JP2001248492A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a misfire detecting device for internal combustion engine capable of avoiding an erroneous decision of a misfire caused by a stabilizing control of engine speed, suitably maintaining the control, even when the misfire is generated in any mode during the control. SOLUTION: Required time per a prescribed rotation angle (30 deg. CA) of an engine output shaft is calculated in each prescribed angle period (points of time a, b, c, d, e, f, g, h) and rotation fluctuation amount DLTMFL for every 360 deg. CA at the time of the idle stabilizing time control is calculated as DLTMFL =(d-c)-(b-a) or DLTMFL=(h-g)-(f-e), or instance. When the rotation fluctuation amount DLTMFL exceeds a prescribed threshold value LVKMF to be a misfire decision value, the misfire is decided. In the case of (d-c)<0 or (h-g)<0 at this stage, calculation of the rotation fluctuation amount DLTMFL is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection device for an internal combustion engine which detects misfires occurring in the internal combustion engine from fluctuations in rotation of the engine.

[0002]

2. Description of the Related Art As is well known, when an internal combustion engine misfires, complete combustion cannot be obtained in a combustion chamber of the engine, and the engine speed decreases. A misfire detection device that detects the occurrence of a misfire based on such properties is also well known.

On the other hand, when the internal combustion engine is idling,
In order to stabilize the rotational speed, feedback control is performed to detect a rotational fluctuation and change an intake air amount, an ignition timing, and the like. Therefore, when the engine speed decreases for some reason during idling, to increase the engine speed,
The intake air amount, ignition timing, and the like are controlled. In some cases, after the engine speed once rises rapidly, the speed is stabilized. However, if the decrease in the engine speed at this time is caused by the misfire, the following inconveniences cannot be ignored.

[0004] That is, if a misfire occurs at the time of idling, first, the misfire detection device detects misfire based on a decrease in the engine speed at that time. However, since the engine speed is rapidly increased through the above-described feedback control related to the idle speed control, the sudden change in the engine speed may be erroneously determined to be a new misfire by the misfire detection device. is there.

Therefore, conventionally, in order to solve such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-146996, if a misfire occurs during the stabilization control of the idle speed, the stabilization control is performed. It has also been proposed to reduce the control amount. As a result, the degree of increase in the engine speed after the misfire has occurred is reduced, and erroneous misfire determination is suppressed.

[0006]

As described above, even when a misfire occurs during idling, by suppressing the control amount for stabilizing control of the idling rotational speed, an erroneous misfire caused by the control amount is suppressed. Judgment can be avoided. However, when such misfires occur continuously, the engine speed is excessively reduced due to the suppression of the control amount, and consequently, the drivability is deteriorated and the engine is stalled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide a method for controlling a rotational speed while stably controlling the rotational speed while maintaining the control in a suitable manner. It is an object of the present invention to provide a misfire detection device for an internal combustion engine that can avoid misjudgment of misfire caused by the misfire.

[0008]

The means for achieving the above object and the effects thereof will be described below. The invention according to claim 1 calculates an amount of rotation fluctuation of the engine output shaft,
In a misfire detection device for an internal combustion engine that detects the occurrence of misfire based on the calculated amount of rotation fluctuation exceeding a predetermined threshold value, in the rotational speed stabilization control of the engine, the speed of the engine output shaft to a low speed side is reduced. The gist of the present invention is to make the detection result of the occurrence of misfire valid only when the rotation fluctuation is larger than the rotation fluctuation that can maintain the control rotation speed for the stabilization control.

There is a clear difference between the rotation fluctuation of the engine output shaft due to misfiring of the engine and the rotation fluctuation relating to the rotation speed stabilization control. In other words, in the case of the rotation fluctuation due to misfire, there is a time when the rotation speed sharply decreases, while in the case of the rotation fluctuation according to the rotation speed stabilization control, there is a time when the rotation speed rapidly increases.

According to the above configuration, focusing on this point, in the rotation speed stabilization control, the rotation fluctuation of the engine output shaft to the low speed side also occurs in the rotation speed stabilization control. By validating the detection result of the misfire occurrence only when it is larger than the above, the problem of the erroneous determination described above can be avoided.

According to a second aspect of the present invention, there is provided a misfire detection system for an internal combustion engine which calculates a rotation fluctuation amount of an engine output shaft and detects occurrence of a misfire based on the calculated rotation fluctuation amount exceeding a predetermined threshold value. In the device, during the rotation speed stabilization control of the engine, only when the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation that can maintain the control rotation speed according to the stabilization control, The gist is to calculate the rotation fluctuation amount.

According to the above configuration, during the rotation speed stabilization control, only when the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation of the engine that occurs also during the rotation speed stabilization control, Calculation of the rotation fluctuation amount is performed. Therefore, the same effect as that of the first aspect can be obtained. Further, when the above condition is not satisfied, the calculation load can be reduced by omitting various procedures for detecting the occurrence of misfire.

According to a third aspect of the present invention, in the second aspect of the present invention, the rotation fluctuation amount is calculated as a value corresponding to a difference in rotation angular velocity every time the engine output shaft has the same rotation angle, The condition that the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation that can maintain the control rotation speed according to the stabilization control is the current rotation angular velocity of the engine output shaft at the same rotation angle. The gist is that the condition is smaller than the previous rotational angular velocity of the engine output shaft at the same rotational angle.

