JP2766610B2 - Misfire detection device for internal combustion engine - Google Patents

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 an internal combustion engine, and more particularly to a misfire detection device for an internal combustion engine for detecting a misfire due to an abnormality in an ignition system, a fuel system, or the like of the internal combustion engine.

[0002]

2. Description of the Related Art A conventional misfire detection apparatus for an internal combustion engine is disclosed, for example, in Japanese Patent Application Laid-Open No. 2-414000. In this method, the rotation of the internal combustion engine is detected using a crank angle sensor, and misfire is determined based on rotation fluctuations caused by the presence or absence of misfire. In this misfire detecting device, a time ratio detecting means for detecting a time ratio of each required time of a predetermined angle section before and after the predetermined crank angle of the internal combustion engine as a reference, and an acceleration of the time ratio are obtained, and from this acceleration, A misfire determination means for determining misfire is provided, and the misfire determination means compares the acceleration with a predetermined value corresponding to a predetermined misfire to determine the presence or absence of misfire.

[0003]

However, in such a conventional apparatus, the method of determining misfire is a single method that does not distinguish between intermittent misfire and continuous misfire. influenced by the rotation fluctuations transmitted to the internal combustion engine via the tires when traveling road surface of a vehicle internal combustion engine is driven is not flat, there are problems such as erroneous misfire determination. Further, the like when the traveling road surface of a vehicle internal combustion engine is driven is not flat, the rotation fluctuations transmitted to the internal combustion engine via the tires is larger than the value corresponding to the misfire occurs in the internal combustion engine misfire It is difficult to discriminate between the fluctuation caused by the road and the fluctuation transmitted by the traveling road surface, and there is a problem that a misfire determination is erroneously made. Further, when the state of occurrence of misfire changes, or when the load or rotation speed of the internal combustion engine changes, there is a problem that misfire determination is erroneously made.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and distinguishes intermittently or continuously occurring misfires, improves the detectability thereof, and causes misfires on rough roads. It is an object of the present invention to provide a misfire detection device for an internal combustion engine that can prevent erroneous detection due to factors other than misfire.

[0005] The present invention also relates to an abrupt rotation fluctuation transmitted to an internal combustion engine when a vehicle travels on a road surface such as a rough road, or a vehicle traveling on an uneven road surface such as a wavy or stone pavement. It is an object of the present invention to obtain a misfire detection device for an internal combustion engine capable of distinguishing between a periodic rotation change transmitted to the internal combustion engine and a rotation variation caused by a misfire of the internal combustion engine and accurately detecting a misfire. And

Further, the present invention distinguishes intermittently or continuously occurring misfires, improves the detectability thereof, and changes the misfire determination value according to the load or the number of revolutions of the internal combustion engine to change the load or the like. The misfire detection of the internal combustion engine can be accurately performed by invalidating the misfire determination when the load or the rotation speed of the internal combustion engine is equal to or less than a predetermined value regardless of the fluctuation of the internal combustion engine. The aim is to obtain a device.

[0007]

According to a first aspect of the present invention, there is provided a misfire detection apparatus for an internal combustion engine which is connected to an internal combustion engine having a plurality of cylinders, and which determines a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A crank angle detecting means for detecting a position in a predetermined angle section before and after the reference crank angle as a reference; and a predetermined angle before and after the reference crank angle based on an output signal of the crank angle detecting means. An acceleration detecting means for detecting an acceleration of a time ratio of a required time of each section; and a misfire intermittently generated in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means. Is connected to the misfire detection means and the acceleration detection means, and the misfire continuously generated in each cylinder of the internal combustion engine based on the output signal of the acceleration detection means. It is obtained by a continuous misfire detecting means for detecting.

A misfire detecting apparatus for an internal combustion engine according to the invention is connected to an internal combustion engine having a plurality of cylinders, and a predetermined crank angle corresponding to each cylinder of the internal combustion engine is used as a reference. A crank angle detecting means for detecting a position of a predetermined angle section before and after the crank angle, and each of the predetermined angle sections before and after the reference crank angle are connected to the crank angle detecting means and based on an output signal of the crank angle detecting means. Acceleration detecting means for detecting an acceleration of a time ratio of the required time; and an intermittent detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means. Misfire detection means,
A continuous misfire detecting means connected to the acceleration detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; The misfire detection means is provided with a predetermined detection section, and when a misfire greater than a predetermined misfire determination value is detected in the detection section, it is determined that a misfire has occurred in the detection section.

A misfire detection apparatus for an internal combustion engine according to the invention is connected to an internal combustion engine having a plurality of cylinders, and a predetermined crank angle corresponding to each cylinder of the internal combustion engine is used as a reference. A crank angle detecting means for detecting a position of a predetermined angle section before and after the crank angle, and each of the predetermined angle sections before and after the reference crank angle are connected to the crank angle detecting means and based on an output signal of the crank angle detecting means. Acceleration detecting means for detecting an acceleration of a time ratio of the required time; and an intermittent detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means. Misfire detection means,
A continuous misfire detection means connected to the acceleration detection means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; the intermittent misfire detection means and the continuous misfire detection means The misfire detection signals corresponding to the respective cylinders detected by the intermittent misfire detection means and the continuous misfire detection means are respectively counted in predetermined detection sections, and when the count value is equal to or greater than a predetermined misfire determination value, A misfire determining means for determining that the cylinder has intermittently or continuously misfired.

A misfire detection apparatus for an internal combustion engine according to the invention is connected to an internal combustion engine having a plurality of cylinders, and the reference is made based on a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A crank angle detecting means for detecting a position of a predetermined angle section before and after the crank angle, and each of the predetermined angle sections before and after the reference crank angle are connected to the crank angle detecting means and based on an output signal of the crank angle detecting means. Acceleration detecting means for detecting an acceleration of a time ratio of the required time; and an intermittent detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means. Misfire detection means,
A continuous misfire detection means connected to the acceleration detection means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; the intermittent misfire detection means and the continuous misfire detection means The misfire detection signals corresponding to the respective cylinders detected by the intermittent misfire detection means and the continuous misfire detection means are respectively counted in predetermined detection sections, and when the count value is equal to or greater than a predetermined misfire determination value, A misfire determining means for determining that the cylinder is intermittently or continuously misfired, wherein the misfire determination means performs misfire determination in the detection section when the count value is equal to or greater than a predetermined misfire determination value in a plurality of cylinders. It is made invalid.

A misfire detection apparatus for an internal combustion engine according to the invention is connected to an internal combustion engine having a plurality of cylinders, and a predetermined crank angle corresponding to each cylinder of the internal combustion engine is used as a reference. Crank angle detecting means for detecting a position in a predetermined angle section before and after the crank angle, load detecting means connected to the internal combustion engine for detecting a load on the internal combustion engine, and crank angle detecting means connected to the crank angle detecting means; Acceleration detection means for detecting an acceleration of a time ratio of a required time in each of predetermined angle sections before and after the reference crank angle based on an output signal of the detection means, and an acceleration detection means connected to the crank angle detection means; A rotational speed detecting means for detecting a rotational speed of the internal combustion engine based on the output signal; and a rotational speed detecting means connected to the load detecting means, the acceleration detecting means, and the rotational speed detecting means. A misfire detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; and a load detection means, the acceleration detection means, and the rotation speed detection means. A continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means, wherein the intermittent misfire detecting means and the continuous misfire detecting means The misfire determination value is changed based on an output signal of the detection means or the rotation speed detection means.

According to a sixth aspect of the present invention, there is provided a misfire detecting apparatus for an internal combustion engine, wherein the intermittent misfire detecting means and the continuous misfire detecting means have output signals of a load detecting means or a rotational speed detecting means satisfying a predetermined condition. At this time, the misfire determination is invalidated.

[0013]

According to the first aspect of the present invention, intermittent misfires are detected for each cylinder by the intermittent misfire detection means, and continuous misfires are detected for each cylinder by the continuous misfire detection means. These misfire detecting means improve the detectability of the misfire by adopting an optimal detection method for each of the misfire patterns of the intermittent misfire and the continuous misfire, and determine the misfire occurrence rate in a predetermined section to determine the misfire, etc. Erroneous detection due to factors other than misfires caused by rotation fluctuations transmitted to the internal combustion engine via tires when the vehicle travels is eliminated, and misfires are detected accurately.

According to the second aspect of the present invention, the intermittent misfire is detected by the intermittent misfire detecting means for each cylinder, and the continuous misfire is detected for each cylinder by the continuous misfire detecting means. These misfire detection means provide a predetermined detection section, and when a misfire equal to or greater than a predetermined misfire determination value is detected in the detection section, determine that a misfire has occurred in the detection section, and enhance the misfire detectability. At the same time, erroneous detection due to factors other than misfire caused by rotation fluctuation transmitted to the internal combustion engine via tires when traveling on a bad road or the like is removed, and misfire is detected accurately.

