JP2015140664A - Fuel injection controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection controller capable of improving the accuracy for calculating an inter-cylinder variation of an injection amount.SOLUTION: A fuel injection controller comprises: an injection-time angular-velocity-difference-variation calculation unit 23 calculating an inter-cylinder variation of an angular velocity difference in a compression stroke or an expansion stroke during fuel injection, and calculating a deviation of this angular velocity difference; a non-injection-time angular-velocity-difference variation calculation unit 24 calculating an inter-cylinder variation of the angular velocity difference during non-injection and calculating a deviation of this angular velocity difference; and a final-injection-amount variation calculation unit 26 calculating an inter-cylinder variation of an injection amount on the basis of the deviation of the angular velocity difference during the injection and the deviation of the angular velocity difference during the non-injection, the injection amount of the injected fuel to each cylinder 2 being corrected on the basis of the injection-amount inter-cylinder variation calculated by the final-injection-amount-variation calculation unit 26.

Description

  The present invention is provided in an engine having a plurality of cylinders and a plurality of fuel injection devices capable of injecting fuel to the respective cylinders, and corrects an injection amount injected from the fuel injection device to each cylinder. It relates to a possible fuel injection control device.

  Conventionally, in a multi-cylinder engine, the injection amount and the combustion state injected from the injector fluctuate between cylinders due to individual differences of injectors, that is, variations in injector machine differences, aging deterioration of the injectors, etc., and the vibration of the engine increases. In order to solve the problem, an injection amount is corrected by calculating an inter-cylinder fluctuation amount of the injection amount.

  For example, Patent Document 1 discloses a device that corrects the injection amount in accordance with the deviation between the rotational speed fluctuation of each cylinder during injection and the average value of these rotational speed fluctuations in all cylinders.

JP 2003-254139 A

  In the apparatus of Patent Document 1, the correction amount of the injection amount is calculated on the assumption that the difference in the rotational speed variation between the cylinders at the time of injection is all due to the variation amount between the cylinders of the injection amount. The difference in rotational speed fluctuation between cylinders at the time of injection includes fluctuations between cylinders due to engine machine difference factors, and this engine machine difference causes an error in the calculation of the injection amount correction amount. is there.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a fuel injection control device capable of calculating the amount of fluctuation of the injection amount between cylinders with higher accuracy.

  In order to solve the above-described problems, the present invention is provided in an engine having a plurality of cylinders and a plurality of fuel injection devices capable of injecting fuel to the respective cylinders. A fuel injection control device capable of correcting an injection amount to be injected based on an angular velocity of a crankshaft, wherein each fuel injection device is in a non-injection state in which fuel injection is stopped. An angular speed difference which is a difference between an angular speed at one crank angle and an angular speed at a specific second crank angle is calculated, and a deviation between the cylinders of the angular speed difference is calculated as an inter-cylinder fluctuation amount of the angular speed difference at the time of no injection. A specific third crank angle of the expansion stroke for each cylinder in a state where the non-injection angular velocity difference variation calculation unit and each of the fuel injection devices inject fuel. An angular velocity difference that is the difference between the angular velocity at the specific fourth crank angle of the expansion stroke and the angular velocity at the expansion stroke is calculated, and the deviation of the angular velocity difference between the cylinders is calculated as the amount of variation between the cylinders in the angular velocity difference at the time of injection The hourly angular velocity difference variation calculation unit, the inter-cylinder variation amount of the angular velocity difference during injection calculated by the injection angular velocity difference variation calculation unit, and the non-injection angular velocity difference variation calculation unit calculated by the non-injection angular velocity difference variation calculation unit A final injection amount fluctuation amount calculation unit that calculates an injection amount inter-cylinder fluctuation amount that is a deviation between cylinders of the injection amount based on an inter-cylinder fluctuation amount of the angular velocity difference at the time, and the final injection amount A fuel injection control device is provided that corrects the injection amount to be injected into each cylinder based on the injection amount variation amount between cylinders calculated by the variation amount calculation unit (Claim 1).

  In this device, based on the fluctuation amount between the cylinders of the angular velocity difference at the time of non-injection caused by causes other than the fluctuation amount between the cylinders of the injection amount and the fluctuation amount between the cylinders of the angular velocity difference at the time of injection. The amount of change in the injection amount between the cylinders is calculated, and the amount of change in the angular velocity difference caused by the amount of change in the injection amount between the cylinders can be accurately extracted. The inter-cylinder fluctuation amount of the injection amount can be calculated with higher accuracy from the inter-cylinder fluctuation amount. Since the injection amount injected into each cylinder is corrected in consideration of the inter-cylinder fluctuation amount of the injection amount calculated with high accuracy in this way, the injection amount actually injected into each cylinder is made more uniform. Rotational fluctuations and vibrations of the engine can be kept small.

  In the present invention, the final injection amount fluctuation amount calculation unit calculates the injection amount inter-cylinder fluctuation amount based on the inter-cylinder fluctuation amount of the angular velocity difference during non-injection when the engine speed is a specific learning speed. When the non-injection angular velocity difference variation calculation unit calculates the inter-cylinder variation amount of the angular velocity difference at an engine speed other than the learning rotational speed, the cylinder of the calculated angular speed difference is calculated. It is preferable to convert the inter-cycle fluctuation amount into the inter-cylinder fluctuation amount of the angular speed difference at the learning rotation speed used in the final injection amount fluctuation amount calculation unit based on the engine speed at the time of calculation and the learning rotation speed ( Claim 2).

  In this way, it is possible to secure a large number of opportunities for calculating the variation amount between the cylinders of the angular velocity difference at the time of non-injection, to increase the calculation frequency of the variation amount, and to convert the value to the value under the same engine speed condition. Because the cylinder-to-cylinder fluctuation amount of the injection amount is calculated based on the cylinder-to-cylinder fluctuation amount of the angular velocity difference during non-injection and the cylinder-to-cylinder variation amount of the angular speed difference during injection, The influence on the inter-cylinder fluctuation amount can be excluded, and the calculation accuracy of the inter-cylinder fluctuation amount of the injection amount can be further increased.

