JPH0533717A - Misfire-fire detection device for multi-cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a device capable of accurately deciding whether misfire occurs only at one air cylinder or at a plurality of air cylinders. CONSTITUTION:The time length 120i required for a rotary angle sensor to rotate 120 deg.CA is determined (step 120), and an average number omegan of rotations. Then, the amount of change DELTAomegan (actually measured value) in the average number of rotations is determined from a difference between the previous average number omegan-1 of rotations and the present average number omegan of rotations (step 140). Next, calculation is made of an average difference MD between the amounts of change in the average numbers of rotations DELTAomegan (step 150). Thereafter, the average difference MD is compared with two decision values REF1 and REF2. If the average difference MD is greater than any one of the two decision values REF1 and REF2, decision is made of that misfire occurs at a plurality of air cylinders. On the other hand, if the average difference MD is greater than the decision value REF1 but is not greater than the decision value REF2, decision is made of that misfire occurs at one air cylinder alone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detecting device for a multi-cylinder internal combustion engine which detects misfire occurring in the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a means for detecting a misfire occurring in an internal combustion engine, complete combustion cannot be obtained in a combustion chamber of the internal combustion engine when the misfire occurs, and the engine speed (hereinafter referred to as engine speed) is Since it decreases, the instantaneous engine speed is detected at at least two points in one ignition cycle to obtain the engine speed fluctuation amount, and the misfire detection value set from the change amount of the engine speed fluctuation amount and the internal combustion engine state. There is a device for comparing the above with the above and discriminating the misfire when the amount of change in the engine speed fluctuation amount becomes larger than the misfire detection value (for example, Japanese Patent Laid-Open No. 61-25.
8955 publication).

[0003]

The misfire discrimination apparatus according to the above-described method can detect the occurrence of misfire when only one cylinder misfires in one cycle of the internal combustion engine. When a plurality of cylinders are continuously misfired, the engine rotation speed fluctuation amount becomes smaller than each other, so that the change amount of the engine rotation speed fluctuation amount becomes small and it may not be possible to determine misfire.

Further, in an internal combustion engine having a large number of cylinders such as a 6-cylinder internal combustion engine, as shown in FIG. 7, the engine speed fluctuation amount in the cylinder next to the cylinder in which the misfire has occurred is reduced and only one cylinder is misfiring. Nevertheless, there is a risk of misjudging that there is a misfire in multiple cylinders.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and it is possible to accurately detect misfire in any misfire occurrence state, and whether only one cylinder is misfired, or An object of the present invention is to provide a misfire detection device capable of accurately determining whether a plurality of cylinders are misfired and executing a misfire process according to the misfire occurrence state.

[0006]

In order to achieve the above object, an internal combustion engine misfire detection device according to the present invention outputs a rotation signal at every predetermined rotation angle according to the rotation of a multi-cylinder internal combustion engine, as shown in FIG. Rotation signal output means for outputting, and an actual measurement value calculation means for obtaining an actual measurement value determined by measuring the time required for rotation between predetermined rotation angles in the explosion stroke of each cylinder based on the output signal of the rotation signal output means, When the measured value is greater than the first determination value and the measured value is greater than a second determination value that is a value greater than the first determination value, a plurality of cylinders of the multi-cylinder internal combustion engine misfires. Multi-cylinder misfire detection means for determining that the multi-cylinder internal combustion engine is misfired when the measured value is greater than the first determination value and less than the second determination value. Determined to be Adopt the technical means that includes a single-cylinder misfire detecting means that.

[0007]

According to the present invention, the actual measurement value calculating means sets the actual measurement value between the predetermined rotation angles in the explosion stroke of each cylinder. Then, the measured value is compared with the first judgment value and the second judgment value set to a value larger than the first judgment value,
When the measured value is larger than the first judgment value and the measured value is larger than the second judgment value, it is determined that a plurality of cylinders of the multi-cylinder internal combustion engine has misfired, and the measured value is the first judgment value. When it is larger than the value and smaller than the second judgment value, it is judged that only one cylinder of the multi-cylinder internal combustion engine is misfiring.

[0008]

The present invention will be described below based on the embodiments shown in the drawings. FIG. 2 is a block diagram of an apparatus according to an embodiment of the present invention.

In FIG. 2, reference numeral 1 denotes an internal combustion engine, and in the present embodiment, the internal combustion engine has six cylinders. Reference numeral 2 is an intake pipe that guides intake air introduced from an air cleaner (not shown) into the internal combustion engine 1. Reference numeral 3 is an intake pipe pressure sensor that detects the pressure in the intake pipe 2, and a detection signal of the intake pipe pressure sensor 3 is input to an electronic control unit described later.

