JP4174502B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection amount control device having a function of correcting a fuel injection amount of an internal combustion engine.

  2. Description of the Related Art In recent years, an internal combustion engine control device achieves improved driving feeling, low fuel consumption, low emission, etc. by highly controlling the engine based on information representing the operating state such as the engine speed and intake air amount. A high performance engine is required. Furthermore, in an engine having a plurality of cylinders, combustion variations among cylinders due to differences in thermal efficiency depending on cylinder positions, fuel injection amount variations due to fuel adhering to the injection ports (injector deposits), plates and crank angles In order to avoid these effects and achieve the above requirements, there are variations in the injection timing and ignition timing due to the tolerance of the sensor and cam angle sensor. It is required to control such as.

  In particular, in-cylinder injection engines, the variation in fuel injection amount due to the problem of injector deposits may cause misfire, and improvements are required.

  Conventionally, for an engine having a plurality of cylinders, the control as shown in FIG. 16 in which the fuel injection amount injected into each cylinder is uniformly calculated has been the mainstream. However, such a control has been proposed that calculates the fuel injection amount independently for each cylinder for such an engine. For example, according to Patent Document 1, the following method is proposed in which the difference in combustion state between cylinders and the like is estimated using the rotational angular velocity of the combustion stroke, and the fuel injection amount for each cylinder is controlled.

  In other words, the rotational angular velocities of the crankshaft when the pistons of the plurality of cylinders are at the same predetermined stroke position are sequentially detected independently. Then, the rotational angular velocity for each cylinder is calculated, the difference in the combustion state between the cylinders is detected based on the rotational angular velocity, and the fuel injection amount correction value is independently calculated for each cylinder. Using the calculated correction value, the fuel injection amount is corrected for each cylinder.

  The rotational angular speed of the crankshaft of the engine varies depending on the combustion state of each cylinder and pulsates, but the rotational speed data is independently obtained from the crankshaft rotational angular speed when the piston of each cylinder is at the same stroke position. If detected, the combustion state for each cylinder is known, and correction for each cylinder becomes possible.

  Further, according to what is disclosed in Patent Document 2, the operating state detecting means detects the operating state of the multi-cylinder engine including the rotation angle of the crankshaft of the multi-cylinder engine and the air-fuel ratio of the fuel mixture sucked into the engine. The control amount calculating means calculates the engine control amount so that the air-fuel ratio detected by the operating state detecting means becomes the target air-fuel ratio, and the control means calculates the engine based on the control amount calculated by the control amount calculating means. Is controlled for each cylinder. Further, the abnormal cylinder detecting means detects an abnormal cylinder causing the engine fluctuation, and the air-fuel ratio deviation detecting means is the average value of the air-fuel ratio and the target air-fuel ratio within a predetermined period corresponding to the air-fuel ratio fluctuation cycle. To detect the deviation between. Then, the correction means corrects the control amount used by the control means for the abnormal cylinder so that the deviation is within the predetermined range when the deviation is out of the predetermined range.

  Therefore, the control means can control the abnormal cylinder so that the deviation between the average value of the air-fuel ratio and the target air-fuel ratio falls within a predetermined range. For this reason, the average value within a predetermined period corresponding to the fluctuation period of the air-fuel ratio is the target air-fuel ratio due to mechanical variations in the intake valve opening / closing mechanism for each cylinder and variations in the injection characteristics of the fuel injection valve for each cylinder. It is possible to suppress deviation from the above.

JP 03-15645 JP 2004-346807 A

  However, in the method of detecting the variation in the fuel injection amount between the cylinders in the technology of Patent Document 1, the fuel variation cylinder is specified using the angular acceleration of the explosion stroke. In this method, the relative evaluation for each cylinder is performed. Therefore, it is difficult to accurately specify the fuel variation cylinder and the fuel variation direction, for example, when the fuel variation occurs in a plurality of cylinders.

Here, as an example, in the case of an in-line four-cylinder engine, combustion is performed in the order of # 1 cylinder, # 3 cylinder, # 4 cylinder, and # 2 cylinder. Among these, the angular acceleration of each cylinder when the fuel injection amount variation in which the fuel injection amounts of the # 1 cylinder and the # 4 cylinder decrease is as shown in FIG. On the other hand, the angular acceleration of each cylinder when the fuel injection amount variation in which the fuel injection amounts of the # 2 cylinder and the # 3 cylinder increase is as shown in FIG. As can be seen from these figures, the two are indistinguishable.
In this state, if a cylinder having a large absolute value of angular acceleration is determined as a fuel injection amount variation cylinder and correction is performed, the normal cylinder and the fuel injection amount variation cylinder cannot be distinguished from each other. is there.

  That is, if correction is performed using only the angular acceleration of each cylinder, there is a possibility that a normal cylinder is erroneously determined as an abnormal cylinder and correction is made. Thus, it took time to complete the correction, and during that time, there was a problem that the exhaust gas was also adversely affected and the running feeling deteriorated.

In Patent Document 2, control is performed so that the air-fuel ratio becomes the target air-fuel ratio (O ₂ feedback). Explaining in detail an example of an in-line four-cylinder engine, for example, as shown in FIG. 19A, when a variation occurs in the fuel injection amount in the # 1 cylinder, a deviation occurs between the air-fuel ratio and the target air-fuel ratio. However, if the control is performed so that the average air-fuel ratio becomes the target air-fuel ratio by O ₂ feedback, the fuel amount of all the cylinders is uniformly corrected, and the average air-fuel ratio of all the cylinders is corrected as shown in FIG. It becomes the target air-fuel ratio. In this state, the average air-fuel ratio matches the target air-fuel ratio, but the air-fuel ratio of each cylinder does not become the target air-fuel ratio but varies. When the variation in air-fuel ratio of each cylinder in this state is corrected using the technique of Patent Document 2, there is no difference between the average air-fuel ratio and the target air-fuel ratio, so variation in air-fuel ratio among the cylinders cannot be detected. The fuel injection amount cannot be corrected for each cylinder. For this reason, there are problems such as deterioration of exhaust gas, reduction of fuel consumption, and deterioration of running feeling.