Since the above-mentioned difference exists between the rotation fluctuation caused by the misfire and the rotation fluctuation caused by the rotation speed stabilization control, the rotation fluctuation amount is determined by the rotation angular velocity every time the engine output shaft has the same rotation angle. In the case of calculating as a value corresponding to the difference, there is the following difference. In other words, if the amount of rotation fluctuation is large due to rotation fluctuation due to misfire, the current rotation angular velocity of the engine output shaft at the same rotation angle is larger than the previous rotation angular velocity of the engine output shaft at the same rotation angle. Is also small. On the other hand, during the stabilization control, the current rotational angular velocity of the engine output shaft at the same rotational angle is higher than the previous rotational angular velocity of the engine output shaft at the same rotational angle.

According to the above configuration, by focusing on this point, the condition that the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation that can maintain the control rotation speed for the stabilization control is set. It can be set accurately. Moreover, the accuracy of the misfire determination can be improved with a relatively simple configuration in which the above-described logic is newly added to the known misfire determination method based on the rotation fluctuation of the engine during the rotational speed stabilization control.

According to a fourth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for rotating the engine output shaft at a predetermined angle for each ignition of the engine is maximized and minimized. For the time required for the rotation at the same predetermined angle corresponding to the angle to be performed, the previous required time at the same rotation angle of the engine output shaft is represented by A,
When the minimum time is B, and the required time at the same rotation angle of the engine output shaft at the same rotation angle is C on the maximum side and D on the minimum side, the rotational fluctuation amount is DLTMFL, and the calculation is DLTMFL = ( The gist is that the calculation of the rotation fluctuation amount is prohibited at least under the condition that (DC) <0, which is obtained by (DC)-(BA).

Normally, since the ignition timing in each cylinder of the internal combustion engine is evenly distributed, minute fluctuations in the engine speed related to this ignition are periodic. For example, in a four-cylinder internal combustion engine, ignition is performed in separate cylinders at every 180 ° crank angle (CA).
The rotation number periodically reaches a maximum every 180 ° CA.

According to the above configuration, the predetermined period for calculating the rotation fluctuation amount DLTMFL of the engine is determined within the period determined by the minimum point and the maximum point in one cycle of the substantially periodic rotation fluctuation. The rotation fluctuation amount can be determined by reflecting the influence of the periodic rotation fluctuation. That is, by setting the amount of change in the rotation speed of the engine to be substantially calculated as the difference between the maximum value and the minimum value of the period, in the case of rotation fluctuations related to misfire detection, While (DC) has a positive value,
In the case of the rotation fluctuation related to the rotation speed stabilization control, since the first term (DC) has a negative value without fail, the difference between the two can be grasped more accurately. Therefore, the above condition (DC) <0 can be set as a preferable condition that is not at least the rotation fluctuation due to misfire, and as a result, the subsequent calculation load can be greatly reduced.

According to a fifth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for rotation of the engine output shaft at a predetermined angle for each ignition of the engine is maximized and minimized. For the time required for the rotation at the same predetermined angle corresponding to the angle to be performed, the previous required time at the same rotation angle of the engine output shaft is represented by A,
When the minimum time is B, and the required time at the same rotation angle of the engine output shaft at the same rotation angle is C on the maximum side and D on the minimum side, the rotational fluctuation amount is DLTMFL, and the calculation is DLTMFL = ( That is, the calculation of the rotation fluctuation amount is prohibited under the condition that (DC) <0 and (BA) <0, which is obtained by (DC)-(BA). And

According to the above configuration, in the case of the rotation fluctuation relating to the rotation speed stabilization control, the second term (BA) has a negative value larger than the value relating to the periodic rotation fluctuation. Therefore, by further adding (BA) <0 to the above-mentioned condition for prohibiting the calculation of the amount of rotation fluctuation, the misfire determination of the invention according to claim 4 can be made more accurate.

According to a sixth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for rotation of the engine output shaft at a predetermined angle for each ignition of the engine is maximized and minimized. For the time required for the rotation at the same predetermined angle corresponding to the angle to be performed, the previous required time at the same rotation angle of the engine output shaft is represented by A,
When the minimum time is B, and the required time at the same rotation angle of the engine output shaft at the same rotation angle is C on the maximum side and D on the minimum side, the rotational fluctuation amount is DLTMFL, and the calculation is DLTMFL = ( (DC)-(BA), (DC) <0, and the condition that the rotation speed e1 of the engine output shaft before one ignition and the current rotation speed e satisfy e1 <e. Therefore, the gist is that the calculation of the rotation fluctuation amount is prohibited.

The rotation speed during the rotation speed stabilization control has a value larger than the rotation speed due to the temporary decrease in speed due to misfire. According to the configuration, focusing on this point, the condition in the invention according to claim 4 is further added to the condition e1 <
More accurate control can be performed by adding e.

According to a seventh aspect of the present invention, in the invention according to any one of the fourth to sixth aspects, the angle at which it is estimated that the time required for rotation of the engine output shaft at a predetermined angle for each ignition is minimized is determined by the engine. The main point is to make it variable in accordance with the ignition timing retarding mode.

[0024] The minute rotation fluctuation generated in the engine described above is as follows.
When the ignition timing is changed, the timing at which the periodic maximum and minimum points appear changes. This change is particularly likely to occur at the minimum point. According to the above configuration, in consideration of this point, by varying the angle estimated that the time required for the rotation of the engine output shaft at the predetermined angle to be the minimum angle for each ignition in accordance with the ignition timing is variable, the maximum value is obtained. The difference from the minimum value can be calculated as the amount of change in the rotational speed (corresponding to (DC), (BA)). Therefore, it is possible to more clearly grasp the difference between the rotational fluctuations at the time of misfire and at the time of normal operation for the reasons described above.