  In the above-described configuration, the non-injection angular velocity difference variation calculation unit calculates a plurality of inter-cylinder variation amounts of the angular velocity difference during non-injection at the learning rotational speed, and then averages the plurality of inter-cylinder variation amounts. Is calculated for each cylinder, and the average value is preferably calculated as an inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection used in the final injection quantity fluctuation amount calculation unit.

  In this way, it is possible to eliminate the influence of the difference in operating conditions other than the presence or absence of injection on the variation amount between cylinders of the angular velocity difference, and it is possible to further improve the calculation accuracy of the variation amount between cylinders of the injection amount.

  In the above-described configuration, the non-injection angular velocity difference variation calculation unit calculates a value exceeding this when the calculated inter-cylinder variation of the angular velocity difference during non-injection at the learning rotational speed exceeds a preset normal range. Is preferably not used for calculating the average value of the inter-cylinder variation.

  In addition, the non-injection angular velocity difference variation calculation unit calculates, for each cylinder, a standard deviation of an inter-cylinder variation in angular velocity difference at the time of non-injection at the calculated plurality of learning rotational speeds. The limit value set based on the standard deviation is compared with the inter-cylinder fluctuation amount of the angular speed difference when there is no injection at each of the learning rotational speeds. When exceeding the limit value, it is preferable not to use the value exceeding the limit value for calculating the average value of the inter-cylinder fluctuation amount (Claim 5).

  In this way, accidental abnormal values can be excluded, so that the calculation accuracy of the inter-cylinder fluctuation amount of the injection amount can be further increased.

  In the present invention, it is preferable that the third crank angle is the same angle as the first crank angle, and the fourth crank angle is the same angle as the second crank angle. 6).

  In this way, the influence other than the presence or absence of the injection of the difference in the crank angle is excluded, and the injection amount of the injection amount is determined based on the inter-cylinder fluctuation amount of the angular velocity difference during injection and the inter-cylinder fluctuation amount of the angular velocity difference during non-injection. Since the inter-cylinder fluctuation amount can be calculated, the calculation accuracy of the inter-cylinder fluctuation amount of the injection amount can be further increased.

  Further, in the present invention, an external input unit capable of inputting an external signal is provided, and the non-injection angular velocity difference variation calculation unit calculates the angular velocity difference when a specific signal is input from the external input unit. It is preferable to start calculation of the inter-cylinder fluctuation amount.

  By doing this, it is possible to calculate the variation amount between the cylinders of the angular velocity difference at the time of non-injection under more preferable conditions, and it is possible to calculate the variation amount and thus the variation amount between the cylinders of the injection amount more accurately.

  In the present invention, the engine is mounted on a vehicle, and the non-injection angular velocity difference variation calculation unit is configured to perform the fuel cut when each fuel injection device stops fuel injection while the vehicle is running. It is preferable to calculate the variation amount between the cylinders of the angular velocity difference.

  In this way, it is possible to secure a large number of opportunities for calculating the variation amount between the cylinders of the angular velocity difference at the time of non-injection, and to calculate the variation amount and thus the variation amount between the cylinders of the injection amount with high accuracy.

  As described above, according to the present invention, it is possible to accurately calculate the inter-cylinder fluctuation amount of the injection amount.

1 is a schematic diagram of an engine system according to an embodiment of the present invention. It is a figure for demonstrating the angular velocity difference variation | change_quantity between cylinders. It is a figure for demonstrating the angular velocity difference variation | change_quantity between cylinders. It is the flowchart which showed the correction | amendment procedure of the injection quantity. It is the figure which showed the average value of the fluctuation amount between cylinders of the angular velocity difference at the time of no injection in the learning rotation speed memorize | stored in a non-volatile memory. It is the flowchart which showed the calculation procedure of the angular velocity difference fluctuation amount at the time of non-injection. It is the flowchart which showed the injection quantity correction | amendment procedure. It is the graph which showed the angular velocity difference variation | change_quantity at the time of the non-injection in several engine speed. It is the graph which showed the angular velocity difference variation | change_quantity at the time of the non-injection after converting into learning rotation speed. It is a figure for demonstrating the calculation procedure of the variation amount between cylinders of an angular velocity difference. It is a figure for demonstrating the calculation procedure of the variation amount between cylinders of an angular velocity difference. It is a figure for demonstrating the correction procedure of the injection quantity.

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

  FIG. 1 is a schematic diagram of an engine system 100 including an engine 1 to which a fuel injection control device of the present invention is applied. Here, a case where the engine 1 is a four-cycle engine and a four-cylinder direct injection engine will be described.

  The engine system 100 is different from at least the engine 1, a plurality of injectors 3 (fuel injection devices), a pressure accumulation rail 4, a fuel pressure sensor 5, a crank angle sensor 6, a cam angle sensor 7, and the engine 1. And a controller 10 that performs control.

  As described above, the engine 1 is a four-cycle four-cylinder direct injection engine and includes four cylinders 2 (a first cylinder 2a, a second cylinder 2b, a third cylinder 2c, and a fourth cylinder 2d). Each cylinder 2 performs four strokes of intake, compression, expansion, and exhaust while a crankshaft (not shown) connecting the cylinders 2 rotates twice. In the present embodiment, each stroke is performed in the order of the first cylinder 2a, the third cylinder 2c, the fourth cylinder 2d, and the second cylinder 2b.

  The injector 3 is attached to each cylinder 2 and directly injects fuel into these cylinders 2. The pressure accumulation rail 4 stores high-pressure fuel sent from a fuel pump (not shown). The high-pressure fuel in the pressure accumulation rail 4 is sent to each injector 3, and each injector 3 injects this high-pressure fuel into the cylinder 2 at a predetermined timing for a predetermined period. The fuel pressure sensor 5 is for detecting the pressure in the pressure accumulation rail 4, that is, the injection pressure of the injector 3, and is attached to the pressure accumulation rail 4.

