JP6421720B2 - Misfire detection device for internal combustion engine - Google Patents

Description

  The present invention relates to a misfire determination device that determines the presence or absence of misfire in an internal combustion engine.

  A multi-cylinder internal combustion engine is often provided with a misfire determination device that detects the presence or absence of misfire based on the rotational speed of the internal combustion engine. For example, Patent Document 1 discloses a technique for determining misfire by performing frequency analysis on a detected rotational speed of an internal combustion engine and comparing gains obtained for each frequency.

Japanese Patent No. 28438871

  If a misfire occurs in one cylinder, a large fluctuation occurs in the rotational speed of the internal combustion engine. This fluctuation affects the fluctuation of the rotational speed that occurs when fuel is burned in another cylinder next time, and even if the fuel is burned normally in that cylinder, the fluctuation amount is assumed to be large. The In this case, the technique described in Patent Document 1 may erroneously determine that misfire has occurred in the cylinder.

  The present invention has been made to solve the above-mentioned problems, and its main purpose is to cause misfire in other cylinders due to the influence of fluctuations in the rotational speed of the internal combustion engine caused by misfire in one cylinder. An object of the present invention is to provide a misfire determination device for an internal combustion engine that suppresses erroneous determination that occurrence has occurred.

  The present invention is a misfire determination apparatus for an internal combustion engine, and calculates a rotational speed detection unit that detects a rotational speed of an internal combustion engine having a plurality of cylinders, and a fluctuation amount of the rotational speed detected by the rotational speed detection unit. A fluctuation amount calculation unit, a storage unit that stores in advance, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount, and the fluctuation amount calculation A determination unit that determines that misfiring has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by a unit. Features.

  According to the above configuration, the fluctuation amount of the rotation speed detected by the rotation speed detection unit is calculated by the fluctuation amount calculation unit. If misfire occurs in one cylinder, a large change occurs in the fluctuation amount calculated by the fluctuation amount calculation unit. This change affects the fluctuation of the rotational speed that occurs when the fuel is burned in another cylinder next time, and even if the fuel is burned normally in that cylinder, the fluctuation amount is assumed to be large. The In this case, there is a risk of misjudging that misfire has occurred in the cylinder. For this reason, the effect of the change in the amount of change in one combustion cycle of the internal combustion engine on the amount of change after the change in the amount of change is stored in advance in the storage unit as a model. Then, the determination unit determines that a misfire has occurred in the internal combustion engine based on the corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. By subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit, the corrected variation amount corrected results from the individual cylinders. Therefore, the determination unit can perform misfire determination for each cylinder. As a result, it is possible to suppress erroneous determination that misfire has occurred in other cylinders due to the influence on the fluctuation amount of the rotational speed given when misfire occurs in a certain cylinder.

1 is a schematic configuration diagram of an engine system to which a misfire determination device according to an embodiment is applied. It is a graph which shows the influence given to rotation speed after that when a misfire occurs in an internal combustion engine. It is a flowchart of misfire determination implemented by ECU which concerns on this embodiment. It is the figure shown about the method of correct | amending the fluctuation amount of rotational speed using a model. It is a graph shown about the correction | amendment of the rotational speed implemented by ECU which concerns on this embodiment. It is the figure which each showed the state which the some model stored in ECU which concerns on another example assumes.

  Referring to FIG. 1, an engine system 10 includes an engine 11 that is a spark ignition type internal combustion engine. A combustion chamber 11b and a water jacket 11c are formed inside an engine block 11a constituting the main body of the engine 11. The combustion chamber 11b is provided to accommodate the piston 12 so as to be capable of reciprocating. The water jacket 11c is a space through which a coolant (also referred to as cooling water) can flow, and is provided so as to surround the combustion chamber 11b.

  An intake port 13 and an exhaust port 14 are formed in the cylinder head, which is an upper portion of the engine block 11a, so as to communicate with the combustion chamber 11b. The cylinder head includes an intake valve 15 for controlling the communication state between the intake port 13 and the combustion chamber 11b, an exhaust valve 16 for controlling the communication state between the exhaust port 14 and the combustion chamber 11b, A valve drive mechanism 17 for opening and closing the valve 15 and the exhaust valve 16 at a predetermined timing is provided.