According to an eighth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for the engine output shaft to rotate at a predetermined angle becomes maximum every two consecutive ignitions of the engine. Regarding the time required for the rotation at the same predetermined angle corresponding to each of the two angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition, and the engine output. When the current required time at the same rotation angle of the shaft is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is DDTDC,
It is determined that DDTDC = (D′−C) − (B′−A), and that the calculation of the rotation fluctuation amount is prohibited at least under the condition that (D′−C) <0. I do.

According to a ninth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for rotating the engine output shaft at a predetermined angle becomes maximum each time two consecutive ignitions of the engine occur. Regarding the time required for the rotation at the same predetermined angle corresponding to each of the two angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition, and the engine output. When the current required time at the same rotation angle of the shaft is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is DDTDC,
Operation DDTDC = (D′−C) − (B′−A), where (D′−C) <0 and (B′−A) <
The gist is that the calculation of the rotation fluctuation amount is prohibited under the condition of zero.

According to a tenth aspect of the present invention, in the third aspect of the invention, it is estimated that the time required for the engine output shaft to rotate at a predetermined angle becomes maximum every two consecutive ignitions of the engine. Regarding the time required for the rotation at the same predetermined angle corresponding to each of the two angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition, and the engine output. Assuming that the current required time of the shaft at the same rotation angle is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is DDTDC, and the calculation is DDTDC = (D'-C)- (B'-A), (D'-C) <0, and the rotation speed e1 of the engine output shaft before one ignition and the current rotation speed e are e1 <e.
The gist is that the calculation of the rotation fluctuation amount is prohibited under the following conditions.

At the time of the stabilization control, the size of the local maximum point is substantially constant. However, when the rotation speed rapidly recovers by the rotation speed stabilization control after the fall of the rotation speed due to the misfire, complete stabilization is achieved. The maximum point tends to be slightly larger than after the conversion. According to the above configuration, focusing on this point,
By mainly using the above condition (D′−C) <0, it is possible to obtain the function and effect according to claims 4 to 6.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of a misfire detecting apparatus for an internal combustion engine according to the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of an internal combustion engine abnormality detection apparatus according to the present embodiment. In this system,
The engine 1 includes a cylinder block 1a having a cylinder bore 2 for four cylinders, and a cylinder head 1b. A piston 3 movably provided in each cylinder bore 2 is connected to a crankshaft 10 as an output shaft of the engine 1 via a connecting rod 3a. Further, inside the cylinder bore 2, the combustion chamber 4 is defined by a space surrounded by the piston 3 and the cylinder head 1b.
Are formed.

The cylinder head 1b is provided with an ignition plug 11 corresponding to each combustion chamber 4. An intake port 5a communicating with each combustion chamber 4 is provided in the cylinder head 1b.
And an exhaust port 6a, respectively, and the intake port 5a and the exhaust port 6a are connected to the intake path 5 and the exhaust path 6, respectively. At each open end of the intake port 5a and the exhaust port 6a communicating with the combustion chamber 4, an intake valve 7 and an exhaust valve 8 are provided, respectively.
The intake valve 7 and the exhaust valve 8 are connected to the crankshaft 1
It is opened and closed by intake and exhaust camshafts 31 and 32 that rotate with zero power. The power of the crankshaft 10 is transmitted to the intake and exhaust camshafts 31 and 32 via a timing belt 35 and timing pulleys 33 and 34.

In the vicinity of the intake port 5a, injectors 9 for fuel injection are provided for each cylinder. Fuel at a predetermined pressure is supplied to each injector 9 via a fuel supply system (not shown).

The operation of the engine 1 is started and the intake passage 5
When the fuel is injected from the injector 9 together with the introduction of the intake air into the interior, the intake air and the fuel are mixed to form an air-fuel mixture. In the intake stroke of the engine 1, the intake port 5a is opened by the intake valve 7 so that the air-fuel mixture flows through the intake port 5a to the combustion chamber 4a.
When the air-fuel mixture is taken into the combustion chamber 4 and ignited by the ignition plug 11, the air-fuel mixture explodes and burns, and a driving force is obtained in the engine 1. The exhaust gas after combustion is discharged to the exhaust passage 6 by opening the exhaust port 6 a by the exhaust valve 8. The ignition plug 11 is ignited according to the application timing of the high voltage output from the igniter 13. In the present embodiment, when the rotation speed of the engine 1 is controlled to the target rotation speed during the idling operation, the application timing of the high voltage, that is, the ignition timing is also controlled.

On the other hand, a surge tank 16 is provided in the intake passage 5, and a throttle valve 18 which is opened and closed in response to operation of an accelerator pedal 21 is provided upstream of the surge tank 16. According to the opening of the throttle valve 18, that is, the throttle opening TA, the intake passage 5
The amount of intake air to be introduced into the air is adjusted. The amount of intake air introduced into the intake passage 5 depends on the throttle valve 1
8 is always detected by an air flow meter 22 provided further upstream.

A throttle sensor 19 for detecting the throttle opening and an idle switch 20 for detecting the full closing of the throttle valve 18 are provided near the throttle valve 18. The throttle sensor 19 outputs a detection signal corresponding to the throttle opening, and the idle switch 20 is turned on when the throttle valve 18 is fully closed.