  The crank angle sensor 6 and the cam angle sensor 7 are for calculating the rotation angle of the crankshaft, that is, the crank angle and the engine speed. A crank angle side pulse rotor 6a that rotates integrally with the crankshaft is fixed to the crankshaft. Notches are formed in the crank angle side pulse rotor 6a at predetermined intervals. The crank angle sensor 6 is provided opposite to the crank angle side pulse rotor 6 a, and outputs a predetermined signal when a notch of the crank angle side pulse rotor 6 a passes through the crank angle sensor 6. In the present embodiment, the crank angle sensor 6 outputs a signal every 6 ° CA. A camshaft side pulse rotor 7b that rotates integrally with the camshaft 7a is fixed to the camshaft 7a that rotates once while the crankshaft rotates twice. The camshaft side pulse rotor 7b is also formed with a notch at a predetermined position. The cam angle sensor 7 is provided so as to face the camshaft side pulse rotor 7b, and detects passage of a notch in the camshaft side pulse rotor 7b.

  The signals of these sensors 6 and 7 are sent to the controller 10, respectively. Based on these signals, the controller 10 rotates the crankshaft 2 rotations as one unit, that is, in the range of 0 to 720 ° CA. And the engine speed is calculated.

  As described above, the controller 10 calculates the crank angle and the engine speed, and performs various controls on the engine 1. In the present embodiment, the controller 10 functions as a fuel injection control device according to the present invention. Specifically, the controller 10 is provided with various control units for controlling the engine 1, and the fuel injection amount control unit 20 as a part thereof functions as the fuel injection control device according to the present invention. . The controller 10 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that includes a RAM and a ROM, for example, and stores a program and data, And an input / output (I / O) bus for inputting and outputting signals.

  In the present embodiment, the controller 10 is configured to be connectable to a manual switch 30 for inputting a predetermined signal to the controller 10 at the time of inspection after vehicle assembly, inspection at a dealer, or the like. An external signal input unit 26 for receiving a signal from the manual switch 30 is provided.

  Further, the vehicle equipped with the engine 1 according to the present embodiment is provided with an accelerator sensor 8 for detecting the opening degree of the accelerator pedal, and the controller 10 detects the accelerator detected by the accelerator sensor 8. The pedal opening is input.

  The fuel injection control unit 20 provided in the controller 10 determines a target injection amount that is an injection amount to be injected into the cylinder 2 by the injector 3 for each injector 3, that is, for each cylinder 2. The fuel injection control unit 20 functionally includes a basic target injection amount calculation unit 21 and an injection amount correction amount calculation unit 22.

  The basic target injection amount calculation unit 21 calculates a basic target injection amount that is a basic value of the injection amount to be injected into the cylinder 2 by the injector 3 based on the operating state. Although a detailed description of the calculation procedure of the basic target injection amount is omitted, in brief, the basic target injection amount calculation unit 21 is based on the engine speed and the accelerator pedal opening detected by the accelerator sensor 8. In addition, the reference target injection amount is calculated from the stored map and the like, and the basic target injection amount is calculated by correcting the reference target injection amount based on the engine water temperature or the like.

  The injection amount correction amount calculation unit 22 calculates the amount of fluctuation of the injection amount actually injected by each injector 3 between the injectors 3, that is, between the cylinders. That is, the injectors 3 may inject different injection amounts with respect to the same command injection amount due to individual differences and the like, and the injection amount correction amount calculation unit 22 determines the difference between the injection amounts among the cylinders. That is, the fluctuation amount of the injection amount between the cylinders is calculated.

  The fuel injection control unit 20 converts the basic target injection amount calculated by the basic target injection amount calculation unit 21 into an injection amount correction amount calculation unit 22 so that the injection amount actually injected into each cylinder 2 becomes uniform. The final injection amount, which is a target value of the final injection amount, is calculated for each injector 3, that is, for each cylinder, by correcting the amount of injection calculated in step 5 between the cylinders.

  As described above, in the engine system 100 according to the present embodiment, the basic target injection amount is corrected by the variation amount of the injection amount between the cylinders, and the variation amount of the actual injection amount between the cylinders is suppressed to be small. Therefore, the combustion state between the cylinders becomes more uniform, and the rotational fluctuation and vibration of the engine 1 can be suppressed to a small level.

  Here, conventionally, in a multi-cylinder engine, a fluctuation amount of the injection amount between cylinders is calculated and the injection amount is corrected by the fluctuation amount. Specifically, the angular velocity difference of the crankshaft during the compression stroke and the expansion stroke (combustion stroke), that is, the rotational fluctuation difference is calculated for each cylinder, and the difference from the average value between the cylinders, that is, the deviation, is calculated as the injection amount. In other words, the amount of injection is changed between cylinders, and the amount of injection is corrected by this amount of change.

  The details of the conventional injection amount correction procedure will be described with reference to FIG. FIG. 2 schematically shows fluctuations in the rotational speed of the crankshaft with the horizontal axis being the crank angle and the compression top dead center of the first cylinder being 0 ° CA. In FIG. 2, the solid line is a waveform of fluctuations in rotational speed when fuel is injected into each cylinder 2 and combustion is performed in each cylinder 2. In FIG. 2, the first cylinder is in the expansion stroke (combustion process) at 0 ° CA to 180 ° CA, the third cylinder is in the expansion stroke at 180 ° CA to 360 ° CA, and 360 ° CA to 540 ° CA. The fourth cylinder is in the expansion stroke, and the second cylinder is in the expansion stroke at 540 ° CA to 720 ° CA. Then, 0 ° CA is the compression top dead center of the first cylinder, 180 ° CA is the compression top dead center of the third cylinder, 360 ° CA is the compression top dead center of the fourth cylinder, and 540 ° CA is the compression top dead center of the second cylinder. Top dead center.