  Further, as shown in FIG. 19C, when the two cylinders have the same amount of air-fuel ratio deviation in the opposite direction, there is no difference between the average air-fuel ratio and the target air-fuel ratio. In the technique of Patent Document 2, as described above, since there is no difference between the average air-fuel ratio and the target air-fuel ratio, variations in the air-fuel ratio among the cylinders cannot be detected, and the fuel injection amount is corrected for each cylinder. I can't. For this reason, there are problems such as deterioration of exhaust gas, reduction of fuel consumption, and deterioration of running feeling.

The present invention has been made in order to solve the above-described problems. Based on the O ₂ feedback value obtained from the angular acceleration of each cylinder and the measured value of the O ₂ sensor, the fuel injection amount variation among the cylinders. An object is to obtain a stable operation state by accurately identifying a cylinder and performing fuel correction to suppress adverse effects on exhaust gas.

The fuel injection amount control device for an internal combustion engine according to the present invention uses the fuel injection amount injected by an injector capable of supplying fuel independently for each cylinder to an internal combustion engine having a plurality of cylinders as the oxygen concentration in the exhaust pipe. An internal combustion engine fuel injection amount control apparatus for performing feedback correction based on the above-mentioned embodiment includes an angular acceleration detecting means for detecting angular acceleration in an explosion stroke section for each cylinder, and the fuel injection amount is corrected to the increase side by the feedback correction. Corrects the fuel injection amount of the cylinder, which is the minimum value of the angular acceleration in the explosion stroke section of each cylinder detected by the angular acceleration detection means, to the fuel increase side, and the fuel injection amount decreases to the decrease side by the feedback correction. When the correction is made, the fuel injection amount of the cylinder that has the maximum value among the angular accelerations in the explosion stroke section of each cylinder detected by the angular acceleration detection means is reduced. It is corrected to the side.

The present invention relates to a fuel injection for an internal combustion engine in which a fuel injection amount injected by an injector capable of independently supplying fuel for each cylinder to an internal combustion engine having a plurality of cylinders is feedback-corrected based on an oxygen concentration in an exhaust pipe. The amount control device includes an angular acceleration detection means for detecting an angular acceleration of an explosion stroke section for each cylinder, and when the fuel injection amount is corrected to the increase side by the feedback correction, the angular control is detected by the angular acceleration detection means. When the fuel injection amount of the cylinder that has the minimum value among the angular accelerations in the explosion stroke section of each cylinder is corrected to the fuel increase side, and the fuel injection amount is corrected to the decrease side by the feedback correction, the angular acceleration since the fuel injection quantity of the cylinder giving the maximum value of the angular acceleration of the expansion stroke section of each cylinder detected by the detecting means for correcting the fuel reduction side, a plurality of cylinders Identify the al optimal correction target cylinder made the proper fuel injection amount correction, the erroneous correction can be suppressed, it is possible to shorten the correction time. Further, the correction can be made even when there is no difference between the air-fuel ratio and the target air-fuel ratio. Therefore, stabilization of engine rotation and improvement of exhaust gas can be obtained early.

Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings.
FIGS. 1 and 2 are block diagrams schematically showing an in-cylinder fuel injection type internal combustion engine according to Embodiment 1 of the present invention. For example, FIG. 1 and FIG. 2 show a case where it is configured by a control device for an internal combustion engine mounted on a vehicle. .

  In FIG. 1, an engine 1 constituting an in-cylinder fuel injection type internal combustion engine has a plurality of cylinders, and high pressure fuel is directly injected into a combustion chamber 2 of each cylinder via a fuel rail 3. It is configured. Here, in order to avoid the complexity of the drawings, a configuration related to only one cylinder is typically shown.

  The crankshaft of the engine 1 is provided with a crank angle sensor 4, and the camshaft is provided with a cam angle sensor 5. The crank angle sensor 4 outputs a pulse signal corresponding to the rotational speed Ne of the engine 1.

  In each combustion chamber 2 for each cylinder, an injector 6 for directly injecting fuel and an ignition plug 7 for generating a spark for burning the fuel are provided. Further, the camshaft for the intake valve (or exhaust valve) of the engine 1 is provided with a pump cam 8 that rotates integrally with the camshaft.

  The fuel pressure control means provided in association with the pump cam 8 comprises a high-pressure fuel pump whose output port communicates with the fuel rail 3, and is driven so that the fuel pressure in the fuel rail 3 coincides with the target fuel pressure. Here, the fuel pressure in the fuel rail 3 is averaged or filtered by an electronic control unit (hereinafter referred to as “ECU”) 9. The fuel rail 3 is provided with a fuel pressure sensor 10 for measuring the fuel pressure in the fuel rail 3.

The exhaust pipe is provided with an O ₂ sensor 11 for detecting the oxygen concentration contained in the exhaust gas. The target air-fuel ratio is set according to various demands such as optimum exhaust gas purification by the catalyst and catalyst protection, and the actual air-fuel ratio is made to coincide with the target air-fuel ratio based on the oxygen concentration detected by the O ₂ sensor 11. O ₂ feedback control (hereinafter referred to as “O ₂ F / B”) is provided. O ₂ F / B is constituted by so-called PID control having proportional, integral, and differential elements, for example, and the ECU 9 executes a calculation that uniformly corrects the fuel injection amounts of all the cylinders.

  The ECU 9 detects the engine rotation speed Ne based on output information from the crank angle sensor 4 and discriminates each cylinder based on output information from the cam angle sensor 5.

  FIG. 2 shows a cylinder in the case of in-line four cylinders and a configuration in which fuel injection is controlled independently for each cylinder. In FIG. 2, the ECU 9 controls the fuel injection amount independently for each cylinder based on the output values of various sensors with respect to the injector 6 attached to each cylinder. At this time, each injector 6 is driven by an injection pulse signal output from the ECU 9. Further, the ECU 9 controls the ignition timing independently for each cylinder with respect to the ignition plug 7 attached to each cylinder. At this time, each spark plug 7 is driven by an ignition signal output from the ECU 9.