On the other hand, the intake passage 5 is provided with a bypass passage 42 which bypasses the throttle valve 18 and communicates the upstream side and the downstream side of the throttle valve 18. An idle speed control valve (hereinafter, referred to as “ISCV”) 41 of, for example, a linear solenoid type for adjusting the amount of air passing through the bypass passage 42 is provided in the middle of the bypass passage 42. IS
The CV 41 is a proportional solenoid valve that adjusts the flow path area through which a valve element (not shown) is displaced in accordance with the value of a current flowing through a solenoid coil (not shown). In the present embodiment, the ISCV 41 controls the rotation speed of the engine 1 during idling to the target rotation speed, and also controls the above-described ignition timing to stabilize the rotation speed (idle stabilization). .

The engine system further includes a crank angle sensor 27 for detecting the number of revolutions of the crankshaft (engine output shaft) 10, a water temperature sensor 15 for detecting the temperature of the cooling water of the engine 1, and the like. Is provided.

Electronic control unit (hereinafter referred to as "ECU") 6
1 includes, for example, a microcomputer, and fetches detection signals from the idle switch 20, the crank angle sensor 27, the water temperature sensor 15, and the like, and based on the detection signals, the injector 9, the igniter 13, and the like. It controls the ISCV 41 and the like.

Next, a method for detecting misfire during idling according to the present embodiment will be described with reference to FIG. At the time of idling when the idle switch 20 is on, the water temperature sensor 15, the air flow meter 22,
The detection result of the crank angle sensor 27 and the like is supplied to the ECU 61 as the operating state of the engine 1, and based on these values, the ECU 61 controls the opening of the ISCV 41 to control the idling speed of the engine 1 to a target speed. And control the ignition timing.

FIG. 2 shows a transition example of each parameter when a misfire occurs in stabilizing the idling of the engine 1. Among them, FIG. 2A shows the ignition accompanying the idling stabilization in the present embodiment. An example of a timing control mode is shown. In the present embodiment, as shown in FIG. 2A, the first cylinder is # 1, and similarly, the second to fourth cylinders are # 2 to ##.
4, each cylinder is ignited in the order of # 1- # 3- # 4- # 2. FIG. 2B shows the engine 1
FIG. 2 (c) shows the relationship between the rotational fluctuation amount DLTFL calculated each time of the engine 1 and the misfire determination value (threshold) LVMF, and FIG. 2 (d) shows the misfire The number of detection counts is shown. These figures 2
The horizontal axis of (a) to (d) is defined by the crank angle,
The interval between the vertical dashed lines is 1 with respect to the top dead center of the first cylinder.
It is defined as 80 ° crank angle (CA). Note that FIG.
As shown in FIG. 2B and FIG. 2C, in the present embodiment, for convenience, the required time per predetermined crank angle is used instead of the engine speed, and the change in the required time is used as the change in the engine speed. Is used.

Here, a misfire detection method in the present embodiment using the required time will be described. The graph of FIG. 2B is a graph in which the predetermined crank angle is set to 30 ° CA, and the time required during the rotation of the crankshaft 10 by 30 ° CA is calculated and the required time is plotted. Therefore, for example, the interval between the crank angles of the values y and x on the graph shown in FIG. 2B is 30 ° CA, and the value x is changed from the crank angle corresponding to the value y to the crank angle corresponding to the value x. This is the time required for the crankshaft 10 to rotate.

FIG. 2C shows the relationship between the rotational fluctuation amount DLTMFL of the crankshaft 10 and the threshold value LVMF for determining misfire, as described above. In this case, first, with reference to the top dead center (vertical broken line) of each cylinder, 0 ° to 30 ° C. on the retard side before 360 ° CA.
A, and the time required for CA rotation from 90 ° to 120 ° CA are calculated as A and B, respectively. Each of these times A and B is at 30 ° C. for each ignition.
30 ° CA corresponding to the angle estimated to be the maximum time to rotate by A and the angle estimated to be the minimum
Is the required time. Next, the current, ie, 3
0 ° to 30 ° CA, 90 ° also on the retard side after 60 ° CA
° to 120 ° CA
And D. The times C and D are also the required times of the same 30 ° CA corresponding to the angles at which the time during which the crankshaft 10 rotates by 30 ° CA is maximized and the angles at which the crankshaft 10 is estimated to be minimal at each ignition. It is. Then, the rotation fluctuation amount DLTMFL is calculated based on these timings A to D, DLTMFL = (D−C)
-(BA) ... It is determined in (1), and when the obtained rotation fluctuation amount DLTMFL exceeds the threshold value LVMF, it is determined that a misfire has occurred.

Next, an example of the misfire determination in this embodiment will be described. As shown in a period T1 in FIG. 2B, during idling, the rotation speed of the engine 1 is in a stable state with periodic rotation fluctuations because the above-described rotation speed stabilization control is performed. is there. In the present embodiment, since the engine 1 has four cylinders, the cycle of this variation is a 180 ° CA cycle.

At this time, as shown in FIG. 2 (b), if misfire occurs at a point in time when 60 ° CA elapses from the top dead center of the third cylinder # 3 to the retard side, the subsequent rotation speed Decreases. Therefore, the rotation fluctuation amount DLT at that time
The value of MFL (1) DLTMFL (1) = (dc)-(ba) (1-1) is a very large value as shown in FIG. 2 (c).

Then, the rotation fluctuation amount DLTMFL
When (1) exceeds the threshold value LVLMF, FIG.
As shown in (d), the misfire counter (misfire count number) is incremented by "1".