  Further, an injector 18 and a spark plug 19 are attached to the engine block 11a. In the present embodiment, the injector 18 is disposed in the vicinity of the spark plug 19 and is provided so as to inject fuel directly into the combustion chamber 11b. The spark plug 19 is provided so as to ignite the fuel mixture in the combustion chamber 11b.

  An intake manifold 21 a is connected to the intake port 13. A surge tank 21b is disposed upstream of the intake manifold 21a in the intake air flow direction. An exhaust pipe 22 is connected to the exhaust port 14.

  The EGR passage 23 is provided such that a part of the exhaust gas discharged to the exhaust pipe 22 can be introduced into the intake air by connecting the exhaust pipe 22 and the surge tank 21b (EGR is an abbreviation for Exhaust Gas Recirculation). is there). An EGR control valve 24 is interposed in the EGR passage 23. The EGR control valve 24 is provided so as to be able to control the EGR rate (exhaust gas mixing ratio in the pre-combustion gas sucked into the combustion chamber 11b) by its opening.

  A throttle valve 25 is interposed in the intake pipe 21 upstream of the surge tank 21b in the intake air flow direction. The opening degree of the throttle valve 25 is controlled by the operation of a throttle actuator 26 such as a DC motor. Further, an air flow control valve 27 for generating a swirl flow or a tumble flow is provided in the vicinity of the intake port 13.

  The exhaust pipe 22 is provided with a catalyst 41 such as a three-way catalyst for purifying CO, HC, NOx, etc. in the exhaust gas, and the air-fuel ratio of the air-fuel mixture is detected upstream of the catalyst 41 with exhaust gas as a detection target. An air-fuel ratio sensor 40 (linear A / F sensor or the like) is provided for detecting the above.

  The crank angle sensor 33 (corresponding to the rotation speed detection unit) is a sensor for outputting a rectangular crank angle signal for each predetermined crank angle of the engine 11 (for example, at a cycle of 30 ° CA). The crank angle sensor 33 is mounted on the engine block 11a. The cooling water temperature sensor 34 is a sensor for detecting (acquiring) the cooling water temperature that is the temperature of the coolant flowing through the water jacket 11c, and is attached to the engine block 11a.

  The air flow meter 35 is a sensor for detecting (acquiring) the intake air amount (the mass flow rate of the intake air introduced into the combustion chamber 11b through the intake pipe 21). The air flow meter 35 is attached to the intake pipe 21 upstream of the throttle valve 25 in the intake air flow direction. The intake pressure sensor 36 is a sensor for detecting (acquiring) intake pressure, which is the pressure in the intake pipe 21, and is attached to the surge tank 21b.

  The throttle opening sensor 37 is a sensor that generates an output corresponding to the opening (throttle opening) of the throttle valve 25 and is built in the throttle actuator 26. The accelerator position sensor 38 is provided so as to generate an output corresponding to the accelerator operation amount.

  In such a system, the ECU 32 is the part that mainly controls the engine as an electronic control unit. The ECU 32 (engine control ECU) includes a well-known microcomputer (not shown), grasps the operating state of the target engine and the user's request based on the detection signals of the various sensors, and according to the above, By operating various actuators such as the injector 18, various controls related to the engine are performed in an optimum manner according to the situation at that time.

  The microcomputer mounted on the ECU 32 includes a CPU (basic processing unit) that performs various calculations, a RAM as a main memory that temporarily stores data and calculation results during the calculation, and a ROM as a program memory. An EEPROM as a data storage memory, a backup RAM (a memory that is always powered by a backup power source such as an in-vehicle battery after the main power of the ECU 32 is stopped), and the like. The ROM stores various programs and control maps related to engine control including the program related to the fuel injection control, and the data storage memory stores various control data including design data of the target engine. Etc. are stored in advance. Therefore, the ECU 32 corresponds to a fluctuation amount calculation unit, a storage unit, a determination unit, and a required torque calculation unit.

  In such a multi-cylinder engine 11, when a misfire occurs in one cylinder, the rotational speed of the engine 11 is greatly reduced as indicated by the fluctuation range at the time of misfire shown in FIG. Note that the fluctuation range indicates the magnitude of the difference from the minimum value to zero during the transition period in one combustion cycle (180 CA). This decrease in the rotational speed affects the amount of fluctuation in the rotational speed that occurs when fuel is burned in another cylinder next time, and even if the fuel is normally burned in that cylinder, the fluctuation in the rotational speed is affected. It is assumed that the fluctuation range of the quantity becomes large. In this case, since the fluctuation range of the increased fluctuation amount becomes larger than a threshold value provided for determining misfire, the ECU 32 that performs misfire determination may erroneously determine that misfire has occurred in the cylinder.

