backup RAM 34 as diagnosis data. As a result, it is possible to enhance the reliability of misfire notification by the misfire indicator lamp 12 and the diagnosis, and to provide the driver or the like with reliable misfire determination information in the case of a misfire abnormality to prompt early countermeasures for misfire.

Further, in this embodiment, the rotational fluctuation amount ΔNE which is the difference between the rotational speed NEn of the cylinder concerned and the rotational speed NEB (n-1) of the preceding cylinder in the current control cycle is a predetermined reference value. When it becomes larger than the value X, the rotation speed NEB (n-1) in the previous cylinder in the next control cycle is set to be larger than the rotation speed NEn in the cylinder by the reference value X.

Therefore, even if an abnormality occurs due to a misfire in any of the cylinders, and even if an accidental misfire, that is, an irregular misfire occurs in the cylinder that is in the explosion stroke immediately before that cylinder, it continues. It is possible to correctly determine the cylinder in which the abnormal state has occurred as abnormal. In such an irregular misfire, when a failure occurs due to foreign matter being caught in any of the injectors 6A to 6D and the air-fuel ratio of the corresponding cylinder is misfiring due to overrich, the air-fuel ratio feedback control causes the air-fuel ratios of other cylinders to change. It becomes easy to occur by becoming an ovary. In this embodiment, in response to the above-mentioned irregular misfire, the occurrence of abnormal cylinders due to misfire can be continuously and accurately detected.

Further, in this embodiment, even if the rotational speed NEn at that time is judged to be abnormal and the number of abnormal rotations CDINJn is increased for the cylinder in which the misfire has occurred, the rotational fluctuation amount ΔNE is next determined. If it is less than the reference value Y of, the number of times CDINJn is reduced by the value B. Therefore, due to irregular misfire, engine speed N
When E falls accidentally, the corresponding cylinder is not erroneously determined to be abnormal due to misfire, and the accuracy of the abnormal cylinder determination, that is, the accuracy of misfire determination can be increased.

(Second Embodiment) Next, a second embodiment embodying the misfire detection device for an internal combustion engine according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In this embodiment, the general construction of the gasoline engine system to which the misfire detection device is applied and the construction of the engine ECU are the same as those of the first embodiment, and the same reference numerals are used for the same members. And the description is omitted. And below, FIGS.
Only the processing operation for detecting the occurrence of the abnormal cylinder due to the misfire will be described according to each flowchart of 0.

8 to 10 show an abnormal cylinder detection processing routine executed by the engine ECU 30, which is executed by a regular interruption every predetermined time. When the processing shifts to this routine, first, at step 300, the intake air amount Q and the engine speed NE are read from the detection values of the air flow meter 22 and the speed sensor 25, and ECTE
CU41, TRCECU42 and auto drive ECU
Data signals such as those control signals are read from 43.

Next, in the series of determination processing from step 311 to step 318, it is determined whether or not the abnormal cylinder due to misfire is detected based on the previously read data signal and the like.
That is, it is determined whether to enable or disable the misfire determination. That is, similar to the processing of steps 111 to 118 of the flow chart shown in FIG. 4 of the first embodiment, whether or not the command for ECT torque control is being executed, and whether or not the command for automatic drive torque control is being executed. Whether or not the TRC torque control command is being executed, whether or not the deceleration amount is being increased,
Whether the fuel cut return reduction amount is being performed, whether the cylinder is a stopped cylinder due to the cutoff cylinder operation control, whether the fuel cut is being performed, or whether two control cycles have elapsed after the fuel cut return Each judgment is step 311
318.

If the determination in step 318 is affirmative, the series of determinations in steps 311 to 317 before that are all negative, and various controls for intentional torque fluctuation of the engine 1 are performed. Since it has not been performed, it is determined that abnormal cylinder detection is performed, that is, misfire determination is performed, and the process proceeds to step 330.

On the other hand, the above-mentioned steps 311 to 317
If the determinations in step 318 are affirmative or the determination in step 318 is negative, various controls for intentional torque fluctuations of the engine 1 are respectively performed, so abnormal cylinder detection is not performed. As a result, that is, the misfire determination is invalidated, the process proceeds to step 320.