On the other hand, when the aforementioned decrease in the rotational speed is detected through the crank angle sensor 27, a well-known idle stabilizing function is activated, and the opening control of the ISCV 41 and the opening degree control of the ISCV 41 are performed in order to restore the rotational speed of the engine 1 to the target value. The ignition timing advance control is performed. In this example, the advance control of the ignition timing is performed after 330 ° CA elapses after the misfire as shown in FIG.

After the ignition timing advance control is performed, after a while, as shown in a period T2 of FIG. 2B, the required time sharply decreases. The rotation fluctuation amount DL at this time
The value of TMFL (2) DLTMFL (2) = (h−g) − (fe) (1-2) is also a very large value as shown in FIG. The threshold value LVLMF will be exceeded. In other words, there is a possibility that a misfire is erroneously determined to have occurred even though no misfire has occurred. Therefore, in the present embodiment, the above condition is satisfied only when the condition (DC)> 0 and (BA) <0 in the equation (1), that is, when the rotation fluctuation occurs on the low rotation side. The rotation fluctuation amount DLTMFL is calculated, and under other conditions, at least under the condition that (D−C) <0, the rotation fluctuation amount DLTMFL is calculated.
It is set so that the calculation of TMFL is prohibited.

As a result, in the example of FIG. 2, at the timing relating to the above equation (1-1), the first term (d
−c) has a positive value, so that the rotational fluctuation amount DLTMFL
The calculation of (1) is executed, and the calculated rotation fluctuation amount D
Misfire is determined based on a comparison between LTMFL (1) and the threshold value LVLMF. On the other hand, at the timing relating to the above equation (1-2), since the first term (hg) has a negative value, the calculation of the rotation fluctuation DLTMFL (2) is prohibited, and the rotation fluctuation DLTMFL (2) is prohibited. ) Is avoided.

Note that, in FIG. 2, FIG.
The transition example represented by the solid line in (d) shows a determination mode based on the conventional misfire detection method, and the transition example represented by the dashed line represents the determination mode based on such a misfire detection method of the present embodiment. It is shown. As shown in FIG. 2D, the misfire detection method according to the present embodiment correctly counts once, whereas the conventional misfire detection method incorrectly counts twice.

Hereinafter, the processing procedure of misfire detection according to the present embodiment based on such a principle will be described in more detail with reference to FIG. FIG. 3 shows an idling misfire detection routine according to the present embodiment. This routine is executed as logic to be added to the conventional well-known misfire detection logic when the above-described idle stabilization control is being performed.

In this routine, first, at step 10
At 0, it is determined whether the misfire detection precondition is satisfied. Here, it is determined whether or not the vehicle is traveling on a rough road, for example. When it is determined in step 100 that the misfire detection precondition is not satisfied, the routine is temporarily terminated.

On the other hand, if it is determined in step 100 that the prerequisite for misfire detection is satisfied, then in step 11
Then, it is determined whether or not the rotation fluctuation amount DLTMFL should be calculated. If it is determined in step 110 that the calculation condition is not satisfied, for example, the first term (DC) of the above equation (1) is negative (<0), the routine is temporarily terminated. Is done.

On the other hand, if it is determined in step 110 that the condition for calculating the rotation fluctuation amount DLTMFL is satisfied, the routine proceeds to step 120. In step 120,
The calculated rotation fluctuation amount DLTMFL is compared with the threshold value LVLMF. If the rotation fluctuation amount DLTMFL is equal to or smaller than the threshold value LVLMF, the routine is terminated once, since there is no misfire.

In the comparison in step 120, the rotation fluctuation amount DLTMFL is equal to the threshold value LVLMF.
If it is larger, the process proceeds to step 130. In step 130, after the misfire counter is incremented by "1", this routine is ended once.

According to the present embodiment in which misfire detection during idling stabilization control is performed in the manner described above, the following effects can be obtained. (1) As a misfire determination during idle stabilization control, by adding the above logic to the conventional logic, after a misfire occurs, it is erroneously determined that a new misfire has occurred due to execution of the same control. Can be avoided.

(2) When the first term (DC) of the above equation (1) is negative (<0), the calculation of the equation (1) (rotational fluctuation amount) is prohibited. The calculation load can be significantly reduced.

(3) During steady operation of the engine 1, it is estimated that the time required for rotation of the crankshaft 10 at a predetermined angle (for example, 30 ° CA) for each ignition is maximized and is estimated to be minimal. The amount of rotation fluctuation is determined based on the time required for the rotation of the same predetermined angle corresponding to the angle to be performed, so that the amount of rotation fluctuation can be accurately calculated, and the rotation fluctuation based on the required time can be calculated. The execution of the amount calculation and the determination of prohibition can be accurately performed.

The above embodiment may be modified as follows. In the above-described embodiment, the time required to calculate the required time per predetermined crank angle is 0 ° to 30 ° and 90 ° to 120 ° CA on the retard side with respect to each top dead center. Is optional. For example, the following can be considered. First, 0 ° to 30 ° and 180 ° on the retard side before 360 ° CA with respect to each top dead center.
° A to 210 ° CA
And B ′. Each of these times A and B ′ is a required time corresponding to an angle at which it is estimated that the time during which the crankshaft 10 rotates by 30 ° CA for each two consecutive ignitions is maximized. Next, the current, that is, 0 ° to 30 ° on the same retard side after 360 ° CA therefrom.
And the time required for CA rotation from 180 ° to 210 ° is C and D ′, respectively. These times C and D '
Also, three crankshafts 10 for every two consecutive ignitions
This is the required time corresponding to the angle at which the time to rotate by 0 ° CA is estimated to be maximal. Then, the rotation fluctuation amount DD
The TDC is calculated as DDTDC = (D′−C) − (B′−A) (2) based on A, B ′, C, and D ′, and the rotational fluctuation amount DDTDC is a predetermined threshold. It is determined that a misfire has occurred when the value exceeds the value. Then, when the first term (D′−C) <0 in the above equation (2), the calculation of the rotation fluctuation amount DDTDC may be prohibited. Samples of the required time at this time are shown in FIG.
c, d ', e, f', g, h '. In addition, the amount of rotation fluctuation in this case is shown by a broken-line graph in FIG. In this graph, in the case of the rotation fluctuation related to the stabilization control, the first term (D′−C) of the rotation fluctuation amount DDTDC is:
(H'-g), which has a negative value,
The calculation of the rotation fluctuation amount DDTDC is prohibited.