  As already described, when a misfire occurs in a certain cylinder, the rotational speed is greatly reduced, which affects the amount of fluctuation of the subsequent rotational speed. However, when the combustion of fuel occurs in the cylinder, the fluctuation range of the fluctuation amount of the rotational speed is not greatly increased, and the subsequent influence is small. The inventor who has paid attention to this point has found a method of modeling an effect that is assumed to be given to the fluctuation amount based on the fluctuation range of the fluctuation amount of the rotational speed. In the present embodiment, a plurality of models assumed according to the fluctuation range of the fluctuation amount of the rotational speed are stored in the ECU 32. Therefore, a model that most closely approximates the fluctuation range of the actually detected rotation speed fluctuation amount is selected, and subtraction is performed using the selected model from the fluctuation width of the actually detected rotation speed fluctuation amount. As a result, even if a misfire occurs in the cylinder, it is possible to suppress the influence on the fluctuation of the rotational speed, and it is possible to perform misfire determination for each cylinder.

  In the present embodiment, the ECU 32 executes a misfire determination process shown in FIG. The misfire determination process shown in FIG. 3 is repeatedly executed by the ECU 32 at a predetermined cycle while the ECU 32 is powered on.

  First, the rotational speed of the engine 11 is calculated based on the crank angle signal detected by the crank angle sensor 33 in step S100. The calculated rotation speed includes factors (hereinafter referred to as noise) that change the rotation speed in addition to the combustion of fuel generated in the cylinder. Therefore, it is desirable to eliminate noise as much as possible when performing misfire determination from a change in rotational speed. For this reason, in step S110, the calculated rotational speed is filtered by passing it through a band-pass filter having a pass band corresponding to the timing at which fuel combustion occurs (for example, 180 ° CA). A first-order differential process is performed on the rotation speed after the filter process (rotation speed excluding noise), thereby calculating the fluctuation amount of the rotation speed as shown in FIG. Then, the process proceeds to step S120.

  In step S120, a model that approximates the fluctuation range of the fluctuation amount of the rotational speed is selected from the stored models, and the process proceeds to step S130. In step S130, as shown in FIG. 4, the correction fluctuation amount is calculated by subtracting the fluctuation amount of the actual rotation speed affected by the model selected in step S120 by the model. To do. The calculated correction fluctuation amount is a value obtained by extracting the fluctuation amount of the rotational speed caused by the individual cylinders from which the influence of the fluctuation of the rotational speed caused by another cylinder is removed.

  However, in this embodiment, the threshold value for determining the misfire to be described later is set based on the required torque (assumed required torque) and the rotational speed (assumed rotational speed) assumed by the selected model. Misfire detection value. Therefore, when the actually detected actual rotational speed or the actual required torque is different from the assumed rotational speed or the assumed required torque, the amplitude of the fluctuation amount of the rotational speed also changes. is there. Therefore, in step S140, when the assumed rotation speed and the assumed required torque are different from the actual rotation speed and the actual required torque, the correction fluctuation amount is corrected based on the ratio thereof.

  Specifically, when the actual rotational speed is higher than the assumed rotational speed, the amplitude of the actual rotational speed fluctuation amount may be smaller than the amplitude of the rotational speed fluctuation amount assumed by the threshold. Therefore, correction is performed so that the correction fluctuation amount becomes large. If the actual rotational speed is lower than the assumed rotational speed, the amplitude of the actual rotational speed fluctuation amount may be greater than the amplitude of the rotational speed fluctuation amount assumed by the threshold value. Correction is performed so that the fluctuation amount is small. Alternatively, when the actual required torque is larger than the assumed required torque, the rotational torque increases, and accordingly, the amplitude of the actual rotational speed fluctuation amount is larger than the amplitude of the rotational speed fluctuation amount assumed for the threshold value. Therefore, correction is performed so that the correction fluctuation amount is small. If the actual required torque is smaller than the assumed required torque, the rotational torque becomes small, and the amplitude of the actual rotational speed fluctuation amount may be smaller than the amplitude of the rotational speed fluctuation amount assumed by the threshold. Therefore, correction is performed so that the correction fluctuation amount becomes large.