Then, in step 320, the intake air amount Q of this time is also divided by the engine speed NE of this time, and the result is set as the load value L. Further, in step 325, the function f3 (L) having the previously set load value L as a parameter is obtained by referring to a predetermined map (not shown), and the value of the function f3 (L) is corrected by the correction value α ( It is set as 0 <α <1), and the subsequent processing is once ended.

In step 330 after the step 318, it is determined whether the elapsed time CD from the start of the process of detecting the abnormal cylinder due to the misfire is "0".
That is, it is determined whether or not the detection process has just started.

Here, if it is not immediately after the start of the detection process, the process directly proceeds to step 350. If the detection process has just started, in step 340,
After resetting the cylinder number n indicating the number of the cylinder to "0", the process proceeds to step 350. The value of the cylinder number n is a number assigned to each cylinder in the order of the explosion stroke, and is not the actual cylinder number. The cylinder number n has a value of "1 to 4" because the engine 1 has four cylinders.

In step 350, it is determined whether or not the count value Ccrnk representing the rotation timing of the crankshaft of the engine 1 is "3, 9". This count value C
Like the first embodiment, crnk is set according to the "30 ° CA interrupt routine" shown in the flowchart of FIG. The condition that the count value Ccrnk is "3, 9" is that the crank angle is "90 ° CA, 270 ° CA, 450 ° CA,
630 ° CA ”for each crank angle. That is, the judgment becomes affirmative at the timing in the middle of the explosion stroke of each cylinder.

If the count value Ccrnk is not "3, 9" in step 350, the process directly proceeds to step 460. On the other hand, when the count value Ccrnk is “3, 9” in step 350, first,
In step 360, the cylinder number n is incremented by "1". Next, in step 370, it is determined whether or not the cylinder number is "5", and if the value is not "5", the process directly proceeds to step 390.
If the cylinder number n is "5" in step 370, the cylinder number n is set to "1" in step 380, and the process proceeds to step 390. That is, in the processing of steps 360 to 380, the cylinder number n is incremented by "1" within the range of "1 to 4".

Then, the process shifts from steps 370 and 380, and in step 390, the engine speed NE of this time is set to the engine speed NEn of the cylinder of the cylinder number n,
The rotation speed NEn and the rotation speed NE at the previous cylinder number
A rotation fluctuation amount ΔNE which is a difference from B is obtained.

Next, at step 400, a function f1 (L) having the load value L set previously as a parameter is obtained by referring to a predetermined map (not shown), and the value of the function f1 (L) is obtained. Set as the reference value X. Similarly, a function f2 (L) having the load value L as a parameter is obtained by referring to a predetermined map (not shown), and the function f2 (L) is obtained.
The value of 2 (L) is set as the reference value Y.

Thereafter, in step 410, the magnitude of the rotation fluctuation amount ΔNE is determined. This rotation fluctuation amount ΔNE
Becomes smaller when there is no abnormal cylinder due to misfire. When the engine misfires for some reason, the rotational speed NEn of the misfiring cylinder decreases, and the rotational fluctuation amount ΔNE, which is the difference from the rotational speed NEB of the previous cylinder, increases.

Therefore, in step 410, when the rotational fluctuation amount ΔNE is larger than the value obtained by adding the correction value α to the predetermined reference value X, it is determined in step 420 that the rotational speed NEn of the cylinder is abnormal. The number A of rotation abnormalities in the cylinder of cylinder number n is set to the value A
Only increase. Furthermore, the rotational speed NE of the cylinder this time
A value obtained by adding the reference value X and the correction value α to n is updated as the rotation speed NEB in the previous cylinder in the process in the next cylinder.

On the other hand, when the rotation fluctuation amount ΔNE is smaller than the predetermined reference value Y in step 410, it is determined in step 430 that the rotation speed NEn of the cylinder is normal, and the number of abnormal rotations CDINJn is equal to the value B. Reduce. Further, the rotational speed NEn of the cylinder this time is directly changed to the rotational speed NE of the previous cylinder in the process of the next cylinder.
Update as B.