  In the present invention, the rotation angle of the crankshaft is detected by the crank angle sensor 4, and the rotation angular acceleration of a predetermined section in the explosion stroke of each cylinder is calculated. The predetermined section may be arbitrarily determined, but it is preferable to include a point at which the rotational speed of the crankshaft becomes the fastest so that variation in explosion of each cylinder can be reliably detected.

  For example, in a 4-cycle engine and a 4-cylinder in-line engine, each stroke of intake, compression, explosion, and exhaust is repeated by rotating the crankshaft twice. As shown in FIG. 3, when considering the engine as a whole, an explosion occurs every time the crankshaft rotates 180 degrees in the order of # 1, # 3, # 4, and # 2 cylinders. For this reason, for example, the angular acceleration every time the crankshaft rotates 180 degrees may be measured and used for the cylinder-specific fuel correction means.

FIG. 4 is a functional configuration diagram of the fuel injection correction apparatus for each cylinder of the internal combustion engine according to the first embodiment of the present invention. The electronic control unit (ECU) 9 includes an angular acceleration calculation unit 14, an O ₂ feedback. The calculation unit 15, the fuel correction cylinder determination unit 16, the fuel injection amount correction amount calculation unit 17 for each cylinder, and the fuel injection PW calculation unit 18 function as a cylinder-by-cylinder fuel injection correction device of the internal combustion engine.

  The angular acceleration calculation unit 14 calculates the angular acceleration for each cylinder based on the inputs of the crank angle sensor 4 and the cam angle sensor 5. Details of the operation of the angular acceleration calculation unit 14 will be described later with reference to FIG.

Based on the oxygen concentration obtained from the O ₂ sensor 11, the O ₂ feedback calculation unit 15 performs O ₂ feedback control by PID control so that the actual air-fuel ratio matches the target air-fuel ratio. Details of the operation of the O ₂ feedback calculation unit 15 will be described later with reference to FIG.

The fuel correction cylinder determination unit 16 updates the fuel injection amount correction amount for each cylinder based on the angular acceleration calculated by the angular acceleration calculation unit 14 and the O ₂ feedback value calculated by the O ₂ feedback calculation unit 15. Determine the cylinder. The cylinder fuel injection amount correction amount calculation unit 17 updates the cylinder fuel injection amount correction amount based on various operating conditions for the cylinder determined by the fuel correction cylinder determination unit 16. Details of the operations of the fuel correction cylinder determination unit 16 and the fuel injection amount correction amount calculation unit 17 for each cylinder will be described later with reference to FIG.

  The fuel injection PW calculation unit 18 calculates a basic fuel injection amount that has been corrected based on the output values of the various sensors 13, and the cylinder-by-cylinder fuel injection amount correction amount calculation unit 17 calculates the basic fuel injection amount. The fuel injection amount for each cylinder corrected by the fuel injection amount correction amount for each cylinder calculated in step (b) is calculated, and the injector drive time (PW) is calculated according to each operating state so as to achieve the fuel injection amount for each cylinder. Each injector 6 for each cylinder is driven independently for each cylinder based on the injector driving time calculated by the fuel injection PW calculating unit 18. Details of the operation of the fuel injection PW calculator 18 will be described later with reference to FIG.

  Next, the processing as the fuel injection correction apparatus for each cylinder of the internal combustion engine in the electronic control unit (ECU) 9 illustrated in FIG. 4 will be described in more detail with reference to FIGS.

  First, the processing operation of the acceleration calculation unit 14 in FIG. 4 will be described in detail with reference to the operation flowchart shown in FIG.

  If the angular acceleration integration number counter n is 0 in step S501, the angular acceleration integration values Sumα1 to Sumα4 and the processing number achievement flag XCYL of each cylinder are reset to initial values in S502. In step S501, Sumα1 is the angular acceleration integrated value of the # 1 cylinder. Similarly, Sumα2 is the angular acceleration integrated value of the # 2 cylinder, Sumα3 is the # 3 cylinder, and Sumα4 is the # 4 cylinder.

  In steps S503 to S505, a cylinder in the explosion stroke is detected.

  Next, in steps S506 to S509, the correction amount update prohibition switches ZSW1 to ZSW4 are checked to see if the fuel injection amount correction amount prohibition condition for each cylinder in the explosion stroke is satisfied. When the correction amount update prohibition switches ZSW1 to ZSW4 are “1” in steps S506 to S509, that is, when the prohibition condition for updating the fuel injection amount correction amount for each cylinder is satisfied, the angular acceleration is calculated and integrated. It progresses to step S518 without performing. By doing so, the priority of fuel correction for each cylinder is lowered for cylinders whose angular acceleration is close to 0 by the fuel correction for each cylinder, the cylinders with larger variations are preferentially corrected, and the fuel variations are quickly suppressed. it can.

  On the other hand, if the correction amount update prohibition switches ZSW1 to ZSW4 are not established in steps S506 to S509, the angular acceleration α (n) of each cylinder in the explosion stroke predetermined section using [Equation 1] in steps S510 to S513. Is calculated. In steps S514 to S517, the angular acceleration integrated values Sumα1 to Sumα4 calculated by [Equation 1] are calculated.

α (n) = 1 / T (n) ・ (1 / T (n) −1 / T (n-1)) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ [Formula 1]
However, T (n) is the time of the predetermined section of the explosion stroke, and T (n-1) is the time of the predetermined section of the explosion stroke of the previous cylinder.

  Next, in step S518, the processing number counter n is incremented, and in step S519, it is determined whether the processing number for one cylinder has reached a predetermined number m. The processing number counter n is divided by 4 because the number of cylinders is four, and the number of processing times for one cylinder is calculated.

  In step S520, the processing count achievement flag XCYL is set. In step S521, the processing number counter n is initialized to 0, and the average angular accelerations Aveα1 to Aveα4 of each cylinder are calculated from the integrated values of the angular accelerations Sumα1 to Sumα4 of each cylinder.

Next, the processing operation of the O ₂ feedback calculation unit 15 in FIG. 4 will be described in detail with reference to the operation flowchart shown in FIG.