In the invention according to claim 3, the intermittent misfire detecting means detects intermittently occurring misfires for each cylinder, and the continuous misfire detecting means detects continuous misfires for each cylinder. The misfire detection signal corresponding to each cylinder detected by each misfire detection means is counted in a predetermined detection section, and when the count value is equal to or greater than a predetermined misfire determination value, the cylinder is intermittently fired or continuously misfired. It is determined that a misfire has occurred. This makes it possible to improve the detectability of a misfire by adopting the detection method that is optimal for each of the misfiring patterns of the intermittent misfire and the continuous misfire, and to judge the misfire occurrence rate in each of the independently provided predetermined detection sections. Among misfires and continuous misfires, particularly, misfires can be easily identified during continuous misfires with few erroneous detections to improve the accuracy of misfire detection and suddenly transmitted to the internal combustion engine via tires when traveling on bad roads etc. This eliminates erroneous detections caused by factors other than misfires caused by dynamic rotation fluctuations, and accurately detects misfires.

In the invention according to claim 4, the intermittent misfire detected by the intermittent misfire detecting means is detected for each cylinder, and the continuous misfire detected by the continuous misfire detecting means is detected for each cylinder. The misfire detection signal corresponding to each cylinder detected by each misfire detection means is counted in a predetermined detection section, and when the count value is equal to or greater than a predetermined misfire determination value, the cylinder is intermittently fired or continuously misfired. When it is determined that a misfire has occurred and the count value is equal to or greater than a predetermined misfire determination value in a plurality of cylinders, the misfire determination in the detection section is invalidated. As a result, the misfire detection performance is improved, and when the vehicle travels on a rough road or the like, it is not only erroneously detected due to factors other than the misfire caused by sudden rotation fluctuation transmitted to the internal combustion engine through the tires when traveling on a rough road, but also on a wavy road. At this time, erroneous detection due to factors other than misfire caused by periodic rotation fluctuation transmitted to the internal combustion engine via the tire is also removed, and misfire is detected more accurately.

In the invention according to claim 5, intermittently occurring misfires are detected for each cylinder by intermittent misfire detection means, and continuous misfires are detected for each cylinder by continuous misfire detection means. When the operating condition changes, the misfire determination value is changed according to the load or the rotation speed of the internal combustion engine. This makes it possible to enhance the detectability of the misfire by adopting a detection method most suitable for each of the misfire patterns of the intermittent misfire and the continuous misfire, and to stably detect the misfire even when the operating conditions change.

In the invention according to claim 6, the intermittent misfire detection means and the continuous misfire detection means invalidate the misfire determination when the output signal of the load detection means or the rotation speed detection means satisfies a predetermined condition. I do. That is, if the load or the rotation speed of the internal combustion engine is equal to or less than a predetermined value, the misfire is invalidated.
Thus, in the unstable operation region where the signal for detecting misfire is small and the misfire determination is invalidated, misfire can be accurately detected.

[0019]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing one embodiment of the present invention. In the figure, M1 is an engine as an internal combustion engine having a plurality of cylinders, M2 is connected to the engine M1, and crank angle detecting means for detecting the position of a predetermined angle section before and after the predetermined crank angle of the engine M1,
M3 is connected to the crank angle detecting means M2, and the engine M based on the output signal of the crank angle detecting means M2.
The acceleration detecting means detects the acceleration of the time ratio of the required time of each section before and after the reference crank angle corresponding to each cylinder.

M4 is connected to the acceleration detecting means M3, and a misfire detecting means for detecting a misfire occurring intermittently in each cylinder of the engine M1 based on the acceleration detected by the acceleration detecting means M3. M5 is an acceleration detecting means M3. Connected to
From the acceleration detected by the acceleration detecting means M3, the engine M
This is a continuous misfire detection means for detecting misfires that continuously occur in each of the cylinders.

FIG. 2 is a block diagram showing one embodiment of the present invention which embodies FIG. In the drawing, 1 is an engine having cylinders 2 to 5 of # 1 to # 4, 6 is connected to a crankshaft or a camshaft of the engine 1, and each reference position of a crank angle corresponding to an ignition position of the cylinders 2 to 5 (E.g., 180 degrees) is a crank angle sensor that outputs a periodic signal. 7 receives an output signal of the crank angle sensor 6 and obtains an angular acceleration from a required time of a predetermined crank angle section corresponding to each cylinder of the engine 1, and intermittently or continuously supplies each cylinder of the engine 1 from the angular acceleration. It is a misfire detection unit that detects a misfire that occurs.

The misfire detecting section 7 includes a crank angle sensor 6
, An interface 8 for transmitting the output signal to a microcomputer (to be referred to as a microcomputer hereinafter), a memory 10 for storing processing procedures and control information, a timer counter (free-running counter) 11 for counting up for each fixed time clock, and C for executing misfire detection arithmetic processing
The microcomputer 9 includes the PU 12 and the like. In the above configuration, the output signal of the crank angle sensor 6 is input to the microcomputer 9 via the interface 8, and the arithmetic processing is executed.

Next, the operation will be described. First, the relationship between the crank angle sensor 6 and ignition and combustion will be described. FIGS. 3 (a) and 3 (b) show the change in pressure of each of the cylinders 2 to 5 with respect to the crank angle of the four-stroke cycle four-cylinder engine and the waveform of each part. In FIG. 7A, the solid line is the pressure waveform of the first cylinder # 1 of the engine 1, BDC is the bottom dead center, and TDC is the top dead center. The broken line indicates the pressure waveform of the third cylinder # 3, and the dashed line indicates the pressure waveform of the second cylinder # 2, and the dashed line indicates the pressure waveform of the fourth cylinder # 4. As shown in FIG. 3, in a four-cylinder engine, the combustion cycle of each cylinder has a phase difference of a crank angle of 180 degrees. In FIG. 3, the pressure waveform of the first cylinder # 1 continuously shows the stroke of one cycle of suction, compression, explosion, and exhaust, but the second cylinder # 2, the third cylinder # 3, In the pressure waveform of the fourth cylinder # 4, only the strokes of compression and explosion are described, and the strokes of intake and exhaust are omitted.

As shown in FIG. 3B, the crank angle sensor 6 corresponds to the ignition timing of each of the cylinders 2 to 5 and has a cycle of, for example, 180 degrees with reference to a position 6 degrees before TDC, for example. An ignition cycle signal divided into a 110-degree Low section (hereinafter, referred to as L) and a 70-degree High section (hereinafter, referred to as H), and a timing corresponding to the H section of the first cylinder of the ignition cycle signal. , A cylinder identification signal for identifying the number of the ignition cylinder is generated. Generally, ignition control refers to this cylinder identification signal to control the energization of an ignition coil not shown here.

That is, taking the first cylinder # 1 as an example, energization of the ignition coil is started in the H section of the compression stroke at a crank angle of 180 ° to 360 °, and the ignition timing determined according to the rotational speed load is set. Next, referring to the output signal of the crank angle sensor 6 changing from H to L near TDC, the energization of the ignition coil is cut off, and a high voltage generated thereby is applied to the ignition plug to ignite. Correspondingly, as shown by a solid line in FIG.
Ignition occurs in the explosion stroke at 0 degrees, and the combustion pressure increases.
In the same manner, in the 180-degree cycle, the firing order # 1 → # 3
The combustion cycle of → # 4 → # 2 → # 1 is repeated.

Next, a specific method of misfire detection will be described. 3 (a) and 3 (c) show the relationship between combustion and angular velocity. still,
This figure shows the case where the engine speed is 1000 rpm. In the first cylinder # 1 indicated by a solid line in FIG. 7A, the waveform centered on the crank angle of 360 degrees is a case of normal combustion, and the air-fuel mixture filled in the suction stroke is pressurized in the compression stroke and compressed. TDC
It is ignited in the vicinity, rapidly expands in the explosion stroke, and is discharged out of the cylinder in the exhaust stroke.

Next, a description will be given of a misfire state that occurs when ignition fails or when the mixture ratio of air and fuel is inappropriate. A pressure waveform centered on a crank angle of 1080 degrees corresponds to this, and T
It becomes symmetrical about DC. In the case of this example, there is no combustion, that is, a state of complete misfire is shown. However, if the degree of misfire is slight, the pressure transition in the explosion stroke will be in a normal state shown at a crank angle of 360 to 540 degrees. The value is in the middle of the pressure waveform. As shown in FIG. 3 (c), the angular velocity has a characteristic that the angular velocity increases in response to an increase in the torque due to the explosion of each cylinder and decreases in response to the compression as indicated by the crank angle of 0 to 1080 degrees. Here, when a misfire occurs, as shown in the crank angle of 1080 degrees or later, the torque increase due to the explosion cannot be obtained, and the angular velocity decreases, and the next third
It continues to decrease until the explosion of cylinder # 3 occurs. Therefore,
The present invention focuses on this, and attempts to determine misfire from fluctuations in the angular velocity of a predetermined section of the crank angle that occur depending on the presence or absence of misfire.

