JPH07145752A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent false detection of misfire due to generation of swing back securely by mounting an inhibition means for inhibiting misfire detection for a designated period during which an engine rotational speed change caused by misfire becomes ineffective when any misfire is detected. CONSTITUTION:IN an ECU 20 for receiving detection signals of various sensors for detecting driving condition, a period required for a rotation between designated rotational angles in an expansion stroke of each cylinder is measured to take the measured period as an actual value. A first amount of fluctuation is calculated by obtaining the deviation of the actual value between two cylinders whose expansion strokes are successive according to this actual value. A second amount of fluctuation is calculated by obtaining deviation between the proseat first amount of fluctuation and a former first amount of fluctuation and misfire of a combustion engine is detected according to the first and the second amounts of fluctuation. When the misfire is detected, the misfire detection is inhibited for a designated period during which the change in rotational speed of the engine due to the miss fire may become ineffective on the misfire detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a misfire of an engine in a multi-cylinder internal combustion engine by changing the rotational speed of the engine.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting a misfire in an internal combustion engine, as disclosed in Japanese Patent Application Laid-Open No. 58-19532, crankshaft rotational speeds of a reciprocating internal combustion engine after an expansion stroke and before an expansion stroke. It is known that a misfire is detected when the rotation speed difference is less than or equal to a set value. That is, the rotation speed is different between the expansion stroke and the compression stroke, and the former is faster when ignition is normally performed, but when the misfire occurs, the difference is almost eliminated. Is below a predetermined value, that is, when the crankshaft is not accelerated in the expansion stroke, it is determined that there is a misfire.

Further, there is also a method in which a predetermined number of rotation speed fluctuations of the internal combustion engine are obtained and the standard deviation thereof is calculated, and when the standard deviation is large, that is, when the fluctuations of the rotation fluctuations are large, it is determined that there is a misfire. JP-A-58-51243).

[0004]

However, in the above method, misfire may be erroneously detected due to the rolling back of the vehicle that occurs when a single misfire occurs. Here, when the engine fluctuation is reduced due to a misfire as shown in FIG. 10 (a), the engine is rotated by the inertial force of the vehicle, and as a result, the engine fluctuation is caused by a reaction to decrease the rotational fluctuation. The rotation of will increase. However, this time the rotation drops due to the reaction that has risen too much. This is a kind of hunting phenomenon in which such a phenomenon is repeated.
This will eventually decay and settle at a constant speed. This backlash only occurs after the last misfire in the case of continuous misfires. Further, if this swingback occurs, the amount of fluctuation in rotation increases for a predetermined period after the occurrence of misfire, even though no misfire has occurred, and there is a risk of false detection of misfire.

It is an object of the present invention to provide a misfire detection device which can accurately detect misfire even if a swingback occurs.

[0006]

Therefore, according to the present invention, as shown in FIG. 1, a rotation speed detecting means for detecting the rotation speed of the internal combustion engine, and a rotation speed of the internal combustion engine detected by the rotation speed detecting means. On the basis of the measured value calculation means for obtaining a measured value determined by measuring a period required for rotation between predetermined rotation angles in the expansion stroke of each cylinder, based on the calculation result of the measured value calculation means, the expansion stroke Is calculated based on information from the rotation speed detection means and the actual measurement value calculation means, the first variation amount calculation means calculating the first variation amount by obtaining the deviation of the actual measurement value between the two cylinders. Then, the second fluctuation amount is calculated by obtaining the deviation between the first fluctuation amount of this time calculated by the first fluctuation amount calculation means and the first fluctuation amount calculated in the past. Second fluctuation amount Calculating means, a misfire detecting means for detecting a misfire of the internal combustion engine based on the first variation amount and the second variation amount, and when a misfire is detected by the misfire detecting means, this misfire A misfire detection device for an internal combustion engine, comprising: a prohibition unit that prohibits the misfire detection by the misfire detection unit for a predetermined period in which a change in the rotation speed of the internal combustion engine does not affect the misfire detection.

[0007]

If the misfire is detected by the misfire detection means from the first variation amount and the second variation amount, the prohibition means causes the change in the rotation speed of the internal combustion engine due to the misfire to have no influence on the misfire detection. , Prohibit misfire detection.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. First, FIG. 2 is a schematic configuration diagram showing a 6-cylinder internal combustion engine (hereinafter, simply referred to as an internal combustion engine) 2 to which the present invention is applied and its peripheral devices. As shown in FIG. 2, the internal combustion engine 2 has an intake pressure sensor 6 for detecting the pressure in the intake pipe 4 (intake pipe pressure) as a sensor for detecting its operating state, and a water temperature for detecting the temperature of the cooling water. Sensor 8, internal combustion engine 2
Attached to the crankshaft of the internal combustion engine 2 rotates a predetermined crank angle (30 ° CA (crank angle) in this embodiment) to generate a pulse signal, and a high voltage generated by the igniter 12 is output. It is attached to a distributor 14 that sequentially distributes to a spark plug (not shown) provided in each cylinder of the internal combustion engine 2, and a pulse signal is generated once every one rotation of the distributor 14 (once every two rotations of the internal combustion engine 2). A cylinder discrimination sensor 16 for generating is provided.

Detection signals from each of these sensors are input to an electronic control unit (ECU) 20. ECU20 is C
It is configured by a well-known microcomputer mainly including the PU 21, the ROM 22, and the RAM 23, and inputs the detection signals from the above-mentioned sensors through the input / output port 25. Further, the CPU 21 follows the control program stored in the ROM 22 in advance, and the fuel injection amount injected from the fuel injection valve 27 provided in each cylinder of the internal combustion engine 2 and the generation timing of the high voltage of the igniter 12 (that is, the ignition timing). The engine control process for controlling the engine is executed, and the misfire detection process for detecting the misfire of the internal combustion engine 2 from the rotation speed of each cylinder of the internal combustion engine for each expansion stroke and turning on the warning lamp 29 is executed.

Hereinafter, the misfire detection process executed by the ECU 20 configured as described above and the failure diagnosis process for turning on the warning lamp 29 according to the misfire detection result will be described with reference to FIG.
~ It demonstrates according to the flowchart shown in FIG. 9 and FIG. In the misfire detection process shown in FIG. 3, in the CPU 21, a predetermined crank angle (30 ° C. in this embodiment) of the internal combustion engine 2 is output by the output signal from the rotation angle sensor 10.
The interrupt process is performed every A). When this process is started, first, at step 100, the internal combustion engine 2 rotates 30 ° CA from the deviation between the previous interrupt time and the current interrupt time. The time T30 _n required for the calculation is calculated. Then, in the following step 200, it is determined which cylinder is currently at the top dead center (TDC),
If it is not the top dead center, the process proceeds to step 300, and if it is the top dead center, the process proceeds to step 400.

In step 300, T30 _{i (i = n, n-1, n-2) is set} to T3 as a pre-step for calculating the time required for the internal combustion engine 2 to rotate 120 ° CA in step 130.
0 _{i-1 (i = n, n-1, n-2)} (that is, T30 _{n is changed} to T3
0 _n-1 , T30 _n-1 to T30 _n-2 , T30 _n-2 to T30
_n-3 ), and ends this routine. Step 400
Then, before performing the misfire determination, the change amount Δω _n of the rotation fluctuation amount,
The misfire determination value REF and the rough road determination value REF 'are obtained. FIG. 4 shows a flowchart of this processing. Hereinafter, description will be given with reference to FIG.

