JP2012117428A - Fuel injection control device - Google Patents

Abstract

A fuel injection control apparatus that can cope with a change in characteristics of a fuel injection valve, has no drift, and can be effectively corrected even with multi-injection.
A heat generation rate is calculated based on an in-cylinder pressure data string, and a heat generation amount by pilot injection is calculated by integration, a target heat generation amount by pilot injection is set, and heat generation in each cylinder is performed. The fuel injection amount of pilot injection in each cylinder is corrected so that the difference between the amount and the target heat generation amount is small, the indicated mean effective pressure is calculated based on the in-cylinder pressure data sequence, and averaged for all cylinders. Then, the indicated mean effective pressure average value is calculated, and the fuel injection amount of the main injection in each cylinder is corrected so that the difference between the indicated mean effective pressure in each cylinder and the indicated mean effective pressure average value of all the cylinders is reduced.
[Selection] Figure 1

Description

  The present invention relates to a fuel injection control apparatus that can cope with a change in characteristics of a fuel injection valve, has no drift, and can effectively correct even multi-injection.

  The engine has a plurality of cylinders, and a fuel injection valve is provided in each cylinder. The fuel injection amount of one injection in each cylinder depends on the driving time width of the fuel injection valve. The target fuel injection amount is obtained from a map that is referred to in the engine state, and the drive time width to be given to the fuel injection valve is determined accordingly. However, since the fuel injection valve has a mechanical tolerance (for example, an injection hole area tolerance), even if the fuel injection valve of each cylinder is driven with the same driving time width, the fuel injection amount varies from cylinder to cylinder. As a result, the combustion state for each cylinder varies.

  On the other hand, before the vehicle is shipped, the fuel injection amount characteristics (= characteristics of the fuel injection valve) for each cylinder are checked and set in a map, and the driving time width for each cylinder is determined with reference to the map. Thus, the variation in the fuel injection amount is corrected.

JP 2005226663 A JP 2005-194893 A

  However, the characteristics of the fuel injection valve may change due to heat or aging, and accuracy cannot be obtained by correction based on a map set at the time of vehicle shipment.

  Further, as a method of eliminating the variation in the fuel injection amount between the cylinders, it is conceivable to correct each cylinder so that the fuel injection amount in each cylinder converges to the average value of all the cylinders. However, since the average value of all the cylinders does not necessarily coincide with the target fuel injection amount, if the control for converging to the average value is continued, drift (the whole shifts from the target) occurs.

  As a form of fuel injection, multi-injection is known in which a target injection amount is divided into a plurality of times and injected within one combustion cycle. For example, pilot injection is performed prior to main injection for the purpose of slowing combustion and suppressing NOx emissions and noise. However, the smaller the injection amount at one time, the greater the influence of mechanical variations of the fuel injection valves. When a very small injection amount is injected like pilot injection, the variation is very large. For this reason, in multi-injection, it is difficult to effectively correct the variation in the fuel injection amount for each cylinder.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection control device that solves the above-described problems, can cope with changes in the characteristics of the fuel injection valve, has no drift, and can effectively correct even multiple injections.

  In order to achieve the above-mentioned object, the present invention is to sample the cylinder pressure detected by the cylinder pressure sensor in each of a plurality of cylinders at a constant crank angle interval based on a signal detected by the crank angle sensor. A sampling unit that stores an internal pressure data string, a heat generation rate calculation unit that calculates a heat generation rate in each cylinder based on the in-cylinder pressure data sequence for each predetermined crank angle, and each by integrating the heat generation rate A heat generation amount calculation unit that calculates the heat generation amount by pilot injection in the cylinder, a target heat generation amount setting unit that sets a target heat generation amount that is a target value of the heat generation amount by pilot injection, and a heat generation amount in each cylinder A pilot injection amount correction unit for correcting the fuel injection amount of the pilot injection of each cylinder so that the difference between the target pressure and the target heat generation amount is small, and the in-cylinder pressure data string An illustrated average effective pressure calculating unit that calculates an indicated average effective pressure in each cylinder, an indicated average effective pressure average value calculating unit that averages the indicated average effective pressure in all cylinders, and calculates an indicated average effective pressure average value, And a main injection amount correction unit that corrects the fuel injection amount of the main injection in each cylinder so that the difference between the indicated average effective pressure in each cylinder and the indicated average effective pressure average value in all cylinders is reduced. .