  Conventionally, for each cylinder during fuel injection, first, the time required for the crankshaft to change by a predetermined angle during the expansion stroke is calculated as a substitute characteristic of the angular velocity. At this time, each time near two specific angles during the expansion stroke is calculated. Specifically, a time Tmax_k (k = 1 to 4: k is a cylinder number) required to change a predetermined angle near the compression top dead center where the angular velocity is the slowest, and the angular velocity is the highest after the compression top dead center. A time Tmin_k (k = 1 to 4) required for a predetermined angle change in the vicinity of the earlier angle is calculated for each cylinder. Next, a difference ΔT_k between these times is calculated for each cylinder. Specifically, the time difference ΔT_k is calculated by ΔT_k = Tmax_k−Tmin_k (k = 1 to 4). Then, the time difference ΔT_k (k = 1 to 4) is averaged between the cylinders, and the difference, that is, the deviation, of the time difference ΔT_k of each cylinder from these average values is calculated. The deviation is converted into an injection amount correction amount for each cylinder as a difference in injection amount between the cylinders.

  As described above, in the conventional correction procedure, the difference ΔT_k (k = 1 to 4) of the time (Tmax_k, Tmin_k) required to change by a predetermined angle at two specific angles during the compression stroke and the expansion stroke of each cylinder. Assuming that all the fluctuations between the cylinders are caused by fluctuations in the injection quantity, the injection quantity is corrected so that this time difference is uniform between the cylinders. That is, in the example shown in FIG. 2, the injection amount is corrected so that the waveform shown by the solid line becomes the waveform shown by the wavy line. For ease of explanation, FIG. 2 shows the case where the time Tmax_k at the compression top dead center of each cylinder is the same and the time difference ΔT_k is made uniform by making the time difference ΔT_k uniform. When the time at the top dead center is different among the cylinders, the value of Tmin_k after the correction is also different depending on the difference.

  However, the conventional correction procedure may not sufficiently correct the variation in the injection amount among the cylinders. With regard to this point, as a result of intensive studies, the inventors have found that the difference between the cylinders in the difference in time required to change a predetermined angle at the two specific crank angles, that is, the difference in angular velocity at the two crank angles, This may be caused not only by the cylinder-to-cylinder fluctuation of the injection amount, but also by other fluctuations. In the conventional correction procedure, the angular velocity difference caused by the cause other than the cylinder-to-cylinder fluctuation of the injection quantity is changed between the cylinders. Since the calculation is performed as the variation of the injection amount between the cylinders, it has been found that a large error occurs in the variation of the injection amount between the cylinders. Specifically, as schematically shown in FIG. 3, the fluctuation amount of the angular velocity difference between the cylinders is actually a factor other than A resulting from the fluctuation of the injection amount between the cylinders and the fluctuation of the injection amount between the cylinders. In the conventional correction procedure, since the entire value including A and B is calculated as the inter-cylinder variation amount of the injection amount, there is an error in the inter-cylinder variation amount of the injection amount. Arise.

  Therefore, the present inventors exclude the fluctuation amount B caused by causes other than the fluctuation of the injection amount between the cylinders from the fluctuation amount of the angular velocity difference between the cylinders, and change the injection amount among the fluctuation amounts of the angular velocity difference between the cylinders. By extracting only the resulting variation amount A and calculating the inter-cylinder variation amount of the injection amount based on this variation amount A, the calculation accuracy of the inter-cylinder variation amount of the injection amount and hence the correction accuracy of the injection amount is improved. I made it.

  Further, the present inventors mainly cause variations in the shape of the missing teeth of the crank angle sensor 6, the mounting error of the crank angle sensor 6, the crankshaft as causes other than the injection amount that causes the variation in the angular velocity difference between the cylinders. There is a crank angle detection error due to torsion of the cylinder, and the variation in the angular velocity difference caused by these occurs even when no fuel is injected into the cylinder 2, and the variation B is within the cylinder 2. It was found that this corresponds to the amount of variation between cylinders in the angular velocity difference when no fuel is not injected. Therefore, the present inventors calculate the amount of fluctuation between cylinders of the angular velocity difference at the time of non-injection and set this amount of fluctuation as the amount of fluctuation B. From the amount of fluctuation between the cylinders of the angular velocity difference at the time of injection, the amount of fluctuation B By excluding the above, the inter-cylinder fluctuation amount A of the angular velocity difference due to the injection amount purely between the cylinders is extracted, and the inter-cylinder fluctuation amount of the injection amount is calculated.

  The details of the injection amount correction procedure by the fuel injection control unit 20 will be described next.

  As shown in FIG. 1, the injection amount correction amount calculation unit 22 functionally includes an injection angular velocity difference variation calculation unit 23, a non-injection angular velocity difference variation calculation unit 24, and a final injection amount variation calculation. Part 25.

  As shown in the flowchart of FIG. 4, the fuel injection control unit 20 first reads various signals (step S10). Then, the fuel injection control unit 20 (non-injection angular velocity difference variation calculation unit 24) executes a non-injection angular velocity difference variation calculation process of subroutine S20, and then the fuel injection control unit 20 (injection angular velocity difference variation). The amount calculation unit 23 and the final injection amount fluctuation amount calculation unit 25) execute the injection amount correction processing of the subroutine S40, calculate the amount of fluctuation of the injection amount between cylinders, and correct the injection amount for each cylinder based on the amount of fluctuation. To calculate the final target injection amount for each cylinder.

  As shown in FIG. 6, in step S21 of the subroutine S20, the non-injection angular velocity difference variation calculation unit 24 calculates the non-injection variation amount calculation condition that is a condition for calculating the inter-cylinder variation amount of the angular velocity difference during non-injection. It is determined whether or not is established. In the present embodiment, a predetermined signal is input from the manual switch 30 to the external signal input unit 26 of the controller 10 during traveling of the chassis roller at the time of inspection after vehicle assembly or at the time of inspection by a dealer. When the vehicle is in the predetermined engine speed range and the accelerator is OFF, that is, when no injection is performed in the cylinder 2, it is determined that the condition for calculating the inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection is satisfied. Is done. If this determination is NO, the process is terminated as it is. On the other hand, if this determination is YES, the process proceeds to step S22.

