JP3495463B2 - 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 As a conventional device, there is known a device for determining a misfire based on acceleration in a predetermined angle section of a crank angle position.

This device operates as follows. H is from the predetermined crank angle position BTDC76 ° CA (hereinafter, the crank angle is indicated by CA) to BTDC6 ° CA.
(High) signal, BTDC6 ° CA to next BTDC76
During ° CA, the output of the crank angle sensor, which is a crank angle position detecting means that outputs a low (L) signal, causes the angular acceleration to be calculated by the equation (1) with the time of the H signal as TL and the time of the L signal as TU. When it is above a certain value, it is judged as misfire.

Angular acceleration = TL (i) / (T (i-1)) ³ × {TU (i) / TL (i) -TU (i-1) / TL (i-1)} ( 1)

However, T = TL + TUi is the current value, i-
1 indicates the previous value.

[0006]

The conventional misfire detection device for an internal combustion engine is configured as described above, and in a high revolution state of the internal combustion engine, the variation in angular acceleration during normal combustion becomes large, and the misfire also occurs. There is a problem that misfire determination cannot be performed because the change in angular acceleration due to occurrence is small, or that misfire is normally determined during normal combustion.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a misfire detection device for an internal combustion engine, which can accurately detect misfires in a wide operating range of the internal combustion engine.

[0008]

A misfire detecting device for an internal combustion engine according to claim 1 of the present invention is a cylinder identification signal for an internal combustion engine.
And a crank of the internal combustion engine.
Crank angle sensor for generating angular position signal, and internal combustion engine
In the low engine speed range where the engine speed is less than the first engine speed,
Based on the cylinder identification signal and the crank angle position signal, the pressure
The current angular acceleration is calculated for each compression and combustion stroke,
An angle to obtain the angular acceleration deviation this time based on the angular acceleration of
Acceleration deviation method calculation is performed, and the rotation speed of the internal combustion engine
Is higher than the first rotation speed and higher than the second rotation speed
In the turning range, the cylinder identification signal and the crank angle position signal
The crank angle position for each compression and combustion stroke based on the
The current cycle time of the position signal is calculated, and the past and current cycle times are calculated.
The cycle ratio of this time is calculated based on the
Period ratio deviation method to find the current cycle ratio deviation based on the ratio
Is calculated, and the rotation speed of the internal combustion engine is
In the mid-speed range above the number of revolutions and less than the second number of revolutions,
In addition to performing the calculation of the angular acceleration deviation method,
Calculation of the period ratio deviation method is performed, and the angular acceleration deviation of this time is calculated.
Is above the first misfire judgment value, it is judged as misfire
The misfire determination of the angular acceleration deviation method
If the cycle ratio deviation is greater than or equal to the second misfire determination value, misfire
To perform misfire determination using the periodic ratio deviation method.
And a control unit .

According to a second aspect of the present invention, there is provided a misfire detecting device for an internal combustion engine , which detects a cylinder identifying signal of the internal combustion engine.
Separate sensor and crank angle position signal of the internal combustion engine
Crank angle sensor and the number of revolutions of the internal combustion engine are the first
In the low rotation speed range below the rotation speed of
Based on the crank angle position signal, each compression stroke and combustion stroke
Then, calculate the angular acceleration of this time, and
The angular acceleration deviation of this time is calculated based on the previous and current angles.
Find the difference in angular acceleration deviation this time based on the acceleration deviation,
Based on the current angular acceleration deviation,
Calculation of angular acceleration deviation method to find the difference with the cylinder
However, the rotation speed of the internal combustion engine is higher than the first rotation speed.
In the high rotation speed range above the second rotation speed, the cylinder identification signal
And, based on the crank angle position signal, compression, combustion stroke
The current cycle time of the crank angle position signal is calculated for each
Therefore, based on the past and present cycle times,
Calculate the current cycle ratio deviation based on the previous and current cycle ratios.
Calculate the difference, and based on the cycle ratio deviation of the previous time and this time,
Calculate the difference in the cycle ratio deviation, and based on this cycle ratio deviation,
Cycle ratio deviation method to obtain the difference of cycle ratio deviation from the opposite cylinder
The calculation of the formula is performed so that the rotation speed of the internal combustion engine is equal to the first
In the medium rotation range of the rotation speed or more and less than the second rotation speed,
While performing the calculation of the angular acceleration deviation method,
Calculation of the period ratio deviation method is performed to
If the difference is greater than or equal to the first fire threshold value, then fire fire
It is determined that the opposite cylinder with the angular acceleration deviation of this time
If the difference from the first continuous misfire judgment value is greater than or equal to
Acceleration deviation type misfire that determines that there is continuous misfire
Judgment is made, and the difference of the cycle ratio deviation this time is the second intermittent
If it is more than the misfire judgment value, it is judged that there is a intermittent fire,
The difference between the cycle ratio deviation this time and the opposite cylinder is the second consecutive loss.
If it is above the fire judgment value, it means that the same cylinder has continuously misfired.
A control for performing misfire determination using the periodic ratio deviation method
And a unit.

A misfire detecting device for an internal combustion engine according to claim 3 of the present invention is the misfire detecting device for an internal combustion engine according to claim 1 or 2, wherein the control unit is the
The result of misfire judgment by the angular acceleration deviation method and the cycle ratio deviation
This is the logical sum of the results of the system misfire determination .