  The target indicated mean effective pressure map in which the relationship between the target indicated fuel injection amount and the indicated indicated effective effective pressure corresponding to the target indicated fuel injection amount is set, and the calculated indicated indicated effective effective pressure. The fuel injection amount estimation unit that estimates the actual fuel injection amount with reference to the target indicated mean effective pressure map, and the fuel injection amounts of all cylinders so that the difference between the actual fuel injection amount and the target fuel injection amount is small. You may provide the collective fuel injection amount correction | amendment part correct | amended collectively.

  The difference between the air-fuel ratio calculation unit that estimates the air-fuel ratio of the exhaust gas based on the intake air amount and the target fuel injection amount and the estimated air-fuel ratio detected by the air-fuel ratio sensor is small. A collective fuel injection amount correction unit that collectively corrects the fuel injection amounts of all cylinders may be provided.

  The present invention exhibits the following excellent effects.

  (1) Correction can be made in response to changes in the characteristics of the fuel injection valve.

  (2) Correction can be made without drift.

  (3) Effective correction can be performed even with multi-injection.

It is a block diagram of the fuel-injection control apparatus which shows one Embodiment of this invention. It is a block diagram of the engine system with which the fuel-injection control apparatus of FIG. 1 is applied. FIG. 5 is a characteristic diagram of in-cylinder pressure, heat generation rate, and heat generation amount with respect to a crank angle.

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

  As shown in FIG. 1, the fuel injection control device 1 according to the present invention has a constant crank based on a signal detected by the crank angle sensor 3 for the cylinder pressure detected by the cylinder pressure sensor 2 in each of a plurality of cylinders. A sampling unit 4 that samples at an angular interval and stores the in-cylinder pressure data sequence of each cylinder, and a heat generation rate calculation unit 5 that calculates a heat generation rate in each cylinder based on the in-cylinder pressure data sequence for each predetermined crank angle. And a heat generation amount calculation unit 6 that calculates the heat generation amount by pilot injection in each cylinder by integrating the heat generation rate, and a target heat that sets a target heat generation amount that is a target value of the heat generation amount by pilot injection. A pilot injection amount compensation that corrects the fuel injection amount of the pilot injection in each cylinder so that the difference between the heat generation amount and the target heat generation amount in each cylinder is reduced. Unit 8, an indicated mean effective pressure calculation unit 9 for calculating an indicated mean effective pressure in each cylinder based on the in-cylinder pressure data string, and an indicated average effective pressure for all cylinders. The indicated average effective pressure average value calculation unit 10 for calculating the average effective pressure average value, and the main injection of each cylinder so that the difference between the indicated average effective pressure in each cylinder and the indicated average effective pressure average value of all cylinders is reduced. And a main injection amount correction unit 11 for correcting the fuel injection amount.

  In the present embodiment, the target heat generation amount setting unit 7 calculates the heat generation amount average value by averaging the heat generation amount in all the cylinders, and uses the heat generation amount average value as the target heat generation amount. The value calculation unit 7a is used. Therefore, the pilot injection amount correction unit 8 corrects the fuel injection amount of the pilot injection in each cylinder so that the difference between the heat generation amount in each cylinder and the average heat generation amount in all cylinders becomes small.