Reference numeral 5 denotes a crankshaft (not shown) of the internal combustion engine 1, which outputs a signal for each predetermined crank angle (in this embodiment, every 30 ° C. A) in response to the rotation of the internal combustion engine 1 to output the signal. Is a rotation angle sensor that serves as rotation signal output means for obtaining a rotation speed Ne of the engine (hereinafter, referred to as engine speed).
Reference numeral 6 denotes a reference position sensor which is also built in the distributor 7 and outputs a signal for discriminating the cylinder, specifically, for example, outputs a signal every time the piston 13 of the first cylinder reaches the highest position (top dead center). Is. The detection signals from the rotation angle sensor 5 and the reference position sensor 6 are also input to the electronic control device described later.

A water temperature sensor 8 is provided in the cooling water passage of the internal combustion engine 1 and detects the temperature of the cooling water.
The detection signal from is also input to the electronic control unit described later.
Reference numeral 9 is a well-known device that calculates optimum control amounts of the fuel system and the ignition system based on detection signals from the above-mentioned sensors and a sensor (not shown), and outputs a control signal for accurately controlling the injector 10, the igniter 11 and the like. It is an electronic control unit (hereinafter referred to as ECU).

Further, the ECU 9 is a well-known C that performs arithmetic processing.
PU 9a, read-only ROM 9b for storing control programs and control constants necessary for calculation, R for temporarily storing calculation data while the CPU 9a is operating.
It is composed of an AM 9c and an I / O port 9d for inputting / outputting a signal from outside the ECU 9.

Further, the ECU 9 obtains the average rotation speed ω _n from the time required to rotate a predetermined crank angle using the method described later based on the detection signal from the rotation angle sensor 5 and calculates the variation amount thereof. The average rotational speed fluctuation amount Δω _n (actual measurement value) is calculated by (actual measurement value calculation means), and based on this, whether or not a plurality of cylinders of the internal combustion engine 1 are misfired or only one cylinder is misfired. The operation of determining (plural cylinder misfire detection means, single cylinder misfire means) is executed.

Reference numeral 12 is a warning lamp for notifying the driver of the occurrence of misfire when the ECU 9 determines that misfire has occurred. Next, the misfire detection process executed in the ECU 9 will be described with reference to the flowchart shown in FIG. The routine of FIG. 3 is interrupted at every predetermined crank angle (every 30 ° C. in this embodiment) by the output signal of the rotation angle sensor 5.

In step 100, the time T30i required to rotate 30 ° C. A is calculated from the deviation between the previous interrupt time and the current interrupt time. In step 110, it is judged whether or not the interrupt timing at this time is the top dead center (TDC), and if it is not the top dead center, this routine is ended.
On the other hand, if the interrupt timing this time is the top dead center, the process proceeds to step 120.

In step 120, the time T30i required for rotating 30 ° C. calculated in step 100 is T30i.
And all 4 of T30i-1, T30i-2, and T30i-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 time data T120i required to rotate 120 ° C. A is calculated by accumulating the batch data.

In step 130, the crank angle is 120 ° C. A
The average rotation speed ω _n between them is calculated. For details, see Step 1
The reciprocal of the time T120i obtained in 20 is obtained, and is set as the average rotation speed ω _n .

[0018] Based on the step 140 following equation in (Equation 1), i.e. the average rotational speed omega _n-1 and the average speed change amount from a difference between the current calculated average rotation speed omega _n [Delta] [omega determined at the previous TDC timing Calculate _n (measured value).

[0019]

## EQU1 ## Δω _n = ω _n-1 −ω _n Here, as described above, ω _n is the current average rotation speed calculated in step 130, and ω _{n- 1} is the previous average rotation speed. The rotation speed change amount Δω _n is the change amount of the average rotation speed of the cylinder in which the explosion stroke is continuous.

In step 150, the average deviation MD of the average rotational speed change amount Δω _n is obtained using the data for one cycle of the average rotational speed change amount Δω _n calculated in step 140. Specifically, in the present embodiment, the internal combustion engine is a 6-cylinder engine, and the average rotation speed ω _n is obtained every 120 ° C. Therefore, the number of data of the average rotation speed change amount Δω _n for one cycle is 6, and according to the formula 2, You can ask.

[0021]

[Formula 2] MD = Σ | Δω_i-X | However, Σ indicates the accumulation of i = 1 to 6, and X is 6 pieces.
Average rotation speed change Δω _nIs the average value of
It is a value determined based on 3.