  In step S150, it is determined whether a determination start condition that is a condition for starting misfire determination is satisfied. In the present embodiment, the determination start condition is set to be a state in which the rotation speed does not change significantly. The state in which the rotational speed does not change greatly includes, for example, that the operation amount of the brake pedal is smaller than a predetermined operation amount, the shift position has not changed, or a condition not to inject fuel such as a fuel cut is not established Is applicable. If it is determined that the determination start condition is not satisfied (S150: NO), there is a possibility that fuel is not combusted in the cylinder or the rotational speed may change greatly, and it is accurately determined whether a misfire has occurred in the cylinder. This control is terminated because there is a possibility that it cannot be performed. If it is determined that the determination start condition is satisfied (S150: YES), it is determined that the fuel is combusted in the cylinder and the rotation speed is unlikely to change significantly, and the process proceeds to step S160.

  In step S160, the fluctuation range of the fluctuation amount of the target cylinder is calculated from the corrected fluctuation amount corrected in step S140. In step S170, whether or not the fluctuation range of the fluctuation amount calculated in step S160 is larger than a threshold value. Determine whether.

  If it is determined that the fluctuation range of the calculated fluctuation amount is smaller than the threshold value (S170: NO), it is assumed that the rotational speed has not changed so much and the corresponding cylinder is likely not misfired. The process ends. When it is determined that the calculated fluctuation range of the fluctuation amount is larger than the threshold (S170: YES), it is assumed that the fluctuation amount of the rotational speed has changed greatly and the corresponding cylinder is likely to have misfired. Then, the process proceeds to step S180, where it is determined that misfire has occurred for that cylinder, and this control is terminated.

  Next, the operation of the ECU 32 will be described with reference to FIG.

  FIG. 5A shows fluctuations in rotational speed when one cylinder misfires. In this case, when the rotation speed is obtained based on the crank angle signal detected by the crank angle sensor 33, it is as shown in the uppermost drawing. In this case, the fluctuation amount of the rotational speed includes various noises in addition to the combustion of fuel in the cylinder. For this reason, after the calculated rotation speed is filtered by a band pass filter, the differentiation process is performed. As a result, as shown in the diagram after the filter processing described in FIG. 5A, it is possible to extract the change in the rotational speed caused by the combustion of the fuel in the cylinder.

  However, when performing misfire determination in this state, the amount of fluctuation in rotational speed that occurs in one combustion cycle affects the amount of fluctuation in rotational speed that follows. There is a risk of judging. Actually, in FIG. 5A, the fluctuation amount of the rotational speed when misfire occurs in the specific cylinder affects the fluctuation amount of the rotational speed in the cylinder burned next to the specific cylinder. Since the fluctuation range of the quantity is larger than the threshold value, it is erroneously determined as misfire. In order to suppress this misjudgment, the model with the closest variation in the amount of variation in rotational speed is selected from the stored models, and the actual rotational speed affected by the selected model is estimated. The corrected fluctuation amount is calculated by subtracting the fluctuation amount from the model. As a result, as shown in the diagram after the model subtraction process shown in FIG. 5A, the correction fluctuation amount can eliminate the influence of misfire in the cylinder in which combustion was performed before the own cylinder. However, when the rotational speed or required torque assumed as the threshold value does not match the actual rotational speed or actual required torque, it is possible that normal misfire determination is difficult. Therefore, when the rotational speed or required torque assumed as the threshold value does not match the actual rotational speed or actual required torque, the misfire determination is performed after correcting the calculated correction fluctuation amount. Thereby, it becomes possible to perform misfire determination for each cylinder.

  FIG. 5B shows fluctuations in rotational speed when misfire occurs in two cylinders. In this case as well, the misfire caused by the two cylinders is prevented from affecting the fluctuation of the rotational speed in the cylinder where the combustion is subsequently performed, by performing the same process as above, and the misfire for each cylinder is suppressed. The determination can be performed.

  With the above configuration, the ECU 32 according to the present embodiment has the following effects.

