JP5958221B2 - Control method for internal combustion engine - Google Patents

Description

  The present invention belongs to a technical field related to a control method for an internal combustion engine that transmits an output to a drive system of a vehicle via a dual mass flywheel.

  2. Description of the Related Art Conventionally, a technique using a dual mass flywheel to suppress transmission of torque fluctuations of an internal combustion engine to a vehicle drive system is well known. This dual mass flywheel is obtained by dividing a flywheel into two parts, a main flywheel and a sub flywheel, and connecting them with a spring (see, for example, Patent Document 1).

  In addition, a technique for determining the presence or absence of misfire of the internal combustion engine based on the rotation fluctuation of the internal combustion engine (crankshaft rotation fluctuation) is also well known. However, as disclosed in Patent Document 1, in an internal combustion engine that transmits output to the drive system of a vehicle via the dual mass flywheel, the rotation waveform at the time of misfire is a normal flywheel due to the influence of the sub flywheel. Therefore, the presence or absence of misfire cannot be accurately determined. Therefore, in Patent Document 1, the time required for the crankshaft of the internal combustion engine to rotate the reference angle is detected, the output torque of the internal combustion engine is estimated based on this detection time, and a fly that does not include a relatively movable member. When a wheel is used, the estimated output torque estimates the time that the crankshaft will take to rotate the reference angle, and the presence or absence of misfire is determined based on the estimated time. ing.

JP 2006-9649 A

  However, in the internal combustion engine that transmits the output to the vehicle drive system via the dual mass flywheel, due to an error in mounting the dual mass flywheel on the crankshaft (eccentricity of the main flywheel and the sub flywheel relative to the crankshaft), etc. Since the rotational fluctuation of the internal combustion engine occurs, the presence or absence of misfire cannot be accurately determined unless the rotational fluctuation due to the mounting error or the like is taken into consideration.

  Therefore, in order to grasp the rotational fluctuation due to the mounting error or the like, it is conceivable to detect the rotational state of the crankshaft when the fuel is cut for all the cylinders of the internal combustion engine when the vehicle is decelerated. As a result, it can be understood how much the rotational fluctuation due to the mounting error or the like is present, and even if the rotational fluctuation of the internal combustion engine is detected, the detected rotational fluctuation is misfired by considering the rotational fluctuation due to the mounting error or the like. You can see if it is due to.

  However, in the internal combustion engine, when the fuel is cut, the spring connecting the main flywheel and the sub flywheel may come into contact with a member covering the spring (particularly when the rotational speed of the internal combustion engine is high). In this case, the dual mass flywheel may vibrate abnormally. When the rotational state of the crankshaft is detected while the dual mass flywheel vibrates abnormally in this way, the rotational fluctuation due to the mounting error etc. will be misidentified, resulting in misfire. Presence / absence cannot be determined accurately.

  Here, the frequency of the vibration of the dual mass flywheel is analyzed to determine whether or not the dual mass flywheel is abnormally vibrating, and when it is abnormally vibrating, the rotation state of the crankshaft is not detected. However, in order to perform frequency analysis, it is necessary to increase the capability of the control device, and it is required to be able to accurately determine the presence or absence of misfire by a simple method.

  The present invention has been made in view of such points, and an object of the present invention is to provide a dual mass in a simple method in an internal combustion engine that transmits output to a drive system of a vehicle via a dual mass flywheel. The purpose is to accurately grasp the rotation fluctuation (crankshaft rotation fluctuation) of the internal combustion engine due to an error in attaching the flywheel to the crankshaft, and to accurately determine the presence or absence of misfire.