Next, the angular acceleration used for the actual misfire determination will be described with reference to FIG. In the figure,
T is the ignition cycle of each cylinder at every 180 degrees of crank angle,
TU is the required time of the 110 ° L section, and TL is the required time of the 70 ° H section. The subscript i indicates the current value.
-1 indicates the previous value. In the reciprocating circular motion, the angular acceleration α
(Rad / s ² ) is represented by the following equation.

Α = (ω _i −ω _i−1 ) / T _i (1)

Here, ω _i is the angular velocity in the period T _i , and T _i is the period between each ignition. Also, the angular velocity ω _i (rad / s)
Is represented by the following equation.

Ω _i = 4π / c × (1 / T _i ) (2)

Here, c is the number of cylinders. From the above equations (1) and (2), when the angular velocity ω _i decreases, the angular acceleration α
When the polarity is selected to be positive, the following equation is obtained.

Α = 4π / c × (1 / T _i ) × [T _i / T _i ² − {T _i−1 / (T _i−1 ) ² }} (3)

Here, it is assumed that T _i-1 = T _i + ΔT _i and ΔT _i ²
If ≪1, the angular acceleration α in the above equation (3) is approximately expressed by the following equation.

Α = 4π / c × (T _i −T _i−1 ) / T _i ³ (4)

The period Ti between each ignition and the time ratio TU /
The relationship with TL is T _i = TL + TU, where the term TL is information on the amount of charged air included in the compression stroke, and means that TU is normalized on the basis of the amount of air. Here, if the filling amount of air adjacent cylinders is constant, TL _i = TL _i-1, and the from the relationship _{ΔT i = T i-1 -T} i = TU i-1 -TU i,
The angular acceleration α is given by the following equation.

Α = 4π / c × (TL _i / T _i ³ ) × {TU _i / TL _i − (TU _i−1 / TL _i−1 )} (5)

In the arithmetic expression used in this embodiment, the term of 4π / c is deleted, and the acceleration (1 / s ² ) is obtained as an approximate expression of the angular acceleration.
Determines the angular velocity variation caused by misfire as the acceleration β using the acceleration β expressed by the following equation.

[0039] _{β = (TL i / T i} -1 3) × {TU i / TL i - (TU i-1 / TL i-1)} ... (6)

FIGS. 4, 5, and 6 are a time chart and a calculation flowchart of the microcomputer 9 according to this embodiment.
In the present embodiment, the ignition cycle signal of the crank angle sensor 6, for example, the crank angle 7 before 6 degrees before the top dead center TDC shown in FIG.
The time required for the 0-degree H section TL and the 110-degree L section TU sandwiching TDC is measured, and a misfire is detected from the acceleration.

FIG. 4 shows a detailed time chart of the crank angle and the arithmetic processing. 76 before top dead center based on top dead center TDC
Degree (hereinafter referred to as BTDC 76 degree) by the ignition cycle signal of the crank angle sensor 6 through the interface 8
An interrupt is generated in the microcomputer 9 and the flow of FIG. 5 is executed as an interrupt processing routine, and 6 degrees before the top dead center (hereinafter referred to as B
The flow of FIG. 6 is executed every time TDC is described as 6 degrees).

First, in FIG. 5, in step S1, the CPU 12 refers to the cylinder identification signal of the crank angle sensor 6 shown in FIG. 3B to determine which cylinder number this process corresponds to. This cylinder identification signal has a crank angle of 720
An H section is provided at every timing corresponding to the H section of the ignition cycle signal of the first cylinder # 1. The cylinder identification signal is read in step S1, and if the cylinder identification signal is H, the first cylinder It is determined to be # 1, the process proceeds to step S2, and a value corresponding to the first cylinder # 1 is set in a cylinder counter (not shown) provided in the memory 10 for storing a cylinder identification signal. If the cylinder identification signal is L, it is determined that the cylinder is not the first cylinder # 1, and the process proceeds to step S3, where the cylinder counter is incremented. Therefore, the value of the cylinder counter is updated to the value corresponding to the cylinder number every 76 degrees of BTDC, and the processing for each cylinder is executed with reference to this value.

Next, the CPU 12 proceeds to step S4,
The count value of the timer 11 that counts up at every predetermined time clock is read and stored in a memory MB76 (not shown) provided in the memory 10. Here, the stored value indicates the time at BTDC 76 degrees. Next, the process proceeds to step S5, and it is determined whether or not this processing is the first time after the start of the program with reference to a flag (not shown). This flag is set to indicate the first time at the start of the program. In this case, the flag is cleared and the process ends.

Next, the CPU 12 waits until the ignition cycle signal of the crank angle sensor 6 becomes 6 degrees BTDC. When the engine rotates and reaches the time point of 6 degrees BTDC shown in FIG. 4, an interrupt is generated again by the ignition cycle signal of the crank angle sensor 6, and the flow of FIG. 6 is executed. First, in step S6, the counter value of the timer 11 is read, and B
The value indicating the time at 6 degrees TDC is stored in the memory MB6 (not shown). Next, in step S7, the required time of the section TLi _-1 shown in FIG. 4 is calculated by the following equation with reference to the time at 76 degrees BTDC given in step S4 of FIG. 5, and stored in the memory TL (not shown). And terminates the process.

TL = MB76−MB6 (7)

Next, B corresponding to the ignition signal of the next cylinder
When the position of TDC 76 degrees is reached, the processing of FIG. 5 is executed again. Here, steps S1 to S3 are executed,
The cylinder number is updated, and the routine goes to Step S4. Step S4
Then, the value of the memory MB76 is updated to prepare for the next process, and since the initial flag has been cleared in the previous process in step S5, the process proceeds to step S8. In step S8, the BTDC given in step S6 of FIG.
Referring to the time at 6 degrees, the section TU _i-1 shown in FIG.
Is calculated by the following equation.

TU = MB6-MB76 (8)

Next, the time ratio is calculated by the following equation.

Time ratio = TU / TL (9)

Next, the flow proceeds to step S9, T _i-1 in FIG. 4
The required time of the section shown by the value of the memory TL and the step S
The value is calculated by the following equation using the value of the TU calculated in step 8.

T _i = TL + TU (10)

Next, in step S10, it is determined whether or not this processing is the second time from the start of the program with reference to a flag (not shown). This flag is set to indicate the second time at the start of the program. In this case, the flag is cleared and
Move to step S13. Here, the memory T _i-1 for holding the value of the last T _i provided in the memory 10 this the
(10) as well as store the T _i calculated in equation holds a value of the last TU / TL in the same manner, the memory TU _i-1 /
The time ratio TU / TL obtained by the above equation (9) is used for TLi _-1.
Is stored, and the process ends.

When the engine rotates and reaches the position of 6 degrees BTDC located immediately before the TDC of FIG. 4, the flow of FIG. 6 is executed, and the time at this point is stored in the memory MB6, and the TL of FIG. The required time of the section indicated by _i is calculated by the above equation (7) and stored in the memory TL. Next, when the crank angle reaches the position of BTDC 76 degrees corresponding to the ignition signal of the next cylinder, the flow of FIG. 5 is executed again. However, since this processing is the third time, steps S1, S3, S4, S5 , the route of S8, S9, time at the present time is stored in the memory MB 76, at the required time, respectively (8) and (10) of duration TU and the interval T _i interval TU _i in FIG. 4 Is calculated.

Next, the process proceeds to step S10, where the number of processes is determined. Since the flag has been cleared in the second process in step S10, the process proceeds to step S11. Here, the acceleration is calculated by using the above-mentioned equation (6) using the above-mentioned memory value and the calculated value. Next, step S12
The acceleration calculated in step S11 with reference to the cylinder identification information given in steps S1 to S3 is stored in a memory β # 1, β # 2 (not shown) provided for each cylinder in the memory 10. The data is sequentially stored in β # 3 and β # 4, and a misfire determination described later is performed.

Next, the flow proceeds to step S13, in preparation for operation of the fourth and later stores respective current T _i and TU / TL in memory T _i-1 and _{TU i-1 / TL i-} 1, processing To end. Hereinafter, similarly, at BTDC 76 degrees, FIG.
When the BTDC is 6 degrees, the flow of FIG. 6 is executed, the accelerations corresponding to the respective cylinders are sequentially calculated according to the ignition order, and the misfire determination is performed for each cylinder.

FIG. 3D is a diagram showing the relationship between misfire and acceleration (1 / s ² ). In the figure, solid lines indicate the cylinders # 1 to # 1.
The acceleration is calculated corresponding to # 4. If a value of, for example, 5 (1 / s ² ) indicated by a broken line in FIG. #
It is apparent that the misfire can be determined from the acceleration because the acceleration increases in response to the misfire of 1 and becomes equal to or greater than the determination value.

Next, a method of detecting an intermittent misfire or a continuous misfire will be described. 7 and 8 are flowcharts of a misfire determination subroutine for intermittent misfire and continuous misfire.
FIG. 10 is a time chart showing the behavior of acceleration β when intermittent fire and continuous misfire have occurred.