If the rotation fluctuation amount ΔNE exceeds the value Y and is less than the reference value X plus the correction value α in step 410, the number of abnormal rotations CDINJn is increased or decreased in step 440. Instead, the rotational speed NEn of the current cylinder is updated as it is to the rotational speed NEB of the previous cylinder in the process of the next cylinder. In this way, the number of abnormal rotations CDIN
Jn is increased correctly.

Then, step 420 and step 430
Alternatively, the process proceeds from step 440, and in step 450, the correction value α is reset to “0”. here,
The correction value α is set by the function f3 (L) in step 325 only when the current cylinder corresponds to the control for intentional torque fluctuation. Therefore, when the cylinder this time corresponds to the control for intentional torque fluctuation, in step 410 of the next control cycle, the rotation fluctuation amount ΔNE adds the predetermined correction value α to the reference value X. If it is larger than the value, the process proceeds to step 420. Further, in step 420, the rotation speed NEn
The correction value α is further added to the reference value X to be added to. Alternatively, if the rotation variation amount ΔNE exceeds the reference value Y and is less than the reference value X plus the correction value α, the process proceeds to step 440. Then, the correction value α
Is reset to "0" in step 450, and thereafter, the correction value α remains "0" until the control for torque fluctuation is performed in another cylinder next time. That is, the correction value α is set to a predetermined value as the function f3 (L) only when it corresponds to the control for the intentional torque fluctuation, and the next value of the cylinder corresponding to the control for the torque fluctuation is set. In step 410, the reference value X to be compared with the rotation fluctuation amount ΔNE is added to the correction value α and is set to a large value only in the cylinder of No. Further, the correction value α becomes “0” for the second and subsequent cylinders counted from the cylinders corresponding to the control for torque fluctuation, and in step 410, the reference value X to be compared with the rotation fluctuation amount ΔNE is the correction value. It is not added by α.

Then, step 350 or step 4
After shifting from 50, in step 460, it is determined whether or not "1 second" has elapsed from the start of the processing of this routine. Here, if "1 second" has not elapsed, the process directly proceeds to step 480. On the other hand, if "1 second" has elapsed, then in step 470, the elapsed time C
Increment D by "1" and then step 480
Move to.

At step 480, the elapsed time CD
Is greater than or equal to a predetermined value L (“25 seconds” in this embodiment) or not. Here, when the elapsed time CD is not equal to or greater than the predetermined value L, it is determined that the data that can be used to determine the abnormality of each cylinder has not been collected, and the subsequent processing is temporarily terminated.

In step 480, the elapsed time C
When D is equal to or greater than the predetermined value L, it is determined in step 490 whether the number of abnormal rotations CDINJn in the cylinder number n is equal to or greater than the predetermined value M ("100 times" in this embodiment). Then, the number of times CDINJn is a predetermined value M
In the above case, it is determined that there is abnormal rotation in the cylinder of cylinder number n, that is, misfire is determined, and step 50
At 0, a process of outputting a misfire determination signal and turning on the misfire display lamp 12 in the driver's seat is performed. At the same time, the misfire determination signal is stored in the backup RAM 34 as diagnosis data.

Subsequently, in step 510, the operation of the injectors 6A to 6D corresponding to the cylinder this time is stopped, and the fuel injection in that cylinder is stopped thereafter. In step 520, the control for intentional torque fluctuation is stopped.

Further, at step 530, each variable used for detecting the abnormal cylinder, that is, the elapsed time CD due to the counting of the counter, the number CDIN of the abnormal rotations in the cylinder number n.
A process of resetting Jn to "0" is performed. Then, the subsequent processing is once ended.

On the other hand, in step 490, the number of times CD
If INJn is not equal to or greater than the predetermined value M, the number of times CD
Since the number of times before INJn can be determined to be abnormal has not been reached, it is determined to be normal and the process proceeds to step 530. Then, in the same step 530, each variable used for detecting the abnormal cylinder, that is, the elapsed time CD by the counting of the counter, the number of times of abnormal rotation CDI in the cylinder number n
A process of resetting NJn to "0" is performed.
Then, the subsequent processing is once ended.