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an internal combustion engine that produces an output by burning a mixture of fuel and air. Reference numeral 2 is an air cleaner that purifies the air taken in by the internal combustion engine 1,
An air flow sensor 3 measures the amount of air taken in. Reference numeral 4 is a throttle valve that is linked with an accelerator pedal (not shown) and adjusts the intake air amount according to the load state of the internal combustion engine 1. Reference numeral 5 is an intake pipe, 6 is an exhaust pipe, and 7 is a three-way catalyst capable of simultaneously promoting purification of HC, CO, and NOx discharged from the internal combustion engine 1. Reference numeral 8 denotes a distributor that distributes the high voltage generated by the built-in ignition coil to a spark plug (not shown) of each cylinder to burn the air-fuel mixture in the cylinder.

Further, the distributor 8 has a built-in cylinder identification sensor for outputting a cylinder identification signal S3. 9
Is a signal rotor, and 10 is an electromagnetic pickup, and the projection of the signal rotor 9 passes through the electromagnetic pickup 10 by the rotation of the internal combustion engine, whereby a predetermined angular position signal S
A crank angle sensor that outputs 4 is configured. Reference numeral 11 denotes a control unit for calculating and controlling the fuel injection amount and ignition timing based on the information of each sensor, detecting misfire, and identifying the misfiring cylinder.

S1 is an intake air amount signal of the air flow sensor, and S2 is a throttle position signal of a throttle position sensor (not shown).

Next, the operation of the first embodiment of the present invention will be specifically described. First, a cylinder identification signal (hereinafter SG
C signal) S3 and crank angle position signal (hereinafter Ne
A cylinder identifying method in S4 (referred to as a signal) will be described.

The SGC signal and the Ne signal are shown in FIG.
The waveform is as shown in (c), and the Ne signal is at the top dead center (hereinafter TD).
1) with reference to the position 6 ° CA before
The periodic signal is distributed in the L section of 110 ° CA and the H section of 70 ° CA in the 80 ° CA cycle. SGC
The signal is before the top dead center of the Ne signal (hereinafter referred to as BTDC) 7
The period signal is divided into H and L sections of 180 ° CA each in 360 ° CA period with the position 55 ° CA before the rising position of 6 ° CA as a reference.

The control unit 11 is the BTDC 7
The cylinder corresponding to the compression / combustion stroke is identified in the interrupt process at each rising cycle of the Ne signal at 6 ° CA.
When the previous value of the GC signal is L, the current value is H, # 1 cylinder, the previous value is H, the current value is H, # 3 cylinder, the previous value is H, the current value is L, # 4 cylinder, the previous value Is L, and the current value is L, it is identified as the # 2 cylinder (the previous value is the last interrupt processing,
This time value shows the value at the time of this interrupt processing).

Next, the control of fuel and ignition will be briefly described. The control unit 11 controls the air flow sensor 3 by interrupt processing at every rising cycle of the Ne signal.
The operating time of the injector is calculated on the basis of the intake air amount of the internal combustion engine 1 measured in step 1, the internal combustion engine speed and the water temperature calculated from the Ne signal, the battery voltage, etc. # 4 if the cylinder is # 1
Cylinder, # 2 cylinder when identification cylinder is # 3 cylinder, # 1 cylinder when identification cylinder is # 4 cylinder, # 3 cylinder when identification cylinder is # 2 cylinder) That is, the injector of the cylinder in the exhaust stroke ( (Not shown) is energized for the injector drive time previously obtained, and fuel is supplied into the intake pipe 6.

Further, the energization of the ignition coil in the distributor 8 is controlled by referring to the Ne signal. That is, the energization of the ignition coil is started in the section where the Ne signal of the compression stroke is H, and the energization of the ignition coil is interrupted at the ignition timing calculated by the control unit 11 according to the internal combustion engine speed and the load. A high voltage ignites the spark plug to burn the air-fuel mixture in the cylinder.

Therefore, if the above-mentioned fuel injection and ignition are normally performed and the air-fuel mixture in the cylinder of the internal combustion engine 1 normally burns, the TDC as shown at a crank angle of 180 degrees or 360 degrees in FIG. The in-cylinder pressure waveform becomes such that the in-cylinder pressure peaks later. If misfire occurs due to ignition failure, improper mixture, etc., the crank angle 900 of FIG.
Cylinder pressure peaks at TDC as shown in
The waveform becomes symmetrical with respect to the center, and the in-cylinder pressure peak value becomes lower than that during normal combustion. When a misfire occurs, the torque increase due to combustion cannot be obtained, and therefore the time required for rotation in the predetermined crank angle section is longer than that during normal combustion. There are several methods for detecting a misfire due to periodic fluctuations in the predetermined crank angle section, but the present invention includes angular acceleration deviation method (hereinafter referred to as α method) and cycle ratio deviation method (hereinafter referred to as S method) among them. Focusing on the fact that the internal combustion engine operating states with good detectability are different, each of them is detected by switching depending on the conditions.

The misfire detection method will be specifically described below. 2 and 3 are flowcharts of the α system according to the first embodiment, FIG. 4 is a flowchart of the calculation procedure in the S system control unit 11, and the flow of FIG. 2 is an interrupt process at the rising edge of the Ne signal. The flow of FIG. 4 is executed by an interrupt process at the fall of the Ne signal.
Further, (i) shown in the description and flowcharts of the embodiments and subsequent embodiments show the current value, and (i-1) shows the previous value.

First, regarding the operation of the α method, the time TU which is the L section of the Ne signal in step S201 in FIG.
(i) and the time TA (i) at each rising edge of the Ne signal are saved in TU (i-1) and TA (i-1), respectively. Next, step S
At 202, the counter value stored in the input capture register (hereinafter referred to as ICR) at the time of rising Ne is saved in the memory BT76 (i) as the time at the time of rising Ne.