First, the intermittent misfire will be described with reference to FIGS. FIG. 9 shows the behavior of the acceleration when the first cylinder # 1 intermittently misfires. In the figure, the horizontal axis represents the combustion cycle, and the vertical axis represents the acceleration β. In the combustion cycle on the horizontal axis, a section is provided according to the detection order of the acceleration β of each cylinder, the acceleration β of the first cylinder # 1 is indicated by a solid line, the acceleration β of the third cylinder # 3 is indicated by a broken line, and the acceleration of the fourth cylinder # 4 is indicated by a broken line. β is represented by a two-dot chain line, and the acceleration of the second cylinder # 2 is represented by a one-dot chain line. In addition, the acceleration β on the vertical axis is a bar graph, but the length of the bar in this graph has no physical meaning, and the visibility of the data is taken into consideration. It corresponds to acceleration.

In the figure, time point # 1 before the occurrence of misfire
previous acceleration beta # 1 _i-1 in the _i-1 whereas indicates a value near 0, the acceleration beta # 1 _i in the misfire occurs when # 1 _i
Increases with misfire. Next, when it returns to normal,
The acceleration returns to near zero again as shown after time point # 1 _{i + 1} . In this embodiment, focusing on this phenomenon, the history of the acceleration of the same cylinder is obtained by the following equation as indicated by reference numeral A in FIG.

[0060] _{ΔβKj = β # j i -β #} j i-1 ... (11)

Here, K represents an evaluation index of intermittent fire,
j is a cylinder number (j = 1, 2, 3, 4), which is treated as a continuous number in the processing, and this number and the actual cylinder number are j
= 1,2,3,4 for # 1, # 3, # 4 respectively
# 2. For example, when j = 2 (# 3), j-1 corresponds to the first cylinder # 1 and indicates an adjacent previous ignition cylinder.
Next, this Δβj is compared with the misfire determination value βKC, and when the following relationship is satisfied, the cylinder is determined to be intermittent misfire.
KC is a constant for the cylinder at the time of detection of the intermittent misfire.

ΔβKj> βKC (12)

Steps S101, S102, S1 in FIG.
03 shows the arithmetic processing of the intermittent fire. That is, in step 101, a misfire detection calculation for each cylinder is performed using the above equation (11), and then, in step 102, misfire determination is performed using the above equation (12). here,
If the above equation (12) is satisfied, the routine proceeds to step 103, where the misfire count of the cylinder is added to the intermittent misfire counter NKj provided in the memory 10 (not shown) for storing the number of intermittent misfires for each cylinder. At this time, the intermittent misfire counter NKj is cleared to zero at the start of the program, and sequentially adds the number of misfires in a predetermined detection section described later. On the other hand, if the above expression (12) is not satisfied, the flow branches to No and the determination of intermittent misfire is terminated.

Next, the continuous misfire will be described with reference to FIGS. FIG. 10 shows the behavior of acceleration when the first cylinder # 1 continuously misfires.
The horizontal axis and the vertical axis indicate the combustion cycle and the acceleration β, respectively, as in FIG. 9, a section is provided in the combustion cycle on the horizontal axis in accordance with the detection order of the acceleration β of each cylinder, the acceleration β of the first cylinder # 1 is indicated by a solid line, and the acceleration β of the third cylinder # 3 is indicated by a broken line. The acceleration β of the fourth cylinder # 4 is indicated by a two-dot chain line, and the acceleration of the second cylinder # 2 is indicated by a one-dot chain line. Also in this case, the acceleration β on the vertical axis is a bar graph. However, the length of the bars in this graph has no physical meaning, and the visibility of the data is taken into consideration. Corresponds to the acceleration of the cylinder.

In FIG. 10, time point # 1 before occurrence of misfire
previous acceleration beta # 1 _i-1 in the _i-1 whereas indicates a value near 0, the acceleration beta # 1 _i in the misfire occurs when # 1 _i
The phenomenon that increases with misfire is the same as that of intermittent fire, but since misfire occurs continuously, time point # 1
_{After i + 1} , the difference in acceleration between the same cylinders decreases, making it impossible to apply equation (10). Therefore, in this embodiment, the acceleration history of the same cylinder is obtained by the following equation, paying attention to the fact that the acceleration of the other cylinder does not change, as indicated by reference numeral C in FIG.

[0066] _{ΔβRj = β # j i -β #} j -2 ... (13)

Here, R represents a continuous misfire evaluation index,
As described above, j is a cylinder number (j = 1, 2, 3, 4).
In the processing, the numbers are treated as consecutive numbers, and this number and the actual cylinder number are # 1, # for j = 1, 2, 3, and 4, respectively.
3, # 4 and # 2. For example, when j = 3 (# 4), j-2 corresponds to the first cylinder # 1, and indicates the immediately preceding ignition cylinder immediately before. Next, this Δβj and the misfire determination value βRC
And when the following relationship is satisfied, it is determined that a continuous misfire has occurred in the cylinder. Note that RC is a constant for the cylinder when the continuous misfire is detected.

ΔβRj> βRC (14)

Steps S104, S105, S1 in FIG.
06 shows the above-mentioned continuous misfire calculation processing. That is, in step 104, a continuous misfire detection calculation for each cylinder is performed using the above equation (13), and then, in step 105, misfire determination is performed using the above equation (14). here,
If the above expression (14) is satisfied, the routine proceeds to step 106, where the number of misfires of the cylinder is added to a continuous misfire counter NRj provided in the memory 10 (not shown) for storing the number of consecutive misfires for each cylinder. At this time, the continuous misfire counter NRj is cleared to zero at the start of the program, and sequentially adds the number of misfires in a predetermined detection section described later. On the other hand, if the above expression (14) is not satisfied, the process branches to No and the determination of the continuous misfire ends. In this way, the determination of misfires and continuous misfires for each cylinder is made for each ignition cycle, and the results of the determination are integrated into counters provided independently for each cylinder.

Next, a misfire determination in a predetermined detection section will be described with reference to FIG. FIG. 8 shows a program executed following the processing of FIG. First, step S1
At 07, the detection section counter NC for counting the detection section provided in the memory 10 (not shown) is incremented. Here, the detection section counter NC has been cleared to zero at the start of the program, and the number of times is sequentially incremented each time this step S107 is passed. Next, the process proceeds to step S108, where the count value of the detection section counter NC is compared with a predetermined value (judgment value) that determines the number of detections.
Returns to step S13, and if it is equal to or more than the predetermined value,
Proceeding to step S109, a final misfire determination in a predetermined detection section is executed.

First, in step S109, the contents of the intermittent misfire counter NKj are read out, and the count value of the number of misfire detections of each cylinder and a predetermined value (judgment value) which defines the misfire rate to be detected in a predetermined detection section are determined. Compare. If the misfire rate of each cylinder, that is, the count value of the number of misfire detections of each cylinder is equal to or more than a predetermined value, the process proceeds to step S110. Here, it is determined that the misfiring has occurred between the cylinders. Then, the cylinder is determined to be normal.
This misfire rate is, for example, the so-called OBB-II in the United States.
Regulations require about 2%, and are affected by rotational fluctuations caused by factors other than misfire. If the number of erroneous detections is smaller than the predetermined value, the misfire determination in this section is invalidated. By doing so, erroneous determination can be prevented.

Next, proceeding to step S112, the contents of the continuous misfire counter NRj are read out, and the count value of the number of misfire detections of each cylinder and a predetermined value (judgment value) defining the misfire rate to be detected in a predetermined detection section Compare with If the misfire rate of each cylinder, that is, the count value of the number of misfire detections of each cylinder is equal to or more than a predetermined value, the process proceeds to step S113. Here, it is determined that the cylinder is continuously misfiring. Then, the cylinder is determined to be normal.

Next, the routine proceeds to step S115, in which the intermittent misfire counter NK is prepared for the misfire determination in the next detection section.
j, continuous misfire counter NRj and detection section counter NC
Is reset to zero, and the process returns to step S13 in FIG. Hereinafter, similarly, the acceleration of each cylinder is calculated for each ignition cycle, the number of misfires is stored in an intermittent misfire counter or a continuous misfire counter provided independently for each cylinder, and the number of misfires in a predetermined detection section is referred to. Then, a final misfire determination is performed.

Embodiment 2 FIG. In the first embodiment, the case where the acceleration of each cylinder is used to evaluate the history of the rotation fluctuation has been described. However, the acceleration difference Δβ between the adjacent cylinders has been described.
S is determined by the following equation, and using this ΔβS, as in the first embodiment, Δβ in Equations (11) to (14) is replaced with ΔβS determined by the following equation to determine intermittent misfire and continuous misfire. You may.

ΔβS = β # j ₋₁ −β # j (15)

In this case, as indicated by reference numeral B in FIGS. 9 and 10, since the deviation between the angular velocity in the misfiring cylinder and the angular velocity in the normal cylinder is large, the change amount of the acceleration β between the normal state and the misfiring is And the detection sensitivity is further improved.