First, in step 401, the time T required to rotate 30 ° CA calculated in step 100 is calculated.
30 _n and T30 _n-1 , T30 _n-2 , and T30 _n-3 obtained at the time of execution of the previous time, the time before the last time, and the time before the third time, respectively.
The data of all four times are accumulated, and the internal combustion engine 2 is 120 °
The time T120 _n required for CA rotation is calculated. Then, in step 402, the calculated time T120
By calculating the reciprocal of _n , the internal combustion engine 2 is
The average rotation speed ω _n during CA rotation is calculated.

Next, in step 403, the average rotational speed ω _n calculated this time and the average rotational speeds ω _n-1 , ω _n-3 , ω _n-4 calculated previously, three times before, and four times before are calculated. Based on
The change amount Δω _n of the rotation fluctuation amount of the internal combustion engine 2 is calculated using the following formula.

[0014]

## EQU1 ## Δω _n = (ω _n-1 −ω _n ) − (ω _n −4 −ω _{n −3} ) In the above formula 1, (ω _n−1 −ω _n ) and (ω _n )
_n-4 −ω _n-3 ) is the rotation fluctuation amount in the cylinder in which the expansion stroke is continuous, and (ω _n-1 −ω _n ) is the latest, (ω _n-4 −ω _n
n-3 ) is a value before 360 ° CA.

Here, in this embodiment, the internal combustion engine 2 is a 6-cylinder internal combustion engine, and during the period in which one cylinder alone is in the expansion stroke, 120 ° CA before top dead center of the cylinder in the next expansion stroke.
Becomes Therefore, by calculating the average rotation speed ω _n of the internal combustion engine 2 every 120 ° CA, the rotation speed during the expansion stroke of each cylinder of the internal combustion engine is calculated. Then, the latest rotation fluctuation amount is obtained from this rotation speed and the previously calculated rotation speed, and the rotation fluctuation amount Δω of the internal combustion engine 2 used for the misfire determination is calculated from this rotation fluctuation amount and the rotation fluctuation amount before 360 ° CA.
_{I am trying} to calculate _n . In the present embodiment, the latest rotation fluctuation amount and the rotation fluctuation amount before 360 ° CA are simultaneously calculated using the above formula 1, but the latest rotation fluctuation amount is stored in the RAM 23. If you do 3
By reading the rotation variation amount before 60 ° CA from the RAM 23, the variation amount Δω _n can be obtained without calculating the rotation variation amount before 360 ° CA.

Next, in the following step 404, the current operating state (rotational speed NE, intake pipe pressure PM) is detected,
Go to step 405. In step 405, based on the operating state (rotational speed NE, intake pipe pressure PM) detected in step 404, the rotational speed NE and the intake pipe pressure PM stored in the ROM 22 in advance are used as parameters.
The misfire determination value REF is set by searching the two-dimensional map (REF map) shown in 2.

Similarly, in step 406, the rotational speed NE is
2 shown in FIG. 13 with the intake air pressure PM and the intake pipe pressure PM as parameters.
The rough road determination value REF 'is set by searching the dimensional map (REF' map), and this routine is finished.
Go to step 500 of. Next, in step 500, a comparison determination value calculation process is executed. This comparison determination value calculation process is a process of calculating a determination value K1 for comparing Δω between the two times before and the previous calculated in step 403 of FIG. 4, and a determination value K2 for comparing Δω between the previous time and this time. . Hereinafter, this process will be described with reference to the flowchart of FIG.

In step 501, step 40 in FIG.
In step 3, Δω _n calculated this time is compared with the misfire determination value REF obtained in step 405 of FIG. And Δ
If ω _n is larger than REF, the process proceeds to step 502.
In step 502, the RAM value MFCYL shown in FIG.
Among the bits of, the bit corresponding to the cylinder for which the current Δω _n is calculated is set to “1”. For example, this time Δω
_{If n} is the value calculated when the # 1 cylinder is ignited, the bit corresponding to the # 1 cylinder is set to “1”, and step 504
Proceed to.

On the other hand, when Δω _n is smaller than REF, the process proceeds to step 503. At this time, among the bits of the RAM value MFCYL shown in FIG. 14, the bit corresponding to the cylinder for which the current Δω _n has been calculated is set to “0”, and step 5
Go to 04. In step 504, the current MF obtained by the processing in steps 502 and 503
CYL (i) and the previous MFCYL obtained in the previous ignition
It is determined whether or not (i-1) is the same. That is, it is determined whether or not the 6-bit RAM values of this time and the previous time are the same, and whether the ignition state of the cylinder for which Δω _n is calculated is the same as the ignition state at the time of pre-ignition of that cylinder is determined. Determine. If the current MFCYL and the previous MFCYL are the same, the process proceeds to step 505, and the counter CMFCN
Increment T (CMFCNT ← CMFCNT +
1) and proceed to step 507.

On the other hand, the current MFCYL and the previous MFCY
If L is not the same, the process proceeds to step 506, the counter CMFCNT is set to "0", and the process proceeds to step 507. That is, in step 505, the counter CMFCNT
Is incremented, the RAM value MFCY
It indicates that the value of L continues to be the same.
That is, it indicates that the ignition state of the engine 2 at this time is the same, and, for example, a state where each cylinder of the engine 2 is reliably ignited or a state where misfire always occurs in the same cylinder continues. It shows that it is doing. On the other hand, the values of the RAM value MFCYL are not the same, and step 50
When the counter CMFCNT is set to "0" in 6, it indicates that the same ignition state of the engine 2 cannot continue.

Then, in step 507, it is judged whether or not the counter CMFCNT is larger than the predetermined value k. When the counter CMFCNT is smaller than the predetermined value k,
The process proceeds to step 509, and the comparison determination values K1 and K2 are set to the preset first set value A and second preset value B, respectively. As the values of the first and second set values A and B, values that do not impair the detectability when a single misfire occurs on a good road surface of the vehicle are selected, and A and B = 1 experimentally. .5-2.0
It has been confirmed that the degree is good.

On the other hand, when the counter CMFCNT becomes larger than the predetermined value k, the routine proceeds to step 508, where the comparison judgment values K1 and K2 are set to preset values a and b, respectively.
And The set values a and b are smaller than the set values A and B, and for example, a = b = 0 in this embodiment. Comparison judgment value K
1 and K2 are obtained, and step 500 in the misfire detection process of FIG. 3 ends. Then, the process proceeds to the next step 600.

At step 600, a temporary misfire determination process is executed for each ignition. Here, a process for executing the provisional misfire determination and incrementing the misfire number integration counter CMIS and the rough road determination integration counter CRAF for determining whether or not the misfire should be displayed as a failure every time the predetermined ignition number has elapsed. Hereinafter, this process will be described with reference to the flowchart of FIG.

First, in step 601, the comparison judgment value K1 calculated in the comparison judgment value calculation process of FIG. 5 is calculated based on Δω _n-1 calculated last time in step 403 of FIG. 4 and Δω _n-2 calculated _two times before. Compare with the value multiplied by. That is, the ratio Δω _n-1 / Δω of the change amount of the rotation fluctuation amount between the previous time and the last time before.
_It is determined whether _n-2 is larger than the comparison determination value K1. Then, when Δω _n-1 / Δω _n-2 is larger than the comparison determination value K1, the process proceeds to step 602, and when Δω _n-1 / Δω _n-2 is not more than the comparison determination value K1, the process proceeds to step 608.