In step S203, the flow chart of FIG. 3, which is the processing at the time of the fall of Ne after the calculation of the angular acceleration α is started, is executed, and the memory BT6 (i) for saving the fall time of Ne is updated once or more. It is determined whether it has been done. As a method, the flag cleared when the calculation of the angular acceleration α is started is also set when BT6 (i) is set. If BT6 (i) has never been updated, this process ends. BT6
If (i) has been updated one or more times, step S20.
At 4, the time from the fall of the Ne signal to the rise according to the equation (2), that is, the time of the Ne signal L section is stored in TU (i).

[0028]   TU (i) = BT76 (i) -BT6 (i) (2)

Next, in step S205, the flow chart of FIG. 3, which is the processing at the fall of Ne, is executed and TL is executed.
It is determined whether (i) has been updated once or more, and if it has not been updated, this processing ends. If it has been updated, in step S206, the total of the Ne signal H section and the L section, that is, the time for each Ne signal rising cycle is calculated by TA from Equation (3).
Save in (i) and end this process.

[0030] TA (i) = TU (i) + TL (i) (3)

Continuing, in step S301 in FIG.
Are the angular acceleration α (i), the angular acceleration deviation Δα [X-2] (i), and the angular acceleration deviation smoothed value AΔα [X-2] (i) respectively α (i-1),
Save to Δα [X-2] (i-1) and AΔα [X-2] (i-1).

[X-2] will be described below.
Represents the cylinder in the compression stroke and combustion stroke identified by the Ne signal and the SGC signal. In the 4-cycle 4-cylinder internal combustion engine of this embodiment, # 1 → # 3 → # 4 → # 2 → # 1.
Move in the order of. Therefore, [X-2] refers to the cylinder before compression and combustion stroke cylinder 2 ignitions (360 ° CA). When [X] is # 1 cylinder, # 4 cylinder, [X] is # 3 cylinder. # 2 cylinder, # 1 cylinder when [X] is # 4 cylinder, # 3 cylinder when [X] is # 2 cylinder. Also, [X-1] described later similarly indicates a cylinder before one ignition (180 ° CA) of compression and combustion strokes. When [X] is # 1 cylinder, # 2 cylinder, [X] is # 3 cylinder. # 1 cylinder in case of, # 3 cylinder in case [X] is # 4 cylinder, # 2 in case of [X]
In the case of cylinders, it is # 4 cylinder.

Next, in step S302, the process shown in FIG. 2 at the time of rising Ne is executed twice or more, and TA (i-
It is determined whether 1) has been updated to a correct value, and if not updated, the process proceeds to step S313. If it has been updated, the angular acceleration α is calculated by the following equation (4) in step S303.

Α (i) = TL (i) / (TA (i-1)) ³ × {TU (i) / TL (i) -TU (i-1) / TL (i-1)} ...・ (4)

As shown in FIG. 8D, α has a waveform that fluctuates to the positive (+) side due to the occurrence of misfire, and fluctuates to the negative (-) side in the next cycle. Next, step S30
In step 4, the calculation S303 of the angular acceleration α is executed twice or more,
It is determined whether or not α (i-1) has been updated to a correct value, and if not updated, the process proceeds to step S313. If it has been updated, the following equation (5) is calculated in step S305 to obtain the angular acceleration deviation.

[0036] Δα [X-2] (i) = α (i-1) -α (i) (5)

Since Δα is the difference between the positive (+) side fluctuation at the time of misfire of the angular acceleration α and the negative (−) side fluctuation of the next cycle,
As shown in FIG. 8 (e), the fluctuation at the time of misfire can be further increased. Subsequently, in step S306, it is determined whether or not this processing is executed twice or more in the same cylinder and AΔα [X-2] (i-1) is updated to a correct value, and if it is updated, in step S307. The difference between the angular acceleration deviation and the previous value is calculated by the following equation (6).

[0038]   ΔΔα [X-2] (i) = Δα [X-2] (i) -AΔα [X-2] (i-1) (6)

ΔΔα has the waveform shown in FIG.
Since variations during normal combustion can be eliminated compared to α, it is easier to distinguish misfire cylinders from normal combustion cylinders, and by comparing this value with the misfire judgment value, intermittent misfires can be determined. Can be detected. Further, in step S308, the smoothed value of Δα is calculated and updated from equation (7).

[0040]   AΔα [X-2] (i) = KA × AΔα [X-2] (i-1)                       + (1 − KA) × Δα [X-2] (i) (7)

Here, KA is a constant and can take a value of 0 to 1, but in this case, about 0.75 is a reasonable value.

If AΔα [X-2] (i-1) is not updated in step S306, AΔ is further increased in step S309.
It is determined whether or not α [X-2] (i) has been updated. If not updated, AΔα [X-2] (i) is determined in step S310.
Δα [X-2] (i) is substituted as the initial value of.

Next, in step S311, the Δα of the opposite cylinder is increased.
It is determined whether or not AΔα [X] (i), which is a smoothing value, is updated, and if it is updated, the difference between the angular acceleration deviation and the opposed cylinder is calculated in step S312 by the following equation (8). To do.

[0044]   Δseg Δα [X-2] (i) = Δα [X-2] (i) -A Δα [X] (i) (8)

By comparing this value with the misfire determination value, it is possible to detect the continuous misfire of the same cylinder which could not be detected by ΔΔα.

Next, in step S313, TL (i), which is the time of the H section of the Ne signal, is saved in TL (i-1), and in step S314, the counter value stored in ICR at the time of falling of Ne is Ne. BT6 (i) as the fall time
Retreat to. BT76 (i), which is the time at which Ne rises at least once after the start of calculation of the angular acceleration α in step S315.
Is updated, and if BT76 (i) has never been updated, this process ends. BT76
If (i) is updated once or more, step S31
In step 6, the Ne signal rises and falls according to the following equation (9), that is, the time of the Ne signal H section is stored in TL (i).