In the above-described embodiment or the modification, the rotation fluctuation amount DLTMFL or the rotation fluctuation amount DDTDC
The prohibition condition of the calculation of (D−C) <0 or (D′−C)
<0, but is not necessarily limited to this. For example,
In the case of the rotation fluctuation related to the stabilization control, (B−A) or (B′−A) becomes very small.
A) <0 or (B′-A) <0 may be further added as a condition. As a result, misfire detection can be performed with higher accuracy.

The change in the number of revolutions in an appropriate period may be added as a judgment as to whether the misfire detection is correct or not. That is, by utilizing the fact that the rotation speed at the time of idling stabilization has a larger value than the rotation speed of the temporary speed drop due to misfire, for example, the rotation speed before and after the period having a large rotation fluctuation amount is increased. In comparison, when the rotation speed changes to the increasing side, calculation of the rotation fluctuation amount can be prohibited.

Here, for example, a first period defined from 0 ° to 180 ° CA as a period including a period for calculating the component (DC) of the rotation fluctuation amount DLTMFL, A period before 180 ° CA, in other words, a period including a period related to the calculation of (BA) is set as a second period, and the number of rotations within this period is set as e and e1, respectively. When (3) is satisfied, calculation of the rotation fluctuation amount may be prohibited.

Further, when calculating the rotation fluctuation amount DDTDC, the condition (3) may be employed using the rotation speed determined by the first period and the second period.

(Second Embodiment) Hereinafter, a second embodiment that embodies a misfire detection device for an internal combustion engine according to the present invention will be described mainly with reference to FIG. 4 with respect to differences from the first embodiment. I do.

In the first embodiment, the angle period required for calculating the required time per predetermined crank angle (30 ° CA) is shifted to the retard side by 30 degrees with respect to the top dead center of each cylinder.
° to 0 ° and 120 ° to 90 ° CA. However, in the periodic rotation fluctuation of the engine 1 at the time of the idling stabilization, it is estimated that the time required for the rotation at the predetermined angle is maximized and the angle estimated to be minimized is particularly minimized. The angle is likely to vary depending on the ignition timing retard mode of the engine 1. Hereinafter, a description will be given of how the rotation fluctuation changes when the ignition timing is retarded.

FIG. 4 is a diagram corresponding to FIG. 2 (b), showing a periodical rotation fluctuation when the ignition timing is not retarded and a periodical rotation fluctuation when the ignition timing is retarded. Are shown in comparison. That is, in FIG. 4, the transition example indicated by the solid line indicates a change mode of the required time per predetermined crank angle under the same conditions as in the period T1 in FIG. 2B. On the other hand, a transition example shown by a broken line in FIG. 4 is a change mode of the required time when the ignition timing is retarded. As described above, when the ignition timing is retarded, the timing at which the required time is minimal in each cycle shifts to the retard side by one plot, and the angle period between the maximum point and the minimum point at the same time is the same as that in the example. In this case, it is 120 ° CA.

Therefore, in the present embodiment, the crank angle for calculating the required time is 0 ° to 0 ° with respect to the top dead center of each cylinder when the ignition timing is retarded.
It was set to 30 ° CA and each angle period of 120 ° to 150 ° CA.

The change of the angle period is specifically carried out in the following manner. First, during the idle stabilization control, when the engine 1 shows a stable periodic motion of the rotational speed, the relationship between the ignition timing at that time and the minimum point of the required time per predetermined crank angle in each cycle is examined. .

Next, the ignition timing at which the minimum point changes from 120 ° CA to 150 ° CA on the retard side with respect to the top dead center of each cylinder is set on the advance side (with respect to the top dead center of each cylinder). B
TDC) is set as X ° CA.

Then, during idle stabilization control,
When the ignition timing falls below BTDC X ° CA,
The angle period required for calculating the required time is 0 ° to 30 °.
CA and 120 ° to 150 ° CA. That is, the rotation fluctuation amount DLTMFL at this time is obtained as DLTMFL = (d "-c)-(b" -a) (4).

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) of the first embodiment. (4) When the rotation speed of the engine 1 is stable, the rotation fluctuation reflects the fact that the maximum point and the minimum point of each cycle of the minute rotation fluctuation change according to the retardation of the ignition timing. Since the calculation mode of the amount is set, it is possible to more accurately calculate the rotation fluctuation amount and determine whether to execute or prohibit the calculation of the rotation fluctuation amount.