  Furthermore, the fuel injection control device 1 includes a collective fuel injection amount correction unit 12 that collectively corrects the fuel injection amounts of all cylinders in order to prevent the fuel injection amounts of all cylinders from drifting from the target fuel injection amount. The collective correction of the fuel injection amounts for all cylinders includes a mode based on the indicated mean effective pressure and a mode based on the air-fuel ratio of the exhaust gas. For this purpose, the fuel injection control device 1 sets a target indicated average effective pressure map in which a relationship between a target fuel injection amount and a target indicated average effective pressure that is an appropriate indicated average effective pressure corresponding to the target fuel injection amount is set. 13, a fuel injection amount estimation unit 14 that estimates an actual fuel injection amount with reference to the target indicated average effective pressure map 13 based on the calculated indicated average effective pressure, and exhaust based on the intake air amount and the target fuel injection amount An air-fuel ratio calculating unit 15 for estimating and calculating the air-fuel ratio of the gas. The collective fuel injection amount correction unit 12 corrects the fuel injection amounts of all the cylinders in a batch so that the difference between the actual fuel injection amount estimated by the indicated mean effective pressure and the target fuel injection amount becomes small, or the air-fuel ratio The fuel injection amounts of all the cylinders are collectively corrected so that the difference between the actual air-fuel ratio of the exhaust gas detected by the sensor and the estimated air-fuel ratio becomes small.

  Each of the members 4 to 15 is realized by software executed by an electronic control unit (hereinafter referred to as ECU) 16 and an internal memory. It is assumed that the ECU 16 knows all engine parameters (sensor detection value, calculation value, control value, etc.) necessary for engine control.

  As shown in FIG. 2, an engine system 201 to which the fuel injection control device 1 is applied includes an exhaust gas recirculation (EGR) in an exhaust manifold 203 of a four-cylinder diesel engine (hereinafter, engine) 202. The EGR pipe 204 and the high-pressure side exhaust pipe 205 are connected. An inlet of an exhaust turbine 207 of a turbocharger 206 is connected to the high pressure side exhaust pipe 205. An exhaust pipe 208 is connected to the outlet of the exhaust turbine 207. An exhaust gas purification device 209 is installed in the exhaust pipe 208.

  An intake pipe 211 is connected to the air filter 210 that takes in air from the atmosphere, and the downstream end of the intake pipe 211 is connected to the inlet of the intake compressor 212 of the turbocharger 206. A high-pressure side intake pipe 213 is connected to the outlet of the intake compressor 212. The high-pressure side intake pipe 213 joins the downstream end of the EGR pipe 204 and is connected to the intake manifold 214.

  Each cylinder of the engine 202 is provided with a fuel injection valve 215. The fuel injection valve 215 injects high-pressure fuel supplied from the common rail 216 into the cylinder at an injection timing and an injection time width commanded by the ECU 16.

  The high-pressure side exhaust pipe 205 is provided with an exhaust throttle 217 that blocks or adjusts the flow of exhaust gas. The EGR pipe 204 is provided with an EGR valve 218 that blocks or regulates the flow of EGR gas. The high-pressure side intake pipe 213 is provided with an intake throttle 219 that blocks or regulates the flow of intake air.

  An in-cylinder pressure sensor 2 is provided in each cylinder of the engine 202 (indicated by reference numerals S1 to S4 when distinction is necessary). A crank angle sensor 3 that outputs a signal at intervals of 5 degrees of crank angle is provided on a crankshaft (not shown). The intake manifold 214 is provided with an intake pressure sensor 220. The exhaust pipe 208 is provided with a λ sensor 221 that detects the air-fuel ratio of the exhaust gas.

  Hereinafter, the operation of the fuel injection control device 1 of the present invention will be described as follows. 1. In-cylinder pressure signal processing 2. Correction of variation in pilot injection amount 3. Correction of variation in main injection amount 4. Batch correction based on the indicated mean effective pressure Description will be made in the order of collective correction based on the air-fuel ratio of the exhaust gas.