[0047]   TL (i) = BT6 (i) −BT76 (i) (9)

Next, regarding the calculation of the S method, in the flowchart of FIG. 4, in step S401, TS (i-2), TS (i-1), and TS (i-2), which are the cycle time for each falling edge of the Ne signal, are calculated.
(i), cycle ratio S (i), cycle ratio deviation ΔS [X-1] (i), cycle ratio deviation smoothed value AΔS [X-1] (i), Ne signal falling time BT6 (i) is TS (i-3), TS (i-2), T
S (i-1), S (i-1), ΔS [X-1] (i-1), AΔS [X-1] (i-
1) Save to BT6 (i-1).

Subsequently, in step S402, the counter value stored in the ICR at the fall of Ne is saved in BT6 (i) as the time at the fall of Ne. Step S4
This processing is executed twice or more from the calculation start of S in 03. B
Determine whether T6 (i-1) has been updated to the correct value,
If the process has not been executed twice or more, this process ends. If it has been executed twice or more, step S404.
Then, the time for each falling edge period of the Ne signal is stored in TS (i) by the following equation (10).

[0050]   TS (i) = BT6 (i) −BT6 (i-1) (10)

Next, in step S405, it is determined whether or not this process is executed five times or more after the calculation of the cycle ratio S is started and TS (i-3) is updated to a correct value. If not, this process is executed. finish. If it is executed five times or more, the cycle ratio S is calculated by the equation (11) in step S406.

[0052]   S (i) = {TS (i) -TS (i-1)} / (TS (i-3) + TS (i-2) + TS (i-1) + TS (i)) / 4 × 100                                                       ... (11)

The cycle ratio S fluctuates to the + side due to the occurrence of misfire as shown in FIG. 9D, and has a waveform in which the fluctuation on the + side remains in the next cycle. Next, in step S407, the operation S406 of S is executed twice or more to determine whether or not S (i-1) has been updated to a correct value. If not updated, this process ends. If it has been updated, in step S408, the period ratio deviation is calculated by the equation (12).

[0054]     ΔS [X-1] (i) = S (i) -S (i-1) (12)

ΔS has the waveform shown in FIG. 9 (e). In S, the + side was changed to the − side in the cycle following the misfire, so that the difference between the misfire and the normal state becomes large. Further, step S4
In 09, this process is executed twice or more in the same cylinder, and AΔS [X
-1] (i-1) is determined to have been updated to a correct value, and if it has not been updated, then in step S412 A
It is determined whether or not ΔS [X-1] (i) has been updated. If not updated, AΔS [X-1] (i) is determined in step S413.
Substitute ΔS [X-1] (i) as the initial value for.

When AΔS [X-1] (i-1) is updated in step S409, the difference between the cycle ratio deviation and the previous value is calculated in step S410 by the following equation (13).

[0057]   ΔΔS [X-1] (i) = ΔS [X-1] (i) −AΔS [X-1] (i-1) (13)

The ΔΔS has the waveform shown in FIG. 9 (f), and the variation in the normal condition can be removed more than ΔS, and the difference between the misfire condition and the normal condition becomes larger. Therefore, the intermittent misfire can be compared by comparing with the misfire determination value. Can be detected. Subsequently, in step S411, the smoothed value of ΔS is calculated by (14) and updated.

[0059]   AΔS [X-1] (i) = KS × AΔS [X-1] (i-1)                       + (1 − KS) × ΔS [X-1] (i) (14)

KS is a constant, and a reasonable value is about 0.75. Next, in step S414,
It is determined whether AΔS [X-3] (i), which is the smoothed value of S, has been updated, and if it has been updated, step S41.
In step 5, the difference between the cycle ratio deviation and the opposite cylinder is calculated by the equation (15).

[0061]   ΔsegΔS [X-1] (i) = ΔS [X-1] (i) -AΔS [X-3] (i) (15)

By comparing this value with the misfire determination value, it is possible to detect the continuous misfire of the same cylinder which could not be detected by ΔΔS.

Next, the misfire determination and misfire cylinder identification method will be described. FIG. 5 is an α method, and FIG. 6 is an S method misfire determination method. First, regarding the misfire detection in the α method, the flowchart of FIG. 3 is executed from the calculation start of the angular acceleration α in step S501 of FIG. 5, and ΔΔα [ It is determined whether X-2] (i) has been updated once or more, and if it has not been updated, the process proceeds to step S505.

If it has been updated, step S502.
Then, it is compared whether ΔΔα [X-2] (i) is larger than the judgment value of interstitial fire. Here, the misfire determination value is an experimentally obtained value, and is stored in a read-only memory (hereinafter referred to as ROM) in the control unit, for example, as a two-dimensional MAP depending on the rotation speed and the charging efficiency of the internal combustion engine.
As a result of comparison, if smaller than the determination value, step S5
It proceeds to 04 and determines that it is normal. If it is larger, the process proceeds to step S503, and it is determined that the cylinder indicated by [X-2] is in the intermittent fire.

Subsequently, in step S505, the angular acceleration α
3 is executed from the start of the calculation of
It is determined whether or not gΔα [X-2] (i) has been updated once or more, and if it has not been updated, this processing ends. If it has been updated, ΔsegΔα [X- in step S506.
2] (i) is compared to see if it is larger than the continuous misfire determination value. If smaller, it proceeds to step S508 and is determined to be normal, and this processing ends. If it is larger, step S
Proceeding to 507, it is determined that the cylinder indicated by [X-2] is continuously misfiring, and this processing ends.