Embodiment 3 FIG. Further, in the above-described first embodiment, the determination of the intermittent misfire has been described with respect to the case where the determination value is a fixed value as shown in the above equation (12). In order to be able to set correspondingly, it is given by a function f composed of a two-dimensional map using rotation and load as parameters. Further, in order to absorb variation between cylinders of acceleration and variation in combustion, acceleration for each cylinder is set. A value obtained by applying a primary digital filter or the like to the detected value may be added.

ΔβKj _(i) > f (Ne, Ce) + ΔβKj (16)

Here, f (Ne, Ce) is a two-dimensional map search value based on the engine speed Ne and the load Ce, and ΔβKj
Is a filter processing result of the cylinder.

Embodiment 4 FIG. Further, in the first embodiment, the determination of the continuous misfire has been described in the case where the determination value is a fixed value as shown in the above equation (14). However, similarly to the case of the intermittent misfire, the following equation is used. The determination value is given by a function g composed of a two-dimensional map using rotation and load as parameters so that the determination value can be set in accordance with the operating region of the engine. May be added to the detected value of each cylinder after applying a primary digital filter or the like.

ΔβRj _(i) > g (Ne, Ce) + ΔβRj (17)

Here, g (Ne, Ce) is a two-dimensional map search value based on the engine speed Ne and the load Ce, and ΔβRj
Is a filter processing result of the cylinder.

Embodiment 5 FIG. In the first to fourth embodiments, the misfire determination value is an average value of a predetermined number of past accelerations,
Other averaging processing values, statistical processing values, learning values, and the like may be used. Although the detection section used for the final determination is a predetermined number of times, a predetermined time may be used. Further, the misfire determination result of each cylinder may be displayed.

Embodiment 6 FIG. FIG. 11 is a functional block diagram showing another embodiment of the present invention. 11, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the figure, M6 is connected to the intermittent misfire detection means M4 and the continuous misfire detection means M5, and each detection means M4 and M
5, a misfire detection signal for each cylinder is counted for a predetermined section, and if this count value is equal to or greater than a predetermined misfire determination value for a predetermined number of times, it is determined that intermittent misfire or continuous misfire has occurred in the cylinder. That is, a misfire determination unit that determines misfire of the engine M1.

FIG. 12 is a block diagram showing another embodiment of the present invention which embodies FIG. 12, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the figure, 7A receives an output signal of the crank angle sensor 6, obtains an angular acceleration from a required time of a predetermined crank angle section corresponding to each cylinder of the engine 1, and intermittently or non-intermittently outputs each cylinder of the engine 1 from the angular acceleration. It is a misfire detecting unit that detects misfires that occur continuously. This misfire detection unit 7A
Is an interface 8 for transmitting an output signal of the crank angle sensor 6 to a microcomputer described later, a memory 10A for storing processing procedures and control information, and a timer counter (free-running counter) for counting up at every fixed time clock.
11 and a microcomputer 9A having a built-in CPU 12A for executing a misfire detection calculation process. In the above configuration, the output signal of the crank angle sensor 6 is input to the microcomputer 9A via the interface 8, and the arithmetic processing is executed.

Next, the operation will be described. In this embodiment, the relationship between the crank angle sensor 6 and the combustion, the specific method of misfire detection, the angular acceleration used for the actual misfire determination, and the arithmetic processing of the microcomputer 9A are substantially the same as those in the first embodiment. Detailed description is omitted, and only the portions different from the first embodiment will be described. First, a method for detecting intermittent misfire or continuous misfire will be described. FIG. 13 is a flowchart of the misfire determination subroutine of the intermittent fire and the continuous misfire together with FIG. 7 described above. The time charts of the behavior of the acceleration β when the intermittent fire and the continuous misfire occur are the same as those in FIGS. 9 and 10 described above. It is. Note that the description of the detection of the intermittent misfire and the continuous misfire is as described above, and the description thereof is omitted here.

The misfire determination in a predetermined detection section will be described with reference to FIG. FIG. 13 shows a program executed after the processing of FIG. First, in step S107, a detection section counter NC for counting detection sections provided in the memory 10A (not shown) is incremented. Here, this detection section counter N
C has been cleared to zero at the start of the program, and the number of times is sequentially added each time this step S107 is passed. Next, the process proceeds to step S108, where the count value of the detection section counter NC is compared with a predetermined value (judgment value) that determines the number of detections. If the count value is equal to or smaller than the predetermined value, the process returns to step S13 in FIG. If it is equal to or more than the value, the process proceeds to step S109, and a final misfire determination in a predetermined detection section is executed.

First, in step S109, the contents of the intermittent misfire counter NKj are read out, and the count value of the number of misfire detections of each cylinder and a predetermined value (judgment value) which defines the misfire rate to be detected in a predetermined detection section are determined. Compare. This misfire rate, for example, in the so-called OBB-II regulations in the United States,
About 2% is required, and is affected by rotational fluctuations caused by factors other than misfire. If the number of erroneous detections is smaller than the above-mentioned predetermined value, the misfire determination in the section is invalidated. Erroneous determination due to sudden rotation fluctuation can be prevented. If it is determined in step S109 that the misfire rate of each cylinder, that is, the count value of the number of misfire detections of each cylinder is equal to or greater than a predetermined value, the process proceeds to step S110, where it is determined that a misfire has occurred between the cylinders, and a misfire has occurred in the memory 10A. The determination flag is set, and if the value is equal to or less than the predetermined value, step S
The routine proceeds to step 111, where it is determined that the cylinder is normal, and the intermittent misfire determination flag provided in the memory 10A corresponding to the cylinder number is cleared.

Next, a description will be given of the periodic rotation fluctuation that occurs when the vehicle travels on an uneven road surface such as a wavy or stone pavement. FIG. 14 shows the specifications of the wavy road used in the experimental running test. In this figure, height 25 mm, width 38
The irregularities of 0 mm are continuously arranged. FIG. 15 and FIG. 16 show the results of a running test on the wavy road at a vehicle speed of 40 Km / h. The vertical axis in FIG. 15 is calculated by the following equation for the misdetection during normal combustion, and the horizontal axis is a bar graph with the cylinder numbers assigned to the results calculated for each cylinder using the following equation. It was done.

Misdetection property = Number of misdetections / Number of predetermined normal combustion times × 100 [%] (18)

In FIG. 15, FIG. 15A shows normal combustion, FIG. 15B shows the case where the third cylinder # 3 is intermittently misfired at a misfire rate of 2%, and FIG. Misfire rate 1 for cylinder # 3
Each shows misdetectability when a misfire occurs continuously at 00%. In the case where the vehicle travels on a wavy road, FIG.
As shown in (b) and (c), an impact occurs when the vehicle passes over unevenness on the road surface, and torque fluctuations, that is, rotation fluctuations are periodically transmitted to the internal combustion engine via the tires, thereby causing a misfire. In spite of not performing the detection, erroneous detection occurs in a plurality of cylinders. Here, no erroneous detection is seen in the third cylinder # 3 in FIG. 3C because the number of normal combustions is zero because the cylinder is continuously misfired, and the above equation (18) cannot be applied. That's why. The vertical axis in FIG. 16 shows the misfire detectability when an artificial misfire is generated by the following equation, and the horizontal axis shows the result calculated using the following equation for each cylinder. Numbers are arranged as bar graphs.

Misfire detectability = Number of misfire detections / Number of misfires × 100 [%] (19)

FIG. 16A shows the third cylinder #.
3 (b) shows the misfire detectability in the case of a continuous misfire in the third cylinder # 3 in the case of a misfire in the third cylinder. When the vehicle travels on a wavy road, as in the case of the above-described misdetection, an impact occurs when the vehicle passes over unevenness on the road surface, and the torque fluctuation is periodically transmitted to the internal combustion engine via the tires. Under the influence, the angular velocity pattern is disturbed, and the misfire detection performance is reduced. In addition, the degree of influence from the road surface varies depending on the detection method.
On the other hand, in the case of a continuous misfire, the degree of influence is relatively small because the angular velocity pattern accompanying the misfire is regular, and the misfire detectability can be maintained at a high rate of about 80%.

In the present invention, utilizing this fact, when a misfire is detected in a single cylinder, misfires are detected in a plurality of cylinders with reference to the misfire detection status of other cylinders. In this case, the misfire determination information is invalidated, and when the vehicle travels on an uneven road surface such as a wavy road surface, the periodic rotation fluctuation transmitted to the internal combustion engine via the tires and the misfire of the internal combustion engine cause This is to distinguish between the rotation fluctuation.

That is, in step S116 of FIG. 13, referring to the misfire information of other cylinders stored in the memory 10A, if misfires are detected in a predetermined number of cylinders, the cycle due to factors other than misfires In step S111, the result of the determination is correctly rewritten, and the misfire detection information is invalidated. In cases other than the above, the process proceeds to step S112, and the determination result of the intermittent misfire is kept.