  The change amount variation in one combustion cycle of the engine 11 is stored in advance as a model of the effect on the amount of change after the change amount change. Then, it is determined that misfire has occurred in the engine 11 based on the corrected fluctuation amount obtained by subtracting the stored model from the fluctuation amount of the actual rotational speed. By subtracting the model from the fluctuation amount of the actual rotation speed, the corrected fluctuation amount is the result of the individual cylinders. Accordingly, it is possible to perform misfire determination for each cylinder. As a result, it is possible to suppress erroneous determination that misfire has occurred in other cylinders due to the influence on the fluctuation amount of the rotational speed given when misfire occurs in a certain cylinder.

  -If the change of the fluctuation amount in one combustion cycle is different, the magnitude of the influence on the fluctuation amount after the change of the fluctuation amount is also different. For this reason, a plurality of models assuming the influence of the fluctuation amount on the subsequent fluctuation amount according to the transition in one combustion cycle are stored, and a model close to the fluctuation amount of the actual rotational speed calculated at the time of misfire determination is stored. By selecting, it is possible to reduce an error between the effect actually given to the fluctuation amount and the effect assumed by the model. Then, by calculating the corrected fluctuation amount by subtracting the selected model from the fluctuation amount of the actual rotational speed, it becomes possible to carry out the misfire determination for each cylinder more closely.

  The rotational speed based on the crank angle signal detected by the crank angle sensor 33 is filtered by a band pass filter having a pass band corresponding to the cycle in which fuel combustion occurs in the cylinder, and then subjected to differential calculation processing. As a result, it is possible to remove almost all the factors that change the rotational speed other than the cycle in which the fuel combustion occurs. For this reason, the fluctuation amount of the actual rotation speed can be narrowed down to that caused by the combustion of the fuel, and the misfire determination can be performed more accurately.

  When the actual required torque is larger than the assumed required torque, the correction fluctuation amount is corrected to be small. When the actual required torque is smaller than the assumed required torque, the correction fluctuation amount is corrected to be large. As a result, it is possible to correct the correction fluctuation amount in accordance with the threshold value, and to perform the misfire determination more accurately.

  When the actual rotation speed is higher than the assumed rotation speed, the correction fluctuation amount is corrected so as to increase. Further, when the actual rotation speed is lower than the assumed rotation speed, the correction fluctuation amount is corrected to be small. This also makes it possible to correct the correction fluctuation amount according to the threshold value, and to perform the misfire determination more accurately.

  The above embodiment can also be implemented with the following modifications.

  In the above embodiment, the misfire determination device is applied to a gasoline engine, but it can be applied not only to a gasoline engine but also to, for example, a diesel engine.

  In the above embodiment, the rotational speed based on the crank angle signal detected by the crank angle sensor 33 is filtered through the bandpass filter, and then the differential process is performed. With respect to this, the rotational speed based on the crank angle signal may be subjected to a differential process and then filtered by passing through a band pass filter. Further, only the rotational speed based on the crank angle signal detected by the crank angle sensor 33 is differentiated, and the filtering process by the band pass filter may be omitted.

  In the above embodiment, a plurality of models are stored in the ECU 32. In this regard, one model may be stored. In this case, the model is corrected based on the ratio between the fluctuation range of the fluctuation amount of the actual rotation speed and the fluctuation amount of the rotation speed assumed by the model. This also makes it possible to assume the magnitude of the influence of the actual change in the rotational speed fluctuation amount on the subsequent fluctuation quantity. Then, by calculating the corrected fluctuation amount by subtracting the corrected model, the misfire determination for each cylinder can be performed more closely.

  The ECU 32 stores a plurality of models assumed according to the fluctuation range of the fluctuation amount of the rotation speed. For example, as shown in FIG. 6, a plurality of models in which the fluctuation range of the fluctuation amount of the rotation speed is set according to the rotation speed and the required torque may be stored in the ECU 32. Specifically, the fluctuation range is set smaller as the rotational speed is higher, and the fluctuation range is set larger as the required torque is larger. In this case, a model that is closest to the actually detected actual rotation speed and actual required torque is selected. At this time, when the actually detected rotational speed and required torque are different from the rotational speed and required torque corresponding to the model, it is assumed that the magnitude of the influence on the subsequent fluctuation amount changes. Therefore, by correcting the fluctuation range of the model based on the ratio of the actually detected rotational speed and required torque to the rotational speed and required torque corresponding to the model, the fluctuation of the rotational speed given later can be more accurately determined. It is possible to assume an influence on the quantity.

  -It has been determined whether or not misfiring has occurred in the cylinder by determining whether or not the fluctuation range of the fluctuation amount is larger than a threshold value. With respect to this, whether or not misfiring has occurred in the cylinder may be determined based on whether or not the minimum value of the fluctuation amount of the rotational speed that fluctuates when fuel combustion occurs once is smaller than a threshold value. In this case, since the minimum value is a negative value, the threshold value must also be set to a negative value.

  The correction fluctuation amount was corrected based on the ratio between the actually calculated actual requested torque and actual rotational speed and the assumed required torque and assumed rotational speed assumed by the threshold. In this regard, it is not always necessary to correct the correction fluctuation amount, and for example, the threshold value may be corrected. The threshold value is a misfire determination value set based on the required torque and the rotational speed assumed by the selected model. Therefore, when the actual required torque or the actual rotational speed is different from the assumed required torque or the assumed rotational speed, the amplitude of the fluctuation amount of the rotational speed also changes as described above. Correct the threshold. Specifically, when the actual required torque is larger than the assumed torque, the threshold is corrected so as to increase. When the actual required torque is smaller than the assumed required torque, the threshold is corrected so as to become smaller. Further, when the actual rotation speed is higher than the assumed rotation speed, the threshold value is corrected so as to be reduced, and when the actual rotation speed is lower than the assumed rotation speed, the threshold value is corrected. In this way, by correcting the threshold according to the magnitude of the required torque or rotational speed, it is possible to perform misfire determination in consideration of the influence of the magnitude of the required torque or rotational speed on the amount of fluctuation in rotational speed. Thus, it becomes possible to carry out a more accurate misfire determination.

  In the misfire determination process described in FIG. 3, the determination as to whether or not the determination start condition corresponding to step S150 is satisfied is performed after the subtraction process is performed using a model that corrects the affected rotational speed. In this regard, the timing for performing the determination as to whether or not the determination start condition is satisfied is not limited to after step S140, and may be performed before step S100, for example. Or it is good also as what always performs a misfire determination process, without providing determination start conditions.

  11 ... Engine, 32 ... ECU.

Claims (13)