Next, regarding the S-system misfire detection, ΔΔS [X− from the start of calculation of the period ratio S in step S601 of FIG.
1] (i) is determined whether it has been updated one or more times, and if it has not been updated, the process proceeds to step S605. If it has been updated, it is compared in step S602 whether or not ΔΔS [X-1] (i) is larger than the inter-firing fire determination value. Here, the misfire determination value is a ROM obtained by an experiment different from the α method.
It is a two-dimensional MAP according to the rotation speed and the charging efficiency of the internal combustion engine. As a result of the comparison, if this value is smaller than the inter-missing fire determination value, the process proceeds to step S604 and it is determined to be normal. If it is larger, the process proceeds to step S503, and it is determined that the cylinder indicated by [X-1] is in the intermittent fire.

Subsequently, in step S605, the flowchart of FIG. 4 is executed from the start of calculation of the period ratio S, and Δseg
Determine if ΔS [X-1] (i) has been updated more than once,
If it has not been updated, this process ends. If it has been updated, ΔsegΔS [X-1] (i) in step S606.
Is larger than the continuous misfire determination value, and if smaller, it proceeds to step S608 and is determined to be normal. If it is larger, the routine proceeds to step S607, where it is determined that the cylinder indicated by [X-1] is continuously misfiring, and this processing ends.

FIG. 7 is a flow chart showing a method of switching the judgment between the S method and the α method. Step S70
1 shows the subroutines of FIGS. 2 and 3, step S702 of FIG. 4, step S704 of FIG. 6 and step S705 of FIG. After the calculation by the α method in step S701 and the calculation by the S method in step S702, it is determined in step S703 whether the internal combustion engine speed is 3000 rpm or more, for example.
If it is equal to or higher than rpm, misfire determination by the S method is performed in step S704. Otherwise, step S705
The α-method is used to determine the misfire.

As described above, according to the first embodiment, there are disadvantages of the α method in which the detection performance is deteriorated in the high rotation speed and low load range and the S method in which the influence of swingback of the missing fire is great in the low rotation speed range. In order to compensate for the above, the misfire can be accurately detected in a wide range of operating conditions of the internal combustion engine by performing the misfire determination in the low speed range using the α method and in the high speed range using the S method.

Embodiment 2. In the first embodiment, the calculations of the α method and the S method are always performed, and only the misfire determination is switched depending on the internal combustion engine rotation condition, so the calculation load of the control unit 11 is large. Therefore, this embodiment will be described as a method for reducing this calculation load.

FIG. 10 is a subroutine which replaces FIG. 7 of the first embodiment, and similar to FIG. 7, step S802.
Shows the subroutine of FIG. 4, step S803 of FIG. 6, step S804 of FIGS. 2 and 3, and step S805 of FIG. In step S801, it is determined whether the internal combustion engine speed is 3000 rpm or higher, and if it is 3000 rpm or higher, step S802.
After the calculation by the S method in step S803, misfire determination by the S method is performed in step S803. If not, after the calculation by the α method in step S804, the misfire determination by the α method is performed in step S805.

As described above, according to the second embodiment, in the low rotation speed range, the α method is used to perform the misfire determination, and in the high rotation speed range, the S method is used to perform the S method. By performing the misfire determination by the method, the misfire can be accurately detected in a wide range of operating states of the internal combustion engine while reducing the calculation load on the control unit.

Third Embodiment In the second embodiment, since the calculation and determination of the α method and the S method are completely switched depending on the internal combustion engine rotation condition, misfire cannot be detected for the convenience of calculation during several ignitions immediately after switching. Therefore, in the third embodiment, a method of compensating for this will be described.

FIG. 11 is a subroutine which replaces FIG. 7 of the first embodiment similarly to the second embodiment.
902 is shown in FIG. 4, and steps S905 and S906 are shown in FIG.
3 and step S907 in FIG. 5 and step S908.
Shows the subroutines of FIG. 6, respectively.

In step S901, it is determined whether the internal combustion engine speed is, for example, 2500 rpm or more. If not, in step S906, the α method is used for calculation. If it is 2500 rpm or more, step S902.
In step S904, the calculation by the S method is performed.
Then, it is determined whether the internal combustion engine speed is lower than 3000 rpm, for example, and if it is low, the α method is further calculated.

Subsequently, in step S907, the misfire determination by the α method is performed, in step S908 the misfire determination by the S method is performed, and in step S909 the logic of the α system misfire determination result and the S method misfire determination result is determined. Take the sum.

As described above, according to the third embodiment, for example, between 2500 rpm and 3000 rpm, both the α method and the S method are operated,
In the low rotation speed range lower than 00 rpm, only the α method is calculated, 3
In the high rotation range of 000 rpm or more, by performing only the calculation of the S method, it is possible to reduce the calculation load on the control unit and accurately detect misfire in a wide range of operating conditions of the internal combustion engine. It is possible to eliminate the portion where misfire detection cannot be detected between several ignitions immediately after switching.

Fourth Embodiment Next, a fourth embodiment of the invention will be described. FIG. 12 is a flowchart showing this mode 4, step S1001 shows the subroutine of FIGS. 2 and 3, and step S1002 shows the subroutine of FIG. After the calculations by the α and S methods are performed in steps S1001 and S1002, respectively, step S10
In 03, it is determined whether or not ΔΔα [X-2] (i) has been updated once or more. If it has been updated, Δ is calculated in step S1004.
It is determined whether or not Δα [X-2] (i) is larger than the inter-firing fire determination value. If smaller, it proceeds to step S1006 and is determined to be normal. If it is larger, the process proceeds to step S1005, and it is determined that the cylinder indicated by [X-2] has an inter-firing fire.