Next, in step S112, the contents of the continuous misfire counter NRj are read out, and the count value of the number of misfire detections of each cylinder and a predetermined value (judgment value) which determines the misfire rate to be detected in a predetermined detection section are set. Compare. If the misfire rate of each cylinder, that is, the count value of the number of misfire detections of each cylinder is equal to or more than a predetermined value, the process proceeds to step S113, where it is determined that the cylinder is a continuous misfire, and a continuous misfire determination flag in the memory 10A is set. If it is equal to or less than the predetermined value, step S11
4 where the cylinder is determined to be normal,
The continuous misfire determination flag provided in A corresponding to the cylinder number is cleared.

Next, the process proceeds to step S117, where the misfire information of the other cylinders stored in the memory 10A is referred to. It is determined that the rotation fluctuation has occurred, and in step S114, the determination result is rewritten normally, and the misfire detection information is invalidated. In cases other than the above, the process proceeds to step S115 to save the determination result of the continuous misfire.

In step S115, the intermittent misfire counter NKj, the continuous misfire counter NRj, and the detection section counter NC are reset to zero in preparation for a misfire determination in the next detection section, and the process returns to step S13 in FIG. Less than,
Similarly, the acceleration of each cylinder is calculated for each ignition cycle, the number of misfires is stored in an intermittent misfire counter or a continuous misfire counter provided independently for each cylinder, and the number of misfires in a predetermined detection section is referred to. In addition to performing misfire determination independently for each cylinder, if misfire of a single cylinder is detected,
The final misfire determination is executed with reference to misfire information of other cylinders.

Embodiment 7 FIG. In the sixth embodiment, the judgment value of the intermittent misfire and the judgment value of the continuous misfire were the same.
As shown in the figure, when a periodic impact such as a wavy road is received from the traveling road surface, the misfire detectability differs depending on the detection method, so the determination value of the continuous misfire with high detectability is smaller than the intermittent fire with low detectability. It may be set higher, in which case the noise immunity against periodic rotation fluctuations is further improved.

Embodiment 8 FIG. In the sixth embodiment, the case where the acceleration of each cylinder is used to evaluate the history of the rotation fluctuation has been described. However, the acceleration difference Δβ between the adjacent cylinders has been described.
S is determined by the following equation, and using this ΔβS, as in the first embodiment, Δβ in Equations (11) to (14) is replaced with ΔβS determined by the following equation to determine intermittent misfire and continuous misfire. You may.

ΔβS = β # j ₋₁ −β # j (20)

In this case, as shown by reference numeral B in FIGS. 9 and 10, since the deviation between the angular velocity in the misfiring cylinder and the angular velocity in the normal cylinder is large, the change amount of the acceleration β between the normal state and the misfiring is And the detection sensitivity is further improved.

Embodiment 9 FIG. Further, in the sixth embodiment, the determination of the intermittent misfire has been described with respect to the case where the determination value is a fixed value as shown in the above equation (12). In order to be able to set correspondingly, it is given by a function f composed of a two-dimensional map using rotation and load as parameters. Further, in order to absorb variation between cylinders of acceleration and variation in combustion, acceleration for each cylinder is set. A value obtained by applying a primary digital filter or the like to the detected value may be added.

ΔβKj _(i) > f (Ne, Ce) + ΔβKj (21)

Here, f (Ne, Ce) is a two-dimensional map search value based on the engine speed Ne and the load Ce, and ΔβKj
Is a filter processing result of the cylinder.

Embodiment 10 FIG. In the sixth embodiment, the determination of the continuous misfire has been described with reference to the case where the determination value is a fixed value as shown in the above equation (14). However, similar to the case of the intermittent misfire, the following equation is used. The determination value is given by a function g composed of a two-dimensional map using rotation and load as parameters so that the determination value can be set in accordance with the operating region of the engine. May be added to the detected value of each cylinder after applying a primary digital filter or the like.

ΔβRj _(i) > g (Ne, Ce) + ΔβRj (22)

Here, g (Ne, Ce) is a two-dimensional map search value based on the engine speed Ne and the load Ce, and ΔβRj
Is a filter processing result of the cylinder.

Embodiment 11 FIG. In the sixth to tenth embodiments, the misfire determination value may be an average value of a predetermined number of past accelerations, another averaging processing value, a statistical processing value, a learning value, or the like. Further, the detection section used for the determination is a predetermined number of times, but a predetermined time may be used. Further, the number of other cylinders for which the final determination is made when misfire of a single cylinder is detected may be arbitrarily determined. Further, the misfire determination result of each cylinder may be displayed.

Embodiment 12 FIG. FIG. 17 is a functional block diagram showing another embodiment of the present invention. In FIG. 17, FIG.
The same reference numerals are given to the portions corresponding to and the detailed description will be omitted. In the figure, M7 is a load detecting means connected to the engine 1 and detecting the load of the engine. As the load detecting means M7, although not shown, for example, an air flow meter or intake pipe pressure sensor for measuring the intake air amount of the internal combustion engine, or a throttle valve opening sensor for detecting the opening of the intake air adjusting throttle valve. Can be used. M8 is a rotational speed detecting means which is connected to the crank angle detecting means M2, measures the cycle of a predetermined angle based on the output signal of the crank angle detecting means M2, and detects the rotational speed of the engine from this.

[0111] M9 is the acceleration detecting means M3, connected to the load detecting means M7 and rotational speed detecting means M8, for detecting the intermittent misfire occurring in each cylinder of the engine M1 from the detected acceleration by the acceleration detecting means M3 At the same time, while detecting the operating state of the engine based on the output signal of the load detecting means M7 or the number-of-turns detecting means M8, a misfire detection means for performing a misfire determination corresponding to the operating state, M10 is an acceleration detecting means It is connected to the load detecting means M7 and the rotational speed detecting means M8, and detects a misfire continuously occurring in each cylinder of the engine M1 from the acceleration detected by the acceleration detecting means M3 for each cylinder. A continuous misfire detection that detects an operation state of the engine based on an output signal of the detection means M8 and executes a misfire determination corresponding to the operation state based on the detected operation state. It is a means.

FIG. 18 is a block diagram showing another embodiment of the present invention which embodies FIG. 18, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. 7B receives an output signal of the crank angle sensor 6 and obtains an angular acceleration from a required time of a predetermined crank angle section corresponding to each cylinder of the engine 1, and intermittently or continuously outputs each of the cylinders of the engine 1 from the angular acceleration. It is a misfire detection unit that detects a misfire that occurs.

The misfire detecting section 7B includes an interface 8 for transmitting an output signal of the crank angle sensor 6 to a microcomputer described later, and a memory 10 for storing processing procedures and control information.
B, a timer counter (free-running counter) 11 that counts up at regular time clocks, and a microcomputer 9B having a built-in CPU 12B and the like for executing misfire detection arithmetic processing. In the above configuration, the output signal of the crank angle sensor 6 is input to the microcomputer 9B via the interface 8, and the arithmetic processing is executed.

Next, the operation will be described. In this embodiment, the relationship between the crank angle sensor 6 and the combustion, the specific method of misfire detection, the angular acceleration used for actual misfire determination, and the arithmetic processing of the microcomputer 9B are substantially the same as those in the first embodiment. Detailed description is omitted, and only the portions different from the first embodiment will be described.

First, a method of detecting intermittent misfire or continuous misfire will be described. FIG. 19 is a flowchart of a misfire determination subroutine for intermittent misfire and continuous misfire, and FIG. 20 is a misfire determination value map corresponding to operating conditions, and is a time chart of the behavior of acceleration β when intermittent misfire and continuous misfire occur, respectively. Are the same as in FIGS. 9 and 10 described above.

The intermittent misfire will be described with reference to FIG. In step 201, the misfire determination value βKC is obtained from the misfire determination value map corresponding to the operation conditions shown in FIG.
Is read. This misfire determination value map is stored in the microcomputer 9B in advance. In FIG. 20, the horizontal axis represents the engine speed N, which is divided into N1, N2, and N3. The number of revolutions is detected by measuring a cycle of a predetermined angle section of the crank angle sensor 6.

The vertical axis is a parameter indicating the load of the engine. Although not shown, the intake air amount Q of the air flow meter for measuring the intake air amount is used, and Q1, Q2, Q
Classified as 3. Zoning by these divisions,
The misfire determination value is stored in the memory Pn, q corresponding to each zone.
Assign to Here, n and q indicate the section numbers of the horizontal axis and the vertical axis, respectively. In the figure, the map value looked up from the table according to the operating state determined by the rotation speed N and the intake air amount Q is the misfire determination value βK of the above equation (12).
Substituted into C.