[0022]

X = ΣΔω _i / 6 In step 160, the average deviation MD calculated in step 150 and the first determination value REF1 are compared, and the average deviation MD is calculated.
Is larger than the first judgment value REF1, step 170
If it is not large, it is judged that no misfire has occurred and the process returns to the main routine.

Similarly, in step 170, the average deviation MD is compared with the second judgment value REF2. If the average deviation MD is larger than the second judgment value REF2, it is judged that a plurality of cylinders has misfired, and the routine proceeds to step 190. If the average deviation MD is not larger than the second determination value REF2, it is determined that only one cylinder is misfiring and the routine proceeds to step 180.
The second judgment value REF2 is set to a value larger than the judgment value of the first judgment value REF1.

At step 180, a warning lamp 12 for informing the driver that one cylinder is misfiring.
Is turned on, and in step 190, a display different from the lighting of the warning light 12 in step 180 (for example, the lighting interval is changed) is displayed to notify the driver or the like that a plurality of cylinders are misfiring. The safe operation is executed and the process returns to the main routine.

The present invention will be further described with reference to the characteristic diagram of the average deviation MD shown in FIG. In FIG.
The horizontal axis represents the crank angle, and the vertical axis represents the average deviation MD. Also, the solid line shows the characteristics when no misfire has occurred, the broken line shows the characteristics when only one cylinder has misfired,
The alternate long and short dash line shows the characteristics when there is a misfire in multiple cylinders.

From this figure, it can be seen that in the case where there is a misfire in a plurality of cylinders, the fluctuation characteristic of the average deviation MD changes at a large value as compared with the case where there is a misfire in only one cylinder. That is, the misfire determination value is set by paying attention to such a variation characteristic. More specifically, by setting the first determination value REF1 and the second determination value REF2 to the values shown in FIG. It can be seen that it is possible to determine whether no misfire has occurred, multiple cylinders have misfired, or only one cylinder has misfired.

FIG. 5 is a flow chart showing the operation of another embodiment of the present invention. The difference from the flow chart of FIG. 3 is the misfire determination method, in which the average rotation speed ω _n is calculated without calculating the average deviation MD. The regression equation is set from the above, and the misfire is determined according to the deviation between the value (estimated value) obtained from this equation and the average rotational speed ω _n .

The routine shown in FIG. 5 is also a routine to be executed for each predetermined crank as in the routine of FIG. 3, and those performing the same processing as in FIG. Since it has been described, the description is omitted here.

In step 200, it is judged whether or not the current execution timing is the compression top dead center of the first cylinder, and if it is not the compression top dead center of the first cylinder, the process returns to the main routine. On the other hand, when it is the compression top dead center of the first cylinder, the routine proceeds to step 210.

In step 210, the average rotational speed ω _i (i = 1 to 6) corresponding to each cylinder obtained in step 130 is used to obtain the constants a and b from the equations 4 and 5, and the regression equation P is set. To do. The regression formula P is defined by Y = a + b · X, and as is well known, the regression formula P is the actual average rotational speed ω.
It is set so that the integrated value of the absolute value of the deviation between _i (i = 1 to 6) and the estimated value obtained for each cylinder from the regression equation P becomes the minimum.

[0031]

B = (6 · Σ (X · Y) −ΣX · ΣY) / (6 · ΣX ² − (ΣX) ² )

[0032]

(In this embodiment all six) Equation 5] a = (ΣX-b · ΣY ) / At sixth step 220 for each cylinder from the regression equation P calculates an estimated value alpha _i (i = 1 to 6) .

At step 230, the integrated value S is obtained from the average rotational speed ω _i and the estimated value α _i . Specifically, the integrated value S is an integrated value of the absolute values of the deviations between the average rotational speed ω _i and the estimated value α _i, and is calculated based on Equation 6.

[0034]

(6) S = Σ | ω _i −α _i | (where Σ is i = 1
In step 240, the integrated value S is compared with the first determination value REF1. If the integrated value S is larger than the first determination value REF1, the process proceeds to step 250, and if not larger, misfire occurs. It judges that it has not done, and returns to the main routine.

Similarly, in step 250, the integrated value S is compared with the second determination value REF2. If the integrated value S is larger than the second determination value REF2, it is determined that a plurality of cylinders has misfired, and the process proceeds to step 190. If the integrated value S is not larger than the second determination value REF2, it is determined that only one cylinder is misfiring and the routine proceeds to step 180. Then, the misfire detection processing as already described in steps 180 and 190 is executed, and the process returns to the main routine.

Here, in order to clarify this embodiment, the regression equation P and the integrated value S will be described below with reference to FIG. FIG. 6 is a diagram in which the average rotational speed ω _i obtained in step 130 is plotted for each cylinder, and the horizontal axis represents each cylinder and the vertical axis represents the average rotational speed ω _i . Further, FIG. 6 (a) shows the characteristics when normal, and FIG. 6 (b) shows the characteristics when the third cylinder is misfiring.