Subsequently, in step S1007, ΔsegΔ
It is determined whether or not S [X-1] (i) has been updated one or more times, and if it has been updated, ΔsegΔS [X- in step S1008.
1] (i) is compared to determine whether it is larger than the continuous misfire determination value, and if smaller, it proceeds to step S1010 and is determined to be normal. If it is larger, the process proceeds to step S1009 [X
It is judged that the cylinder indicated by -1] is continuously misfiring.

As described above, according to the fourth embodiment, there are disadvantages of the α method in which the detectability is deteriorated in the high rotation speed and low load range and the S method in which the influence of swingback of the missing fire is great in the low rotation speed range. To compensate for this, the intermittent fire is determined by the α method and the continuous misfire is determined by the S method, whereby the misfire can be accurately detected in a wide range of operating conditions of the internal combustion engine.

Embodiment 5. In the first embodiment, the cycle ratio S
Is calculated every BTDC 6 ° CA, that is, the combustion stroke of the internal combustion engine, and when there is a difference in the charging efficiency for each cylinder due to the shape of the intake system of the internal combustion engine, etc., the cycle ratio S also differs for each cylinder. Detectability may decrease during continuous misfires when comparing with the opposite cylinder.

Therefore, in the fifth embodiment, the calculation section of the cycle ratio S is set every BTDC 76 ° CA, that is, the compression and combustion strokes, so that a cylinder having a small filling efficiency requires a small amount of energy for compression, so that the compression stroke time is short. Since the amount of energy generated at is small, the combustion stroke time becomes long. On the contrary, in a cylinder having a high filling efficiency, the compression stroke time is long and the combustion stroke time is short. Therefore, as a total, the difference in the charging efficiency for each cylinder does not occur in the cycle ratio S.

Now, a concrete description will be given below with reference to FIGS.
4 is a flowchart showing this embodiment, which is a portion replacing FIG. 4 of the first embodiment. FIG. 13 shows an interrupt process at the rising edge of Ne, and FIG. 14 shows an interrupt process at the falling edge of Ne. Steps S1101 to S in FIG.
1104 and steps S1201 to 1215 of FIG. 14 are processes in which the last two digits of steps S401 to 415 of FIG. 4 correspond to the same number, and description of the same process is omitted.

First, in the interrupt process for each rising edge of Ne shown in FIG. 13, the cycle time TS for each rising edge of Ne is obtained. next,
After the period ratio S is obtained by the interrupt process at each fall of Ne in FIG. 14, the period ratio deviation is obtained by the equation (16) in step S1208.

[0085]   ΔS [X-3] (i) = S (i-1) -S (i) (16)

In this case, the cycle ratio S fluctuates to the + side at the time of misfire and at the next cycle as shown in FIG. 15 (d). Furthermore, the maximum value of the fluctuation is the next cycle after the occurrence of misfire, and it returns to normal after another cycle, so ΔS
The difference between misfire and normal can be maximized by calculating the difference between the previous value and the current value.

Further, since the maximum value of the fluctuation of the cycle ratio S is the next cycle at the time of misfire occurrence and the difference of ΔS from the previous value to the current value, the fluctuation of ΔS due to misfire is different from that of the first embodiment. Cylinder identification is [X-3] because the cycle is delayed.
Becomes

Next, as for the method of judging misfire, ΔΔS [X-3] (i) and ΔsegΔS [X-3] (i) obtained in steps S1210 and S1215 of FIG. If it is larger than the stored MAP value, it is judged as misfire.

Needless to say, the α method may be switched as in the first to fourth embodiments.

As described above, according to the fifth embodiment, the Ne rising cycle, that is, the predetermined section from the compression stroke to the combustion stroke is set as the calculation section of S, so that the difference in the cycle ratio due to the variation in the charging efficiency for each cylinder is small. In particular, during continuous misfires, misfires can be accurately detected in a wide range of operating conditions of the internal combustion engine.

Sixth Embodiment In the fifth embodiment, the variation of the cycle ratio deviation between the cylinders due to the difference in the charging efficiency that affects the intake system of the internal combustion engine can be dealt with, but the variation due to the rigidity of the crankshaft of the internal combustion engine cannot be dealt with. . Therefore, in the sixth embodiment, a method capable of coping with variations due to factors other than the filling efficiency will be described.

The sixth embodiment is similar to the fifth embodiment shown in FIG.
3, the processing procedure of FIG. 14 is used, and only step S1215 takes the expression (17).

[0093]   ΔsegΔS [X-3] (i) = ΔS [X-3] (i) -AΔS [X-1] (i)                           -DS [X-3] + DS [X-1] (17)

However, DS is the average value of ΔS at the time of normal combustion, and the value obtained experimentally for each cylinder is stored in the ROM for each cylinder.

Regarding the above equation (17), FIG. 16 to FIG.
9, the horizontal axis represents the cylinder, and the vertical axis represents ΔS or ΔsegΔS, and FIG. 16 to FIG. 19 show the average value of the center line of the square in the drawing and the range that can be taken above and below for each cylinder. When the difference between the average values of the # 1 cylinder and the # 4 cylinder of ΔS shown in FIG. 16 is a and the difference between the average values of the # 3 cylinder and the # 2 cylinder is b, Δseg ΔS is the difference between the opposite cylinders. As shown in, the average values of # 1 cylinder are −a, # 3 cylinders are −b, # 4 cylinders are + a, and # 2 cylinders are + b.

Therefore, if the correction by ΔS at the time of normal combustion is not performed, for example, if the # 1 cylinder is continuously misfired,
As shown by the solid line, the misfire cylinder # 1 is on the + side, and the opposite cylinder # of the misfire cylinder is #, as shown by the solid line with respect to ΔsegΔS during normal combustion shown by the broken line in FIG.
4 is the negative side, the other cylinders # 2 and # 3 hardly change, and when the lower limit value of the misfire cylinder # 1 is set as the misfire determination value, the normal combustion cylinders # 4 and # 2 exceed the misfire determination value. There is a false judgment.