Further, in step 602, Δω
_n-1 and Δω _n calculated this time in step 403 of FIG.
Is multiplied by the comparison determination value K2 calculated in the comparison determination value calculation process of FIG. That is, it is determined whether or not the ratio Δω _n-1 / Δω _n of the change amount of the rotational fluctuation amount between the previous time and this time is larger than the comparison determination value K2. And Δω
_{If n-1} / Δω _n is larger than the comparison determination value K2, the process proceeds to step 603, and if Δω _n-1 / Δω _n is smaller than the comparison determination value K2, the process proceeds to step 608.

Then, in step 603, Δω _n-1 previously calculated in step 403 of FIG. 4 and step 405
Compare with the REF obtained in. When Δω _n-1 is larger than REF, the routine proceeds to step 604, the provisional misfire detection flag XMF _{n-1 is set} to "1", and at step 605 the misfire number integration counter CMIS is incremented. If it is smaller, the process proceeds to step 606, and Δω _n-1 and step 4
It is compared with REF ′ obtained in 06. Δω _n-1 is RE
If it is larger than F ', the routine proceeds to step 607, where the rough road discrimination integration counter CRAF is incremented. If it is smaller, the process proceeds to step 608. In step 608, the provisional misfire detection flag XMF _{n-1 is set} to "0", and step 609 is performed.
Proceed to. In step 609, the ignition number counter CSPK for determining whether or not the predetermined number of ignitions has elapsed is incremented, and step 600 of FIG. 3 ends.

Returning to FIG. 3, in the next step 700, it is determined whether the vehicle is currently traveling on a rough road. FIG. 7 shows a flowchart of this rough road traveling detection processing. Hereinafter, description will be given with reference to FIG. 7. In FIG. 7, in step 701, it is determined whether or not the value of the counter CSPK incremented for each ignition in step 609 reaches a predetermined value J ₁ . The value of the predetermined value J ₁ is J ₁ = 3000 when a failure determination is made every 1000 revolutions in a 6-cylinder internal combustion engine. Therefore, the processing after step 702 is executed every predetermined rotation.

If it is determined in step 701 that the predetermined rotation has elapsed, the process proceeds to step 702, and the value of the misfire number integration counter CMIS is compared with the misfire state determination value J ₂ . The value of J ₂ is J ₂ = 30 when J ₁ = 3000, assuming that the misfire state that should be displayed as a failure every 1000 revolutions is 1% or more. If the CMIS value is larger than the predetermined value J ₂ , the process proceeds to step 703 to make a rough road determination,
If it is smaller, the process proceeds to step 705.

In step 703, the rough road discrimination counter C
The value of RAF is compared with the value obtained by multiplying the CMIS value by the rough road discrimination coefficient J ₃ . The value of J ₃ is a value that is adapted by actually traveling on a bad road that leads to a misfire state erroneous determination, and is a value of J ₃ = 1 to 2, for example. In this embodiment, the rough road judgment is made by comparison with CMIS × J ₃ , but it may be made by comparison with a predetermined constant such as J ₂ × J ₃ . Step 703
If the rough road discrimination counter value CRAF is smaller, it is judged that the vehicle is not traveling on a rough road, and the rough road determination flag XRAF is set to "0" at step 704. If not, it is determined that the vehicle is traveling on a bad road, and step 7 is performed.
The routine proceeds to 05, where the rough road determination flag XRAF is set to "1".

Next, at step 706, each counter CM
IS, CRAF, CSPK are cleared to "0", the rough road running detection processing is terminated, and the process proceeds to step 800 in FIG.
In step 800, a process for preventing misfire misdetection due to a swing back, which is a main process according to the present invention, is executed. FIG. 8 is a flow chart showing the processing for preventing the false return error detection. Hereinafter, description will be given with reference to FIG.

First, in step 801, it is determined whether the mask execution flag MSK is "0". If it is "0", the process proceeds to step 802, and if it is "1", the process proceeds to step 805.
That is, once the mask execution flag is set to "1", the processes of steps 802 to 804 described below are not executed. Next, at step 802, it is determined whether or not Δω _{n-1 at} which the misfire determination is performed this time is larger than the misfire determination value REF. If larger than REF, step 803
If REF or less, go to step 804. In step 803, the mask delay counter MSKD1 for calculating the misfire determination prohibition period is set to "K" (in this embodiment, "5") and the mask execution counter MSKD2 is set to "L" (in this embodiment, "10"). Set. In this embodiment,
The value of “K” is an experimentally obtained value at which the countdown of MSKD1 ends before the occurrence of the swingback. Also, the value of "L" is an experimentally obtained value at which the countdown of the MSKD2 ends when the influence of the swing back is eliminated.

Next, at step 804, it is judged if the mask delay counter MSKD1 is larger than "0".
When it is larger than “0”, the process proceeds to step 808.
When it is less than “0”, the process proceeds to step 805. In step 808, the mask delay counter MSKD1 is counted down, and the process proceeds to step 809. In step 805, it is determined whether the mask execution counter MSKD2 is larger than 0. If it is larger than “0”, the process proceeds to step 806. When it is less than "0", the routine proceeds to step 809, the mask execution flag MSK is set to "0", and this routine exits. In step 806, the mask execution counter MSKD2
Count down. In the next step 807, the mask execution flag MSK is set to "1" and this routine is finished.
Proceed to step 900 of FIG.

In step 900, misfire determination processing is executed. A flow chart showing this misfire determination processing is shown in FIG.
Is. Hereinafter, description will be given according to this flowchart. First, at step 901, a misfire provisional determination flag XM
It is determined whether Fn _-1 is "1". If it is "1" (if the misfire is tentatively determined), the process proceeds to step 902, and if it is "0", the process proceeds to step 905. In step 902, it is determined whether the rough road determination flag XRAF is "0".
If it is “0” (when not traveling on a bad road), step 9
Go to 03. When it is “1”, the process proceeds to step 905.
Further, in step 903, the mask execution flag MS
It is determined whether K is "0", and if "0", the process proceeds to step 904. When it is “1”, the process proceeds to step 905. When all the above conditions are satisfied, the misfire determination flag MF _{n-1 is set} to "1" in step 904, and it is determined that the misfire is currently occurring, and this routine is ended. Then, the process proceeds to step 1000 in FIG. Also, step 9
In 05, the misfire determination flag XMF _{n-1 is set} to "0" and this routine is ended, and the process proceeds to step 1000 in FIG.

In step 1000, in order to execute the misfire determination of this ignition in the next routine, each ω
_{i (i = n, n-1, n-2, n-3)} to ω _{i-1 (i = n, n-1, n-2, n-3)} and Δω
_{i (i = n, n-1, n-2, n-3) is set} to Δω _{i-1 (i = n, n-1, n-2, n-3)} , and this routine ends. Next, the processing executed in FIG. 8 will be described with reference to the time chart shown in FIG.