The above embodiment may be modified and implemented as follows. In FIG. 4, although the local maximum point does not change between before and after the delay, only the appearance of the local minimum point is shifted by 30 ° CA. As described above, the change is remarkable at the local minimum point. Nevertheless, it is related to the method of setting the required time according to the above embodiment. actually,
It is presumed that by retarding the ignition timing, the maximum point and the minimum point of the required time, in other words, both the maximum point and the minimum point of the rotation speed change. Therefore, the setting of the predetermined period for calculating the amount of change in the required time is not necessarily required to be 90 ° to 120 ° CA and 0 ° to 30 ° as in the above embodiment.
From ° CA, 120 ° to 150 ° CA, and 0 ° to 30
Rather than changing to ° CA, the setting of this predetermined period may be changed as appropriate.

Other elements that can be changed in common to the above embodiments include the following. In the above embodiments and the modifications thereof, the interval of the predetermined period for calculating the first and second terms of the definition equation of the rotation fluctuation amount is set to 360 ° CA, but this interval is arbitrary. Alternatively, it may be appropriately changed within a range in which misfire can be detected by calculating the rotation fluctuation amount. Further, the predetermined angle for obtaining the required time is not limited to 30 ° CA, but may be set to any angle.

In each of the above embodiments and the modifications thereof, the present invention is embodied in a system using the four-cylinder gasoline engine 1, but this is optional. However, it is presumed that the mode of the minute cycle at the time of the above-described stabilization control greatly changes depending on the engine to be employed. Therefore, it is desirable to apply the principle of the present invention in a manner suitable for each case.

In each of the above embodiments and the modifications thereof, the predetermined period for calculating the crank angular speed is set within the period between the maximum point and the minimum point of the required time period during steady operation of the engine 1. However, the setting of the predetermined period is not limited to this. However, when the predetermined period is not set as in the above-described embodiment, there may be a case where the above-described determination of prohibition of the calculation of the rotation fluctuation amount cannot be performed using the above-described determination conditions. However, for example, in the case of the rotation fluctuation related to misfire, the rotation characteristic largely changes to the low speed side, whereas in the case of the rotation fluctuation related to the idling stabilization control, the rotation fluctuation largely changes to the high speed side. In addition, it is possible to determine that the calculation of the rotation fluctuation amount for the misfire determination is prohibited.

In each of the above embodiments and the modifications thereof, the calculation of the rotation fluctuation amount is prohibited to avoid erroneous detection of the occurrence of misfire. However, the following may be adopted.
That is, the calculation of the rotation fluctuation amount is performed, but the comparison with the misfire threshold is prohibited, or the comparison of the rotation fluctuation amount with the misfire threshold is always performed but the increment of the misfire counter is prohibited. Good. In short, the detection result of the misfire occurrence only occurs when the rotation fluctuation of the engine 1 toward the low speed side during the idling stabilization control is larger than the rotation fluctuation amount capable of maintaining the control rotation speed required for the idling stabilization control. What is necessary is just to make it effective. This can also avoid erroneous detection of misfire occurrence.

In each of the above embodiments and its modifications, the case where the present invention is applied to misfire detection during idling stabilization control has been described. However, the present invention also applies to misfire detection during rotation speed stabilization control other than during idling. The detection device can likewise be applied. Even in those cases, the rotational fluctuations related to the control forcibly performed to stabilize the rotational velocity are more rapid than the rotational fluctuations related to the recovery of the rotational velocity after the misfire. In the determination, when there is a possibility that an erroneous determination may occur, the above-described logic can avoid the erroneous determination.

[Brief description of the drawings]

FIG. 1 is a first view of a misfire detection device for an internal combustion engine according to the present invention.
The schematic diagram which shows the schematic structure about embodiment of FIG.

FIG. 2 is a timing chart showing a misfire detection mode of the embodiment.

FIG. 3 is an exemplary flowchart showing a misfire detection procedure according to the embodiment;

FIG. 4 is a second view of the misfire detection device for an internal combustion engine according to the present invention.
6 is a timing chart showing a data plotting mode for the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Cylinder block, 1b ... Cylinder head, 2 ... Cylinder bore, 3 ... Piston, 3a ... Connecting rod, 4 ... Combustion chamber, 5 ... Intake passage, 5a ... Intake port, 6 ... Exhaust passage, 6a ... Exhaust port , 7 ... intake valve, 8 ... exhaust valve, 9 ... injector, 10 ... crankshaft, 11 ... spark plug, 13 ... igniter, 1
5: water temperature sensor, 16 surge tank, 18: throttle valve, 19: throttle sensor, 20: idle switch, 21: accelerator pedal, 22: air follow meter, 27: crank angle sensor, 31: exhaust camshaft, 33, 34 ... Timing pulley, 35 ... Timing belt, 41 ... ISCV, 42 ... Bypass passage, 61 ...
Electronic control unit.

Continued on the front page (72) Inventor Hiroki Kusano 2-1-1 Toyota-cho, Kariya-shi, Aichi F-term in Toyota Industries Corporation (reference) 3G084 AA03 BA06 BA13 BA15 BA17 CA03 DA04 DA27 EA07 EA11 EB00 EB12 EB22 EC04 FA07 FA24 FA34 FA38 FA39

Claims (10)