In order to achieve the above object, the present invention is directed to a method for controlling an internal combustion engine that transmits output to a drive system of a vehicle via a dual mass flywheel. When the fuel is cut, the reference position in the circumferential direction of the rotor plate attached to rotate integrally with the crankshaft of the internal combustion engine from the half-rotated position with respect to the first time until the half-turn from the predetermined angular position. Further, from the time ratio detecting step for detecting the ratio of the second time until it returns to the predetermined angle position after half rotation and the ratio detected in the time ratio detecting step, one temporary cut is made at the time of one fuel cut. a provisional correction value determining step of determining a correction value, the determination of the provisional correction value, after the first predetermined number of times set in an odd number of times, among the provisional correction value of said first predetermined number of times, tentative Supplement And the correction value determination storage step of the median is determined as the correction value storing main correction value in the storage device which is defined as the center corresponding to the value when arranging a value in descending order or ascending order, the present correction value A time detecting step of alternately detecting the first time and the second time for each half rotation of the rotor plate when combustion is performed in all cylinders of the internal combustion engine after the determination storing step; The time required for the half rotation of the rotor plate detected in the time detection step is corrected based on the main correction value stored in the storage device, and is corrected after the half rotation of the rotor plate. Whether or not misfire has occurred in the internal combustion engine based on the post-correction required time determining step for determining the time and the post-correction required time for each half rotation of the rotor plate determined in the post-correction required time determination step Look including the misfire determination process of constant, first the misfire determination process, the determination of the corrected required time, which is set to 1 odd number plus the same or the gas cylinder number and number of cylinders the internal combustion engine 2. Perform a predetermined number of times, and determine, as a reference time, a median value defined as a value corresponding to the center when the post-correction required times for the second predetermined number of times are arranged in order of increasing or decreasing order Then, the difference between the reference time and the corrected required time corresponding to the center when the corrected required times are arranged in chronological order from the oldest of the second predetermined times of the corrected required times is calculated. When the difference is equal to or longer than a predetermined time, it is determined to be a step of determining that a misfire has occurred in the cylinder corresponding to the required time after correction corresponding to the center .

By the above method, the ratio of the second time to the first time is detected at the time of fuel cut, and from this ratio, one temporary correction value is determined at the time of one fuel cut, and the determination of the temporary correction value is performed first. 1 after a predetermined number of times, the median value of the provisional correction value of said first predetermined number of times determined as the correction value storing main correction value in the storage device. If there is no error in attaching the dual mass flywheel to the crankshaft, the value of the ratio is 1. However, in practice, the value of the ratio is not 1 due to the attachment error. From this ratio value, the rotational fluctuation of the internal combustion engine due to the mounting error or the like can be known. The value of the above ratio varies considerably until the operation of the dual mass flywheel stabilizes while the rotor plate rotates during one fuel cut, and the dual mass flywheel may vibrate abnormally. What is necessary is just to determine the value of the said ratio when it is stabilized as much as a temporary correction value. Then, since the median value of the temporary correction values for the first predetermined number of times is determined as the main correction value, the dual mass flywheel vibrates abnormally in the temporary correction values for the first predetermined number of times. Even if there are provisional correction values determined from the detected ratio, the number of such provisional correction values is usually small, and if the first predetermined number of times is set to an appropriate number, an appropriate provisional correction value is obtained. It can be the median. As a result, it is possible to accurately grasp the rotational fluctuation of the internal combustion engine due to the attachment error or the like (this correction value can be accurately determined).

  Then, when combustion is performed in all cylinders of the internal combustion engine, the first time and the second time are alternately detected for each half rotation of the rotor plate, and the alternately detected time for each half rotation of the rotor plate is detected. On the other hand, correction is performed based on the main correction value, and the post-correction required time for each half rotation of the rotor plate is determined. The post-correction required time can be regarded as the time required for half rotation of the rotor plate when there is no attachment error or the like. By determining whether or not misfiring has occurred in the internal combustion engine based on the required time after correction, the presence or absence of misfiring can be accurately determined.

In the control method of the internal combustion engine, the temporary correction for the first predetermined number of times most recently is determined each time the temporary correction value is determined after the determination and storage of the main correction value in the main correction value determination storage step. by determining the median of the values as a new present correction value, updating the present correction values stored in the storage device to the latest present correction value, it is preferable.

  As a result, the correction value can be determined more accurately.