FIG. 10A is a time chart showing the value of Δω at each crank angle (FIG. 10E). If a misfire occurs at a crank angle t ₁ °, then the swingback shown in the figure occurs. At this time, "K" is set in the mask delay counter MSKD1 ((b) in the figure) and "L" is set in the mask execution counter MSKD2 ((c) in the figure). Then, the mask delay counter MSKD1 starts counting down. The mask execution counter MSKD2 does not operate until the count value of the mask delay counter MSKD1 becomes "0" at the crank angle t ₂ °. When the crank angle reaches t ₂ °, the mask delay counter MSKD1 becomes “0” and the mask execution counter MSKD2 starts counting down. further,
At this time, the mask execution flag MSK is set to "1" to prohibit the misfire detection (FIG. 10 (d)). This misfire detection is prohibited by the mask execution counter MS at the crank angle t ₃ .
This is performed until the count value of KD2 becomes "0" and the mask execution flag MSK is reset to "0".

By the above processing, misfire detection is not performed while the reversing of FIG. 10 (a) is occurring, so that erroneous detection due to the reversing can be prevented. Further, the reason why the misfire detection is not prohibited while the mask delay counter MSKD1 is counting is that there is a possibility that continuous misfire will occur before the occurrence of the swingback. When continuous misfires occur, the backlash only occurs after the last misfire.In this case, masking is executed to prevent false detection due to the backflow after the last misfire is detected. It

Next, a description will be given according to the flow chart of the failure diagnosis processing shown in FIG. In this flowchart, the CPU 21 performs interrupt processing at predetermined time intervals. First, at step 1101, for example, an abnormality detection flag that stores information from various sensors that detect whether the actuator is operating normally, Various abnormality detection flags such as the misfire detection flag MF _n-1 which is set to "1" when the misfire is determined in the misfire detection processing are read.

At the next step 1102, the states of the various abnormality detection flags read at step 1101 are discriminated. For example, if the misfire detection flag MF _n-1 is set to "1", the operation proceeds to step 1103 and "0". If it is reset to "," it returns to the main routine. And
In step 1103, for example, in order to protect the catalyst and prevent an increase in the HC concentration in the exhaust gas, the fuel supply to the cylinder determined to have a misfire is cut off, or the driver or the like is notified that a misfire has occurred. The well-known fail-safe processing corresponding to the abnormality detection such as turning on the warning lamp 29 is executed.

Next, the effect of the processing executed in step 500, step 600 and step 700 of this embodiment will be described. In general, when the internal combustion engine 2 is in the normal ignition state while the vehicle is traveling on a good road surface, the change amount Δω of the rotational fluctuation amount shows a value close to zero, and the internal combustion engine 2 misfires. If so, Δω calculated in the cylinder in which the misfire has occurred exhibits a large value. Therefore, as shown in FIG. 15A, the behavior of Δω when a misfire occurs in a specific cylinder is specifically large only when the misfire occurs, and Δω before and after that is a small value because of normal ignition.

On the other hand, when the vehicle is running on a rough road, the rotation of the vehicle fluctuates due to the unevenness of the road surface. At this time,
In many cases, the behavior of the variation Δω of the rotation fluctuation amount depends on the natural frequency of the vehicle, the rotation ratio between the wheel and the crankshaft, the influence of the transmission path from the wheel to the crankshaft, and the like.
It will be as shown in FIG. As is clear from this figure, the value of Δω in FIG. 15 (b) becomes a gentle curve without showing a sharp peak as in FIG. 15 (a). In other words, the behavior of Δω is different between when misfire and when traveling on a rough road,
More specifically, it is possible to obtain the characteristic that the ratio between Δω and the values before and after Δω are both large during misfire and small during traveling on a rough road.

Here, a single misfire occurs in the internal combustion engine 2 and the behavior of Δω as shown in FIG. 15 (a) occurs, or the vehicle runs on a bad road and Δω as shown in FIG. 15 (b). When the behavior of No. occurs, the value of the RAM value MFCYL becomes different from the previous value in the comparison determination value calculation process shown in FIG. Then, in step 506, the counter CMF is
Since CNT becomes “0”, the comparison determination values K1 and K2 are set to A and B, respectively. Therefore, in step 601 of FIG. 6, the ratio Δ of the amount of change in the amount of rotation fluctuation between the previous time and the time before the previous time Δ.
ω _n-1 / Δω _n-2 is compared with the comparison determination value K1, and in step 602, Δω _n-1 / Δω _n is compared with the comparison determination value K2. At this time, according to the characteristics described above, if both of these two ratios are larger than the comparison judgment value, it is judged that a single misfire has occurred, and if at least one of them is small, it is judged that the vehicle is traveling on a bad road. To be done.

With this, it is possible to prevent erroneous detection of a misfire as a rotation fluctuation that occurs when the vehicle is running on a rough road. However, as described above, the comparison judgment values K1, K2
In the case of processing by setting A to B respectively, if a state where misfire occurs in a plurality of cylinders that are continuously ignited continues, this misfire cannot be detected because, for example, continuous ignition is performed. When the ignition state in which both of the two cylinders misfire continues, the behavior of Δω becomes as shown in FIG. 15 (c), and one of the ratios of Δω at the time of misfire and Δω before and after that is a small value. This is because the other shows a large value. Therefore, the ratio of Δω may be smaller than one of the comparison determination values K1 and K2 set to A and B, and there is a possibility that misfire may not be determined.

Here, even in the case where a state of misfire continues in a plurality of cylinders that are continuously ignited as described above, the RAM value MF in the comparison determination value calculation process of FIG.
The value of CYL remains unchanged. Therefore, step 505
In step 507, the counter CMFCNT is increased, and when the counter CMFCNT becomes larger than the predetermined value k in step 507, the comparison determination values K1 and K2 are set to a and b in step 508, respectively. This a, b is A, as described above.
Since it is set to a value smaller than B, even if misfire occurs in the cylinder that continuously ignites and the ratio of Δω becomes small,
The determination in step 601 and step 602 is affirmative. Therefore, since it is possible to proceed to step 603,
Can be identified as a misfire. Therefore, it is possible to prevent erroneous detection of normal ignition even though misfire has occurred in the cylinders that are continuously ignited.

Nevertheless, there are cases where it is not always possible to avoid misfire misdetection when traveling on a bad road only with the behavior pattern of the change amount Δω. Therefore, in addition to the misfire judgment value REF, a bad road judgment value smaller than the misfire judgment value is also present. REF 'is installed,
It is determined whether or not Δω is a bad road based on the number existing between the misfire determination value REF and the bad road determination value REF ′ to finally prevent an erroneous determination. FIG. 16 shows the rotation speed fluctuation amount Δω during normal ignition on a flat road, misfire on a flat road, and normal ignition on a bad road. On a flat road, it is possible to completely distinguish between normal ignition and misfire, but on a bad road, the Δω value varies greatly depending on the condition of the road surface and exists between the misfire judgment value REF and the bad road judgment value REF '. In many cases.

In the first embodiment, the rotation angle sensor 10
Is the rotation speed detecting means, and steps 100 and 30
0, step 401 and step 402 are the actual value calculation means, the previous two terms of the mathematical formula calculated in step 403 are the first variation amount calculation means, step 403 is the second variation amount calculation means, and step 900 is the In the misfire detection means, steps 805 and 807 are prohibition means (misfire detection invalidation means), steps 504 to 509 are continuous misfire detection means, step 802 is prohibition release means, and steps 804 and 808 are prohibition delay means. And function respectively. As described above, in the present embodiment, erroneous detection is prevented at the time of occurrence of swingback, but this swingback occurs when the clutch is engaged in a manual transmission (MT) vehicle or in the case of an automatic transmission (AT) vehicle. Indicates a state where the torque converter is locked by the lockup clutch (lockup state). That is, the case where the engine and the tire are directly connected. Therefore, the neutral state and A
When the fluid clutch of the T car is engaged, the influence of the swing back is small.

Therefore, the masking process for preventing the misfire detection may not be executed under the condition that the influence of the swing back is small as described above. Further, since the swingback varies depending on the operating state of the vehicle, for example, the engine load, the engine rotation speed, etc., the mask execution period may be set according to the engine load, the engine rotation speed, the gear, etc.
In other words, the rebound increases as the inertial force of the vehicle increases, and thus the rebound increases as the gear position is low, the vehicle speed is low, the engine load is large, and the engine speed is low. Therefore, in such a state, it is better to lengthen the mask execution period for prohibiting the misfire detection.

FIG. 17 shows a block diagram of the second embodiment for realizing such processing. In the present embodiment, in the MT vehicle, the set value of the mask execution counter “L” is obtained based on the gear shift position, vehicle speed, throttle opening, and engine speed, and when the gear shift position is in the neutral position, it is reciprocated. It has no effect. Hereinafter, differences from the configuration diagram shown in FIG. 2 will be mainly described according to FIG.

17, in addition to the configuration of FIG. 2, a shift position sensor 30 for detecting the current gear shift position, a vehicle speed sensor 31 for detecting the speed of the vehicle, and a throttle opening sensor 32 for detecting the opening of the throttle valve. Signal from the ECU
It is configured to be input to the input / output port 25 of 20. Next, the processing executed by the ECU 20 in this embodiment will be described with reference to the flowchart shown in FIG. It should be noted that the same step numbers are given to the steps that execute the same processing as in FIG. 8, and the description thereof will be omitted.

When this routine is executed, step 8
In step 10, it is determined whether or not the conditions for occurrence of swingback are satisfied. As mentioned earlier, the conditions for the loopback are as follows:
This is when the clutch is engaged. When this condition is satisfied, the process proceeds to step 801. If not satisfied, the routine proceeds to step 811, the mask execution flag is set to "0", and this routine is ended.

In step 801, the mask execution flag MS
It is determined whether KD2 is "0", and if "0", the process proceeds to step 802. Then, when the change amount Δω _n-1 of the rotation fluctuation amount is larger than the misfire determination value REF in step 802,
Proceeding to step 812, the current operating condition (engine load, engine speed, vehicle speed, current gear shift position)
Then, the process for setting the "L" value of the mask execution counter MSKD2 is executed. FIG. 19 is a flowchart showing this processing. Hereinafter, description will be given according to this flowchart.

When the "L" value setting process is executed in step 812, the mask coefficient m ₁ corresponding to the shift position is calculated based on the output of the shift position sensor 30 in step 813.
It is read from the map shown in 0 (a). Next, based on the output of the vehicle speed sensor 31, in step 814, the mask coefficient m ₂ corresponding to the vehicle speed is read from the map shown in FIG. In step 815, the mask coefficient m ₃ according to the engine load (throttle opening) is read from the map shown in FIG. 20C based on the output of the throttle opening sensor 32. In step 816, the mask coefficient m ₄ according to the engine speed is read from the map shown in FIG. Then, in step 817, the set value "L" of the mask execution counter MSKD2 is calculated based on the following equation.

[0052]

[Formula 2] L = L _BASE · m ₁ · m ₂ · m ₃ · m ₄ Here, L _BASE is a predetermined value set in advance. When the above processing is completed, step 803 in FIG.
Proceed to. Since the subsequent processing is the same as the processing described in the first embodiment, the description is omitted here.

A supplementary explanation of the maps shown in FIG. 20 will be given below. In these maps, the shift position is low, the vehicle speed is low, and the engine load (throttle opening).
Is set to be larger, and the lower the engine speed is, the larger each coefficient value is set. That is, the coefficient values are set to increase as the inertial force of the vehicle increases.

In this second embodiment, step 813
~ Step 817 is the vehicle speed sensor 3 for the predetermined period setting means.
1 corresponds to the vehicle speed detecting means, the shift position sensor 30 corresponds to the shift position detecting means, and the throttle opening sensor 32 corresponds to the load detecting means. Next, a description will be given of a third embodiment in which the set value of the mask execution counter "L" is calculated based on the gear shift position, the vehicle speed, the throttle opening, and the engine speed in the AT vehicle. FIG. 25 shows a configuration diagram at this time. This is a configuration in which the shift position sensor 30 is eliminated from the configuration of the second embodiment shown in FIG. 17 and a lockup state sensor 33 is provided. The lock-up state sensor 33 is a sensor that outputs a signal indicating whether or not it is in the lock-up state. Further, in the present embodiment, it is assumed that there is no influence of swing back when the lockup state is not set.

The present embodiment differs from the second embodiment only in the judgment condition of step 810 of FIG. 18 and the shift position detecting method of step 813 of FIG. 19, and the other processes are the same. Therefore, in the following, FIG.
Will be explained. First, in step 810, as a condition for occurrence of a swing back, in the second embodiment, it is determined whether the gear shift position is not in the neutral state, but it is determined whether it is in the lockup state. The process proceeds to step 801, and if it is not in the lockup state, the process proceeds to step 811. Then, the above-described processing is executed in each step.

Next, the shift position detecting process will be described. In the second embodiment, the shift position is detected by the shift position sensor 30.
Although it was detected, the shift position is determined from the engine speed and the vehicle speed in the third embodiment. FIG. 21 is a flowchart showing this processing. Less than,
It will be described according to this flowchart. Note that this process is additionally executed before step 813 of FIG.

First, the engine speed is detected in step 818, and the vehicle speed is detected in step 819. And
In step 820, the shift position corresponding to these values is read from the engine speed detected in step 818 and the vehicle speed detected in step 819 from the map shown in FIG. 2B. Then, it progresses to step 813 and performs the process mentioned above.

In the third embodiment, steps 822 and
Step 823 corresponds to the shift position detecting means and functions. Next, in the AT vehicle, the fourth embodiment when considering the influence of the swing back when the fluid clutch is engaged when not in the lockup state is different from the second embodiment with reference to FIG. I will explain mainly.

In this embodiment, instead of using the shift position sensor 30 to detect the shift position, the shift position detecting process is executed in the "L" value setting process of step 812.
It will be described according to the flowchart shown in FIG. When the "L" value setting process is executed in step 812, the engine speed is first detected in step 818 and the vehicle speed is detected in step 819 before the process of step 813 is executed in this embodiment. Then, in step 821, it is determined based on the output from the lockup state sensor 33 whether or not the lockup state is present. Here, when the lockup state is not established, the routine proceeds to step 822, where the shift position according to the engine speed and the vehicle speed is read from the map of FIG. Then, the process proceeds to step 813. In step 821,
If it is in the lockup state, the process proceeds to step 823, and FIG.
The shift position corresponding to the engine speed and the vehicle speed is read from the map of 2 (b). Here, the map to be read is selected depending on whether the vehicle is in the lockup state or not because the clutch slips when the vehicle is not in the lockup state and the vehicle speed becomes slower than that in the lockup state even at the same shift position and the same rotation speed. . Then, when the shift position is read, the process proceeds to step 813. Through the above processing, the current shift position is detected.

