JP2000073850A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely perform a detection by providing a means for canceling the misfire detection of a rested cylinder. SOLUTION: When the change quantity is judged to be a misfire determination threshold MSLMT or more by the comparison with the misfire determination threshold by absolute value, the misfire of the third cylinder is judged. When it is judged that the engine is not in cranking at the starting where the rotation is not stable, establishment of a misfire detection start condition is judged. When a cylinder resting mode is judged, the misfire detection is performed by use of the misfire determination threshold MSLMT for cylinders other than the rested cylinder. Namely, the misfire detection is stopped with respect to the rested cylinder, and the misfire detection of the rested cylinder is canceled. When the first group cylinder is rested, the misfire detection is performed only for the third and fourth cylinders of the combustion-operated second group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting misfire of an internal combustion engine, and more particularly to an apparatus for detecting misfire of an internal combustion engine that stops a part of a plurality of cylinders in a predetermined operating state.

[0002]

2. Description of the Related Art Conventionally, a technique has been proposed in which a part of a plurality of cylinders is deactivated in a low load operation state to improve fuel efficiency.
The technology described in Japanese Patent No. 17463 can be cited.

[0003]

However, if a misfire occurs during the operation of the internal combustion engine, the operating performance and the fuel efficiency are deteriorated, and the unburned gas generates afterfire in the exhaust system. Has a negative effect.
In addition, there is a possibility that a failure has occurred in the fuel supply system or the ignition system due to the occurrence of the misfire. In that sense, it is desirable to detect early when the misfire occurs.

However, in the above-mentioned internal combustion engine in which a part of the plurality of cylinders is deactivated, combustion is deliberately deactivated in the deactivated cylinder. Therefore, if misfire detection is performed in this type of engine, the deactivated cylinder will fail due to a failure. There is a possibility of misjudging the cylinder.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned inconvenience, and to provide a misfire detection device for an internal combustion engine which accurately detects a misfire in an internal combustion engine in which a part of a plurality of cylinders is stopped. It is in.

[0006]

According to a first aspect of the present invention, there is provided a vehicle having a plurality of cylinders, wherein a plurality of cylinders are deactivated in a predetermined operation state. A misfire detecting means for detecting a misfire occurring in the internal combustion engine for each cylinder, a cylinder deactivation determining means for determining whether or not a part of the plurality of cylinders is deactivated, and When it is determined that the unit is at rest, the misfire detection invalidating means for invalidating the misfire detection of the cylinder at rest is provided.

Here, "invalidating misfire detection" means that misfire detection itself is stopped for a deactivated cylinder, or misfire detection is also performed for a deactivated cylinder, but the misfire determination threshold value of the combustion operation cylinder is set. All operations that do not mistakenly recognize a paused cylinder as a misfire cylinder, such as increasing it to make it difficult to detect a misfire, or performing a misfire detection on a paused cylinder, but ignoring a misfire even if a misfire is detected Used to mean including

[0008] Further, the term "misfire" refers to a case where combustion does not occur regardless of whether a fuel supply system failure or an ignition system failure has occurred, and whether or not spark discharge has occurred. It is used in the meaning including all.

Thus, in the internal combustion engine in which a part of the plurality of cylinders is deactivated, even if the deactivated cylinder intentionally deactivates the combustion, the deactivated cylinder is not erroneously determined as a misfire cylinder due to a failure. Accordingly, misfire detection can be accurately performed in such an internal combustion engine.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall view schematically showing a misfire detection apparatus for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 10 denotes a main body of an OHC in-line four-cylinder internal combustion engine (hereinafter referred to as "engine").
For simplicity, only one of the four cylinders is shown. The intake air sucked from the air cleaner 14 disposed at the tip of the intake pipe 12 flows through the intake manifold (intake manifold) 18 while its flow rate is adjusted by the throttle valve 16, and flows to the intake valve 22 of each cylinder 20.