Next, when the correction by ΔS at the time of normal combustion is performed, the variation at the time of normal combustion is corrected as shown by the broken line in FIG. Since only # 1 changes to the + side relative to the normal cylinder, even if the lower limit of misfiring cylinder # 1 is set as the misfire determination value, other cylinders will not be erroneously determined as misfire.

As described above, according to the sixth embodiment, by correcting the ΔS variation in the normal state, it is possible to detect misfire with high accuracy in a wide operating range of the internal combustion engine, particularly in the case of continuous misfire, which is compared with the opposite cylinder. it can.

Further, according to the present invention, the ΔS in the normal condition is stored in the ROM as the MAP for each cylinder, but the ΔsegΔS in the normal condition is stored in the ROM for the # 1, # 4 cylinder, # 2 and # 3 cylinders. The same effect can be obtained even if the opposite cylinders are memorized in the above and are corrected by reversing the signs.

Further, the MAP of the ΔS average value at the time of normal combustion may not be stored in the ROM, but a MAP for misfire determination may be provided for each cylinder.

Further, in the present invention, the ΔS at the normal time is stored in the ROM based on the data obtained by the experiment, but the same effect can be obtained even if the learning is performed and corrected in the actual running state. .

[0102]

As described above, according to the present invention, the internal combustion
A cylinder identification sensor for generating an engine cylinder identification signal;
The crank angle sensor that generates the crank angle position signal of the internal combustion engine
And the internal combustion engine has a low rotational speed lower than the first rotational speed.
In the rotation range, the cylinder identification signal and the crank angle position
Based on the signal, the current angular acceleration for each compression and combustion stroke
Is calculated based on the previous and current angular acceleration.
Perform the calculation of the angular acceleration deviation method to obtain the speed deviation,
The second number of revolutions of the internal combustion engine is higher than the first number of revolutions.
In the high rotation range above the number of rotations of
Based on the crank angle position signal, each compression stroke and combustion stroke
To obtain the current cycle time of the crank angle position signal,
Calculate the current cycle ratio based on the past and current cycle times
Therefore, the current cycle ratio deviation based on the previous and current cycle ratios
The internal combustion engine
The number of revolutions is equal to or higher than the first number of revolutions and the second number of revolutions
In the medium rotation range below, the calculation of the angular acceleration deviation method is performed.
In addition to performing the calculation of the period ratio deviation method,
When the angular acceleration deviation this time is greater than or equal to the first misfire determination value
The misfire judgment of the angular acceleration deviation method that determines that there is a misfire
And the current cycle ratio deviation is the second misfire determination value.
Period ratio deviation method that determines misfire in the above cases
And a control unit for carrying out misfire determination of
Therefore , misfire can be accurately detected in a wide range of operating states of the internal combustion engine.

Further, according to the present invention, the cylinder identification of the internal combustion engine is
A cylinder identification sensor that generates a separate signal and a cylinder of the internal combustion engine.
A crank angle sensor for generating a rank angle position signal;
In the low speed range where the rotation speed of the internal combustion engine is less than the first rotation speed,
Based on the cylinder identification signal and the crank angle position signal
Then, the angular acceleration of this time is calculated for each compression and combustion stroke.
And the current angular acceleration deviation is calculated based on the current angular acceleration.
Therefore, based on the angular acceleration deviation of the previous time and this time,
Calculate the difference in speed deviation and calculate the difference based on the current angular acceleration deviation.
Angular acceleration deviation to obtain the difference
The difference type calculation is performed, and the rotation speed of the internal combustion engine is
In the high speed range above the second speed, which is higher than the first speed
Is based on the cylinder identification signal and the crank angle position signal.
Then, the crank angle position signal is calculated for each compression and combustion stroke.
This cycle time is calculated and based on past and current cycle times
The cycle ratio of this time is calculated based on the previous and current cycle ratios.
Based on the current cycle ratio deviation,
The difference of the cycle ratio deviation for this time is calculated based on the deviation, and the
Difference of the cycle ratio deviation this time from the opposite cylinder based on the period ratio deviation
The internal combustion engine
The number of revolutions is equal to or higher than the first number of revolutions and the second number of revolutions
In the medium rotation range below, the calculation of the angular acceleration deviation method is performed.
In addition to performing the calculation of the period ratio deviation method,
The difference in the angular acceleration deviation this time is less than or equal to the deletion fire determination value during the first period.
In the case above, it is judged that there is a gap between fires, and the corner of this time
The difference between the acceleration deviation and the opposite cylinder is less than the first continuous misfire judgment value.
In the case above, the angle that determines that the same cylinder is continuously misfiring
Acceleration deviation method misfire determination was performed, and the cycle ratio
Inter-deletion if the difference in deviation is greater than or equal to the second fire detection value
It is judged that there is a fire, and the opposite cylinder with the current cycle ratio deviation
If the difference between the same and the second continuous misfire judgment value
Cycle ratio deviation type misfire judgment that determines that
Since the control unit for executing the control is provided, it is possible to detect misfire with high accuracy in a wide range of operating states of the internal combustion engine while reducing the calculation load on the control unit.

Further, according to the present invention, the control
The unit is the result of the misfire determination of the angular acceleration deviation method.
And the logical sum of the results of the misfire determination of the period ratio deviation method
Runode, as possible out is possible to accurately detect the misfire in a wide range of engine operating conditions while reducing the calculation load on the control unit.