A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
The variation of transition in one combustion cycle of the internal combustion engine, wherein the impact of variation of transition, the previously stored to that stored as the variation amount of the pulsation model pulsating accordance crank angle of the internal combustion engine in which after Part (32);
Determination for determining that misfire has occurred in the internal combustion engine based on a corrected fluctuation amount obtained by subtracting the pulsation model stored in the storage unit from a transition of the fluctuation amount calculated by the fluctuation amount calculation unit. Part (32);
A misfire determination device for an internal combustion engine, comprising:   The determination unit corrects the model stored in the storage unit based on a transition of the variation amount calculated by the variation amount calculation unit in the one combustion cycle, and calculates the variation amount calculation unit. 2. The misfire determination apparatus for an internal combustion engine according to claim 1, wherein the corrected fluctuation amount is calculated by subtracting the calculated fluctuation amount. The storage unit stores, as the model, a plurality of the influences assumed according to the transition of the fluctuation amount in the one combustion cycle,
The determination unit subtracts the model selected according to the transition of the variation amount calculated by the variation amount calculation unit in the one combustion cycle from the variation amount calculated by the variation amount calculation unit. 2. The misfire determination device for an internal combustion engine according to claim 1, wherein the correction fluctuation amount is calculated. A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
A storage unit (32) for preliminarily storing, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount;
A determination unit (32) that determines that a misfire has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. )When,
With
The storage unit stores, as the model, a plurality of the influences assumed according to the transition of the fluctuation amount in the one combustion cycle,
The determination unit subtracts the model selected according to the transition of the variation amount calculated by the variation amount calculation unit in the one combustion cycle from the variation amount calculated by the variation amount calculation unit. the correction variation misfire identification device of the internal combustion engine you and calculates. A request torque calculation unit (32) for calculating a request torque requested by the driver;
The determination unit determines that misfire has occurred in the internal combustion engine on the condition that the correction variation amount is greater than a threshold value,
The threshold is set according to the magnitude of the required torque,
The determination unit corrects the threshold value to be increased when the request torque calculated by the request torque calculation unit is larger than a predetermined torque, and the request torque calculated by the request torque calculation unit is the predetermined torque. The misfire determination apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the threshold value is corrected so as to be reduced when the torque is smaller than the torque. A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
A storage unit (32) for preliminarily storing, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount;
A determination unit (32) that determines that a misfire has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. )When,
With
A request torque calculation unit (32) for calculating a request torque requested by the driver;
The determination unit determines that misfire has occurred in the internal combustion engine on the condition that the correction variation amount is greater than a threshold value,
The threshold is set according to the magnitude of the required torque,
The determination unit corrects the threshold value to be increased when the request torque calculated by the request torque calculation unit is larger than a predetermined torque, and the request torque calculated by the request torque calculation unit is the predetermined torque. misfire identification device of the internal combustion engine it and correcting to reduce the threshold is smaller than the torque. The determination unit determines that misfire has occurred in the internal combustion engine on the condition that the correction variation amount is greater than a threshold value,
The threshold is set according to the magnitude of the rotation speed,
The determination unit corrects the threshold to be smaller when the rotation speed detected by the rotation speed detection unit is higher than a predetermined rotation speed, and the rotation speed detected by the rotation speed detection unit is The misfire determination device for an internal combustion engine according to any one of claims 1 to 6 , wherein the threshold value is corrected so as to be increased when the rotational speed is lower than a predetermined rotational speed. A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
A storage unit (32) for preliminarily storing, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount;
A determination unit (32) that determines that a misfire has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. )When,
With
The determination unit determines that misfire has occurred in the internal combustion engine on the condition that the correction variation amount is greater than a threshold value,
The threshold is set according to the magnitude of the rotation speed,
The determination unit corrects the threshold to be smaller when the rotation speed detected by the rotation speed detection unit is higher than a predetermined rotation speed, and the rotation speed detected by the rotation speed detection unit is misfire identification device of the internal combustion engine it and correcting so as to increase the threshold is lower than a predetermined rotational speed. A request torque calculation unit for calculating a request torque requested by the driver;
The determination unit corrects the correction fluctuation amount to be small when the request torque calculated by the request torque calculation unit is larger than a predetermined torque, and the request torque calculated by the request torque calculation unit. There wherein when less than the predetermined torque, the correction misfire identification device for an internal combustion engine according to corrected so as to increase variation in any one of claims 1 to 8, characterized. A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
A storage unit (32) for preliminarily storing, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount;
A determination unit (32) that determines that a misfire has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. )When,
With
A request torque calculation unit for calculating a request torque requested by the driver;
The determination unit corrects the correction fluctuation amount to be small when the request torque calculated by the request torque calculation unit is larger than a predetermined torque, and the request torque calculated by the request torque calculation unit. There wherein when less than the predetermined torque, the correction misfire identification device of the internal combustion engine it and corrects variation amount to is increased. The determination unit corrects the correction fluctuation amount to increase when the rotation speed detected by the rotation speed detection unit is higher than a predetermined rotation speed, and the rotation detected by the rotation speed detection unit. The misfire determination of the internal combustion engine according to any one of claims 1 to 6 , 9 , and 10 , wherein when the speed is lower than the predetermined rotational speed, the correction fluctuation amount is corrected to be small. apparatus. A rotational speed detector (33) for detecting the rotational speed of the internal combustion engine (11) having a plurality of cylinders;
A fluctuation amount calculation unit (32) for calculating a fluctuation amount of the rotation speed detected by the rotation speed detection unit;
A storage unit (32) for preliminarily storing, as a model, the influence of the change of the fluctuation amount in one combustion cycle of the internal combustion engine on the fluctuation amount after the change of the fluctuation amount;
A determination unit (32) that determines that a misfire has occurred in the internal combustion engine based on a corrected variation amount obtained by subtracting the model stored in the storage unit from the variation amount calculated by the variation amount calculation unit. )When,
With
The determination unit corrects the correction fluctuation amount to increase when the rotation speed detected by the rotation speed detection unit is higher than a predetermined rotation speed, and the rotation detected by the rotation speed detection unit. speed predetermined when the rotation is lower than the speed, the correction misfire identification device of the internal combustion engine you and correcting to reduce the variation. About a detection period of the rotation speed by the rotation speed detector, a band pass filter having a pass band corresponding to a period in which fuel combustion occurs in the cylinder,
The fluctuation amount calculation unit calculates the fluctuation amount by executing a filtering process and a differential calculation process by the band pass filter with respect to the rotation speed detected by the rotation speed detection unit. The misfire determination device for an internal combustion engine according to any one of claims 1 to 12 .

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