When the main correction value is updated as described above, it is preferable that the first predetermined number of times is set to three in the main correction value determination storing step when the first main correction value is determined. .

That is, since it is not possible to determine the presence or absence of misfire until the final correction value is determined, the first predetermined correction value is reduced as much as possible when determining the initial main correction value, so that the initial main correction value can be determined early. To be able to decide.

On the other hand, in the main correction value determination storage step, it is preferable to set the first predetermined number of times to seven when determining the main correction value for the second and subsequent times.

  Accordingly, the main correction value can be determined more accurately after the second and subsequent (including the second) main correction value is determined.

  As described above, according to the control method for an internal combustion engine of the present invention, in an internal combustion engine that transmits output to a drive system of a vehicle via a dual mass flywheel, a simple method can be applied to the crankshaft of the dual mass flywheel. Therefore, it is possible to accurately determine the rotational fluctuation of the internal combustion engine due to the mounting error or the like and accurately determine the presence or absence of misfire.

1 is a schematic view showing an in-line four-cylinder engine mounted on a vehicle and a part of a drive system as an internal combustion engine to which the present invention is applied. It is a figure which shows the example of the temporary correction value for 3 times determined at the time of determination of the first main correction value. It is a figure which shows the example of the temporary correction value for 7 times determined at the time of determination of the 2nd main correction value. It is a flowchart which shows the control action regarding determination of this correction value by an engine controller. It is a flowchart which shows the control action regarding the presence or absence determination of the misfire by an engine controller.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic view showing an in-line four-cylinder engine 1 mounted on a vehicle and a part of a drive system as an internal combustion engine to which the present invention is applied.

  The output of the engine 1 is output from the vehicle via a dual mass flywheel 11 having a main flywheel 12 and a sub flywheel 13 and a clutch 17 provided on the sub flywheel 13 side of the dual mass flywheel 11. It is transmitted to the manual transmission 18 that constitutes a part of the drive system. The main flywheel 12 is connected to the crankshaft 2 of the engine 1, and the sub flywheel 13 is connected to the drive system of the vehicle.

  The main flywheel 12 and the sub flywheel 13 are connected to each other via a spring 14 and are connected to each other so as to be relatively rotatable in a state where the respective rotary shafts 12 a and 13 a are rotatably supported by bearings 15. . The dual mass flywheel 11 absorbs output fluctuations of the engine 1 using the spring 14 to suppress torsional vibration of the drive system, and to suppress generation of noise and vibration due to this.

  The vehicle is provided with an engine controller 31 for controlling the engine 1. The engine controller 31 is a control device based on a well-known microcomputer, and includes a central calculation processing device (CPU) that executes a program, a memory that is configured by, for example, a RAM or a ROM, and stores a program and data. And an input / output (I / O) bus for inputting and outputting various signals.

  The engine controller 31 receives a crank angle pulse signal from a crank angle sensor 34 that detects the rotation angle of the crankshaft 2 of the engine 1 and a signal related to the intake flow rate from the air flow sensor, although not shown in the figure. An accelerator opening signal from an accelerator opening sensor that detects the depression amount of the accelerator pedal, a vehicle speed signal from a vehicle speed sensor, and the like are input. The engine controller 31 calculates control parameters of the engine 1 such as a fuel injection pulse and an ignition signal based on these input signals. The engine controller 31 outputs these signals to an ignition system including a fuel injection valve and a spark plug for each cylinder. In the present embodiment, the ignition plugs of the cylinders are ignited in the order of the first cylinder, the third cylinder, the fourth cylinder, and the first cylinder.

  The crank angle sensor 34 is provided so as to face the peripheral side surface of the rotor plate 35 that is attached to the crankshaft 2 so as to rotate integrally. According to the rotation of the rotor plate 35 (rotation of the crankshaft 2), A crank angle pulse signal is output to the engine controller 31 corresponding to a number of irregularities provided alternately on the entire circumference of the circumferential side surface of the rotor plate 35. The crank angle sensor 34 outputs a reference pulse signal to the engine controller 31 when the circumferential reference position of the rotor plate 35 is at a predetermined angle position (a position facing the crank angle sensor 35 in the present embodiment). Output to.