Next, in step S202, a misfire detection calculation for each cylinder is performed by using the above equation (12).
Next, in step 203, misfire determination is performed using the above equation (12). Here, if the above expression (12) is satisfied, the routine proceeds to step 204, where the memory 1 not shown
An intermittent misfire flag FKj (j: cylinder number) is set in an intermittent misfire flag provided in 0B to store the intermittent misfire state for each cylinder, and the misfire occurrence of the cylinder is stored. On the other hand, if the above equation (12) is not satisfied, step S2
At 05, the intermittent misfire flag FKj is cleared, and the judgment of intermittent misfire is terminated.

Next, the continuous misfire will be described with reference to FIG. In step 206, not shown in FIG.
The map value corresponding to the operating state is looked up from the table from the continuous misfire determination value map stored in the memory 10B in the same manner as in the case of intermittent misfire, and is substituted into the misfire determination value βRC of the above equation (14). Is done.

Next, in step S207, a continuous misfire detection calculation for each cylinder is performed using the above equation (13).
Next, in step 208, a misfire determination is made using the above equation (14). Here, if the above expression (14) is satisfied, the process proceeds to step 209, and the memory 1 (not shown)
A continuous misfire flag FRj (j: cylinder number) is set in a continuous misfire counter provided in 0B for storing a continuous misfire state for each cylinder, and the occurrence of a continuous misfire of the cylinder is stored. On the other hand, if the above expression (14) is not satisfied, the continuous misfire flag FRj is cleared in step S210, and the determination of the continuous misfire ends. In this way, the determination of misfire and continuous misfire for each cylinder is performed for each ignition cycle, and the determination result is stored in the memory 10B by a flag provided independently for each cylinder.

Embodiment 13 FIG. Next, another embodiment of the present invention will be described with reference to FIGS. FIG.
1 and FIG. 22 are characteristic diagrams showing the relationship between the engine speed and the misfire determination value with respect to the charging efficiency. First, the relationship between the engine speed and the misfire determination value will be described with reference to FIG. In the figure, the horizontal axis represents the engine speed, and the misfire detection signal has a characteristic that increases as the engine speed increases. It is set to increase with. Here, in the region of 1000 rpm or less, the misfire detection signal decreases, the signal level cannot be distinguished from the signal level during normal combustion, and erroneous detection occurs.

FIG. 22 shows the charging efficiency corresponding to the load on the engine (the ratio between the amount of intake air measured by an air flow meter and the amount of air occupying the stroke volume of the cylinder, and increases with the load). FIG. 22 is a characteristic diagram showing a relationship between misfire determination values. As in FIG. 21, erroneous detection occurs in a region where charging efficiency is low, that is, in a low load region. Therefore, means for invalidating the misfire determination result in a low rotation or low load region is required.

FIG. 23 is a flow chart of the operation in another embodiment of the present invention. Note that FIG. 19 is obtained by adding steps S211 and S212 to FIG. 19, and the same portions are denoted by the same reference numerals, and description thereof will be omitted. Step S211 is additionally inserted immediately before the intermittent misfire determination processing. If the number of revolutions or load is read and is equal to or less than a predetermined value, it is determined that the misfire determination condition is not satisfied, and step S205 is performed.
To clear the intermittent misfire determination flag, and set a normal value in the determination result. When the rotational speed or the load is equal to or more than the predetermined value, the normal misfire determination processing of step S201 and subsequent steps is performed.

Step S212 is additionally inserted immediately before the continuous misfire determination processing.
When the load or the rotational speed is equal to or less than the predetermined value, it is determined that the misfire determination condition is not satisfied, and the process proceeds to step S210 to clear the continuous misfire determination flag and set a normal value in the determination result. If the rotational speed or the load is equal to or more than the predetermined value, the normal misfire determination processing of step S206 and subsequent steps is performed. In this manner, in a region where the engine load or the rotation speed is equal to or less than the predetermined value, the misfire determination can be invalidated by setting the normal value to the misfire determination result.

Embodiment 14 FIG. In the thirteenth embodiment, the misfire determination is invalidated by adding steps S211 and S212, but the set value of the low rotation or low load region of the misfire determination value map shown in FIG. 20 is set to be larger than the misfire detection signal. Alternatively, the normal state may be determined irrespective of the value of the signal, and the same effect as that of the thirteenth embodiment can be obtained. In addition, a region where the rotation speed is low or the load is low or less is set as a condition for invalidating the misfire determination. However, if an erroneous detection occurs in other regions, the region may be set.

Embodiment 15 FIG. In the twelfth to fourteenth embodiments, the misfire determination result is stored in the memory. However, a display device may be provided to display the misfire determination result of each cylinder. Furthermore, in each of the embodiments described above, the case of a four-cylinder engine has been described. However, the present invention is not limited to this, and can be similarly applied to engines having other cylinders, and has the same effects as those of the above embodiments.

[0127]

As described above, according to the first aspect of the present invention, the reference crank is connected to an internal combustion engine having a plurality of cylinders, and a predetermined crank angle corresponding to each cylinder of the internal combustion engine is used as a reference. A crank angle detecting means for detecting a position of a predetermined angle section before and after the angle, and a required angle section for each of the predetermined angle sections before and after the reference crank angle based on an output signal of the crank angle detecting means. Acceleration detection means for detecting an acceleration of a time ratio of time;
An intermittent misfire detection means connected to the acceleration detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; and Since there is provided a continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on the output signal of the detecting means, an intermittent fire, a continuous misfire, and a detection method most suitable for each misfire pattern is adopted. By doing so, even if the state of occurrence of misfire changes, the detectability of misfire is enhanced, the misfire occurrence rate in a predetermined section is determined, and rotation transmitted to the internal combustion engine via tires when traveling on a bad road or the like is determined. It is possible to eliminate an erroneous detection due to a factor other than the misfire caused by the fluctuation, and to accurately detect the misfire.

According to the second aspect of the present invention, the engine is connected to an internal combustion engine having a plurality of cylinders, and a predetermined angle around the reference crank angle with respect to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A crank angle detecting means for detecting the position of the section, and a time ratio of a required time of each required time of the predetermined angle section before and after the reference crank angle based on an output signal of the crank angle detecting means, based on an output signal of the crank angle detecting means. Acceleration detection means for detecting acceleration; intermittent misfire detection means connected to the acceleration detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; A continuous misfire detecting means connected to the acceleration detecting means and detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means. The intermittent misfire detection means and the continuous misfire detection means provide a predetermined detection section, and when a misfire greater than or equal to a predetermined misfire determination value is detected in the detection section, determine that a misfire has occurred in the detection section. As a result, even if the state of occurrence of misfire changes, the detectability of misfire is improved, and erroneous detection due to factors other than misfire caused by rotation fluctuation transmitted to the internal combustion engine via tires when traveling on a bad road or the like. And the misfire can be detected more accurately.

According to the third aspect of the present invention, the engine is connected to an internal combustion engine having a plurality of cylinders, and a predetermined angle around the reference crank angle with respect to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A crank angle detecting means for detecting the position of the section, and a time ratio of a required time of each required time of the predetermined angle section before and after the reference crank angle based on an output signal of the crank angle detecting means, based on an output signal of the crank angle detecting means. Acceleration detection means for detecting acceleration; intermittent misfire detection means connected to the acceleration detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; A continuous misfire detecting means connected to the acceleration detecting means and detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; The misfire detection signal corresponding to each cylinder detected by the intermittent misfire detection means and the continuous misfire detection means is connected to the intermittent misfire detection means and the continuous misfire detection means, respectively, and is counted in a predetermined detection section. When a predetermined misfire determination value or more, the misfire determination means that determines that the cylinder is intermittently misfired or continuous misfire is provided, so intermittent misfire, continuous misfire each by adopting a detection method most suitable for the misfire pattern, It is possible to improve the detectability of misfire and determine the misfire occurrence rate in each of the independently provided predetermined detection sections to determine the misfire or continuous misfire. Can be easily identified, so that the accuracy of misfire detection can be improved, and this can be caused by sudden rotation fluctuations transmitted to the internal combustion engine via tires when traveling on rough roads. Removing the erroneous detection due to factors other than fire, there is an effect that it is possible to detect a misfire accurately.

According to the invention described in claim 4, the engine is connected to an internal combustion engine having a plurality of cylinders, and a predetermined angle around the reference crank angle with respect to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A crank angle detecting means for detecting the position of the section, and a time ratio of a required time of each required time of the predetermined angle section before and after the reference crank angle based on an output signal of the crank angle detecting means, based on an output signal of the crank angle detecting means. Acceleration detection means for detecting acceleration; intermittent misfire detection means connected to the acceleration detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; A continuous misfire detecting means connected to the acceleration detecting means and detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; The misfire detection signal corresponding to each cylinder detected by the intermittent misfire detection means and the continuous misfire detection means is connected to the intermittent misfire detection means and the continuous misfire detection means, and is counted in a predetermined detection section. A misfire determination means for determining that the cylinder is intermittently or continuously misfired when the misfire determination value is equal to or greater than
The misfire determination means invalidates the misfire determination in the detection section when the count value is equal to or greater than a predetermined misfire determination value in a plurality of cylinders, so that the same effect as the invention according to claim 1 is obtained. In addition, erroneous detection due to factors other than misfire caused by periodic rotation fluctuation transmitted to the internal combustion engine via tires when traveling on a wavy road or the like can be removed, and misfire can be detected more accurately. This has the effect.