When the shift position detecting process is completed, the processes described above are executed in steps 813 to 816. When the processing of step 816 is completed, the process shown in FIG.
The process shown in 4 is additionally executed. That is, step 824
At, the mask coefficient m ₅ determined depending on whether or not the lockup state is present is read. In this embodiment, for example, this value is set to m ₅ = 1 when the lockup state is set, and is set to m ₅ = 0.5 when the lockup state is not set. And
Next, at step 817, the mask execution counter MSK
The value of the set value "L" of D2 is obtained from the equation 2 in the second embodiment, but is calculated from the following equation in which the correction by the mask coefficient m ₅ is added in the fourth embodiment.

[0061]

## _EQU00003 ## L = L _{BASE.m 1 .m 2} .m ₃ .m ₄ .m ₅ Since the subsequent processes are the same as those of the flowchart shown in FIG. 18 described in the second embodiment. The description is omitted. Although the shift position is obtained from the engine speed and the vehicle speed in the embodiment of the AT vehicle, a sensor for directly detecting the current shift position from the transmission may be provided as in the second embodiment.

By executing the above processing, it is possible to prohibit the misfire detection when the recurring condition is satisfied,
Further, since the misfire detection prohibition period can be set according to the operating state of the engine, more accurate misfire detection can be performed. In the fourth embodiment, the lock-up state sensor 33 serves as the lock-up state determination means, and steps 812 to
Steps 817 and 824 correspond to the predetermined period setting means and function.

In each of the above embodiments, a method of detecting a misfire from the amount of change in the rotational fluctuation amount for every 360 ° CA is adopted as the method of detecting a misfire. However, the present invention is not limited to this and may be used, for example, in a method of detecting a misfire based on the difference in rotational speed between the first and second stages of the expansion stroke. Next, a fifth embodiment will be described. In the fifth embodiment, ATDC (after top dead center) 6 in a 4-cylinder internal combustion engine
Average rotation speed ω _{n-1 from} 0 ° CA to 120 ° CA and TDC
The misfire is detected by comparing with the average rotation speed ω _{n-2 of} ATDC 60 ° CA. Specifically, during normal ignition, the average rotational speed ω _n-1 takes a value larger than the average rotational speed ω _n-2, so when the value obtained by subtracting the former from the latter exceeds a predetermined value (misfire determination level), there is a misfire. It can be judged that there is (because it takes a value larger than that at normal ignition at misfire).
Then, when misfire is detected, the misfire determination level is shifted to a direction in which misfire is difficult to detect for a predetermined period in order to prevent misfire misdetection due to swinging back.

26 and 27 are flowcharts showing the misfire detection and erroneous detection prevention processing. Less than,
The fifth embodiment will be described with reference to these flowcharts. It should be noted that this flowchart is executed by an angle interruption for every predetermined angle, and in this embodiment, it is executed every 60 ° CA. When this process is executed, first, in step 851, the time T60 _n required for 60 ° CA rotation is calculated from the deviation between the previous interrupt time and the current interrupt time. In the next step 852, it is determined whether or not the interrupt timing at this time is the top dead center (TDC). If it is not the top dead center, the process proceeds to step 853. If it is the top dead center, the process proceeds to step 854. In step 853, the T60 _n calculated this time is set to T60 _n-1, and the previously calculated T60 _{n-1 is set} to T60 _n-2 , and then this routine is ended.

Further, in step 854, a reciprocating false detection prevention process is executed. FIG. 27 is a flow chart showing the processing for preventing the false return error detection. When this process is executed, first, in step 855, the counter P counted for each top dead center is incremented (P ← P +
1) Do. In the next step 856, average rotational speeds ω _n-1 and ω _n-2 are calculated from T60 _n-1 and T60 _n-2 calculated in step 851 the previous time and the time before last, respectively. Specifically, the reciprocal of T60 _{i (i = n-1, n-2)} is the average rotation speed ω _{i (i = n-1, n-2)} . Then, in step 857, the deviation Δω between ω _{n- 1} and ω _n-2 is calculated by the following equation.

[0066]

Δω = ω _n-2 −ω _n-1 At this time, ω _n-1 is the average rotation speed in the section where the average rotation speed is maximum during normal ignition. Therefore, at the time of normal ignition, ω _n-2 <ω _{n-1 is established,} and the value of Expression 4 is a negative value. Then, at the time of misfire, ω _n-2 > ω _n-1 , and the value of Expression 4 has a positive value (see FIG. 29).

At the next step 858, the misfire determination mask counter M is decremented and the routine proceeds to step 859.
In step 859, it is determined whether the misfire determination mask counter M is smaller than 0. If an affirmative decision is made here, the routine proceeds to step 860, where the misfire determination mask counter M is set to 0 and guarding is performed, and then the routine proceeds to step 861. When a negative decision is made, the routine directly proceeds to step 861.

In step 861, it is determined whether the misfire determination mask counter M is 0. If the affirmative judgment is made here, the step 862 is carried out, and if the negative judgment is made, the step 863 is carried out.
Proceed to. In step 862, it is determined whether Δω ≧ REFA (first misfire determination level). If an affirmative decision is made, the operation proceeds to step 864. Then, in step 864, the misfire determination mask counter M is set to 20. next,
In step 865, the provisional misfire counter CMIS is incremented to end this processing, and in step 8 of FIG.
Return to 66.

If a negative determination is made in step 861 (that is, the temporary misfire determination is masked to prevent erroneous detection due to swinging back), Δω ≧ REFB (second misfire is detected in step 863. Judgment level). When a positive determination is made here, step 864
26, the processing described above is executed, and step 8 in FIG.
Proceed to 66. When a negative determination is made, this processing is ended as it is, and the routine proceeds to step 866 in FIG.

Here, the first misfire determination level REF
28A shows the misfire determination level REFB as shown in FIG. 28B.
It is obtained from the dimensional map. In addition, these maps show that at the same engine speed and the same intake pressure, RE
FA is created to have a value smaller than REFB.

In step 866, the value of the counter P incremented in step 855 is compared with a predetermined value (400 in this embodiment), and if it is less than the predetermined value, this process is terminated. That is, here, the process cannot proceed to the next step until the data of the provisional misfire counter CMIS when the misfire determination is performed 400 times in total is obtained. Therefore, when the value of the counter P is greater than or equal to the predetermined value, the process proceeds to step 867 to make a misfire determination.

At step 867, the counter P is reset (P ← 0). In the next step 868, it is determined whether or not the provisional misfire counter CMIS is greater than or equal to a predetermined value α. If it is greater than or equal to the predetermined value α, the process proceeds to step 869, and if it is less than the predetermined value α, the process proceeds to step 870. The predetermined value α is a value that is preset according to the required misfire occurrence rate. Specifically, for example, when it is desired to detect a misfire occurrence rate of 5% or more, the predetermined value α is 20 because the misfire determination is performed 400 times in this embodiment.

In step 869, it is determined that a misfire has occurred, the warning lamp 29 is turned on to notify the driver of the misfire, and the flow proceeds to step 871. In step 870, the warning lamp 29 is turned off because the misfire has not occurred or the occurrence frequency is low, and the process proceeds to step 871. At step 871, the temporary misfire counter CMIS is reset (CMIS ← 0), and this processing ends.

Next, changes in the rotational speed between normal ignition and misfire will be described with reference to the time chart shown in FIG. As shown in FIG. 29, during normal ignition, TDC
Since it is ignited immediately before, the rotation speed increases from when it exceeds the TDC of # 1 (first cylinder), and is almost 90 ° CA.
Is the maximum. After that, the speed gradually decreases, and at the next TDC of # 3, the rotation speed at the previous TDC of # 1 becomes almost equal. Here, when the ignition is performed again, the rotational speed also increases again, but when the engine misfires, the rotational speed further decreases as shown in the figure. Therefore, at the time of normal ignition, the value obtained by subtracting ω _n-1 from ω _{n- 2} shown in the figure is a negative value (ω
_{Since n-2} <ω _n-1 ), ω _n-2 > ω _n-1 at the time of misfire, so it takes a positive value. At this time, an affirmative decision is made in step 862 of the flowchart shown in FIG.
It is determined that a misfire has occurred, and the return error detection processing is executed.

In the fifth embodiment, step 861 corresponds to the predetermined value changing means (misfire detection invalidating means) and functions. As described above, in the fifth embodiment, when the misfire is detected in step 862 or step 863, the value of the misfire determination level is maintained for a predetermined period (until the value of the misfire determination mask counter M becomes 0). Is getting bigger. By the way, although Δω takes a positive value at the time of occurrence of swingback, its value is smaller than that at the time of misfire. For this reason, by increasing the misfire determination level, it is possible to prevent erroneous detection of Δω at the time of occurrence of backlash as misfire.

In the fifth embodiment, a period in which the average rotational speed is high and a period in which the average rotational speed is low during normal ignition are compared, and when the value obtained by subtracting the former from the latter is a positive value, it is determined that a misfire has occurred. There is. When a misfire is detected, the misfire determination level is shifted to a side where it is difficult to detect a misfire for a predetermined period in order to prevent misfire misdetection due to a swing back.
You may use for the misfire determination method like an Example. At this time, in step 603 of FIG. 6, when misfire is detected, the misfire determination value REF may be shifted in the direction in which misfire is difficult to detect (that is, the value of REF is increased).

Also in the fifth embodiment, as in the first embodiment, the misfire determination level is not changed to REFB immediately after the misfire is detected in step 862, but is changed after a predetermined period has elapsed. You may do it. further,
As shown in the second to fourth embodiments, the period M in which the misfire determination level is REFB is the operating state (vehicle speed, gear shift position, internal combustion engine load, engine speed, lockup state in the case of an AT vehicle). ). Here, when changing the period M depending on the gear shift position, the shift position may be estimated from the engine speed and the vehicle speed.

In addition, as misfire misjudgment prevention processing due to swingback, the misfire determination itself may not be executed when the swingback occurs, or the misfire determination result may be invalidated after execution of the misfire determination. But it's okay.

[0079]

As described above, after the misfire is detected, the misfire detection is prohibited by the prohibiting means when there is a change in the rotation speed due to the misfire, so that the misfire can be prevented from being erroneously detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing constituent features of the present invention.

FIG. 2 is a configuration diagram of a first embodiment in which the present invention is applied to a 6-cylinder internal combustion engine.

FIG. 3 is a flowchart of misfire detection processing executed by the ECU of the first embodiment.

FIG. 4 is a flowchart of a misfire detection preparation process executed by the ECU of the first embodiment.

FIG. 5 is a flowchart of a comparison determination value calculation process executed by the ECU of the first embodiment.

FIG. 6 is a flowchart of misfire provisional determination processing executed by the ECU of the first embodiment.

FIG. 7 is a flowchart of a rough road traveling detection process executed by the ECU of the first embodiment.

FIG. 8 is a flowchart of a slip-back error detection prevention process executed by the ECU of the first embodiment.

FIG. 9 is a flowchart of a misfire determination process executed by the ECU of the first embodiment.

FIG. 10 is a time chart for explaining a return error detection prevention process executed by the ECU of the first embodiment.

FIG. 11 is a flowchart of a failure diagnosis process executed by the ECU of the first embodiment.

FIG. 12 is an explanatory diagram showing a REF map of the first embodiment.

FIG. 13 is an explanatory diagram showing a REF ′ map of the first embodiment.

FIG. 14 is an explanatory diagram showing a RAM value MFCYL according to the first embodiment.

FIG. 15 is a characteristic diagram showing the behavior of Δω.

FIG. 16 is a characteristic diagram showing a behavior of Δω according to traveling conditions.

FIG. 17 is a configuration diagram of a second embodiment in which the present invention is applied to a 6-cylinder internal combustion engine.

FIG. 18 is a flow chart of a swing back false detection prevention process executed by the ECU of the second embodiment.

FIG. 19 is a flowchart of an “L” value setting process executed by the ECU of the second embodiment.

FIG. 20A is an explanatory diagram showing a map of gear shift positions and mask execution periods. (B) is an explanatory view showing a map of vehicle speed and mask execution period. (C) is an explanatory view showing a map of the engine load and the mask execution period. (D) is an explanatory view showing a map of the engine speed and the mask execution period.

FIG. 21 is a flowchart of a process for detecting a shift position, which is executed by the ECU of the third embodiment.

FIG. 22A is an explanatory diagram showing a map for obtaining a shift position from the engine speed and the vehicle speed of the fourth embodiment. (B) is an explanatory view showing a map for obtaining a shift position from the engine speed and the vehicle speed in the third and fourth embodiments.

FIG. 23 is a flowchart of a process for detecting a shift position, which is executed by the ECU of the fourth embodiment.

FIG. 24 is a part of a flowchart of “L” value setting processing executed by the ECU of the fourth embodiment.

FIG. 25 is a configuration diagram of a third embodiment in which the present invention is applied to a 6-cylinder internal combustion engine.

FIG. 26 is a flowchart of misfire detection processing executed by the ECU of the fifth embodiment.

FIG. 27 is a flow chart of a slip-back error detection prevention process executed by the ECU of the fifth embodiment.

FIG. 28 (a) is an explanatory diagram showing a REFA map of the fifth embodiment. (B) is an explanatory view showing a REFB map of the fifth embodiment.

FIG. 29 is a time chart for explaining changes in rotation speed during normal ignition and during misfire in the fifth embodiment.

[Explanation of symbols]

 2 internal combustion engine 10 rotation angle sensor 16 cylinder discrimination sensor 20 ECU (electronic control unit) 30 shift position sensor 31 vehicle speed sensor 32 throttle opening sensor 33 lockup state sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Yamamoto 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (16)