  The first cylinder of the engine 1 is in the combustion stroke until the reference position of the rotor plate 35 is half-rotated from the predetermined angle position, and further rotates halfway from the half-rotated position to return to the predetermined angle position. In the meantime, the third cylinder is in the combustion stroke. Further, during the next half rotation, the fourth cylinder is in the combustion stroke, and during the next half rotation, the second cylinder is in the combustion stroke. The engine controller 31 can grasp the stroke of each cylinder based on the crank angle pulse signal and the reference pulse signal from the crank angle sensor 34.

  Next, a method for determining the presence or absence of misfire in the engine 1 will be described.

  First, the rotational fluctuation of the engine 1 (the rotational fluctuation of the crankshaft 2) due to the mounting error of the dual mass flywheel 11 to the crankshaft 2 (the eccentricity of the main flywheel 12 and the sub flywheel 13 with respect to the crankshaft 2) or the like is grasped. To do. That is, the engine controller 31 determines the reference position in the circumferential direction of the rotor plate 35 based on the crank angle pulse signal and the reference pulse signal from the crank angle sensor 34 when the fuel is cut for all the cylinders of the engine 1 during deceleration of the vehicle. A ratio (t2 / t1) of the second time t2 from the half-rotated position until the first time t1 until the half-turn from the predetermined angle position until the second angle t returns to the predetermined angle position is detected. In the present embodiment, even if the fuel cut is performed, the dual mass flywheel 11 is likely to vibrate abnormally when the engine speed hardly decreases, such as when the vehicle goes down a slope, etc. The above ratio is detected when it falls at a normal rate of change. That is, the ratio is detected when the engine speed decreases at a rate of change greater than or equal to a predetermined value due to fuel cut. For this reason, even if a fuel cut is performed, the ratio may not be detected.

  Here, if there is no mounting error or the like of the dual mass flywheel 11, the value of the ratio is 1, but in practice, the value of the ratio is not 1 due to the mounting error or the like. The value of the ratio corresponds to the rotational fluctuation of the engine 1 (rotational fluctuation of the crankshaft 2) due to the mounting error or the like.

  The value of the ratio is detected each time the rotor plate 35 rotates while the rotor plate 35 rotates during one fuel cut. The value of the above ratio varies considerably until the operation of the dual mass flywheel 11 is stabilized while the rotor plate 35 rotates during one fuel cut, and the dual mass flywheel 11 may vibrate abnormally. is there. Therefore, the detection data of the above ratio is filtered by a low-pass filter to remove noise, and the data from which this noise has been removed is filtered by a further low-pass filter. The deviation between the maximum value and the minimum value of the ratio after filtering by the further low-pass filter is within a predetermined value, and the value of the ratio does not continue to increase or decrease gradually. When the stable condition that the rate of change of the value is within a predetermined value is satisfied, it is determined that the ratio value is stable, and the stable ratio value is determined as a temporary correction value. However, even in this case, the possibility of detecting the ratio when the dual mass flywheel 11 is abnormally vibrating cannot be completely excluded. Thus, the engine controller 31 determines one temporary correction value at the time of one fuel cut from the above ratio, and stores this temporary correction value in the memory of the engine controller 31.

  When the engine controller 31 performs the fuel cut a plurality of times and determines the temporary correction value for the first predetermined number of times, the engine controller 31 determines the median value of the temporary correction values for the first predetermined number of times as the main correction value. Then, the correction value is stored in the storage device 32. In addition, after the determination and storage of the main correction value, the engine controller 31 sets a new median value among the most recent temporary correction values for the first predetermined number of times each time the temporary correction value is determined. The final correction value is determined and the main correction value stored in the storage device 32 is updated to the latest main correction value.