1. In-cylinder pressure signal processing The sampling unit 4 takes in-cylinder pressure signals from the in-cylinder pressure sensor 2 installed in each cylinder as data in a memory in the ECU 16. At this time, the in-cylinder pressure signal is sampled at every constant crank angle based on the pulse signal from the crank angle sensor 3 and stored as an in-cylinder pressure data string. As the crank angle sensor 3, a rotary encoder having a high resolution of about 0.1 degree may be used, and a magnetic flux change caused by a metal gear called a crank pulser attached to the crankshaft is detected by an electromagnetic pickup or a hall element. A general crank angle sensor may be used. A general crank angle sensor has only a low resolution of about 5 degrees, but the pulse signal has a resolution of 0.1 to 1.0 degrees by internal processing in the ECU 16 based on the pulse signal from the crank angle sensor. And in-cylinder pressure signal may be sampled with this pulse signal. Alternatively, instead of sampling with a pulse signal from the crank angle sensor 3, sampling may be performed at a constant time interval, and the sampling data may be associated with information on a crank angle at which the time interval is not constant.

  The in-cylinder pressure data string is cut from noise having a short angular period by a low-pass filter (not shown). At that time, it is desirable to use a moving average filter or a zero phase filter so as to avoid a phase delay due to the low-pass filter. When sampling at regular time intervals, the amount of data per revolution changes according to the engine speed, so the filter coefficient is changed according to the engine speed to maintain the desired cutoff angular frequency. It is desirable to do.

  The ECU 16 determines which cylinder is currently in which stroke, with reference to a cam signal that obtains one pulse for two rotations of the crankshaft.

  In general, the ECU 16 recognizes the top dead center of the cylinder at discrete angles for each pulse signal from the crank angle sensor 3. However, in reality, the crank angle at which the piston is located at the back of the cylinder, in other words, the crank angle at which the in-cylinder volume is minimum is the true top dead center, and the top dead center recognized by the ECU 16 as the true top dead center. Refers to the displacement of each cylinder due to the effects of the mounting accuracy of the crank angle sensor 3, the processing accuracy of the crank pulser, the mounting accuracy of the crankshaft, conn-rod, and piston pin. Have a gap. Therefore, in the present embodiment, in order for the ECU 16 to recognize the true top dead center, the true top dead center is detected from the in-cylinder pressure signal.

  During engine operation (during combustion operation by fuel injection), the cylinder pressure fluctuates due to combustion, so it is difficult to detect the true top dead center from the cylinder pressure. Therefore, the peak position (crank angle) of the in-cylinder pressure signal is extracted during the non-combustion operation such as when the vehicle is decelerated or before the factory shipment, and the peak position and the ECU 16 are connected to the ECU 16 from the crank angle sensor 3. The amount of deviation from the crank angle to which the pulse signal is input is calculated, and thereafter, this amount of deviation is used for correction of top dead center and correction of the in-cylinder pressure data string. In addition, since the heat balance and gas leakage differ depending on the engine speed, the peak of the detected in-cylinder pressure may deviate from the true top dead center. Therefore, it is preferable to learn the amount of deviation of the top dead center at every appropriate engine speed, for example, every 200 rpm, and store it in the map. Since the engine speed can be arbitrarily given at the time of a motoring test before factory shipment, it is suitable for creating a map. In addition, depending on the characteristics of the in-cylinder pressure sensor 2, absolute pressure drift may occur, and it is necessary to correct the in-cylinder pressure data of each cylinder. This correction is performed by a known correction calculation using the intake manifold pressure near 180 degrees before the top dead center of each cylinder.

  As described above, the in-cylinder pressure data sequence stored by the sampling unit 4 is corrected to data for each predetermined crank angle including the true top dead center.

  Next, the heat generation rate calculation unit 5 uses the corrected in-cylinder pressure data sequence for each predetermined crank angle and the in-cylinder volume for each crank angle determined geometrically, and generates heat according to equation (1). Calculate the rate dQ. The in-cylinder pressure is P, the in-cylinder volume is V, and the specific heat ratio is κ.