First, in step S601, the actual air-fuel ratio AF is calculated from the oxygen concentration detected by the O ₂ sensor. Here, filtering processing may be performed on the calculated actual air-fuel ratio AF.
Next, in step S602, a target air-fuel ratio TAF corresponding to the engine operating state is calculated. Next, in step S603, a deviation EAF of the actual air-fuel ratio AF with respect to the target air-fuel ratio TAF, that is, EAF = TAF-AF is calculated. .

Next, in steps S604 to S608, feedback processing by PID control is performed in order to set the air-fuel ratio deviation EAF to 0, that is, to make the actual air-fuel ratio AF coincide with the target air-fuel ratio TAF. That is, in step S604, the proportional term (P term) O ₂ FBP is calculated by [Expression 2]. In step S605, it is determined whether the air-fuel ratio deviation EAF is 0 or less. If it is 0 or less, the integral term (I term) O ₂ FBI is calculated by [Equation 3] in step S606. On the other hand, if it is not less than 0 in step S605, an integral term (I term) O ₂ FBI is calculated by [Expression 4] in step S607. In step S608, the differential term (D term) O ₂ FBD is calculated by [Equation 5].

O ₂ FBP = GP × EAF ... [Equation 2]
However, GP is a proportional gain.
O ₂ FBI = O ₂ FBI [i−1] + GI (formula 3)
However, GI is an integral gain, and O ₂ FBI [i−1] is the previously calculated O ₂ FBI.
O ₂ FBI = O ₂ FBI [i−1] −GI (formula 4)
O ₂ FBD = GD × (EAF [i] −EAF [i−1]) (Equation 5)
However, GD is the differential gain, EAF [i] is the current EAF, and EAF [i-1] is the previous EAF.

Finally, in step S609, the O ₂ feedback value O ₂ FB is calculated by [Expression 6], and the processing of the O ₂ feedback calculation unit 15 is terminated.

O ₂ FB = O ₂ FBP + O ₂ FBI + O ₂ FBD [Equation 6]

Here, an example of O ₂ feedback by general PID control is shown, and other feedback means may be used in the present invention.

The O ₂ feedback value O ₂ FB calculated by the O ₂ feedback calculation unit 15 of the present invention uniformly corrects the fuel injection amounts of all cylinders. That is, since the average air-fuel ratio of all cylinders is controlled to the target air-fuel ratio, variations in fuel injection amount among cylinders are not taken into consideration. Therefore, if there is a fuel injection amount variation cylinder, a correction is made to compensate for the fuel amount corresponding to the fuel injection amount variation in all cylinders.

For example, when there is a cylinder in which the fuel injection amount decreases, the O ₂ feedback value O ₂ FB takes a value (positive value) that increases the fuel injection amount. Conversely, when there is a cylinder in which the fuel injection amount is increasing, the O ₂ feedback value O ₂ FB takes a value (negative value) that decreases the fuel injection amount.

The present invention pays attention to this and determines the fuel injection amount variation cylinder by the fuel correction cylinder determination unit 16 in FIG. That is, when the O ₂ feedback value O ₂ FB is positive, there is a cylinder in which the fuel injection amount decreases, and it can be said that the angular acceleration of the cylinder is small. The cylinder having the smallest integrated value among the integrated values Sumα1 to Sumα4 of the angular acceleration is determined to be the fuel injection amount variation cylinder. Further, when the O ₂ feedback value O ₂ FB is negative, it can be said that there is a cylinder in which the fuel injection amount is increased and the angular acceleration of the cylinder is increased. Therefore, the integrated values of the angular accelerations Sumα1 to Sumα4 Of these, the cylinder having the largest integrated value is determined to be the fuel injection amount variation cylinder.

  Next, processing operations of the fuel correction cylinder determination unit 16 and the cylinder-by-cylinder fuel injection amount correction amount calculation unit 17 in FIG. 4 will be described in detail with reference to an operation flowchart shown in FIG.

  If the processing number achievement flag XCYL is 0 in step S701, the processing from step S702 to step S725 is not performed. If the processing count achievement flag XCYL is 1, the process proceeds to step S702.

  In step S702, it is determined whether the absolute values of the average angular acceleration values Aveα1 to Aveα4 of each cylinder are equal to or less than a predetermined value. If the average angular acceleration value of all the cylinders is less than or equal to a predetermined value, it means that the variation between the cylinders is small and the engine operating state is stable. That is, there is almost no variation in the fuel injection amount between the cylinders. In this case, the processing from step S703 to step S725 is not performed.

In step S703, the sign of the O ₂ feedback value I term O ₂ FBI calculated in step S606 or step S607 in FIG. 6 described above is determined, and the air-fuel ratio of the cylinder in which the fuel injection amount variation occurs is rich (fuel). Specify whether it is shifted to the excess side) or to the lean side (fuel underside). If the O ₂ feedback value I term O ₂ FBI is “positive” in step S703, it means that the air-fuel ratio of the cylinder in which the fuel injection amount variation occurs is shifted to the lean side, and the fuel amount of the cylinder is reduced. It is necessary to correct to the increase side. On the other hand, if the O ₂ feedback value I term O ₂ FBI is “negative” in step S703, it means that the air-fuel ratio of the cylinder in which the fuel injection amount variation occurs is shifted to the rich side. Must be corrected to the weight loss side.

Here, when the O ₂ feedback value I term O ₂ FBI is “0”, it is possible that the air-fuel ratios of all cylinders coincide with the target air-fuel ratio without correction by O ₂ feedback. Then, there is a high possibility that the variation amount of the cylinders varying on the fuel rich side and the variation amount of the cylinders varying on the fuel lean side coincide. That is, the fuel injection amount variation is offset between the cylinder in which the fuel injection amount is increasing and the cylinder in which the fuel injection amount is decreasing.

In the present invention, in this case, the correction of the fuel injection amount is not prohibited, and the fuel injection amount is corrected to the increase side. This is because it is effective to perform either fuel increase or fuel decrease even when the O ₂ feedback value I term O ₂ FBI is “0” in order to accelerate the decrease in fuel variation between cylinders. . Further, at this time, correcting the fuel injection amount to the decrease side causes a possibility of misfire, so the correction is made on the increase side of the fuel injection amount.

If the O ₂ feedback value I term O ₂ FBI is “positive” or “0” in step S703, the cylinder having the smallest value among the average angular acceleration values Aveα1 to Aveα4 of each cylinder is determined as the corrected cylinder TCYLNO in step S704. select. On the other hand, if the O ₂ feedback value I term O ₂ FBI is “negative” in step S703, the cylinder number that has the largest value among the average angular acceleration values Aveα1 to Aveα4 of each cylinder is set as the corrected cylinder number TCYLNO in step S715. select. When the correction cylinder number TCYLNO = 1, it indicates # 1 cylinder. Similarly, when TCYLNO = 2, # 2 cylinder, when TCYLNO = 3, # 3 cylinder, TCYLNO = 4 Indicates the # 4 cylinder.

  If the increment update count q [TCYLNO] is 0 in step S705, the angular acceleration average value Aveα [TCYLNO] is stored in Aveαold [TCYLNO] in step S706. If TCYLNO = 1, it indicates that the increase update count q [TCYLNO] is the increase update count of the # 1 cylinder. Similarly, those with [TCYLNO] such as Aveα [TCYLNO] and Aveαold [TCYLNO] have variables for each cylinder.

  In step S707, it is determined whether or not the increment update count q [TCYLNO] has reached the predetermined count Addcnt. As a result of the determination in step S707, if the increment update count q [TCYLNO] has not reached the predetermined count Addcnt (if NO), the increment update count q [TCYLNO] is counted up in step S711, and the process proceeds to step S710. move on. As a result of the determination in step S707, if the increased update count q [TCYLNO] has reached the predetermined number Addcnt, the process proceeds to step S708.

  In step S708, the value stored in Aveαold [TCYLNO] is compared with the average angular acceleration value Aveα [TCYLNO]. If the value stored in Aveαold [TCYLNO] is larger or equal, the correction prohibition switch ZSW [TCYLNO] is set in step S709.

  In step S710, q [TCYLNO] is initialized.

If the correction prohibition switch ZSW [TCYLNO] = 0 in step S712, the fuel injection amount correction amount K [TCYLNO] is updated by [Expression 7] in step S713.
K [TCYLNO] = K [TCYLNO] + A ... [Formula 7]
Here, A is a constant that increases the correction value, and can be arbitrarily determined.

  In step S712, if the correction prohibition switch ZSW [TCYLNO] = 0 is not set, K [TCYLNO] = 0 is set and fuel injection amount correction of the corresponding cylinder is prohibited.

If the increment update count q [TCYLNO] is 0 in step S716, the angular acceleration average value Aveα [TCYLNO] is stored in Aveαold [TCYLNO] in step S717.

The increase update count q [TCYLNO] performs countdown processing when processing to reduce fuel is performed. If the increase update count q [TCYLNO] takes a negative value, it means that the initial value is corrected to reduce the fuel.
In step S718, it is determined whether the increased update count q [TCYLNO] is smaller than the predetermined count Subcnt. If larger, the increment update count q [TCYLNO] is counted down in step S722, and the process proceeds to step S721. If the increment update count q [TCYLNO] is smaller than the predetermined count Subcnt in step S718, the process proceeds to step S719. In step S719, the value stored in Aveαold [TCYLNO] is compared with the average angular acceleration value Aveα [TCYLNO]. If the value stored in Aveαold [TCYLNO] is smaller or equal, the correction prohibition switch ZSW [TCYLNO] is set in step S720.

  In step S721, q [TCYLNO] is initialized.

If the correction prohibition switch ZSW [TCYLNO] = 0 in step S723, the fuel injection amount correction amount K [TCYLNO] is updated by [Equation 8] in step S724.
K [TCYLNO] = K [TCYLNO]-B ... [Equation 8]
Here, B is a constant that decreases the correction value, and can be arbitrarily determined.

  In step S723, if the correction prohibition switch ZSW [TCYLNO] = 0 is not set, K [TCYLNO] = 0 is set and fuel injection amount correction of the corresponding cylinder is prohibited.

The fuel injection PW calculation unit 18 in FIG. 4 will be described with reference to FIG.
In step S801, the basic fuel amount FUNSYA is calculated.
In step S802, the basic fuel amount FUNSYA is corrected with the O ₂ F / B correction value O ₂ FB according to [Equation 9] to calculate the fuel injection amount NENRYOa.
NENRYOa = FUNSYA + O ₂ FB …… [Equation 9]

In step S803, the fuel injection amount NENRYOa of each cylinder is corrected by [Expression 10] with various correction KAKUs obtained from the outputs from the various sensors 13.
NENRYOb = NENRYOa x KAKU (various corrections) ... [Formula 10]

In step S804, the fuel injection amount NENRYOb is corrected with the fuel injection amount correction amount K [i] for each cylinder by [Equation 11].
NENRYOc [i] = NENRYOb × K [i] ... [Formula 11]
Here, i is a cylinder number, and I = 1 to 4.

In step S805, the fuel injection amount NENRYOc [i] for each cylinder is converted into a pulse width PW at the time when the injector injects.
In step S806, the pulse width PW is adjusted by the output of the fuel pressure sensor 10 to calculate the fuel injection pulse width for each cylinder.
Based on the calculated fuel injection pulse width, the injector driving time is set, and the injector 6 injects fuel.

  The above is the description of the processing of the fuel injection correction apparatus for each cylinder of the internal combustion engine.

Next, the battery backup process will be described with reference to FIG.
In FIG. 9, engine stop is detected in step S901. If the engine stops, in step S902, the fuel injection correction values K1 to K4 for each cylinder are stored in a battery backup memory that can always be stored by electric power supplied from the battery when the ECU 9 is powered off.

Since the first embodiment is made as described above, the following advantages can be obtained.
Using the angular acceleration and O ₂ F / B value for each cylinder, detect cylinders with variations in fuel injection amount, and determine the fuel injection amount correction amount for each cylinder to correct the variation in fuel injection amount between cylinders. can do.
By determining the fuel injection amount correction amount of the cylinder based on the corrected angular velocity of the cylinder, it is possible to accurately correct the cylinders having variations in the fuel injection amount in accordance with the operating state.
It is possible to prevent excessive increase / decrease in fuel with respect to variations in angular acceleration caused by variations other than fuel injection amount variations.
When all the angular accelerations are within the predetermined value, it is possible to maintain a stable operation state by prohibiting the update of the fuel injection amount correction amount for each cylinder.
Further, by storing the fuel injection amount correction amount for each cylinder in the battery backup memory, it is possible to use the fuel injection amount correction amount for each cylinder during the previous operation at the time of starting.
When the feedback correction value is “0”, it is possible to prevent misfire by starting from the correction that decreases the fuel injection amount correction amount for each cylinder.
In addition, the fuel injection amount variation cylinder and the fuel injection amount variation direction can be identified based on the value of the O ₂ feedback obtained from the angular acceleration of the explosion stroke for each cylinder and the oxygen concentration detected by the O ₂ sensor. Can be suppressed, the correction time can be shortened, and correction is possible even in a state where there is no difference between the air-fuel ratio and the target air-fuel ratio. Therefore, stabilization of engine rotation and improvement of exhaust gas can be obtained early.

  The first embodiment of the present invention has been made as described above. Conceptually, in an internal combustion engine having a plurality of cylinders, a crank angle sensor 4 for detecting the rotation state of the crankshaft, and the rotation state of the camshaft. A cam angle sensor 5 for detecting the angular acceleration, an angular acceleration detecting means 14 for detecting an angular acceleration in an explosion stroke section for each cylinder from the crank angle sensor 4 and the cam angle sensor 5, and fuel for each cylinder independently of the internal combustion engine. The injector 6 that can be supplied in this way, the O2 sensor 11 that measures the oxygen concentration attached to the exhaust pipe, and the amount of fuel injected by the injector 6 based on the oxygen concentration measured by the O2 sensor 11 is fed back. Fuel injection amount control means 17 and 18 for correcting, and a feedback correction value in the fuel injection amount control means and the angular acceleration detection. A cylinder to be corrected is specified based on the angular acceleration of the explosion stroke section of each cylinder detected by the output means, and the fuel injection amount corrected by the fuel injection amount control means is corrected for each cylinder. This is a fuel injection amount control device.

  The first embodiment of the present invention has been made as described above, and more conceptually, the fuel injected by the injector 6 capable of supplying fuel to the internal combustion engine having a plurality of cylinders independently for each cylinder. In a fuel injection amount control device for an internal combustion engine that feedback-corrects an injection amount based on an oxygen concentration in an exhaust pipe, the fuel injection amount control device includes an angular acceleration detection unit that detects an angular acceleration of an explosion stroke section for each cylinder, and the feedback correction value and the A fuel injection amount control device for an internal combustion engine in which a cylinder to be corrected is specified based on the angular acceleration in the explosion stroke section of each cylinder detected by the angular acceleration detection means, and the fuel injection amount is corrected for each cylinder. is there.

  The first embodiment of the present invention has been made as described above, and more conceptually, the fuel injected by the injector 6 capable of supplying fuel to the internal combustion engine having a plurality of cylinders independently for each cylinder. In a fuel injection amount control device for an internal combustion engine that feedback-corrects an injection amount based on an oxygen concentration in an exhaust pipe, the fuel injection amount control device includes an angular acceleration detection unit that detects an angular acceleration of an explosion stroke section for each cylinder, and the feedback correction value and the A fuel injection amount control device for an internal combustion engine in which the fuel injection amount is corrected for each cylinder based on the angular acceleration in the explosion stroke section of each cylinder detected by the angular acceleration detection means.

Embodiment 2. FIG.
As shown in FIG. 10, the second embodiment of the present invention is obtained by adding the processing functions of steps S1001, S1002, S1004, and S1005 to the first embodiment of the present invention (step S1003 in FIG. 10). is there.

  In step S1001, it is determined whether the rotational speed is a predetermined value 1 or more or the load is a predetermined value 2 or more. If the rotational speed is less than the predetermined value 1 or the load is less than the predetermined value 2, the process proceeds to step S1002, and the process of the first embodiment is performed. If the rotational speed is a predetermined value 1 or more or the load is a predetermined value 2 or more, it is determined in step S1003 whether the rotational speed is a predetermined value 3 or more or the load is a predetermined value 4 or more. Here, the predetermined value 3 is a predetermined value 1 or more, and the predetermined value 4 is a predetermined value 2 or more. If the rotational speed is less than the predetermined value 3 or the load is less than the predetermined value 4, the process proceeds to step S1004. In step S1004, each cylinder is corrected using the fuel injection amount correction amount for each cylinder that has been used so far. At this time, since the process of step S1002 is not performed, the fuel injection amount correction amount for each cylinder is not updated. In step S1003, when the rotational speed is equal to or greater than the predetermined value 3 or the load is equal to or greater than the predetermined value 4, correction by the fuel injection amount correction amount for each cylinder is prohibited. At this time, since the process of step S1002 is not performed, the fuel injection amount correction amount for each cylinder is not updated.

  In Embodiment 2 of the present invention, when the rotational speed is equal to or greater than the predetermined value 1 or the load is equal to or greater than the predetermined value 2, it is difficult to cause variations in angular acceleration and the possibility of erroneous correction is high. In addition, by maintaining the fuel injection amount correction amount for each cylinder obtained at a predetermined load or less and enabling it to be used in a region above a predetermined rotation speed or a predetermined load or higher, high rotation that may be erroneously corrected, Correction is possible even at high loads. In addition, in a region where the rotational speed is a predetermined value 1 or a region where the load is further above the predetermined value 2 and the rotational speed is a predetermined value 3 or more, or in a region where the load is a predetermined value 4 or more, the rotational speed is the predetermined rotational speed or less and the predetermined load or less. Using the cylinder-by-cylinder fuel injection amount correction amount obtained in (1) may adversely affect engine operation. By prohibiting the fuel injection amount correction for each cylinder, adverse effects can be suppressed.

Embodiment 3 FIG.
In the third embodiment of the present invention, as shown in FIG. 11, the processing function in step S1102 is added to the first embodiment (step S1101 in FIG. 11). In step S1102, the fuel pressure fuel injection amount correction amount corresponding to the fuel pressure is obtained, and the cylinder fuel injection amount correction amount obtained in the first embodiment is corrected.

  Generally, when the fuel pressure increases, the speed at which the fuel is injected increases, and the load for injecting the fuel increases. Therefore, the variation in the fuel injection amount of the injector changes depending on the fuel pressure. Even in the state where updating of the fuel injection amount correction amount for each cylinder is prohibited at high rotation and high load, by correcting the fuel injection amount correction amount for each cylinder according to the fuel pressure, the variation in the fuel injection amount due to the change of the fuel pressure can be corrected. It can be corrected.

Embodiment 4 FIG.
As shown in FIG. 12, the fourth embodiment of the present invention is obtained by adding the processing function of step S1202 to the first embodiment (step S1201 of FIG. 12). In step S1202, a rotational speed fuel injection amount correction amount corresponding to the rotational speed is obtained, and the cylinder-by-cylinder fuel injection amount correction amount obtained in the first embodiment is corrected.

  As a result, even in a state where updating of the fuel injection amount correction amount for each cylinder is prohibited at high rotation and high load, by correcting the fuel injection amount correction amount for each cylinder according to the rotational speed, The fuel injection amount variation can be corrected.

Embodiment 5 FIG.
In the fifth embodiment of the present invention, as shown in FIG. 13, the processing function in step S1302 is added to the first embodiment (step S1301 in FIG. 13). In step S1302, the load fuel injection amount correction amount corresponding to the load is obtained, and the cylinder fuel injection amount correction amount obtained in the first embodiment is corrected. Thus, even in a state where updating of the fuel injection amount correction amount for each cylinder is prohibited at high rotation and high load, the fuel injection due to the change in load is corrected by correcting the fuel injection amount correction amount for each cylinder according to the load. The amount variation can be corrected.

  The correction values for correcting the fuel injection amount correction amount for each cylinder can also be obtained using the above-described third to fifth embodiments of the present invention as a parameter using the fuel pressure, the rotational speed, and the load as parameters. Moreover, you may obtain | require the correction value which correct | amends the fuel injection amount correction amount for every cylinder by selecting two out of three, fuel pressure, rotational speed, and load.

Embodiment 6 FIG.
As shown in FIG. 14, the sixth embodiment of the present invention is obtained by adding the processing functions of steps S1401 and S1402 to the first embodiment (step S1403 of FIG. 14). When starting is determined in step S1401, the process proceeds to step S1402. In step S1402, updating of the fuel injection amount correction amount for each cylinder and correction of the fuel injection amount for each cylinder are prohibited. Thereby, it is possible to prevent erroneous correction due to correction in an unstable region at the time of starting.

Embodiment 7 FIG.
As shown in FIG. 15, the seventh embodiment of the present invention is obtained by adding the processing functions of steps S1501 and S1502 to the first embodiment (step S1503 of FIG. 15). If start is determined in step S1501, the process proceeds to step S1502. In step S1502, correction is performed using the fuel injection amount correction amount for each cylinder stored in the battery backup memory during the previous operation. At this time, updating of the fuel injection amount correction amount for each cylinder is prohibited. As a result, it is possible to perform correction in a region where the operation state at the start is unstable.

  Note that the present invention is not limited to the in-cylinder spark ignition gasoline engine described in the embodiment of the present invention, and can be applied to various internal combustion engines. For example, the present invention is also applicable to an internal combustion engine that supplies fuel to an intake port.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of this invention, and is a block diagram which illustrates schematically a cylinder fuel injection type internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of this invention, and is a block diagram which illustrates schematically the fuel-injection control apparatus of a cylinder fuel-injection internal combustion engine. It is a figure which shows Embodiment 1 of this invention, and is explanatory drawing which illustrates the relationship between an engine speed and an operation stroke. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of this invention, and is a block block diagram which illustrates the fuel-injection control apparatus of an internal combustion engine. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the operation | movement flow of the angular acceleration calculating part in FIG. A diagram showing a first embodiment of the invention, showing the example of operation flow of O ₂ feedback arithmetic unit in Fig. FIG. 5 is a diagram illustrating the first embodiment of the present invention, and is a diagram illustrating an example of an operation flow of a fuel correction cylinder determination unit and a cylinder-by-cylinder fuel injection amount correction amount calculation unit in FIG. 4. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the operation | movement flow of the fuel-injection PW calculating part in FIG. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of a battery backup process with an operation | movement flow. It is a figure which shows Embodiment 2 of this invention, and is a figure which shows the example of an operation | movement flow. It is a figure which shows Embodiment 3 of this invention, and is a figure which shows the example of an operation | movement flow. It is a figure which shows Embodiment 4 of this invention, and is a figure which shows the example of an operation | movement flow. It is a figure which shows Embodiment 5 of this invention, and is a figure which shows the example of an operation | movement flow. It is a figure which shows Embodiment 6 of this invention, and is a figure which shows the example of an operation | movement flow. It is a figure which shows Embodiment 7 of this invention, and is a figure which shows the example of an operation | movement flow. FIG. 2 is a block diagram showing a general fuel injection control device for an internal combustion engine according to the prior art. It is a figure which shows the angular acceleration of the explosion stroke of each cylinder when fuel injection amount dispersion | variation generate | occur | produces. It is a figure which shows the angular acceleration of the explosion stroke of each cylinder when fuel injection amount dispersion | variation generate | occur | produces. It is a figure which shows the air fuel ratio and target air fuel ratio of each cylinder when fuel injection amount dispersion | variation generate | occur | produces.

Explanation of symbols

1 engine (cylinder fuel injection internal combustion engine),
2 combustion chamber,
3 Accumulation chamber (fuel rail),
4 Crank angle sensor,
5 Cam angle sensor,
6 injectors,
7 Spark plug,
8 Pump cam,
9 ECU,
10 Fuel pressure sensor,
11 O ₂ sensor,
14 Angular acceleration calculation unit (angular acceleration detection means).