  Even if the ignition switch of the vehicle is in an off state, the storage device 32 is continuously supplied with power from the vehicle battery and stores the correction value. However, since the power supply from the battery is interrupted when the battery is replaced, the correction value stored in the storage device 32 is deleted. For this reason, the initial correction value is determined and stored immediately after manufacture of the vehicle or immediately after replacement of the battery.

  As described above, since the median value of the temporary correction values for the first predetermined number of times is determined as the main correction value, the dual mass flywheel 11 has abnormal vibration in the temporary correction values for the first predetermined number of times. Even if there are provisional correction values determined from the ratio detected during the operation, the number of such provisional correction values is usually small, and if the first predetermined number of times is set to an appropriate number, the number of provisional correction values is appropriate. The temporary correction value becomes the median value. The first predetermined number of times is an odd number and preferably 5 times or more (more preferably 7 times or more). In the present embodiment, the engine controller 31 basically sets the first predetermined number of times to seven. With this number of times, the correction value can be accurately determined in combination with the update of the correction value. However, when the first correction value is determined for the first time, the first predetermined number of times is set to three from the viewpoint of enabling the determination of the presence or absence of misfire as soon as possible. Then, when determining the correction value for the second time and thereafter (including the second time), the first predetermined number of times is set to seven.

  Therefore, in the present embodiment, when the main correction value is not stored in the storage device 32, after determining the temporary correction value three times, the median value of the three temporary correction values is set as the main correction value. The final correction value is determined and stored in the storage device 32. FIG. 2 shows an example of the provisional correction values for three times determined when the first main correction value is determined. In this example, the third temporary correction value is determined as the main correction value. In this example, the second temporary correction value is a temporary correction value determined from the ratio detected when the dual mass flywheel 11 is abnormally vibrating, and the values of the other temporary correction values are It is quite different. However, the main correction value can be accurately determined by determining the median value among the three temporary correction values as the main correction value.

  After that, the temporary correction value is newly determined four times (a total of seven times including the first three times when the final correction value is determined), and then the median value of the seven temporary correction values is set to the final value. The correction value is determined and the main correction value stored in the storage device 32 is updated to the latest main correction value (the main correction value among the seven temporary correction values). FIG. 3 shows an example of seven temporary correction values determined when determining the second main correction value. In this example, the seventh temporary correction value is determined as the main correction value. In this example, the second temporary correction value (same as the second temporary correction value in FIG. 2) and the sixth temporary correction value are detected when the dual mass flywheel 11 vibrates abnormally. The temporary correction value determined from the ratio is considerably different from the values of the other temporary correction values. However, the main correction value can be accurately determined by determining the median value among the seven temporary correction values as the main correction value.

  Thereafter, each time the temporary correction value is determined, the median value of the last seven temporary correction values is determined as a new main correction value. In other words, provisional correction values for the previous seven times are excluded from the median candidate. For example, when the eighth temporary correction value is determined after the seventh temporary correction value, the latest seven temporary correction values, that is, the median value of the second to eighth temporary correction values are newly set. This correction value is determined. In this way, the main correction value stored in the storage device 32 is updated to the latest main correction value.

  After determining and storing the initial correction value for the first time, the engine controller 31 performs the first time t1 and the first time every half rotation of the rotor plate 35 when combustion is performed in all the cylinders of the engine 1. Two hours t2 are detected alternately. Here, even if the combustion conditions of the first to fourth cylinders are the same, the combustion stroke time does not become the same due to the attachment error or the like. For example, the first to the first time t1 corresponding to the first time t1. The combustion stroke time of the third cylinder (second cylinder) corresponding to the second time t2 is longer than the combustion stroke time of the cylinder (fourth cylinder). In this example, the ratio value (main correction value) is greater than 1. If the presence / absence determination of misfire is performed at the first time t1 and the second time t2, the possibility of erroneous determination increases. Therefore, in order to eliminate the influence of the rotation fluctuation due to the mounting error or the like, the time for each half rotation of the rotor plate 35 (the first time t1 and the second time t2) is changed to the main correction value as follows. Correct based on.