[0105]

[0106]

[0107]

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a misfire detection device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 5 is a flowchart for explaining the operation of the first embodiment of the present invention.

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

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

FIG. 8 is a time chart for explaining the operation of the first embodiment of the present invention.

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

FIG. 10 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 11 is a flowchart for explaining the operation of the third embodiment of the present invention.

FIG. 12 is a flowchart for explaining the operation of the fourth embodiment of the present invention.

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

FIG. 14 is a flowchart for explaining the operation of the fifth embodiment of the present invention.

FIG. 15 is a time chart for explaining the operation of the fifth embodiment of the present invention.

FIG. 16 is a graph for explaining the operation of the sixth embodiment of the present invention.

FIG. 17 is a graph for explaining the operation of the sixth embodiment of the present invention.

FIG. 18 is a graph for explaining the operation of the sixth embodiment of the present invention.

FIG. 19 is a graph for explaining the operation of the sixth embodiment of the present invention.

[Explanation of symbols]

1 internal combustion engine, 2 air cleaner, 3 air flow sensor, 4 throttle valve, 5 intake pipe, 6 exhaust pipe,
7 three-way catalyst, 8 distributor, 9 signal rotor, 10 electromagnetic pickup, 11 control unit.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiki Kuroda 6-1-2 Hamayama-dori, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Control Software Co., Ltd. (56) Reference JP-A-6-207552 (JP, A) ) JP-A-5-202800 (JP, A) JP-A-6-2609 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 45/00

Claims (3)

(57) [Claims] 1. A cylinder for generating a cylinder identification signal of an internal combustion engine.
An identification sensor and a crank that generates a crank angle position signal of the internal combustion engine
In the low speed region where the rotation speed of the internal combustion engine is less than the first rotation speed
Is based on the cylinder identification signal and the crank angle position signal.
Based on this, the current angular acceleration is calculated for each compression and combustion stroke,
Angular acceleration deviation of this time based on the previous and current angular acceleration
An angular acceleration deviation method is performed to determine that the number of revolutions of the internal combustion engine is greater than the first number of revolutions.
In the high rotation speed range of 2 or more, the cylinder identification signal and
Based on the crank angle position signal, every compression stroke and combustion stroke
To obtain the current cycle time of the crank angle position signal,
Calculate the current cycle ratio based on the past and current cycle times
Therefore, the current cycle ratio deviation based on the previous and current cycle ratios
And a rotational speed of the internal combustion engine is equal to or higher than the first rotational speed and is equal to or higher than the first rotational speed.
In the middle rotation speed range below the second rotation speed, the angular acceleration deviation method
The calculation of the equation is performed and the operation of the period ratio deviation method is performed.
Calculation is performed and the angular acceleration deviation at this time is equal to or greater than the first misfire determination value.
The misfire judgment of the angular acceleration deviation method that determines that there is a misfire
If the cycle ratio deviation this time is equal to or greater than the second misfire determination value,
Determines that a misfire has occurred.
Misfire detecting device for an internal combustion engine characterized by comprising a control unit to implement. 2. A cylinder for generating a cylinder identification signal of an internal combustion engine.
An identification sensor and a crank that generates a crank angle position signal of the internal combustion engine
In the low speed region where the rotation speed of the internal combustion engine is less than the first rotation speed
Is based on the cylinder identification signal and the crank angle position signal.
Based on this, the current angular acceleration is calculated for each compression and combustion stroke,
Angular acceleration deviation of this time based on the previous and current angular acceleration
Is calculated based on the angular acceleration deviations of the previous time and this time.
Calculate the difference in angular acceleration deviation, and based on this angular acceleration deviation
Angular acceleration that obtains the difference between this time's angular acceleration deviation and the opposite cylinder
Degree calculation is performed, and the rotation speed of the internal combustion engine is greater than the first rotation speed.
In the high rotation range of not lower than the rotational speed of 2, the cylinder identification signal and
Based on the crank angle position signal, every compression stroke and combustion stroke
To obtain the current cycle time of the crank angle position signal,
Calculate the current cycle ratio based on the past and current cycle times
Therefore, the current cycle ratio deviation based on the previous and current cycle ratios
Is calculated based on the cycle ratio deviations of the previous time and this time.
Calculate the difference in period ratio deviation, and based on this cycle ratio deviation,
Ratio Deviation Method for Finding Difference in Period Ratio Deviation from Opposed Cylinder
Is performed and the rotation speed of the internal combustion engine is equal to or higher than the first rotation speed and
In the middle rotation speed range below the second rotation speed, the angular acceleration deviation method
The calculation of the equation is performed and the operation of the period ratio deviation method is performed.
Calculation is performed, and the difference in the angular acceleration deviation this time is equal to or less than the deletion fire judgment value during the first period.
In the case above, it is judged that there is a gap between fires, and the corner of this time
The difference between the acceleration deviation and the opposite cylinder is less than the first continuous misfire judgment value.
In the case above, the angle that determines that the same cylinder is continuously misfiring
Acceleration deviation method misfire determination is performed, and the difference in the cycle ratio deviation this time is equal to or greater than the missing fire determination value during the second period.
In the case of, it is judged that there is a fire between deletions, and the cycle
The difference between the relative deviation and the opposite cylinder is equal to or greater than the second continuous misfire determination value.
If the same cylinder is continuously misfiring, the cycle ratio
With a control unit that performs deviation type misfire determination
A misfire detecting device for an internal combustion engine, comprising: 3. The control unit includes the corner adder.
The result of misfire determination by the speed deviation method and the cycle ratio deviation method
Claims characterized by taking the logical sum of the results of the misfire determination of
Item 1. A misfire detection device for an internal combustion engine according to item 1 or 2 .