Claims (15)

In a fuel injection amount control device for an internal combustion engine that feedback-corrects a fuel injection amount injected by an injector capable of independently supplying fuel for each cylinder to an internal combustion engine having a plurality of cylinders based on an oxygen concentration in an exhaust pipe ,
An angular acceleration detection means for detecting the angular acceleration of the explosion stroke section for each cylinder is provided,
When the fuel injection amount is corrected to the increase side by the feedback correction, the fuel injection amount of the cylinder that becomes the minimum value among the angular accelerations in the explosion stroke section of each cylinder detected by the angular acceleration detection means is increased. To the side,
When the fuel injection amount is corrected to the reduction side by the feedback correction, the fuel injection amount of the cylinder that becomes the maximum value among the angular accelerations in the explosion stroke section of each cylinder detected by the angular acceleration detection means is reduced. A fuel injection amount control apparatus for an internal combustion engine, wherein the fuel injection amount control apparatus corrects the fuel injection amount to the side . The fuel injection amount control apparatus for an internal combustion engine according to claim 1 ,
The fuel injection amount control device for an internal combustion engine, wherein the correction amount corrected for each cylinder is calculated based on the magnitude of the angular acceleration to be corrected. The fuel injection amount control device for an internal combustion engine according to claim 1 or 2 ,
The fuel injection amount control apparatus for an internal combustion engine, wherein the correction amount corrected for each cylinder is corrected so as to increase as the absolute value of the angular acceleration of the corrected cylinder increases. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 3 ,
Load amount detecting means for detecting the load amount of the internal combustion engine;
Rotation speed detection means for detecting the rotation speed of the internal combustion engine;
With
If at least one of the load detected by the load amount detecting means and the rotational speed detected by the rotational speed detecting means is equal to or greater than a predetermined value, updating of the fuel injection amount correction amount for each cylinder is prohibited, and the cylinder before the prohibition is prohibited. A fuel injection amount control device for an internal combustion engine, wherein the fuel injection amount for each cylinder is corrected based on the fuel injection amount correction amount. The fuel injection amount control device for an internal combustion engine according to claim 4 ,
If at least one of the load detected by the load amount detecting means and the rotational speed detected by the rotational speed detecting means is equal to or greater than another predetermined value that is larger than the predetermined value, the fuel injection amount correction amount for each cylinder is increased. A fuel injection amount control apparatus for an internal combustion engine, which prohibits renewal and prohibits correction of fuel injection amount for each cylinder. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 4 ,
Fuel pressure detecting means for detecting the pressure of fuel injected from the injector;
When the fuel pressure detected by the fuel pressure detection means is equal to or higher than a predetermined pressure, a fuel pressure fuel injection amount correction amount based on the fuel pressure is obtained, and the fuel injection amount correction amount for each cylinder is calculated as the fuel pressure fuel injection amount correction amount. A fuel injection amount control apparatus for an internal combustion engine, wherein the fuel injection amount for each cylinder is corrected with the corrected fuel injection amount correction amount for each cylinder. In the fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 4 and claim 6 ,
When the detected rotational speed of the internal combustion engine becomes equal to or higher than a predetermined rotational speed, a rotational speed fuel injection amount correction amount based on the rotational speed is obtained, and the fuel injection amount correction amount for each cylinder is calculated as the rotational speed fuel injection amount correction amount. A fuel injection amount control apparatus for an internal combustion engine, which corrects and corrects the fuel injection amount for each cylinder with the corrected fuel injection amount correction amount for each cylinder. In the fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 4 , claim 6 , and claim 7 ,
When the detected load is equal to or greater than a predetermined load, a load fuel injection amount correction amount based on the load is obtained, and the corrected fuel injection amount correction amount for each cylinder is corrected by the load fuel injection amount correction amount. A fuel injection amount control apparatus for an internal combustion engine, wherein a fuel injection amount for each cylinder is corrected by a fuel injection amount correction amount for each cylinder. In the fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 8 ,
The fuel injection of the internal combustion engine is characterized in that at the start of the internal combustion engine, updating of the fuel injection amount correction amount for each cylinder is prohibited, and the fuel injection amount for each cylinder is corrected by the fuel injection amount correction amount for each cylinder at the previous operation. Quantity control device. In the fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 8 ,
A fuel injection amount control device for an internal combustion engine, which prohibits updating of the fuel injection amount correction amount for each cylinder and prohibits correction of the fuel injection amount for each cylinder when the internal combustion engine is started. In the fuel injection control apparatus for an engine according to any one of claims 1 to 1 0,
It has a battery backup memory that can always store and hold power from the battery.
Fuel injection control apparatus for an engine, characterized in that each cylinder fuel injection amount correction amount before Symbol battery backup memory is retained. The fuel injection amount control device for an internal combustion engine according to any one of claims 1 to 11,
When the correction value is updated to increase the fuel injection amount of the same cylinder more than a predetermined number of times, but the angular acceleration of the cylinder does not increase, the correction of the fuel injection amount correction amount for each cylinder is prohibited. A fuel injection amount control device for an internal combustion engine. In the fuel injection control apparatus for an engine according to any one of claims 1 to 1 2,
When the correction value is updated to reduce the fuel injection amount of the same cylinder more than a predetermined number of times, but the angular acceleration of the cylinder does not decrease, the correction of the fuel injection amount correction amount for each cylinder is prohibited. A fuel injection amount control device for an internal combustion engine. In the fuel injection control apparatus for an engine according to any one of claims 1 to 1 3,
A fuel injection amount control device for an internal combustion engine, which prohibits updating of a fuel injection amount correction amount for each cylinder when angular accelerations of all cylinders are within a certain range. In the fuel injection control apparatus for an engine according to any one of claims 1 to 1 4, when the feedback correction value is "0" which is the feedback correction by the fuel injection quantity control means, of the angular acceleration A fuel injection amount control device for an internal combustion engine, wherein the fuel injection amount correction amount for each cylinder of a small cylinder is updated.

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