  Specifically, the engine controller 31 is stored in the storage device 32 for each half-rotation of the rotor plate 35 detected alternately (the first time t1 and the second time t2). Correction is made based on the main correction value, and the post-correction required time for each half rotation of the rotor plate 35 is determined. This corrected time is stored in the memory of the engine controller 31.

  The post-correction required time is determined, for example, as follows. That is, the main correction value is multiplied by the first time t1, and the second time t2 is left as it is (may be regarded as multiplying the second time by 1). Alternatively, the first time t1 is left as it is (the first time t1 is multiplied by 1), and the second time t2 is multiplied by the reciprocal of the main correction value. Alternatively, the first time t1 is multiplied by the square root of the main correction value, and the second time t2 is multiplied by the inverse of the square root of the main correction value. In this way, the post-correction required time for each half rotation of the rotor plate 35 is determined. The post-correction required time can be regarded as the time required for half rotation of the rotor plate 35 when there is no attachment error or the like.

  The engine controller 31 determines whether or not misfiring has occurred in the engine 1 based on the determined required time for each half rotation of the rotor plate 35. In the present embodiment, first, the median value of the required time after the correction for the second predetermined number of times determined by the correction for the time of the half rotation of the rotor plate 35 for the second predetermined number of times detected most recently is calculated. Determine as the reference time. This reference time is stored in the memory of the engine controller 31. The second predetermined number of times is an odd number, and is set to the same number as the number of cylinders of the engine 1 or a value obtained by adding 1 thereto. In this embodiment, since there are four cylinders, it is set to five times. With this number of times, the change in the engine speed can be ignored, and the reference time for determining the presence or absence of misfire can be accurately determined in the same manner as the determination of the main correction value. Therefore, the engine controller 31 determines the median value of the required time after correction for the latest five times as the reference time.

  Then, the engine controller 31 calculates the third required time after correction (the corrected required time that becomes the center when arranged in chronological order) from the oldest of the latest five corrected times, and the reference time. When the difference is calculated and the difference is equal to or longer than the predetermined time, it is determined that the cylinder has a long combustion stroke corresponding to the third post-correction required time, and misfire has occurred in the cylinder. On the other hand, when the difference is shorter than the predetermined time, it is determined that there is no misfire in the cylinder (normal determination).

  Subsequently, when the engine controller 31 next newly detects the first time t1 or the second time t2, the corrected required time for the latest five times including the corrected required time determined by the correction for that time. Is determined as a new reference time, and the reference time stored in the memory is updated to the latest reference time. Then, a difference between the third required time after the oldest correction time for the latest five times and the reference time is calculated, and when the difference is equal to or longer than the predetermined time, the third correction is performed. It is determined that the combustion stroke of the cylinder corresponding to the post-required time is long and misfire has occurred in that cylinder.

  For example, if the required time after correction for the last five times corresponds to the combustion stroke times of the first cylinder, the third cylinder, the fourth cylinder, the second cylinder, and the first cylinder in order, the oldest one of them The third post-correction required time corresponds to the time of the combustion stroke of the fourth cylinder, and it is determined whether or not misfire has occurred in the fourth cylinder. The next required time after the correction for the last five times corresponds to the combustion stroke times of the third cylinder, the fourth cylinder, the second cylinder, the first cylinder, and the third cylinder in order, It is determined whether or not a misfire has occurred in the second cylinder next to the fourth cylinder that has been determined whether or not it has occurred. In this way, each time the first time t1 or the second time t2 is newly detected and the post-correction required time is determined, the cylinder for determining whether or not misfiring has occurred is sequentially changed.

  Next, the control related to the determination of the correction value by the engine controller 31 will be described based on the flowchart of FIG.

  In the first step S1, the ratio (t2 / t1) of the second time t2 to the first time t1 is detected when the fuel is cut for all the cylinders of the engine 1 during deceleration of the vehicle. However, as described above, the ratio is detected only when the engine speed decreases at a rate of change greater than or equal to a predetermined value due to fuel cut.