  The heat generation rate dQ represents heat generated by fuel injection generated during a predetermined crank angle. By integrating the heat generation rate dQ from the past appropriate crank angle (for example, the drive start angle of the fuel injection valve 215) to the current crank angle, the heat generation amount up to the present time can be calculated. Since the in-cylinder volume V and the in-cylinder volume change amount dV are determined by the engine specifications, they may be set in the ECU 16 in advance.

  As shown in FIG. 3, an in-cylinder pressure data string corresponding to an actual in-cylinder pressure waveform is obtained as the crank angle advances. In FIG. 3, since the crank angle interval for sampling is sufficiently small, the data string is shown as a smooth curve. The heat generation rate has a small peak due to pilot injection before the start of main injection driving, and then has a large peak due to main injection. The amount of heat generation increases slightly due to pilot injection, and then greatly increases due to main injection.

2. Correction of variation in pilot injection amount As shown in FIG. 3, in this embodiment, the amount of heat generated by pilot injection hr pilot is defined as the amount of heat generated immediately before heat generation by main injection occurs. The heat generation amount calculation unit 6 calculates the heat generation amount from the start of pilot injection (not shown) to the timing obtained by adding the delay time inj delay main to the drive start timing (time) of the main injection. The delay time inj delay main is a time required from the start of driving to the actual opening of the injection valve, and is set in advance. This heat generation amount hr pilot is set as a heat generation amount by pilot injection. The amount of heat generation hr pilot varies from cylinder to cylinder due to individual differences during production and changes over time.

  As shown in the equation (2), the heat generation amount of the first cylinder S1 is hr pilot1, the heat generation amount of the second cylinder S2 is hr pilot2, the heat generation amount of the third cylinder S3 is hr pilot3, and the fourth cylinder S4 The amount of heat generated is hr pilot4.

  Next, the heat generation amount average value calculation unit 7a as the target heat generation amount setting unit 7 uniformly generates the heat generation amount by the pilot injection for each cylinder. Calculate the average value hr pilot ave of the quantity.

  The pilot injection amount correction unit 8 corrects the pilot injection amount of each cylinder by, for example, PI control (proportional integration control) using the average value as the target heat generation amount. For example, the deviation e hr pilot1 between the heat generation amount hr pilot1 and the average value of the first cylinder S1 is calculated by Expression (4). The same applies to the other cylinders.

  The correction amount dq pilot1 of the pilot injection of the first cylinder S1 is as shown in Expression (5). Kpp and Kip are pilot injection correction coefficients set in advance. The same applies to the other cylinders.

3. As shown in the equation (6), the indicated mean effective pressure calculation unit 9 uses the indicated mean effective pressures imep1, imep2, imep3, and imep4 in each cylinder using the respective in-cylinder pressure data strings. It calculates with a well-known arithmetic expression.

  The indicated average effective pressure average value calculation unit 10 calculates an indicated average effective pressure average value imep ave obtained by averaging the indicated average effective pressures of all the cylinders, using Expression (7).

  The main injection amount correction unit 11 corrects the main injection amount of each cylinder by PI control, for example, with the indicated average effective pressure average value imep ave as a target. For example, the deviation e imep1 between the indicated average effective pressure imep1 and the target value of the first cylinder S1 is calculated by the equation (8). The same applies to the other cylinders.

  The correction amount dq main1 of the main injection of the first cylinder S1 is as shown in Expression (9). Kpm and Kim are main injection correction coefficients set in advance. The same applies to the other cylinders.

  The correction performed by the main injection amount correction unit 11 is based on the indicated mean effective pressure obtained from the total in-cylinder pressure data string by the pilot injection and the main injection, but has been corrected based on the heat generation amount with respect to the pilot injection. Therefore, the variation in the main injection is substantially corrected.

  In the pilot injection variation correction and the main injection variation correction, the correction amount dq pilot1 and the correction amount dq main1 may be added to the pilot injection and main injection command injection amounts in the ECU 16, but the fuel injection valve 215 may be corrected. Correction may be performed by adding a correction time corresponding to the correction amount to the pulse width of the drive signal.