  In step S22, the non-injection angular velocity difference variation calculation unit 24 calculates the angular velocity difference of each cylinder during non-injection. Here, in the present embodiment, as in the example described in the conventional correction procedure, for each cylinder 2 (k = 1 to 4), a predetermined value near the compression top dead center (first crank angle) where the angular velocity is the slowest. Time required for angle change TNemax_k (k = 1 to 4) and time TNemin_k (k = 1 to 4) required for a predetermined angle change in the vicinity of the angle (second crank angle) after the compression top dead center where the angular velocity is the fastest. ) And the time difference DTNE_k corresponding to the angular velocity difference at the time of no injection of each cylinder is calculated.

  Next, in step S23, the non-injection angular velocity difference variation calculation unit 24 calculates the average value of the time differences DTNE_k of the cylinders calculated in step S22, and the difference between the average value and the time difference DTNE_k of each cylinder, that is, The deviation of the time difference DTNE_k between the cylinders is calculated as an inter-cylinder fluctuation amount (angular speed difference deviation) DTNEOF1_k (k = 1 to 4) of the angular velocity difference when there is no injection.

  Here, the amount of change in angular velocity difference during no injection varies depending on the engine speed. Therefore, in order to more accurately calculate the fluctuation amount of the angular velocity difference caused by the fluctuation of the injection amount between the cylinders and hence the fluctuation amount of the injection amount between the cylinders, it is determined in advance to exclude the influence of the difference in the engine speed. An inter-cylinder fluctuation amount of the angular speed difference at the time of non-injection at the learning rotational speed N1 at the most frequent rotational speed during normal traveling is calculated, It is preferable to calculate the inter-cylinder fluctuation amount of the injection amount based on the inter-cylinder fluctuation amount of the angular velocity difference at the time of injection at the learning rotational speed, thereby excluding the influence due to the difference in engine speed. However, if the inter-cylinder fluctuation amount of the angular velocity difference during non-injection is detected and calculated only when the engine speed is the learning rotational speed, the chances of detecting and calculating the inter-cylinder fluctuation amount are reduced.

  On the other hand, the present inventors have found that the amount of variation between cylinders in the angular velocity difference during non-injection changes in proportion to the engine speed. In the present embodiment, based on this knowledge, the fluctuation amount between the cylinders of the angular velocity difference at the time of non-injection is calculated even at a rotational speed other than the learning rotational speed, and the calculation result is converted into a value at the learning rotational speed. Thus, the calculation accuracy of the inter-cylinder fluctuation amount of the injection amount is maintained high while ensuring the opportunity to calculate the inter-cylinder fluctuation amount of the angular velocity difference when there is no injection.

  That is, in the present embodiment, as described above, the engine speed is not specified as the non-injection fluctuation amount calculation condition, and the non-injection angular velocity difference fluctuation amount calculation unit 24 performs the non-injection non-injection time at various engine speeds. The inter-cylinder fluctuation amount DTNEOF1_k of the angular velocity difference is calculated. Then, the inter-cylinder fluctuation amount DTNEOF1_k of the angular speed difference at the various engine speeds is converted into a value DTNEOF2_k at the learning speed N1.

  Specifically, in step S24, the inter-cylinder fluctuation amount DTNEOF2_k of the angular speed difference during non-injection at the learning rotational speed N1 is calculated as the inter-cylinder fluctuation amount DTNEOF1_k of the angular speed difference during non-injection of each cylinder calculated in step S23. Then, using the engine speed Ne when the angular speed difference DTNE_k used to calculate the inter-cylinder fluctuation amount DTNEOF1_k is calculated, a conversion formula DTNEOF2_k = DTNEOF1_k × Ne / N1 is used. When the engine speed at the time of detection is the learning speed, the variation amount between cylinders (angular speed difference deviation) DTNEOF1_k of the non-injection angular speed difference calculated in step S23 remains unchanged at the learning speed. The variation amount between cylinders of the angular velocity difference at the time of injection is defined as DTNEOF2_k.

  The broken lines in FIGS. 8 and 9 indicate the inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection before and after the conversion to the value at the learning rotational speed. FIG. 8 shows the inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection before conversion (time difference deviation at the time of no injection) DTNEOF1_k, and FIG. 9 shows the value after conversion to the value at the learning rotational speed. A variation amount between cylinders of an angular velocity difference at the time of injection (deviation of a time difference at the time of non-injection) DTNEOF2_k is shown. The plurality of lines in FIGS. 8 and 9 are values when the engine speeds are different from each other. As is apparent from the comparison of these figures, the amount of fluctuation between cylinders of the angular velocity difference at the time of non-injection calculated at various engine speeds is converted to a value close to each other by the conversion using the conversion formula.

  In step S25, which proceeds after step S24, the non-injection angular velocity difference variation calculation unit 24 calculates a normal range in which the inter-cylinder variation amount DTNEOF2_k of the angular velocity difference in non-injection at the learning rotation speed calculated in step S24 is set in advance. Determine if it is within. For example, the normal range is set as a guard value that is theoretically impossible even when the machine difference of the crank angle sensor 6 is considered. When the determination in step S25 is YES and the inter-cylinder variation amount DTNEOF2_k of the angular velocity difference at the time of no injection at the learning rotational speed is in the normal range, the process proceeds to step S26.

  In step S26, the non-injection angular velocity difference fluctuation amount calculation unit 24 stores the inter-cylinder fluctuation amount DTNEOF2_k of the angular velocity difference in the non-injection angular velocity at the learning rotational speed calculated in step S24 in a temporary memory (S-RAM) for each cylinder. Remember.

  On the other hand, if the determination in step S26 is NO, and the inter-cylinder fluctuation amount DTNEOF2_k of the angular speed difference during non-injection at the learning rotational speed calculated in step S24 is outside the normal range, the calculated value of DTNEOF2_k is abnormal. Assuming that the value is a value, the process returns to S21 without storing this value in the temporary memory.

  In step S27, which proceeds after step 26, the non-injection angular velocity difference variation calculation unit 24 calculates the number of samples of each cylinder stored in the temporary memory (the inter-cylinder variation amount DTNEOF2_k of the angular velocity difference during non-injection at the learning rotational speed). It is determined whether or not (number) has reached a preset number N. If this determination is NO and the number of stored samples of each cylinder is N or less, the process returns to step S21. On the other hand, if the determination in step S27 is YES and the number of stored samples is N, the non-injection angular velocity difference variation calculation unit 24 proceeds to step S28, and for each of these N DTNEOF2_k for each cylinder. The standard deviation σ of each is calculated.