  In the next step S2, the detection data of the above ratio is filtered by a low-pass filter to remove noise, and the data from which this noise has been removed is filtered by a further low-pass filter. In the next step S3, when the stability condition is satisfied, a stable value of the ratio is determined as a temporary correction value.

  In the next step S4, it is determined whether or not the initial main correction value is determined and stored. If the determination in step S4 is NO, the process proceeds to step S5 to determine the temporary correction value 3 It is determined whether or not it has been performed once. If the determination in step S5 is NO, the process returns as it is. If the determination in step S5 is YES, the process proceeds to step S6, and the median value among the three temporary correction values is determined as the main correction value. The main correction value is stored in the storage device 32, and then the process returns.

  On the other hand, when the determination in step S4 is YES, the process proceeds to step S7 to determine whether or not the provisional correction value has been determined seven times. When the determination in step S7 is NO, the process returns as it is. On the other hand, when the determination in step S7 is YES, the process proceeds to step S8, and seven temporary correction values (the eighth and subsequent temporary correction values are determined). In some cases, the median of the latest seven temporary correction values) is determined as the main correction value, the latest main correction value is updated and stored in the storage device 32, and then the process returns.

  Next, control related to the determination of the presence or absence of misfire by the engine controller 31 will be described based on the flowchart of FIG.

  In the first step S21, it is determined whether or not the correction value has been determined and stored. If the determination in step S21 is NO, the process directly returns. That is, the presence or absence of misfire is not determined.

  When the determination in step S21 is YES, the process proceeds to step S22, and when the combustion is performed in all the cylinders of the engine 1, the first time t1 and the second time every half rotation of the rotor plate 35. t2 is detected alternately.

  In the next step S23, the main correction value stored in the storage device 32 (the book stored in the step S6 or S8) with respect to the half-rotation time of the rotor plate 35 detected alternately. Based on the correction value), the post-correction required time for each half rotation of the rotor plate 35 is determined.

  In the next step S24, the median value of the latest five times after the correction is determined as a reference time, and in the next step S25, the oldest of the five latest correction times after the oldest is determined. The difference between the corrected required time and the reference time is calculated, and in the next step S26, it is determined whether or not the difference is equal to or greater than a predetermined time.

  When the determination in step S26 is YES, the process proceeds to step S27, where it is determined that a misfire has occurred in the cylinder corresponding to the third required time after correction, and then the process returns. On the other hand, when the determination in step S26 is NO, the process proceeds to step S28, where it is determined that no misfire has occurred in the cylinder (normal determination), and then the process returns.

  Accordingly, in the present embodiment, the median value of the temporary correction values for the predetermined number of times is determined as the main correction value, and thus the dual mass flywheel 11 is abnormally vibrated in the temporary correction values for the predetermined number of times. Even if there is a temporary correction value determined from the above ratio detected at times, the appropriate temporary correction value becomes the median value, and as a result, the rotation of the engine 1 due to an attachment error of the dual mass flywheel 11 to the crankshaft 2 or the like. The fluctuation can be accurately grasped (this correction value can be accurately determined). Then, when combustion is performed in all cylinders of the engine 1, the first time t1 and the second time t2 are alternately detected every half rotation of the rotor plate 35, and the half of the rotor plate 35 detected alternately is detected. The time required for each rotation is corrected based on the above correction value, and the required time after correction for each half rotation of the rotor plate 35 (the time required for half rotation of the rotor plate 35 when there is no such mounting error) Is determined, and it is determined whether or not misfire has occurred in the engine 1 based on the required time after correction. Therefore, the presence or absence of misfire can be accurately determined.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

Here, in the above-described embodiment, the median value of the latest five corrected times is determined as the reference time, and the third corrected time from the oldest of the latest five corrected times Based on the difference from the reference time, it was determined whether or not misfire occurred in the cylinder corresponding to the third post-correction required time, but as a reference form different from the present invention, as in the above embodiment, After determining the median value of the latest five corrected times as the reference time, all the corrected time for the latest five times are compared with the reference time, and all the corrected time It may be determined whether or not misfire has occurred in the cylinder corresponding to. In this case, when the corrected time for the next five times is determined, a new reference time is determined from the corrected time for the next five times, and the corrected time for the next five times and its new time. It is determined whether or not misfiring has occurred in the cylinders corresponding to all of the required time after correction in comparison with the reference time. Alternatively, instead of using the median as the reference time as described above, a reference time is set in advance, and each time the first time t1 or the second time t2 is detected and the corrected required time is determined. The post-correction required time may be compared with a preset reference time to determine whether a misfire has occurred in the cylinder corresponding to the post-correction required time.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention is useful for a method for controlling an internal combustion engine that transmits output to a vehicle drive system via a dual mass flywheel, and is particularly useful for determining whether or not a misfire has occurred in the internal combustion engine.

1 engine (internal combustion engine)
2 Crank Angle 11 Dual Mass Flywheel 31 Engine Controller 32 Storage Device 34 Crank Angle Sensor 35 Rotor Plate

Claims (4)

A control method for an internal combustion engine that transmits output to a drive system of a vehicle via a dual mass flywheel,
When the fuel is cut for all the cylinders of the internal combustion engine during deceleration of the vehicle, the reference position in the circumferential direction of the rotor plate attached to the crankshaft of the internal combustion engine rotates halfway from the predetermined angular position A time ratio detecting step of detecting a ratio of the second time from the half-rotated position to the predetermined angle position with respect to the first time of
A temporary correction value determining step for determining one temporary correction value at the time of one fuel cut from the ratio detected in the time ratio detecting step;
The determination of the provisional correction value, after the first predetermined number of times set in an odd number of times, among the provisional correction value of said first predetermined number of times, when arranged in descending order or ascending order provisional correction value A main correction value determining and storing step of determining a central value defined as a central value as a main correction value and storing the main correction value in a storage device;
Time detection for alternately detecting the first time and the second time every half rotation of the rotor plate when combustion is performed in all cylinders of the internal combustion engine after the main correction value determination storing step. Process,
After correcting for each half rotation of the rotor plate detected in the time detection step based on the main correction value stored in the storage device, after correction for each half rotation of the rotor plate A post-correction required time determination process for determining the required time;
Based on the required time after correction of the half rotation each of the rotor plates as determined by the corrected desired time determining step, see contains a misfire determination step of determining whether a misfire on the internal combustion engine occurs,
In the misfire determination step, the required time after correction is determined a second predetermined number of times that is the same as the number of cylinders of the internal combustion engine or an odd number of times obtained by adding 1 to the number of cylinders. Of the required time after correction for the number of times, a median value defined as a value corresponding to the center when the required time after correction is arranged in descending order is determined as a reference time, and then the reference time and the above Of the above-mentioned required time after correction for the second predetermined number of times, a difference from the corrected required time corresponding to the center when the required time after correction is arranged in chronological order is calculated, and the difference is not less than the predetermined time. A method of controlling an internal combustion engine, characterized in that it is a step of determining that misfiring has occurred in a cylinder corresponding to the corrected required time corresponding to the center at a certain time . The method for controlling an internal combustion engine according to claim 1,
In the present correction value decision storage step, after determining and storing the present correction value, each time the provisional correction value is determined, the median of the most recent of the provisional correction value of the first predetermined number of times A control method for an internal combustion engine, characterized in that it is determined as a new main correction value, and the main correction value stored in the storage device is updated to the latest main correction value. The method of controlling an internal combustion engine according to claim 2,
In the main correction value determination storing step, when the first main correction value is determined for the first time, the first predetermined number of times is set to three. The control method for an internal combustion engine according to claim 3,
In the main correction value determination storing step, the first predetermined number of times is set to seven when determining the main correction value for the second and subsequent times.

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