An injector (fuel injection valve) 24 is provided upstream of the intake valve 22, and injects fuel pumped from a fuel supply system (not shown). When the intake valve 22 is opened, the air-fuel mixture that has been injected and integrated with the intake air flows into the combustion chambers 28 of the respective cylinders 20, and the first and the second ignition plugs 30 are disposed at positions facing the combustion chambers 28. 3, fourth,
It is ignited by spark discharge in the order of the second cylinder, burns, and drives a piston (not shown).

The exhaust gas after combustion flows through an exhaust valve (not shown) and an exhaust manifold 32 to an exhaust pipe (not shown), where it is purified by a catalytic device (not shown) and released to the atmosphere.

In the engine body 10, the camshaft 3
4, a camshaft sensor 36 is arranged to output a signal corresponding to the piston crank angle position, and a water temperature sensor 38 is arranged in the cooling water passage of the cylinder block to output a signal corresponding to the engine cooling water temperature TW. I do.

The throttle valve 16 of the intake pipe 12
Is provided downstream of the throttle valve, outputs a signal corresponding to the absolute pressure of the intake pressure PBA downstream of the throttle valve, and a throttle opening sensor 42 is connected to the throttle valve 16 to control the throttle opening θTH. Outputs the corresponding signal.

Further, an O ₂ sensor (not shown) is arranged downstream of the catalyst device in the exhaust system, and outputs a signal corresponding to the oxygen concentration in the exhaust gas.

These sensor outputs are sent to an ECU (electronic control unit) 52.

The ECU 52 comprises a microcomputer having a CPU, a ROM, a RAM (not shown) and the like.
The output of the camshaft sensor 36 is counted in the ECU 52 to calculate the engine speed NE.

In the ECU 52, the CPU searches a map previously set in the ROM based on the detected engine speed NE and the intake pipe absolute pressure PBA (engine load parameter), and determines a basic fuel injection amount (fuel injection). (Indicated by the valve opening time) and the basic ignition timing,
The output fuel injection amount and the output ignition timing are calculated by correcting the basic value calculated from the engine coolant temperature TW and the like.

The CPU, via an output circuit and a drive circuit (both not shown), a time injector 24 corresponding to the output fuel injection amount calculated in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder. At the same time, a spark discharge is generated in the spark plug 30 at a crank angle corresponding to the output ignition timing via an igniter (not shown) to ignite and burn the air-fuel mixture.

In the illustrated engine 10, fuel injection and ignition to two of the four cylinders are stopped in a predetermined operating state.

That is, the cylinders 20 are divided into a first group of cylinders including a first cylinder and a second cylinder, and a second group of cylinders including a third cylinder and a fourth cylinder. The CPU determines from the detected engine speed NE and the absolute pressure PBA in the intake pipe whether or not the engine is in a low-load operation state in which the cylinder can be operated in a deactivated state. Pause injection and ignition.

Therefore, no fuel injection is performed and no ignition is performed in the idle cylinder, so that no combustion occurs in the idle cylinder, and thus no misfire occurs.

Next, the operation of this apparatus will be described with reference to the flow chart of FIG.

In the following, it is determined in S10 whether a misfire detection start condition is satisfied.

In this embodiment, the misfire detection is
This is performed based on the method proposed by the present applicant in Japanese Patent Laid-Open No. Hei 6-93919.

That is, the average value FM (n) of the engine speed NE for each of the first, third, fourth, and second cylinders during each ignition cycle (crank angle of 180 degrees) is calculated. The difference (change amount) ΔM (n) from the calculated value (the previous ignition cylinder) FM (n−1) is calculated. ΔM (n) = FM (n) −FM (n−1)

Next, the calculated change amount ΔM (n) is compared with a misfire determination threshold value (negative predetermined value) MSLMT, and ΔM
Is greater than or equal to the absolute value of MSLMT, it is determined that the previous ignition cylinder has misfired.

As described above, the term “misfire” means that combustion occurs regardless of whether a fuel supply system failure or ignition system failure has occurred, and whether or not spark discharge has occurred. This includes all cases that do not occur.