[Claims] A misfire detection device for an internal combustion engine that calculates a rotation fluctuation amount of an engine output shaft and detects occurrence of a misfire based on the calculated rotation fluctuation amount exceeding a predetermined threshold value. In the rotation speed stabilization control, only when the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation capable of maintaining the control rotation speed related to the stabilization control, the detection result of the misfire occurrence is determined. A misfire detection device for an internal combustion engine, which is effective. 2. A misfire detection device for an internal combustion engine, which calculates a rotation fluctuation amount of an engine output shaft and detects occurrence of a misfire based on the calculated rotation fluctuation amount exceeding a predetermined threshold value. During the rotation speed stabilization control, only when the rotation fluctuation of the engine output shaft to the low speed side is larger than the rotation fluctuation that can maintain the control rotation speed related to the stabilization control, the calculation of the rotation fluctuation amount is performed. An apparatus for detecting a misfire of an internal combustion engine. 3. The rotational fluctuation amount is calculated as a value corresponding to a difference in rotational angular velocity each time the engine output shaft has the same rotational angle, and the rotational fluctuation of the engine output shaft to a low speed side is stabilized. The condition that is larger than the rotation fluctuation that can maintain the control rotation speed for the control is that the current rotation angular velocity of the engine output shaft at the same rotation angle is the previous rotation of the same engine output shaft at the same rotation angle. The misfire detection device for an internal combustion engine according to claim 2, wherein the condition is that the angular velocity is smaller than the angular velocity. 4. A misfire detection apparatus for an internal combustion engine according to claim 3, wherein the time required for rotation of said engine output shaft at a predetermined angle for each ignition of said engine is estimated to be maximized and minimized. For the time required for the rotation at the same predetermined angle corresponding to each of the angles, the previous required time at the same rotation angle of the engine output shaft is A on the maximum side, B on the minimum side,
When the required time at the same rotation angle of the engine output shaft at this time is C on the maximum side and D on the minimum side, the rotation fluctuation amount is calculated as DLTMFL, and DLTMFL = (D−C) − A misfire detection device for an internal combustion engine, wherein the calculation of the amount of rotation fluctuation is prohibited at least under the condition that (DC) <0, which is obtained by (BA). 5. An apparatus for detecting a misfire of an internal combustion engine according to claim 3, wherein the time required for rotation of the engine output shaft at a predetermined angle for each ignition of the engine is estimated to be maximized and minimized. For the time required for the rotation at the same predetermined angle corresponding to each of the angles, the previous required time at the same rotation angle of the engine output shaft is A on the maximum side, B on the minimum side,
When the required time at the same rotation angle of the engine output shaft at this time is C on the maximum side and D on the minimum side, the rotation fluctuation amount is calculated as DLTMFL, and DLTMFL = (D−C) − A misfire of the internal combustion engine, wherein the calculation of the rotation fluctuation amount is prohibited under the condition that (DC) <0 and (BA) <0, which are obtained by (BA). Detection device. 6. A misfire detecting apparatus for an internal combustion engine according to claim 3, wherein the time required for rotation of said engine output shaft at a predetermined angle is maximized and estimated to be minimized for each ignition of said engine. For the time required for the rotation at the same predetermined angle corresponding to the respective angles, the previous required time at the same rotation angle of the engine output shaft is A on the maximum side, B on the minimum side, and the same time on the engine output shaft. Assuming that the current required time at the rotation angle is C on the maximum side and D on the minimum side, the rotation fluctuation amount is obtained by calculating DLTMFL = (D−C) − (B−A) using this as DLTMFL. And (DC) <0, and the calculation of the rotation fluctuation amount is prohibited under the condition that the rotation speed e1 of the engine output shaft before one ignition and the current rotation speed e satisfy e1 <e. A misfire detection device for an internal combustion engine, comprising: 7. The misfire detection apparatus for an internal combustion engine according to claim 4, wherein the engine estimates that the time required for rotation of the engine output shaft at a predetermined angle for each ignition is minimized. A misfire detection device for an internal combustion engine, wherein the misfire detection device is variable in accordance with the ignition timing retard mode. 8. A misfire detecting apparatus for an internal combustion engine according to claim 3, wherein it is estimated that the time required for rotating the engine output shaft at a predetermined angle becomes maximum every two consecutive ignitions of the engine. For the time required for the rotation at the same predetermined angle corresponding to each of the three angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition,
When the current required time of the engine output shaft at the same rotation angle is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is calculated as DDTDC, and the calculation DDTDC = (D'-C)-(B'-A), wherein at least (D'-C) <0, the calculation of the rotational fluctuation amount is prohibited, and the misfire detection apparatus for an internal combustion engine is prohibited. . 9. A misfire detecting apparatus for an internal combustion engine according to claim 3, wherein it is estimated that the time required for rotation of said engine output shaft at a predetermined angle becomes maximum every two consecutive ignitions of said engine. For the time required for the rotation at the same predetermined angle corresponding to each of the three angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition,
When the current required time of the engine output shaft at the same rotation angle is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is calculated as DDTDC, and the calculation DDTDC = (D'-C)-(B'-A), where (D'-C) <0 and (B'-A) <
A misfire detection device for an internal combustion engine, wherein calculation of the rotation fluctuation amount is prohibited under a condition of zero. 10. The apparatus for detecting misfire of an internal combustion engine according to claim 3, wherein it is estimated that the time required for the engine output shaft to rotate at a predetermined angle becomes maximum every two consecutive ignitions of the engine. For the time required for rotation at the same predetermined angle corresponding to each of the three angles, the previous required time at the same rotation angle of the engine output shaft is A for the first ignition, B 'for the second ignition,
When the current required time of the engine output shaft at the same rotation angle is C in the first ignition and D 'in the second ignition, the rotation fluctuation amount is calculated as DDTDC, and the calculation DDTDC = (D' −C) − (B′−A), (D′−C) <0, and the engine speed e1 of the engine output shaft before one ignition and the current speed e are e1 <e.
A misfire detection device for an internal combustion engine, wherein calculation of the rotation fluctuation amount is prohibited under the following conditions: