JP4827022B2 - Misfire detection device for internal combustion engine - Google Patents

Description

  The present invention relates to a misfire detection device for an internal combustion engine that determines the presence or absence of misfire in each cylinder of the internal combustion engine based on the rotational speed fluctuation amount of the internal combustion engine.

  This type of misfire detection device for an internal combustion engine, for example, as described in Patent Document 1 (Japanese Patent No. 2982381), is a rotational speed fluctuation amount (hereinafter referred to as “first engine”) between two cylinders in which a combustion stroke continues. (Referred to as “rotational speed fluctuation amount”) based on the detection value of the rotational speed detection means, and combustion strokes 360 ° C. ahead of the combustion strokes of the two cylinders for which the first rotational speed fluctuation amount is calculated. A rotational speed fluctuation amount between two consecutive cylinders (hereinafter referred to as “second rotational speed fluctuation amount”) is calculated based on a detection value of the rotational speed detection means, and the first rotational speed fluctuation amount and the second rotational speed are calculated. In some cases, the difference between the rotational speed fluctuation amount and the misfire determination threshold value is compared to determine the presence or absence of misfire.

In general, during operation of an internal combustion engine, rotational fluctuation tends to be detected at a cycle of 360 ° C. due to mechanical backlash and deformation of the crankshaft, manufacturing variation of the rotational speed detection means (crank angle sensor), and the like. Therefore, the second rotational speed fluctuation amount, which is the rotational speed fluctuation amount between the two cylinders, each of which has a combustion stroke of 360 ° C. before the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount is calculated, is The difference obtained by subtracting the second rotation speed fluctuation amount from the first rotation speed fluctuation amount is used as a parameter for eliminating an error caused by the rotation fluctuation of the 360 ° C. period included in the first rotation speed fluctuation amount. By using the value, an error due to the rotational fluctuation of the 360 ° C. cycle is removed from the first rotational speed fluctuation amount.
Japanese Patent No. 2982381

  By the way, in the case of a four-cylinder internal combustion engine, the first rotational speed fluctuation amount is ωn−1−ωn, and the second rotational speed fluctuation amount is ωn−3−ωn-2. The rotational speed fluctuation amount of 1 is ωn−1−ωn, and the second rotational speed fluctuation amount is ωn−4−ωn−3. Where ωn is the current rotational speed, ωn-1 is the rotational speed before the first combustion stroke, ωn-2 is the rotational speed before the second combustion stroke, ωn-3 is the rotational speed before the third combustion stroke, and ωn-4 is 4 Rotational speed before the combustion stroke.

For example, in the case of a 6-cylinder internal combustion engine, the difference value Δωn between the first rotation speed fluctuation amount and the second rotation speed fluctuation amount is calculated by the following equation.
Δωn = (ωn-1 −ωn) − (ωn-4 −ωn-3)

  In the above equation, if the cylinder before the 4th combustion stroke (before 480 ° C A) has misfired, the rotational speed ωn-4 before the 4th combustion stroke decreases, so the current difference value Δωn increases. As a result, there is a possibility that it is erroneously determined that the cylinder in the current combustion stroke has misfired despite being normally ignited.

As a countermeasure, in another embodiment described in Patent Document 1, in the case of a 6-cylinder internal combustion engine, a difference value Δωn + 4 after 4 combustion strokes (after 480 ° C. A) is calculated, and the current difference value is calculated. When both Δωn and the difference value Δωn + 4 after the four combustion strokes are larger than the misfire determination threshold, a misfire is determined (Δωn> misfire determination threshold and Δωn + 4> misfire determination threshold). If it is a value, it is determined as misfire).
Δωn + 4 = (ωn + 3 −ωn + 4) − (ωn −ωn + 1)

In the case of a four-cylinder internal combustion engine, misfire may be determined when the current difference value Δωn and the difference value Δωn + 3 after three combustion strokes (after 540 ° C. A) are both greater than the misfire determination threshold value. .
Δωn + 3 = (ωn + 2 −ωn + 3) − (ωn −ωn + 1)

  However, according to the recent inventor's research results, even in the misfire detection method, depending on the rotational fluctuation behavior at the time of misfire, the type and structure of the transmission, the mounting position of the rotation speed detection means (crank angle sensor), etc., It has been found that misfires may not be detected accurately. The reason for this will be described with reference to FIGS.

  4 and 5 are examples in which one cylinder intermittently misfires in a four-cylinder internal combustion engine. FIG. 4 is an example in which misfire can be detected by the prior art, and FIG. This is an example that cannot be detected.

  When misfire can be detected, as shown in FIG. 4, since the rotational speed ω that has fallen due to the misfire of the current cylinder immediately increases due to the ignition of the cylinder in the next combustion stroke, the current difference value Δωn and the three combustion strokes Both later (after 540 ° C. A) difference values Δωn + 3 become larger than the misfire determination threshold, and misfire can be detected.

  On the other hand, as shown in FIG. 5, the rotational speed ω that has fallen due to the misfire of the cylinder this time does not increase so much even if the cylinder in the next combustion stroke normally ignites, and the increase in the rotational speed ω after the misfire is slow. May be. In such a case, only the current difference value Δωn increases, and the difference value Δωn + 3 after the third combustion stroke (after 540 ° C. A) does not increase, so the difference value after the third combustion stroke (after 540 ° C. A) Δωn + 3 falls below the misfire judgment threshold, and misfire cannot be detected.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide a misfire detection apparatus for an internal combustion engine that can detect misfire more accurately than in the past for each combustion stroke of each cylinder.

In order to achieve the above object, the invention according to claim 1 is the rotational speed fluctuation means between the rotational speed detecting means for detecting the rotational speed of the internal combustion engine, and the cylinder subject to misfire detection and the cylinder in which the combustion stroke continues. A first rotation speed fluctuation amount calculating means for calculating an amount (hereinafter referred to as “first rotation speed fluctuation amount”) based on a detection value of the rotation speed detection means, and calculating the first rotation speed fluctuation amount. The rotational speed fluctuation amount between the two cylinders in which the combustion stroke before 360 ° C. before the combustion stroke of the two cylinders continues (hereinafter referred to as “second rotational speed fluctuation amount”) is detected by the rotational speed detecting means. And determining whether or not a misfire detection target cylinder is misfired based on the first rotation speed fluctuation amount calculating means and the first rotation speed fluctuation amount and the second rotation speed fluctuation amount. Internal combustion engine having misfire determination means In the misfire detecting device, the misfire determining means, as a condition of the second engine speed variation (claim to eliminate errors due to rotation fluctuation of 360 ° C. A period) is not a factor in false detection of misfire, the second If the condition that the rotational speed fluctuation amount is smaller than the first rotational speed fluctuation amount and the condition is satisfied, then based on the first rotational speed fluctuation amount and the second rotational speed fluctuation amount is set. The presence or absence of misfire in the cylinder that is the misfire detection target is determined.

  According to this configuration, the second rotation speed fluctuation amount (a term that eliminates an error due to rotation fluctuation at a period of 360 ° C.) is included in the first rotation speed fluctuation amount in a range that does not cause misdetection of misfire. Since it is possible to determine whether or not misfiring has occurred by eliminating the error due to the rotational fluctuation of the 360 ° C. cycle by the second rotational speed fluctuation amount, when the cylinder in the combustion stroke before 540 ° C. is misfiring, In addition to preventing misjudgment of misfiring, as shown in FIG. 5, even if the increase in rotational speed that has fallen due to the misfiring of this cylinder becomes slow, the misfiring of this cylinder can be prevented. Thus, it is possible to detect misfire for each combustion stroke of each cylinder with higher accuracy than before.

In general, in consideration of the fact that the error due to the rotational fluctuation of the 360 ° C. cycle is smaller than the rotational speed fluctuation amount due to misfire, in the invention according to claim 1 , the second rotational speed fluctuation amount is an erroneous detection of misfire. conditions that do not factor, are the second rotational speed fluctuation amount is smaller than the first engine speed variation as a condition. As a result, misdetection of misfire due to the influence of the second rotational speed fluctuation amount can be prevented in advance.

Alternatively, as in claim 2 , the condition that the second rotational speed fluctuation amount does not cause a misdetection of misfire is that the ratio between the second rotational speed fluctuation amount and the first rotational speed fluctuation amount is a predetermined value. The following conditions may be used. Even in this case, it is possible to prevent erroneous detection of misfire due to the influence of the second rotational speed fluctuation amount.

Further, as in claim 3 , the conditions under which the second rotational speed fluctuation amount does not cause misdetection of misfire are the difference value between the first rotational speed fluctuation amount and the second rotational speed fluctuation amount, It is good also as a condition that ratio with 1 rotation speed fluctuation amount is below a predetermined value. Even in this case, it is possible to prevent erroneous detection of misfire due to the influence of the second rotational speed fluctuation amount.

  Hereinafter, an embodiment in which the best mode for carrying out the present invention is applied to an intake port injection type internal combustion engine will be described.

First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine having four or more cylinders, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 15 whose opening is adjusted by a DC motor or the like and a throttle opening sensor 16 for detecting the throttle opening are provided.

  A surge tank 17 is provided downstream of the throttle valve 15, and an intake pipe pressure sensor 18 that detects the intake pipe pressure is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. Yes.

  A spark plug 21 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated by an ignition coil (not shown) is applied to the spark plug 21 of each cylinder in synchronization with the ignition timing. The mixture in the cylinder is ignited.

  On the other hand, the exhaust pipe 22 of the engine 11 is provided with a catalyst 23 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas, and the exhaust gas air-fuel ratio or lean is provided upstream of the catalyst 23. / An exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting rich or the like is provided. Further, a water temperature sensor 25 for detecting the coolant temperature and a crank angle sensor 26 (rotation speed detecting means) for outputting a pulse signal each time the crankshaft of the engine 11 rotates by a predetermined crank angle are attached to the cylinder block of the engine 11. The engine rotation speed is detected from the output period (output interval) of the pulse signal of the crank angle sensor 26.

  A cam angle sensor 27 that outputs a reference position signal (cylinder discrimination signal) at a reference position in synchronization with rotation of the camshaft is attached to the cylinder head of the engine 11, and a reference position signal from the cam angle sensor 27 is attached. The crank angle is detected based on the count value of the pulse signal of the crank angle sensor 26, and cylinder discrimination is performed.

  These various sensor outputs are input to an engine control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control routines stored in a built-in ROM so that the fuel injection amount of the fuel injection valve 20 and the spark plug 21 are controlled according to the engine operating state. Control ignition timing.

  Further, the ECU 28 executes the misfire determination routine of FIG. 2 or FIG. 3 described later during engine operation, thereby detecting the engine rotation speed detected for each combustion stroke of each cylinder (required to rotate a predetermined crank angle). Time) and calculating a rotational speed fluctuation amount (hereinafter referred to as “first rotational speed fluctuation amount”) between the cylinder in the current combustion stroke to be detected for misfire and the cylinder before the one combustion stroke, The rotational speed fluctuation amount between two cylinders (hereinafter referred to as “second rotational speed fluctuation amount”) in which the combustion stroke before 360 ° C. is continued from the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount is calculated. Based on the difference value between the first rotational speed fluctuation amount and the second rotational speed fluctuation amount in consideration of the condition that the second rotational speed fluctuation amount does not cause misdetection of misfire. The current combustion line subject to misfire detection It determines the presence or absence of a misfire of the cylinder, at the time of misfire detection or lighting a warning lamp 29, or a warning of misfire warning display unit of the instrument panel (not shown).

  In general, during engine operation, the rotational speed tends to be detected at a cycle of 360 ° C. due to mechanical backlash and deformation of the crankshaft, manufacturing variation of the crank angle sensor 26, and the like. The second rotational speed fluctuation amount, which is the rotational speed fluctuation amount between the two cylinders in which the combustion stroke before 360 ° C. continues before the combustion stroke of the two cylinders for which the fluctuation amount is calculated, is the first rotational speed fluctuation. It is a parameter that reflects an error due to rotational fluctuation of a 360 ° C. period included in the quantity.

  From this characteristic, in the above-described prior art (Patent Document 1), by using a difference value obtained by subtracting the second rotational speed fluctuation amount from the first rotational speed fluctuation quantity, 360 ° C. from the first rotational speed fluctuation amount. The error due to the rotational fluctuation of the A cycle is to be eliminated, but if the presence or absence of misfire is judged by comparing only the current difference value with the misfire judgment threshold value, the combustion stroke before 540 ° C. A (in the case of four cylinders) When the cylinder is misfired, the rotational speed before 540 ° C. is reduced, and thus the current difference value is increased. As a result, the cylinder in the current combustion stroke is ignited normally. There is a possibility of misjudging that it has misfired.

  As a countermeasure against this, in another embodiment described in Patent Document 1 described above, as shown in FIG. 4, the current difference value and the difference value after 540 ° C. A (in the case of four cylinders) are both determined as misfires. In this misfire detection method, misfire is detected accurately depending on the rotational fluctuation behavior at the time of misfire, the type and structure of the transmission, the mounting position of the crank angle sensor 26, and the like. May not be detected. For example, as shown in FIG. 5, when the rotational speed that has fallen due to the misfire of the cylinder this time does not increase much even if the cylinder in the next combustion stroke ignites, and the increase in the rotational speed after the misfire becomes slow Only the difference value this time becomes large, and the difference value after 540 ° C. A does not become large, so the difference value after 540 ° C. A falls below the misfire determination threshold value, and misfire cannot be detected.

  Therefore, in the present embodiment, by executing the misfire determination routine of FIG. 2 or FIG. 3, the second rotational speed fluctuation amount (a term that eliminates an error due to a rotational fluctuation of a 360 ° C. A cycle) is detected as misfire detection. The presence or absence of misfiring of the cylinder in the current combustion stroke, which is a misfire detection target, is determined based on the difference value between the first rotational speed fluctuation amount and the second rotational speed fluctuation amount in consideration of a condition that does not become a factor.

  In this case, considering that the error due to the rotational fluctuation of the 360 ° C. period is smaller than the rotational speed fluctuation amount due to misfire, the condition under which the second rotational speed fluctuation amount does not cause misdetection of misfire is ( 1) On condition that the second rotational speed fluctuation amount is smaller than the first rotational speed fluctuation amount, or (2) the ratio between the second rotational speed fluctuation amount and the first rotational speed fluctuation amount. Is equal to or less than a predetermined value, or (3) the ratio between the difference between the first rotational speed fluctuation amount and the second rotational speed fluctuation amount and the first rotational speed fluctuation amount is It is good also as conditions that it is below a predetermined value. In short, the influence of the second rotation speed fluctuation amount on the difference value between the first rotation speed fluctuation amount and the second rotation speed fluctuation amount is small (in other words, the influence of the first rotation speed fluctuation amount is large). It is sufficient to use a condition that can be determined.

  The misfire determination of the present embodiment described above is executed by the ECU 28 according to the misfire determination routine of FIG. 2 or FIG. The misfire determination routine of FIG. 2 is used for the misfire determination of the 4-cylinder engine, and the misfire determination routine of FIG. 3 is used for the misfire determination of the 6-cylinder engine.

  The misfire determination routines of FIGS. 2 and 3 are started by interruption processing, for example, every 30 ° C. based on the pulse signal of the crank angle sensor 26, and serve as misfire determination means in the claims. When the misfire determination routine of FIG. 2 and FIG. 3 is started, first, in step 101, the time required for the crankshaft to rotate 30 ° C. from the difference between the previous interrupt time and the current interrupt time of this routine. T30i is calculated.

  Thereafter, the routine proceeds to step 102, where the current interrupt timing is the TDC (top dead center), which is the start timing of the combustion stroke, based on the reference position signal of the cam angle sensor 27 and the count value of the pulse signal of the crank angle sensor 26. If the current interrupt timing is not TDC, this routine is terminated without performing the subsequent processing.

  On the other hand, if it is determined in step 102 that the current interrupt timing is TDC, the misfire determination process in step 103 and subsequent steps is executed as follows.

  First, in step 103, in the case of a four-cylinder engine, a time T180i required to rotate 180 ° C. corresponding to the crank angle section of the combustion stroke is calculated (in the case of a six-cylinder engine, the combustion stroke Time T120i required to rotate 120 ° C. corresponding to the crank angle section is calculated).

  Note that the time required to rotate a part of the crank angle section of the combustion stroke (a crank angle section of an arbitrary integer multiple of 30 ° C.) may be calculated. The section may be changed according to the engine operating state such as the engine speed. Also, the time measurement start timing is not limited to TDC, and time measurement may be started from ATDC 30 ° C., for example.

Thereafter, the routine proceeds to step 104, where the crank angular speed ωn (corresponding to the rotational speed in the claims) is calculated from the time T180i (or T120i) required to rotate the 180 ° C. A (or 120 ° C. A). .
For a 4-cylinder engine: ωn = 180 / T180i
For a 6-cylinder engine: ωn = 120 / T120i
The processing in steps 103 and 104 serves as a rotational speed detection means in the claims.

  After that, the routine proceeds to step 105, where the first rotational speed fluctuation amount (ωn-1 −), which is the rotational speed fluctuation amount between the cylinder in the current combustion stroke that is the target of misfire detection and the cylinder before the one combustion stroke. ωn) and the second rotational speed fluctuation amount between the two cylinders in which the combustion stroke before the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount has been calculated is 360 ° C. A before. (4 for a 4-cylinder engine: ωn-3-ωn-2, for a 6-cylinder engine: ωn-4-ωn-3), and a difference value Δωn between them is calculated.

For a 4-cylinder engine: Δωn = (ωn-1 -ωn)-(ωn-3 -ωn-2)
In the case of a 6-cylinder engine: Δωn = (ωn-1−ωn) − (ωn-4−ωn-3)
The processing in step 105 serves as first rotation speed fluctuation amount calculation means and second rotation speed fluctuation amount calculation means in the claims.

Thereafter, the process proceeds to step 106, in which it is determined whether or not the second conditional expression for preventing the second rotational speed fluctuation amount from causing erroneous detection of misfire is satisfied.
For a 4-cylinder engine: (ωn-1 −ωn)> − (ωn-3 −ωn-2)
For 6-cylinder engine: (ωn-1 −ωn)> − (ωn-4 −ωn-3)
That is, the condition that the second rotational speed fluctuation amount does not cause misdetection of misfire is that the second rotational speed fluctuation amount is smaller than the first rotational speed fluctuation amount.

Alternatively, instead of the above conditional expression, it may be determined whether or not the second rotational speed fluctuation amount causes a misdetection of misfire depending on whether or not the following conditional expression is satisfied.
For a 4-cylinder engine: (ωn-1 −ωn)> − (ωn-3 −ωn-2) × α
For 6-cylinder engine: (ωn-1 −ωn)> − (ωn-4 −ωn-3) × α
[Α: Predetermined value (for example, a value of 1 or more)]
That is, the condition that the second rotational speed fluctuation amount does not cause a misdetection of misfire is that the ratio of the second rotational speed fluctuation amount and the first rotational speed fluctuation amount is a predetermined value (1 / α) or less. This may be a condition.

Alternatively, it may be determined whether or not the second rotational speed fluctuation amount causes misdetection of misfire depending on whether or not the following conditional expression is satisfied.
(Ωn-1 −ωn)> Δωn × β
Here, β is a predetermined value (for example, a value of 0.5 or more). The above conditions are common regardless of the number of cylinders.

  That is, the conditions under which the second rotational speed fluctuation amount does not cause misdetection of misfire are the difference value Δωn between the first rotational speed fluctuation amount and the second rotational speed fluctuation amount, and the first rotational speed fluctuation amount. The ratio of (ωn−1−ωn) may be a condition that the ratio is equal to or less than a predetermined value (1 / β).

  In short, the influence of the second rotational speed fluctuation amount on the difference value Δωn between the first rotational speed fluctuation quantity and the second rotational speed fluctuation quantity is small (in other words, the influence of the first rotational speed fluctuation amount is large). It is sufficient to use a conditional expression that can be determined.

  If it is determined in step 106 that the conditional expression is not satisfied, it is determined that the second rotational speed fluctuation amount causes a misdetection of misfire, and the process proceeds to step 109, where the misfire flag XMF is not misfired (ignition). Is maintained or reset to “0” which means

  On the other hand, if it is determined in step 106 that the conditional expression is satisfied, it is determined that the second rotational speed fluctuation amount does not cause misdetection of misfire, and the process proceeds to step 107, where the difference value If Δωn is compared with the misfire determination threshold value CK and the difference value Δωn is larger than the misfire determination threshold value CK, the routine proceeds to step 108, where it is determined that misfire has occurred, and the misfire flag XMF is set to “1” which means misfire. If the difference value Δωn is equal to or smaller than the misfire determination threshold value CK, it is determined that ignition (no misfire) occurs, and the process proceeds to step 109 to maintain or reset the misfire flag XMF to “0” meaning ignition. .

  In this case, when “1” is set in the misfire flag XMF, it is determined that there is a possibility that a malfunction such as deterioration of the emission or damage to the catalyst 23 may occur, and the warning lamp 29 is turned on.

  After setting / resetting the misfire flag XMF, the routine proceeds to step 110, where the past data of the crank angular speed ωn stored in the memory of the ECU 28 (for a four-cylinder engine: ωn to ωn-2, for a six-cylinder engine: ωn) .About..omega.n-3) are updated to the previous data, and this routine is terminated.

ωn-1 ← ωn
ωn-2 ← ωn-1
ωn-3 ← ωn-2
ωn-4 ← ωn-3

  According to the present embodiment described above, the first rotation speed is considered in consideration of the condition that the second rotation speed fluctuation amount (a term that eliminates the error due to the rotation fluctuation of the 360 ° C. A cycle) does not cause misdetection of misfire. Since the presence or absence of misfiring of the cylinder in the current combustion stroke, which is a misfire detection target, is determined based on the difference value between the speed fluctuation amount and the second rotational speed fluctuation amount, 540 ° C. A before (in the case of four cylinders) ) When the cylinder in the combustion stroke is misfired, it is possible to prevent a misjudgment that the current cylinder is misfired, and as shown in FIG. Even when the increase in the rotational speed becomes slow, it is possible to detect the misfire of the current cylinder, and it is possible to detect misfire more accurately than in the past for each combustion stroke of each cylinder.

  The present invention is not limited to 4-cylinder and 6-cylinder engines, and can be applied to multi-cylinder engines such as 8-cylinders and 12-cylinders.

  In addition, the present invention is not limited to the intake port injection type internal combustion engine as shown in FIG. 1, but is an in-cylinder injection type internal combustion engine, a fuel injection valve for intake port injection, and a fuel injection valve for in-cylinder injection. Needless to say, the present invention can be applied to a dual-injection internal combustion engine having both of the above and various modifications can be made without departing from the scope of the invention.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a flowchart which shows the flow of a process of the misfire determination routine for 4 cylinder engines. It is a flowchart which shows the flow of a process of the misfire determination routine for 6 cylinder engines. It is a time chart which shows the behavior of rotational speed (omega) and difference value (DELTA) omega for demonstrating the example (in the case of a 4-cylinder engine) which can detect misfire by a prior art. It is a time chart which shows the behavior of rotational speed (omega) and difference value (DELTA) omega for demonstrating the example (in the case of a 4-cylinder engine) which cannot detect misfire by a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 15 ... Throttle valve, 18 ... Intake pipe pressure sensor, 20 ... Fuel injection valve, 21 ... Spark plug, 22 ... Exhaust pipe, 26 ... Crank angle Sensor (rotation speed detection means), 28... ECU (misfire determination means, rotation speed detection means, first rotation speed fluctuation amount calculation means, second rotation speed fluctuation amount calculation means)

Claims (3)

Rotation speed detection means for detecting the rotation speed of the internal combustion engine;
A first calculation that calculates a rotational speed fluctuation amount (hereinafter referred to as “first rotational speed fluctuation amount”) between a cylinder that is a misfire detection target and a cylinder that has a continuous combustion stroke based on a detection value of the rotational speed detection means. Rotational speed fluctuation amount calculation means,
Rotational speed fluctuation amount between two cylinders (hereinafter referred to as “second rotational speed fluctuation amount”) in which the combustion stroke is 360 ° C. before the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount is calculated. 2) a second rotation speed fluctuation amount calculation means for calculating the rotation speed based on the detection value of the rotation speed detection means;
A misfire detection device for an internal combustion engine, comprising: misfire determination means for determining whether or not a misfire is detected in a cylinder to be misfired based on the first rotation speed fluctuation amount and the second rotation speed fluctuation amount;
The misfire determination means sets a condition that the second rotation speed fluctuation amount is smaller than the first rotation speed fluctuation amount as a condition that the second rotation speed fluctuation amount does not cause erroneous detection of misfire. And determining whether or not the misfire detection target cylinder is misfired based on the first rotation speed fluctuation amount and the second rotation speed fluctuation amount when the condition is satisfied. Misfire detection device. Rotation speed detection means for detecting the rotation speed of the internal combustion engine;
A first calculation that calculates a rotational speed fluctuation amount (hereinafter referred to as “first rotational speed fluctuation amount”) between a cylinder that is a misfire detection target and a cylinder that has a continuous combustion stroke based on a detection value of the rotational speed detection means. Rotational speed fluctuation amount calculation means,
Rotational speed fluctuation amount between two cylinders (hereinafter referred to as “second rotational speed fluctuation amount”) in which the combustion stroke is 360 ° C. before the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount is calculated. 2) a second rotation speed fluctuation amount calculation means for calculating the rotation speed based on the detection value of the rotation speed detection means;
Misfire determination means for determining whether or not the misfire detection target cylinder is misfired based on the first rotation speed fluctuation amount and the second rotation speed fluctuation amount;
In a misfire detection device for an internal combustion engine comprising:
In the misfire determination means, as a condition that the second rotational speed fluctuation amount does not cause misdetection of misfire, a ratio between the second rotational speed fluctuation amount and the first rotational speed fluctuation amount is a predetermined value or less. Is set, and when the condition is satisfied, the presence or absence of misfiring of the cylinder subject to misfire detection is determined based on the first rotational speed fluctuation amount and the second rotational speed fluctuation amount. misfire detecting device of the internal combustion engine you characterized. Rotation speed detection means for detecting the rotation speed of the internal combustion engine;
A first calculation that calculates a rotational speed fluctuation amount (hereinafter referred to as “first rotational speed fluctuation amount”) between a cylinder that is a misfire detection target and a cylinder that has a continuous combustion stroke based on a detection value of the rotational speed detection means. Rotational speed fluctuation amount calculation means,
Rotational speed fluctuation amount between two cylinders (hereinafter referred to as “second rotational speed fluctuation amount”) in which the combustion stroke is 360 ° C. before the combustion stroke of the two cylinders for which the first rotational speed fluctuation amount is calculated. 2) a second rotation speed fluctuation amount calculation means for calculating the rotation speed based on the detection value of the rotation speed detection means;
Misfire determination means for determining whether or not the misfire detection target cylinder is misfired based on the first rotation speed fluctuation amount and the second rotation speed fluctuation amount;
In a misfire detection device for an internal combustion engine comprising:
The misfire determination means includes a difference value between the first rotation speed fluctuation amount and the second rotation speed fluctuation amount as a condition that the second rotation speed fluctuation amount does not cause a misdetection of misfire, A condition is set such that a ratio with the first rotational speed fluctuation amount is a predetermined value or less, and the first rotational speed fluctuation amount and the second rotational speed fluctuation amount are satisfied based on the first rotational speed fluctuation amount when the condition is satisfied. misfire detecting device of the internal combustion engine you characterized by determining the presence or absence of misfire in the cylinder giving the misfire detected.

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