For example, a case where misfire detection is performed for the third cylinder will be described. An average value FM (n) is calculated in the ignition cycle of the fourth cylinder, and the ignition cycle of the third cylinder is calculated from the calculated value FM (n). The difference ΔM (n) is calculated by subtracting the average value FM (n−1) obtained in
SLMT is compared with the absolute value, and when ΔM (n) is determined to be equal to or greater than MSLMT, it is determined that the third cylinder has misfired.

Accordingly, the misfire detection start condition in S10 is determined in more detail by judging whether or not the engine 10 is not in cranking during start-up in which rotation is not stable.
If it is determined that cranking is not being performed, it is determined that the misfire detection start condition in S10 is satisfied.

Then, the program proceeds to S12, in which it is determined whether or not the cylinder is in the cylinder deactivation mode. This is done by referring to the appropriate flag bits.

When the result in S12 is affirmative, the program proceeds to S14,
According to the above-described method, misfire detection is performed for cylinders other than the deactivated cylinders using the misfire determination threshold value MSLMT. In other words, by stopping the misfire detection for the deactivated cylinder,
Disables misfire detection of idle cylinders.

Therefore, when the first group of cylinders is inactive, misfire detection is performed only for the third and fourth cylinders of the second group of cylinders that are operated for combustion.

The detection of a misfire of the third cylinder will be described as an example. First cylinder deactivation, third cylinder operation, fourth cylinder operation, second cylinder
Since the cylinder is at rest, the average value FM (n) is calculated at the ignition cycle of the fourth cylinder for the misfire detection of the third cylinder, and the difference from the previous calculated value (of the third cylinder) FM (n-1) is calculated. (Change amount) ΔM is calculated and a misfire determination threshold value (negative predetermined value) M
The determination is made by comparing the absolute value with SLMT. The same goes for the misfire detection of the fourth cylinder.

If a misfire is detected, an operation such as incrementing a misfire counter of the cylinder is performed as necessary.

On the other hand, when the result in S12 is NO, the program proceeds to S16, where 4 is calculated using the above-mentioned misfire determination threshold value MSLMT.
Misfire detection is performed for all the cylinders, and operations such as incrementing the misfire counter of the misfire detection cylinder are performed as necessary.

In this embodiment, as described above, misfire detection is performed only for the combustion operating cylinders other than the idle cylinders.
In other words, the misfire detection of the deactivated cylinder is stopped by canceling the detection of the misfire of the deactivated cylinder.Therefore, in the engine that deactivates a part of the plurality of cylinders, the combustion is intentionally deactivated in the deactivated cylinder. However, the inactive cylinder is not erroneously determined as a misfire cylinder due to a failure. Therefore, misfire detection can be accurately performed in such an engine.

FIG. 3 is a flowchart similar to FIG. 2, for explaining the operation of the apparatus according to the second embodiment of the present invention.

In the following, it is determined in S100 whether or not the misfire detection start condition is satisfied in the same manner as in the first embodiment. If the determination is affirmative, the process proceeds to S102 to determine whether or not the cylinder deactivation mode is set. .

When the result in S102 is affirmative, the program proceeds to S104, in which the misfire determination threshold value MSLMT for the deactivated cylinder (for example, the first group cylinder) is increased or an infinite value MSLMT # is used.

In other words, the misfire determination threshold value MSLMT
Is set to a large value MSLMT # so that misfire is not determined for the deactivated cylinder, thereby invalidating misfire detection of the deactivated cylinder.

To explain the detection of misfire in the first cylinder as an example, an average value FM (n) is calculated in the ignition cycle of the third cylinder.
A difference (change amount) ΔM from a previously calculated value (of the first cylinder) FM (n−1) is calculated, and the increased misfire determination threshold value MS is calculated.
Judgment is made by comparing LMT∞ with the absolute value.

In this case, when the first cylinder is at rest, there is a high possibility that .DELTA.M will be equal to or larger than the normal threshold value MSLMT in absolute value, but the value MSL with the increased threshold value is high.
Since MT∞, the first cylinder is not determined to be misfired.

For the other combustion operation cylinders, the normal misfire determination threshold value MSL used in the first embodiment is used.
Misfire detection is performed using MT.