[Claims] 1. A rotation speed detecting means for detecting a rotation speed of an internal combustion engine, and a rotation between predetermined rotation angles in an expansion stroke of each cylinder based on the rotation speed of the internal combustion engine detected by the rotation speed detecting means. By measuring an actual measurement value that determines an actual measurement value that is determined by measuring the required period, and by calculating the deviation of the actual measurement value between the two cylinders in which the expansion stroke is continuous, based on the calculation result of the actual measurement value calculation means. , The first variation amount calculating means for calculating the first variation amount, and the current variation amount calculated by the first variation amount calculating means based on the information from the rotation speed detecting means and the actually measured value calculating means. Second variation amount calculation means for calculating a second variation amount by obtaining a deviation between the first variation amount and the first variation amount calculated in the past; and the first variation amount. And the second fluctuation Based on, and a misfire detection means for detecting a misfire of the internal combustion engine, when a misfire is detected by the misfire detection means, a change in the rotational speed of the internal combustion engine due to this misfire has no influence on the misfire detection for a predetermined period of time. A misfire detecting device for an internal combustion engine, comprising: a prohibiting means for prohibiting misfire detection by the misfire detecting means. 2. A rotation speed detecting means for detecting a rotation speed of an internal combustion engine; a rotation speed of an expansion stroke early period of the internal combustion engine detected by the rotation speed detecting means; Rotational fluctuation amount detecting means for obtaining the rotational fluctuation amount of the internal combustion engine, misfire detecting means for comparing the rotational fluctuation amount with a predetermined value to detect misfire of the internal combustion engine, and misfire is detected by the misfire detecting means. A misfire detection device for an internal combustion engine, comprising: and a prohibition unit that prohibits the misfire detection by the misfire detection unit for a predetermined period in which a change in the rotation speed of the internal combustion engine due to the misfire does not affect the misfire detection. 3. A continuous misfire detecting means for detecting a continuous misfire occurring in the internal combustion engine, and a prohibition for canceling the prohibition of the misfire detection by the prohibiting means while the continuous misfire detecting means detects the continuous misfire. A misfire detection device for an internal combustion engine according to claim 1 or 2, further comprising a releasing means. 4. A predetermined period from the occurrence of misfire to the occurrence of a change in the rotation speed of the internal combustion engine, which influences the detection of misfire,
4. A prohibition delay unit that does not execute the misfire detection prohibition by the prohibition unit.
A misfire detection device for an internal combustion engine according to any one of the above. 5. A rotation speed detecting means for detecting a rotation speed of the internal combustion engine, and a rotation between predetermined rotation angles in an expansion stroke of each cylinder based on the rotation speed of the internal combustion engine detected by the rotation speed detecting means. By measuring an actual measurement value that determines an actual measurement value that is determined by measuring the required period, and by calculating the deviation of the actual measurement value between the two cylinders in which the expansion stroke is continuous, based on the calculation result of the actual measurement value calculation means. , The first variation amount calculating means for calculating the first variation amount, and the current variation amount calculated by the first variation amount calculating means based on the information from the rotation speed detecting means and the actually measured value calculating means. Second variation amount calculation means for calculating a second variation amount by obtaining a deviation between the first variation amount and the first variation amount calculated in the past; and the first variation amount. And the second fluctuation By comparing a predetermined amount obtained from and a preset predetermined value, misfire detection means for detecting misfire of the internal combustion engine, and when misfire is detected by the misfire detection means, this misfire A misfire detection device for an internal combustion engine, comprising: predetermined value changing means for changing the predetermined value so that misfire is less likely to be detected during a predetermined period in which a change in the rotation speed of the internal combustion engine does not affect the misfire detection. . 6. A rotational speed detecting means for detecting the rotational speed of the internal combustion engine, the rotational speed of the internal combustion engine in the first half of the expansion stroke and the rotational speed in the middle of the expansion stroke, which are detected by the rotational speed detecting means. Rotational fluctuation amount detecting means for obtaining the rotational fluctuation amount of the internal combustion engine, misfire detecting means for comparing the rotational fluctuation amount with a predetermined value to detect misfire of the internal combustion engine, and misfire is detected by the misfire detecting means. And a predetermined value changing means for changing the predetermined value so that the misfire is less likely to be detected for a predetermined period when the change in the rotation speed of the internal combustion engine due to the misfire does not affect the misfire detection. Engine misfire detection device. 7. A predetermined period from the occurrence of misfire to the occurrence of a change in the rotation speed of the internal combustion engine, which influences the detection of misfire,
The misfire detection device for an internal combustion engine according to claim 5 or 6, further comprising: a change delay unit that does not cause the predetermined value changing unit to change the predetermined value. 8. A predetermined period setting means for setting the predetermined period after a misfire is detected by the misfire detecting means, and a change in the rotation speed of the internal combustion engine due to the misfire has no influence on the misfire detection, and a vehicle speed. And a vehicle speed detecting means for detecting, wherein the predetermined period setting means includes means for setting the predetermined period to be longer as the vehicle speed detected by the vehicle speed detecting means is slower. The misfire detection device for an internal combustion engine according to any one of claims 1 to 7. 9. A predetermined period setting means for setting the predetermined period after the misfire is detected by the misfire detecting means, and a change in the rotation speed of the internal combustion engine due to the misfire has no influence on the misfire detection, and a gear shift of the vehicle. Shift position detecting means for detecting a shift position of a gear of the machine, wherein the predetermined period setting means sets the predetermined period to be longer as the shift position of the gear is at a lower speed position. The misfire detection device for an internal combustion engine according to any one of claims 1 to 8. 10. A predetermined period setting means for setting the predetermined period after a misfire is detected by the misfire detection means, and a change in the rotation speed of the internal combustion engine due to the misfire does not affect the misfire detection, and the internal combustion engine. 2. The load detecting means for detecting the load according to claim 1, wherein the predetermined period setting means sets the predetermined period to be longer as the load detected by the load detecting means is larger. The misfire detection device for an internal combustion engine according to claim 9. 11. A predetermined period setting means for setting the predetermined period after a misfire is detected by the misfire detecting means, and a change in the rotation speed of the internal combustion engine due to the misfire does not affect the misfire detection. 11. The period setting means sets the predetermined period to be longer as the rotation speed of the internal combustion engine detected by the rotation speed detection means is lower. An internal combustion engine misfire detection device according to claim 1. 12. A predetermined period setting means for setting the predetermined period after the misfire is detected by the misfire detecting means, and the change in the rotation speed of the internal combustion engine due to the misfire has no influence on the misfire detection, and an automatic transmission. The torque converter for transmitting the rotation of the internal combustion engine, a lockup state determination means for determining whether to directly transmit the rotation to the internal combustion engine via a lockup clutch, the predetermined period setting means is the torque When the converter is transmitting the rotation directly to the internal combustion engine via the lock-up clutch, the predetermined period is set to be longer than when the converter is not in this state. 13. A misfire detection device for an internal combustion engine according to any one of items 11 to 11. 13. The misfire detection of an internal combustion engine according to claim 9, wherein the shift position detection means detects the shift position of the gear from the rotation speed and the vehicle speed of the internal combustion engine. apparatus. 14. A rotation speed detecting means for detecting a rotation speed of an internal combustion engine, and a rotation fluctuation for detecting a rotation fluctuation amount of the internal combustion engine based on the rotation speed of the internal combustion engine detected by the rotation speed detecting means. Quantity detection means, based on the rotation fluctuation amount detected by the rotation fluctuation amount detection means, a misfire detection means for detecting a misfire, when a misfire is detected by the misfire detection means, the internal combustion engine of the misfire A misfire detection device for an internal combustion engine, comprising: misfire detection invalidating means for invalidating the misfire detection by the misfire detecting means for a predetermined period in which a change in rotational speed has no influence on the misfire detection. 15. The misfire detection invalidating means detects, when the misfire is detected by the misfire detecting means, the misfire detecting means for a predetermined period during which a change in the rotation speed of the internal combustion engine due to the misfire has no influence on the misfire detection. 15. The misfire detection device for an internal combustion engine according to claim 14, further comprising means for invalidating the obtained result. 16. The misfire detection invalidating means detects, when the misfire is detected by the misfire detecting means, a misfire by the misfire detecting means for a predetermined period during which a change in the rotation speed of the internal combustion engine due to the misfire has no influence on the misfire detection. The misfire detection device for an internal combustion engine according to claim 14, further comprising means for not performing detection.