According to the fifth aspect of the present invention, the engine is connected to an internal combustion engine having a plurality of cylinders, and a predetermined angle around the reference crank angle with respect to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. Crank angle detecting means for detecting the position of the section, load detecting means connected to the internal combustion engine for detecting the load of the internal combustion engine, and connecting to the crank angle detecting means, Acceleration detecting means for detecting an acceleration of a time ratio of each required time in a predetermined angle section before and after the reference crank angle based on the crank angle detecting means, and based on an output signal of the crank angle detecting means, A rotational speed detecting means for detecting the rotational speed of the internal combustion engine; and the load detecting means, the acceleration detecting means, and the acceleration detecting means connected to the rotational speed detecting means. An intermittent misfire detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on the output signal; and the acceleration detecting means connected to the load detecting means, the acceleration detecting means and the rotational speed detecting means, Continuous misfire detection means for detecting misfires continuously occurring in each cylinder of the internal combustion engine based on the output signal of the internal combustion engine, wherein the intermittent misfire detection means and the continuous misfire detection means are either the load detection means or the rotation speed. Since the misfire determination value is changed based on the output signal of the detection means, the intermittent misfire, the most suitable misfire pattern for each continuous misfire is adopted,
This has the effect of improving the detectability of misfire and stably detecting misfire even when the operating conditions change.

According to the present invention, the intermittent misfire detection means and the continuous misfire detection means invalidate the misfire determination when the output signal of the load detection means or the rotation speed detection means satisfies a predetermined condition. Therefore, in an unstable operating region where the signal for detecting misfire is small and invalid, the misfire determination can be invalidated, thereby providing an effect that misfire can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing one embodiment of the present invention that embodies FIG. 1;

FIG. 3 is a time chart for explaining the operation of the embodiment of the present invention;

FIG. 4 is a time chart for explaining the operation of one embodiment of the present invention.

FIG. 5 is an operation flowchart for explaining the operation of the embodiment of the present invention;

FIG. 6 is a calculation flowchart for explaining the operation of one embodiment of the present invention.

FIG. 7 is a calculation flowchart for explaining the operation of one embodiment of the present invention.

FIG. 8 is a calculation flowchart for explaining the operation of one embodiment of the present invention.

FIG. 9 is a time chart for explaining the operation of the embodiment of the present invention;

FIG. 10 is a time chart for explaining the operation of one embodiment of the present invention.

FIG. 11 is a functional block diagram showing another embodiment of the present invention.

FIG. 12 is a configuration diagram showing another embodiment of the present invention that embodies FIG. 11;

FIG. 13 is a calculation flowchart for explaining the operation of another embodiment of the present invention.

FIG. 14 is a cross-sectional view of a wavy traveling road surface for explaining the operation of another embodiment of the present invention.

FIG. 15 is a diagram showing a driving test result related to erroneous detection of another embodiment of the present invention.

FIG. 16 is a diagram showing a traveling test result related to detectability of another embodiment of the present invention.

FIG. 17 is a functional block diagram showing another embodiment of the present invention.

FIG. 18 is a configuration diagram showing another embodiment of the present invention that embodies FIG. 17;

FIG. 19 is a calculation flowchart for explaining the operation of another embodiment of the present invention.

FIG. 20 is a calculation flowchart for explaining the operation of another embodiment of the present invention.

FIG. 21 is a characteristic diagram for describing the operation of another embodiment of the present invention.

FIG. 22 is a characteristic diagram for describing the operation of another embodiment of the present invention.

FIG. 23 is a calculation flowchart for explaining the operation of another embodiment of the present invention.

[Explanation of symbols]

 M1 engine M2 Crank angle detection means M3 Acceleration detection means M4, M9 Misfire detection means M5, M10 Continuous misfire detection means M6 Misfire determination means M7 Load detection means M8 Revolution detection means

Continuation of front page (56) References JP-A-3-81544 (JP, A) JP-A-3-249359 (JP, A) JP-A-4-81548 (JP, A) JP-A-4-198731 (JP) JP-A-4-224258 (JP, A) JP-A-4-262225 (JP, A) JP-A-4-279767 (JP, A) JP-A-3-138433 (JP, A) JP-A-3-246347 (JP, A) JP-A-3-253770 (JP, A) JP-A-4-311651 (JP, A) JP-A-4-311649 (JP, A) JP-A-5-17172 (JP, A) U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F02D 45/00 F02P 17/12

Claims (6)

(57) [Claims] Crank angle detecting means connected to an internal combustion engine having a plurality of cylinders and detecting a position in a predetermined angle section before and after the reference crank angle with reference to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. Acceleration detection means connected to the crank angle detection means for detecting, based on an output signal of the crank angle detection means, an acceleration of a time ratio of each required time in a predetermined angle section before and after the reference crank angle; An intermittent misfire detecting means connected to the acceleration detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; and A continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the internal combustion engine. Misfire detection device. 2. A crank angle detecting means which is connected to an internal combustion engine having a plurality of cylinders and detects a position in a predetermined angle section before and after the reference crank angle with reference to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. Acceleration detection means connected to the crank angle detection means for detecting, based on an output signal of the crank angle detection means, an acceleration of a time ratio of each required time in a predetermined angle section before and after the reference crank angle; An intermittent misfire detection means connected to the acceleration detection means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detection means; and Continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the means. The continuous misfire detection means is provided with a predetermined detection section, and when a misfire greater than a predetermined misfire determination value is detected in the detection section, it is determined that a misfire has occurred in the detection section. A misfire detection device for an internal combustion engine. 3. A crank angle detecting means which is connected to an internal combustion engine having a plurality of cylinders and detects a position in a predetermined angle section before and after the reference crank angle with reference to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. Acceleration detection means connected to the crank angle detection means for detecting, based on an output signal of the crank angle detection means, an acceleration of a time ratio of each required time in a predetermined angle section before and after the reference crank angle; An intermittent misfire detecting means connected to the acceleration detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; and A continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the means; When the misfire detection signal corresponding to each cylinder detected by the intermittent misfire detection means and the continuous misfire detection means is connected to the detection means and counted in a predetermined detection section, and the count value is equal to or more than a predetermined misfire determination value. And a misfire determining means for determining that the cylinder has undergone intermittent or continuous misfire. 4. A crank angle detecting means connected to an internal combustion engine having a plurality of cylinders and detecting a position in a predetermined angle section before and after the reference crank angle with reference to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. Acceleration detecting means connected to the crank angle detecting means, and detecting, based on an output signal of the crank angle detecting means, an acceleration of a time ratio of a required time in each of predetermined angle sections before and after the reference crank angle; An intermittent misfire detecting means connected to the acceleration detecting means for detecting a misfire occurring intermittently in each cylinder of the internal combustion engine based on an output signal of the acceleration detecting means; and A continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the internal combustion engine based on an output signal of the internal combustion engine; When the misfire detection signal corresponding to each cylinder detected by the intermittent misfire detection means and the continuous misfire detection means is connected to the detection means in a predetermined detection section, and the count value is equal to or greater than a predetermined misfire determination value. A misfire determining means for determining that the cylinder has intermittently fired or a continuous misfire, wherein the misfire determination means is configured to: A misfire detection device for an internal combustion engine, wherein the determination is invalidated. 5. A crank angle detecting means connected to an internal combustion engine having a plurality of cylinders and detecting a position in a predetermined angle section before and after the reference crank angle with reference to a predetermined crank angle corresponding to each cylinder of the internal combustion engine. A load detecting means connected to the internal combustion engine to detect a load on the internal combustion engine; a predetermined angle around the reference crank angle based on an output signal of the crank angle detecting means An acceleration detecting means for detecting an acceleration of a time ratio of a required time of each section; a rotational speed connected to the crank angle detecting means for detecting a rotational speed of the internal combustion engine based on an output signal of the crank angle detecting means Detecting means, connected to the load detecting means, the acceleration detecting means, and the rotational speed detecting means, and based on an output signal of the acceleration detecting means, the internal combustion engine An intermittent misfire detecting means for detecting a misfire occurring intermittently in each of the cylinders, and the internal combustion engine is connected to the load detecting means, the acceleration detecting means and the rotational speed detecting means, based on an output signal of the acceleration detecting means. A continuous misfire detecting means for detecting a misfire continuously occurring in each cylinder of the engine, wherein the intermittent misfire detecting means and the continuous misfire detecting means are based on an output signal of the load detecting means or the rotational speed detecting means. A misfire detection device for an internal combustion engine, wherein a misfire determination value is changed. 6. The intermittent misfire detection means and the continuous misfire detection means invalidate the misfire determination when an output signal of the load detection means or the rotation speed detection means satisfies a predetermined condition.
A misfire detection device for an internal combustion engine according to the above.