At the same time, if necessary, work such as incrementing the misfire counter is performed. If the result in S102 is NO, the program proceeds to S106, in which misfire detection is performed for all cylinders using the normal misfire determination threshold value MSLMT, and work such as incrementing a misfire counter is performed as necessary.

In the second embodiment, as described above, the misfire detection of the idle cylinder is made invalid by increasing the misfire determination threshold value of the idle cylinder to perform the misfire detection.
The same operation and effect as those of the embodiment can be obtained.

As described above, in the first and second embodiments, an internal combustion engine (engine 10) having a plurality of cylinders 20 and suspending a part of the plurality of cylinders in a predetermined operating state. A misfire detection means (ECU5) for detecting misfires occurring in the internal combustion engine for each cylinder.
2, S16, S106), cylinder deactivation determining means (ECU 5) for determining whether or not some of the plurality of cylinders are deactivated.
2, S12, S102), and when it is determined that some of the plurality of cylinders are inactive, misfire detection invalidating means (EC) for invalidating misfire detection of the inactive cylinders
U52, S14, S104).

In the above description, the detection of misfire in the deactivated cylinder is stopped, or the detection of misfire in the deactivated cylinder is performed.
Although the misfire detection of the deactivated cylinder is invalidated by using the increased misfire determination threshold value MSLMT∞, other than the above, the deactivated cylinder also has the same threshold value MSLMT as the combustion operation cylinder.
May be used to detect misfire, and if misfire is detected, the determination result may be forcibly rewritten or ignored so that misfire was not detected.

In the above description, the misfire was detected from the fluctuation of the engine speed. In addition, the misfire was detected by detecting the voltage waveform proposed by the present applicant in, for example, JP-A-5-223050. May be used,
Further, other methods may be used.

In any case, a method of detecting misfire, that is, whether combustion has not occurred regardless of whether spark discharge has occurred or not due to the fuel supply system or the ignition system. Anything is acceptable.

In the above description, the fuel injection and the ignition are simply stopped when the cylinder is deactivated. However, as described in the above-mentioned prior art (Japanese Patent Application Laid-Open No. Hei 7-217463), an intake control valve is provided. May be. Alternatively, the operation of the intake valve may be stopped using a variable valve timing mechanism proposed by the present applicant in Japanese Patent Application Laid-Open No. 2-275043.

[0054]

According to the first aspect of the present invention, in an internal combustion engine in which part of a plurality of cylinders is deactivated, even if the deactivated cylinder intentionally deactivates combustion, the deactivated cylinder is mistaken for a misfired cylinder due to a failure. There is no judgment. Accordingly, misfire detection can be accurately performed in such an internal combustion engine.

[Brief description of the drawings]

FIG. 1 is an overall view schematically showing a misfire detection device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart showing the operation of the apparatus in FIG. 1;

FIG. 3 is a flowchart similar to FIG. 2, showing the operation of the device according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 internal combustion engine (engine) 20 cylinder 22 intake valve 24 injector 28 combustion chamber 30 spark plug 34 camshaft sensor 52 ECU

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryuji Kono 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G084 AA03 BA00 BA13 BA16 BA23 DA04 DA27 EA11 EB12 EB22 EC04 FA00 FA11 FA20 FA24 FA33 FA34 FA38 3G092 AA01 AA13 BA08 BB01 CA04 CB05 DA01 DA03 DC01 EA09 EC01 FB06 HA05Z HC06Z HE00Z HE01Z HE02Z HE03Z HE05Z HE08Z

Claims (1)

[Claims] An internal combustion engine having a plurality of cylinders, wherein a part of the plurality of cylinders is deactivated in a predetermined operating state, comprising: a. Misfire detecting means for detecting a misfire occurring in the internal combustion engine for each cylinder; b. Cylinder deactivation determining means for determining whether or not some of the plurality of cylinders are deactivated, and c. A misfire detection invalidating means for invalidating misfire detection of the deactivated cylinder when it is determined that a part of the plurality of cylinders is deactivated. .