As described above, according to the misfire detecting device for the internal combustion engine in this embodiment, steps 311 to 31 are executed prior to the abnormal cylinder detection, that is, the misfire determination.
In 8, it is determined whether or not to invalidate the misfire determination depending on whether or not the control for intentional torque fluctuation of the engine 1 is performed. And the ECT ECU 41,
When the TRCECU 42, the automatic drive ECU 43, or the engine ECU 30 performs various controls for intentional torque fluctuations of the engine 1, the misfire determination is invalidated. That is, the misfire determination is not performed.

Therefore, while various controls for intentional torque fluctuation of the engine 1 are being performed, even if the engine 1 fluctuates in rotation, it is determined that each cylinder is abnormal due to misfire. It is possible to prevent erroneous determination of misfire in advance. Therefore, the misfire indication lamp 12 is prevented from being turned on by the misjudgment of misfire, and the driver is not informed of the result of the misjudgment. At the same time, the result of the erroneous determination is prevented from being stored in the backup RAM 34 as diagnosis data. As a result, it is possible to enhance the reliability of misfire notification by the misfire indicator lamp 12 and the diagnosis, and to provide the driver or the like with reliable misfire determination information in the case of a misfire abnormality to prompt early countermeasures for misfire.

Further, in this embodiment, the rotational fluctuation amount ΔNE, which is the difference between the rotational speed NEn of the cylinder concerned in the present control cycle and the rotational speed NEB of the previous operating cylinder, is corrected to a predetermined reference value X. When the value becomes larger than the value α added, the rotation speed NEB in the previous operating cylinder in the next control cycle is added by the correction value α added to the reference value X from the rotation speed NEn in the cylinder. I am trying to set a large value. Therefore, even if there is an abnormality due to misfire in any of the cylinders, and even if accidental misfire, that is, irregular misfire occurs in the cylinder that is in the explosion stroke immediately before that cylinder, the abnormal state continues. The cylinder in which it is occurring can be correctly determined to be abnormal. Therefore, in response to an irregular misfire, the occurrence of abnormal cylinders due to misfire can be continuously and accurately detected.

Further, in this embodiment, even if the rotational speed NEn at that time is judged to be abnormal and the number of abnormal rotations CDINJn is increased for the cylinder in which the irregular misfire has occurred, the rotational fluctuation amount ΔNE is next determined. If it is less than the reference value Y of, the number of times CDINJn is reduced by the value B. Therefore, when the engine speed NE is accidentally reduced due to irregular misfire, the relevant cylinder is not erroneously determined to be abnormal due to misfire, and the determination accuracy of the abnormal cylinder, that is, the accuracy of misfire determination. Can be increased.

Furthermore, in this embodiment, the correction value α is obtained only when various controls for intentional torque fluctuation are performed.
Is set to a predetermined value, and in the cylinder next to the cylinder corresponding to the control for the torque fluctuation, the reference value X to be compared with the rotation fluctuation amount ΔNE is added to the correction value α to be set large. Therefore, in the cylinder next to the cylinder corresponding to the control for intentional torque fluctuation, the engine speed NE decreases due to the influence of the torque fluctuation, and the rotational fluctuation amount ΔNE
Even if fluctuates greatly, it is possible to determine the abnormal cylinder according to the fluctuation. That is, even if a misfire occurs in a cylinder that should be operating during control for intentional torque fluctuation, an abnormal cylinder is properly detected while eliminating the influence of the control for torque fluctuation. Therefore, it is possible to prevent erroneous detection of an abnormal cylinder and further improve the accuracy of misfire determination.

In addition, in this embodiment, in the case of misfire,
Since fuel injection is stopped after that for the misfiring cylinder,
It is possible to prevent discharge of unburned gas, and thus prevent damage to the three-way catalyst in the catalytic converter 7 in advance. Further, in this embodiment, in the case of misfire, various controls for intentional torque fluctuation are stopped,
Control for torque fluctuation and misfire are combined, and engine 1
Can be prevented from becoming extremely insufficient in output or causing an engine stall.