  In step S29, which proceeds after step S28, the non-injection angular velocity difference variation calculation unit 24 calculates the angular velocity at non-injection at the N learning rotation speeds of each cylinder calculated in step S24 and stored in the temporary memory in step S26. It is determined whether the inter-cylinder fluctuation amount DTNEOF2_k of the difference does not exceed the limit value calculated based on the standard deviation σ for the same cylinder calculated in step S28. This limit value is calculated to a value that is a predetermined multiple of the standard deviation σ, for example. When this determination is YES and the inter-cylinder fluctuation amount DTNEOF2_k of the angular velocity difference at the time of no injection at the learning rotational speed does not exceed the limit value, the process proceeds to step S32. In step S32, the non-injection angular velocity difference variation calculation unit 24 calculates the non-injection angular velocity difference inter-cylinder variation DTNEOF2_k of the non-injection angular velocity at a plurality of learning rotational speeds determined not to exceed the limit value for each cylinder. The average value DTNEOFave_k is calculated. On the other hand, when the determination in step S29 is NO and the inter-cylinder fluctuation amount DTNEOF2_k of the angular speed difference during non-injection at the learning rotational speed exceeds the limit value, the non-injection angular speed difference fluctuation calculating unit 24 A value exceeding this limit value is not used in the average value calculation in step S32 (step S31). In step S32, an average value other than the value exceeding this limit value is used as the learning rotational speed of each cylinder. It is calculated as an average value DTNEOFave1_k of the inter-cylinder fluctuation amount DTNEOF2_k of the angular velocity difference at the time of no injection.

  After step S32, the process proceeds to step S33, and the non-injection angular velocity difference variation calculation unit 24 calculates the average value of the inter-cylinder variation DTNEOF2_k of the angular velocity difference during non-injection at the learning rotational speed of each cylinder calculated in step S32. DTNEOFave1_k is stored in the nonvolatile memory (EEP-ROM), and the subroutine S20 is terminated. In this manner, as shown in FIG. 5, the average value DTNEOFave1_k of the cylinder-to-cylinder variation amount of the angular velocity difference at the time of no injection at the learning rotational speed is stored in the nonvolatile memory for each cylinder.

  In the subroutine S40 executed after the subroutine S20, first, in step S41, the basic target injection amount calculation unit 21 calculates the basic target injection amount according to the operating state as described above. In step S42, which proceeds after step S41, the injection angular velocity difference variation calculation unit 23 calculates the angular velocity difference DTNEinj_k during injection for each cylinder in the same procedure as the angular velocity difference calculation procedure during non-injection. At this time, the injection angular velocity difference DTNEinj_k is calculated for each cylinder at the same angle as that used in step S22. That is, in step S42, for each cylinder 2 (k = 1 to 4), a time TNEinjmax_k (k = k) required for a predetermined angle change near the compression top dead center (third crank angle = first crank angle) at which the angular velocity is the slowest. 1-4) and a time TNEinjmin_k (k = 1 to 4) required for a predetermined angle change in the vicinity of the angle at which the angular velocity is the fastest after the compression top dead center (fourth crank angle = second crank angle). At the same time, taking these differences, a time difference DTNEinj_k corresponding to the angular velocity difference at the time of injection of each cylinder is calculated.

  Next, in step S43, the injection angular velocity difference variation calculation unit 23 calculates the average value of the inter-cylinder variation of the angular velocity difference during non-injection at the learning rotational speed of each cylinder stored in the nonvolatile memory (non-injection). Read hourly angular velocity average deviation) DTNEOFave1_k (k = 1 to 4 (cylinder)).

  After step S43, the non-injection angular velocity difference variation calculation unit 24 calculates, in step S44, the average value DTNEOFave1_k of the inter-cylinder variation of the angular velocity difference during non-injection at the learning rotational speed read in step S44 by the following conversion formula. In step S42, the angular speed difference during injection DTNEinj_k is converted to a value at the engine speed (rotation speed during injection) Ne. Specifically, a value DTNEOFave_k of the variation amount between cylinders of the angular velocity difference at the time of no injection at the engine speed Ne is calculated as DTNEOFave_k = DTNEOFave1_k × Ne / N1.

  After step S44, the final injection amount fluctuation amount calculation unit 25 obtains the angular speed difference DTNEinj_k at the time of injection obtained at step S42 at step S45, and the angular speed difference at the time of no injection at the engine speed Ne obtained at step S44. Is corrected by the value DTNEOFave_k of the inter-cylinder fluctuation amount (DTNEOFave_k is added to or subtracted from DTNEinj_k). As a result, the final injection amount fluctuation amount calculation unit 25 eliminates the angular velocity difference fluctuation amount caused by factors other than the injection amount, such as the engine difference, included in the injection angular velocity difference DTNEinj_k, so that only the inter-cylinder fluctuation amount of the injection amount is obtained. A variation amount between cylinders based on the angular velocity difference is calculated.

  In step S46, which proceeds after step S45, the final injection amount fluctuation amount calculation unit 25 calculates the average value (inter-cylinder average value) DTNEinjave of all cylinders of the angular velocity difference DTNEinj_k at the time of injection corrected for each cylinder in step S45. DTNEinjave = (DTNEinj_1 + DTNEinj_2 +... + DTNEinj_4) / 4.

  Next, in step S47, the final injection amount fluctuation amount calculation unit 25 determines the amount of deviation of the angular velocity difference of each cylinder from the average value DTNEinjave of the angular velocity difference during injection obtained in step S46, that is, between the cylinders of the angular velocity difference. Find the amount of variation.

  Then, in step S48, the final injection amount fluctuation amount calculation unit 25 calculates the angular velocity difference calculated in step S47 so that the angular velocity difference fluctuation amount of each cylinder matches the average value of all the angular velocity difference fluctuation amounts. An injection amount correction amount for each cylinder is calculated in accordance with the inter-cylinder fluctuation amount (each deviation amount).

  Thereafter, the fuel injection control unit 20 corrects the basic target injection amount obtained in step S41 with the injection amount correction amount of each cylinder calculated in step S47 (adds or subtracts the injection amount correction amount to the basic target injection amount), and The final injection amount is calculated for the cylinder.

  Here, the steps S42 to S49 will be further described with reference to FIG. 10, FIG. 11, and FIG.

  The broken line in FIG. 10 is the injection angular velocity difference DTNEinj_k calculated in step S42. The angular velocity difference DTNEinj_k at the time of injection of each cylinder is detected including variations due to crankshaft torsion and crank angle sensor mounting errors. On the other hand, the average value DTNEOFave1_k of the cylinder-to-cylinder fluctuation amount of the angular velocity difference at the time of non-injection read from the nonvolatile memory in step S43, which is indicated by the bar graph of FIG. 8 and the shaded portion of FIG. This is due to variations due to the installation error of the crank angle sensor. In the examples shown in these drawings, the average value DTNEOFave1_k of the variation amount between the cylinders in the angular velocity difference at the time of non-injection in the second and third cylinders is a value on the plus side (the direction in which the angular velocity variation increases) from the average value of all the cylinders. In the first and fourth cylinders, the average value DTNEOFave1_k is a negative value (the direction in which the angular velocity fluctuation is reduced).

  For this reason, in step S45, by performing an offset correction for adding / subtracting the average value DTNEOFave1_k of the inter-cylinder fluctuation amount of the angular velocity difference at the time of non-injection read from the nonvolatile memory, the cause of the angular velocity difference due to the engine machine difference or the like is obtained. Excluded, the inter-cylinder fluctuation amount of the angular velocity difference caused by the inter-cylinder fluctuation amount of the injection amount is calculated. In the example shown in FIG. 10, for the first cylinder, offset correction is performed by subtracting the average value DTNEOFave_1 of the cylinder-to-cylinder fluctuation amount of the angular velocity difference at the time of non-injection from the angular velocity difference DTNEinj_1 at the time of injection as shown by the downward arrow in the drawing. Thus, the corrected angular velocity difference at injection DTNEinj_1 indicated by the bold line is calculated. Similarly, offset correction is also performed for the other cylinders, and corrected angular velocity differences DTNEinj_2, DTNEinj_3, and DTNEinj_4 after correction indicated by bold lines are calculated.

  The post-correction angular velocity difference DTNEinj_k after injection, which is calculated by the thick line in FIG. 10, is only due to variations in the injection amount due to injector variations and the like, in which factors of angular velocity differences due to engine machine differences and the like are eliminated. Therefore, in the present embodiment, as described above, the average value DTNEinjave (horizontal solid line in FIG. 10) of all the cylinders of the injection angular velocity difference DTNEinj_k after correction in steps S46 and S47 is obtained, and this average value DTNEinjave and the correction of each cylinder are obtained. The difference in angular velocity difference DTNEinj_k after injection, that is, a deviation amount is obtained, and in step S48, an injection amount correction amount is calculated according to this deviation amount so that the angular velocity difference of each cylinder matches the average value. In the example shown in FIG. 10, the difference between the average value DTNEinjave and the corrected angular velocity difference at injection DTNEinj_k, that is, the deviation amount is calculated as shown in FIG. The injection amount correction amount is calculated as indicated by the shaded portion in FIG. Then, the corrected injection amount in the shaded portion is adjusted with respect to the target basic injection amount (before correction in the drawing) indicated by the broken line in FIG. 12, and the final injection amount is calculated as indicated by the thick line in FIG. . Specifically, in the example shown in FIGS. 10 to 12, as shown in FIG. 10, the true angular velocity difference at the time of injection is smaller than the average value of all the cylinders in the first and fourth cylinders. As shown in FIG. 12, the injection amount is increased and corrected so as to match the average value with a positive correction. On the other hand, in the second and third cylinders, the true angular velocity difference at the time of injection is larger than the average value of all the cylinders. Therefore, the negative side correction as shown in FIG. In this way, the injection amount is corrected to decrease.

  In the embodiment, in order to facilitate the calculation, various calculations are performed using a time during which the crank angle changes by a predetermined angle instead of the angular speed. However, the angular speed may be used. For example, instead of the time required for the change between the predetermined crank angles near the compression top dead center, a crank angle that changes during the predetermined time near the compression top dead center is used, and the predetermined angular velocity becomes the fastest after the compression top dead center. Instead of the time required for the change between the crank angles, a crank angle that changes during a predetermined time of the crank angle at which the angular velocity becomes fastest after compression top dead center may be used.

  Also, only when the injection pressure detected by the fuel pressure sensor 5 becomes a specific injection pressure, the angular velocity difference during injection may be detected, and the angular velocity difference during non-injection may be added or subtracted from the angular velocity difference during injection.

  Further, in the above embodiment, the engine is rotated when a predetermined signal is input to the controller 10 from the outside at the time of inspection after assembling the vehicle, during running of the chassis roller, or at the time of inspection by a dealer, etc. In the case where the amount of change in the angular velocity difference at the time of non-injection is calculated when injection is not performed in the cylinder 2, the accelerator pedal is not depressed during normal vehicle travel, In addition, when no injection is performed in the cylinder 2, it may be determined that the non-injection fluctuation amount calculation condition is satisfied, and the fluctuation amount of the angular velocity difference at the time of no injection may be calculated.

  Moreover, the setting reference | standard of learning rotation speed is not restricted above.

  As described above, in the engine system 100 according to the present embodiment, the fluctuation amount between the cylinders of the angular velocity difference at the time of injection is excluded from the fluctuation amount between the cylinders of the angular velocity difference at the time of non-injection, thereby changing the injection amount between the cylinders. Only the fluctuation amount between cylinders of the angular velocity difference caused by the amount is extracted, the fluctuation amount between cylinders of the injection amount is calculated from this fluctuation amount, and the fluctuation amount between cylinders of the injection amount can be accurately calculated, It is possible to correct the injection amount with high accuracy and suppress vibrations and the like accompanying the injection amount fluctuation amount.