In FIG. 6, the regression equation P becomes a straight line as shown by the one-dot chain line, and the estimated value α _i can be obtained for each cylinder. Therefore, the integrated value S is the average rotational speed ω _i and the estimated value α.
_Since the absolute value of the deviation from _i is added, the integrated value S can be obtained by adding K _{1 to} K ₆ in FIG. 6A, for example. Therefore, when a misfire occurs, it is shown in FIG.
_Since the absolute value of the deviation between the average rotational speed ω _i and the estimated value α _i in the misfire occurrence cylinder becomes large as shown in 3, the integrated value S becomes large and it can be determined that misfire has occurred.

Further, at this time, the integrated value S becomes larger than that in the case where only one cylinder misfires, as in the case of the average deviation MD, because the value is larger than that in the case where only one cylinder misfires. Not only the deviation MD, but a regression equation is set from the average rotational speed ω _n, and the estimated value α and the average rotational speed ω obtained from this equation are set.
The integrated value S of the absolute value of the deviation from _n is set to the first judgment value REF.
By comparing with 1 and the second judgment value REF2,
It is possible to accurately determine whether misfire has occurred, whether there is misfire in a plurality of cylinders, or whether misfire has occurred in only one cylinder.

Further, when a multi-cylinder misfire occurs, a large amount of unburned gas is introduced into the catalyst as compared with a single-cylinder misfire, which accelerates the deterioration of the catalyst and increases harmful components in the exhaust gas. From the above, the misfire detection device of the above-described embodiment can determine whether there is a misfire in a plurality of cylinders or a misfire in only one cylinder. Therefore, a misfire in a plurality of cylinders occurs continuously. When the fuel cell is in use, a process of immediately cutting off the fuel supply to the cylinder may be executed.

[0040]

As described above, in the present invention, the measured value between the predetermined rotation angles in the explosion stroke of each cylinder and the first
And the second judgment value set to a value larger than the first judgment value are compared, and when the actual measurement value is larger than the first judgment value and the actual measurement value is larger than the second judgment value, When it is determined that a plurality of cylinders of the multi-cylinder internal combustion engine are misfiring and the actual measurement value is larger than the first determination value and smaller than the second determination value, only one cylinder of the multi-cylinder internal combustion engine is By determining that the misfire has occurred, it is possible to accurately detect the misfire in any misfire occurrence state and to determine whether only one cylinder is misfiring or multiple cylinders are misfiring. Therefore, it is possible to execute the misfire process according to the misfire occurrence state.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is an overall configuration diagram showing a configuration of an apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart for explaining a misfire detection operation of the present invention.

FIG. 4 is a diagram showing characteristics of an average deviation MD in all misfire occurrence states.

FIG. 5 is a flow chart for explaining a misfire detection operation of another embodiment of the present invention.

6A and 6B are characteristic diagrams of the average rotational speed ω _n for explaining the misfire detection operation shown in FIG. 5 in detail, in which FIG. 6A is a normal characteristic, and FIG. 6B is an abnormal (misfire) characteristic. Is.

FIG. 7 is a diagram showing the characteristic of the amount of change in the rotational speed of the internal combustion engine.

[Explanation of symbols]

16-cylinder internal combustion engine 5 Rotation angle sensor 6 Reference position sensor 9 Electronic control unit (ECU) 12 Warning lamp

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Claims (3)

[Claims] 1. A rotation signal output means for outputting a rotation signal for each predetermined rotation angle according to the rotation of a multi-cylinder internal combustion engine, and a predetermined rotation angle in an explosion stroke of each cylinder based on the output signal of the rotation signal output means. An actual measurement value calculating means for obtaining an actual measurement value that is determined by measuring the time required for rotation, and the actual measurement value is greater than the first determination value and the actual measurement value is greater than the first determination value. A plurality of cylinders in the multi-cylinder internal combustion engine for determining that a plurality of cylinders have misfired when the measured value is larger than the first judgment value. A misfire detection device for a multi-cylinder internal combustion engine, comprising: a single-cylinder misfire detection means for determining that only one cylinder of the multi-cylinder internal combustion engine has misfired when the judgment value is smaller than 2. . 2. The misfire detection device for an internal combustion engine according to claim 1, wherein the measured value calculation means calculates an average rotation time in the explosion stroke. 3. The misfire detection device for an internal combustion engine according to claim 1, wherein the measured value calculation means calculates an engine speed of the internal combustion engine in the explosion stroke.