The present invention is not limited to the above-described embodiments, but can be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In each of the above-described embodiments, in addition to the engine ECU 30, the ECT ECU 41 and the TRCECU are provided as the rotation variation command means.
Although 42 and the automatic drive ECU 43 are provided, a control device that causes an intentional torque fluctuation in the engine 1 may be provided as the rotation fluctuation command means.

(2) In each of the above embodiments, the misfire detection device for an internal combustion engine is applied to a gasoline engine, but it may be applied to other internal combustion engines such as a diesel engine. (3) In the second embodiment, in step 410,
Although the correction value α is added to the reference value X to be compared with the rotation variation amount ΔNE, the reference value X is multiplied by a value obtained by adding “1” to the correction value α and the multiplication result is the rotation variation amount. ΔNE
You may make it compared with.

(4) In the second embodiment, step 42
At 0, the reference value X and the correction value α were added to the current rotational speed NEn of the cylinder, and the addition result was set as the rotational speed NEB. However, the value obtained by adding “1” to the correction value α is set as the reference value X. The result obtained by multiplying and adding the multiplied value to the rotation speed NEn may be set as the rotation speed NEB.

[0082]

As described above in detail, according to the present invention, the rotation fluctuation for each cylinder explosion stroke is indexed based on the detection of the rotation of the internal combustion engine, and when each index explosion result exceeds a predetermined value, each cylinder explosion occurs. In the misfire detection device that determines misfire in the stroke, the misfire determination is invalidated when the intentional rotation fluctuation of the internal combustion engine is commanded to be executed according to the operating state of the internal combustion engine. In addition, it is possible to prevent an erroneous misfire determination from occurring before the misfire is determined due to the rotation fluctuation when the engine torque is varied.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system to which the misfire detection device according to the first embodiment of the present invention is applied.

FIG. 3 is a block diagram showing a configuration of an engine ECU in the first embodiment.

FIG. 4 is a flowchart illustrating an abnormal cylinder detection processing routine executed by an engine ECU in the first embodiment.

FIG. 5 is a flowchart for explaining the continuation of the abnormal cylinder detection processing routine that is similarly executed by the engine ECU in the first embodiment.

FIG. 6 is a flowchart illustrating the continuation of the abnormal cylinder detection processing routine that is similarly executed by the engine ECU in the first embodiment.

FIG. 7 is a flowchart illustrating a 30 ° CA interrupt routine executed by the engine ECU in the first embodiment.

FIG. 8 is a flowchart illustrating an abnormal cylinder detection processing routine executed by an engine ECU in the second embodiment of the present invention.

FIG. 9 is a flowchart illustrating the continuation of the abnormal cylinder detection processing routine that is similarly executed by the engine ECU in the second embodiment.

FIG. 10 is a flowchart illustrating the continuation of the abnormal cylinder detection processing routine executed by the engine ECU in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 25 ... Rotation speed sensor as rotation detection means, 30 ... Engine ECU which constitutes rotation fluctuation indexing means, misfire determination means, misfire determination invalidation means and rotation fluctuation command means, 41 ... ECT ECU , 42 ... T
RC ECU, 43 ... Auto drive ECU (41, 4
Reference numerals 2 and 43 constitute rotation fluctuation command means).

Claims (1)

[Claims] 1. A rotation detecting means for detecting the rotation of an internal combustion engine; a rotation fluctuation calculating means for calculating a rotation fluctuation for each cylinder explosion stroke of the internal combustion engine based on a detection result of the rotation detecting means; When the indexing result of the variable indexing means exceeds a predetermined value, in a misfire detection device for an internal combustion engine, which comprises a misfire determination means for determining misfire in each cylinder explosion stroke, the internal combustion engine according to the operating state of the internal combustion engine. An internal combustion engine provided with a rotation fluctuation command means for commanding an intentional rotation fluctuation of the engine, and a misfire determination invalidation means for invalidating the misfire determination by the misfire determination means when the rotation fluctuation command means executes the command. Misfire detection device.