  In particular, in this embodiment, the angular velocity difference with respect to the same crank angle is calculated during non-injection and during injection, and the inter-cylinder variation amount of the angular velocity difference caused by the inter-cylinder variation amount of the injection amount is accurately calculated. be able to.

  In addition, the amount of change in the angle difference at the time of non-injection is also calculated at an engine speed other than the learning speed, and the calculated value is converted to a value at the learning speed, An opportunity to calculate the angular velocity difference variation amount can be secured, and the calculation accuracy of the angular velocity difference variation amount at the time of no injection can be increased.

  Further, a plurality of angular velocity difference fluctuation amounts at the time of non-injection are detected and calculated, these are converted into values at the learning rotational speed, and then averaged, and the angular speed difference fluctuation amount at the time of non-injection at the average learning rotational speed is used. Since the variation amount of the injection amount between the cylinders and hence the correction amount of the injection amount is calculated, the correction amount of the injection amount can be calculated with high accuracy. In particular, of the angular velocity difference fluctuation amount at the time of no injection, only the value that does not exceed the limit value set based on the standard deviation and the value within the preset normal range are averaged, and this average value is calculated as the injection amount. Since the inter-cylinder variation amount and thus the injection amount correction amount are calculated, the injection amount correction amount can be calculated more accurately.

1 engine 2 cylinder 3 injector (fuel injection device)
10 controller 20 fuel injection control unit (fuel injection control device)

Claims (8)

Provided in an engine having a plurality of cylinders and a plurality of fuel injection devices capable of injecting fuel to the respective cylinders, the amount of injection injected from each of the fuel injection devices into each of the cylinders is determined according to the angular velocity of the crankshaft. A fuel injection control device that can be corrected based on:
In the non-injection state where each fuel injection device stops fuel injection, for each cylinder, an angular velocity difference that is a difference between an angular velocity at a specific first crank angle and an angular velocity at a specific second crank angle is calculated. A non-injection angular velocity difference variation calculating unit that calculates the difference between the angular velocity differences between the cylinders as a non-injection angular velocity difference variation between the cylinders;
In a state where each fuel injection device is injecting fuel, an angular velocity difference that is a difference between an angular velocity at a specific third crank angle of the expansion stroke and an angular velocity at a specific fourth crank angle of the expansion stroke is set for each cylinder. An angular velocity difference variation calculation unit for injection that calculates a difference between the cylinders of the angular velocity difference as a variation amount between cylinders of the angular velocity difference at the time of injection,
The inter-cylinder fluctuation amount of the angular velocity difference during injection calculated by the injection angular velocity difference fluctuation amount calculation unit and the inter-cylinder fluctuation amount of the angular velocity difference during non-injection calculated by the non-injection angular velocity difference fluctuation calculation unit. And a final injection amount fluctuation amount calculation unit that calculates an injection amount fluctuation amount between cylinders, which is a deviation between the cylinders of the injection amount,
A fuel injection control device that corrects the injection amount injected into each cylinder based on the injection amount variation amount between cylinders calculated by the final injection amount variation amount calculation unit. The fuel injection control device according to claim 1,
The final injection amount fluctuation amount calculation unit calculates the injection amount inter-cylinder fluctuation amount based on the inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection when the engine speed is a specific learning rotation speed,
When the non-injection angular velocity difference fluctuation amount calculation unit calculates the inter-cylinder fluctuation amount of the angular speed difference at an engine speed other than the learning rotational speed, the calculated inter-cylinder fluctuation amount of the angular speed difference is calculated. Is converted into an inter-cylinder fluctuation amount of the angular speed difference at the learning rotation speed used in the final injection amount fluctuation amount calculation unit based on the engine speed at the time of calculation and the learning rotation speed. Control device. The fuel injection control device according to claim 2,
The non-injection angular velocity difference variation calculating unit calculates a plurality of inter-cylinder variation amounts of the angular velocity difference during non-injection at the learning rotational speed, and then calculates an average value of the plurality of inter-cylinder variation amounts for each cylinder. The fuel injection control device is characterized in that the average value is calculated as an inter-cylinder fluctuation amount of the angular velocity difference at the time of no injection used in the final injection quantity fluctuation amount calculation unit. The fuel injection control device according to claim 3, wherein
The non-injection angular velocity difference variation calculation unit calculates a value between the cylinders when the inter-cylinder variation of the angular velocity difference during non-injection at the calculated learning rotational speed exceeds a preset normal range. A fuel injection control device that is not used for calculating an average value of fluctuation amounts. The fuel injection control device according to claim 3 or 4,
The non-injection angular velocity difference fluctuation amount calculation unit calculates, for each cylinder, a standard deviation of an inter-cylinder fluctuation amount of an angular velocity difference at the time of no injection at the calculated plurality of learning rotation speeds, and for each cylinder, the standard deviation Is compared with the fluctuation amount between cylinders of the angular velocity difference during non-injection at each learning rotational speed, and the variation amount between cylinders of the angular speed difference during non-injection at the learning rotational speed is compared with the limit. When the value exceeds the value, the value exceeding the value is not used for calculating the average value of the inter-cylinder variation. In the fuel-injection control apparatus in any one of Claims 1-5,
The fuel injection control device, wherein the third crank angle is the same angle as the first crank angle, and the fourth crank angle is the same angle as the second crank angle. In the fuel-injection control apparatus in any one of Claims 1-6,
It has an external input unit that can input external signals,
The fuel injection control device, wherein the non-injection angular velocity difference variation calculation unit starts calculation of the variation amount between cylinders of the angular velocity difference when a specific signal is input from the external input unit. In the fuel-injection control apparatus in any one of Claims 1-7,
The engine is mounted on a vehicle;
The non-injection angular velocity difference variation calculation unit calculates an inter-cylinder variation amount of the angular velocity difference when the fuel injection is stopped when each fuel injection device stops fuel injection while the vehicle is running. Injection control device.

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