  The calculation of the correction amount is performed when the operation state of the engine 202 is relatively stable. The correction amount is stored, and the engine 202 is in a sudden transient state or the in-cylinder pressure sensor 2 is lost. The stored correction amount can be read out and applied.

4). Collective correction based on the indicated mean effective pressure By the processing so far, it is possible to suppress variations in the fuel injection amount between the cylinders. However, when the variation is biased, the average injection amount may drift from the target injection amount. For example, when the injection amount is smaller than the standard in all four cylinders, the average value is smaller than the target injection amount. Conversely, when the injection amount is larger than the standard in all four cylinders, the average value is larger than the target injection amount.

  Therefore, in this embodiment, the collective fuel injection amount correction unit 12 collectively corrects the fuel injection amounts of all the cylinders, thereby preventing the fuel injection amounts of all the cylinders from drifting from the target fuel injection amount. The collective fuel injection amount correction unit 12 can execute collective correction based on the indicated mean effective pressure and collective correction based on the air-fuel ratio of the exhaust gas.

  Here, the relationship between the target injection amount q target and the target indicated average effective pressure imep target for each engine state (for example, engine speed and injection amount) is mapped to the target indicated average effective pressure map 13. The fuel injection amount estimation unit 14 estimates the actual fuel injection amount q real with reference to the target indicated average effective pressure map 13 based on the indicated average effective pressure imep calculated by the indicated average effective pressure calculation unit 9. The right side of Expression (10) indicates that the map q imep is referred to by the indicated mean effective pressure imep.

  When the map q imep is referred to by the target indicated mean effective pressure imep target, the target injection amount q target is obtained as shown in Expression (11).

  When the map q imep is referred to by the indicated average effective pressure average value imep ave, the actual fuel injection amount q imep ave is obtained as shown in Expression (12).

  The collective fuel injection amount correction unit 12 calculates a difference between the actual fuel injection amount q imep ave estimated by the indicated average effective pressure average value imep ave and the target injection amount q target as a drift amount q error. The drift amount q error is obtained by applying the equation (5) to the first cylinder in the pilot injection variation correction, and applying the equation (9) to the first cylinder in the main cylinder variation correction. This is caused by applying the same formula to other cylinders. Therefore, the collective fuel injection amount correction unit 12 calculates the correction amount q correct according to the equation (13) so that the drift amount q error becomes small.

  The final command injection quantity q fnl of the collective correction is calculated by the equation (14).

  Note that the indicated average effective pressure average value imep ave of all the cylinders is not used, but for each cylinder, for example, for the first cylinder S1, refer to the map q imep with the indicated average effective pressure imep1 as shown in Expression (15). The correction amount dq main1 may be calculated by obtaining the actual fuel injection amount q imep1. Kpm and Kim are main injection correction coefficients set in advance.

5. Collective correction based on the air-fuel ratio of exhaust gas When the fuel density (here fixed value) is RoFuel and the theoretical air-fuel ratio is AfrStoich, the air-fuel ratio calculation unit 15 is detected by an intake air amount sensor (not shown). The air-fuel ratio λcal of the exhaust gas is estimated and calculated based on the intake air amount MAF and the target fuel injection amount q target.

  On the other hand, the air-fuel ratio λsense of the exhaust gas is detected by the λ sensor 221 installed in the exhaust pipe 208.

  In the collective fuel injection amount correction unit 12, the fuel injection amounts of all the cylinders are calculated by equation (17) so that the difference between the actual air-fuel ratio λsense of the exhaust gas detected by the λ sensor 221 and the estimated air-fuel ratio λcal becomes small. Correct all at once. Kp and Ki are injection correction coefficients set in advance.

  The final command injection amount q fnl of the collective correction is calculated by the equation (18).

  The calculation of the correction amount is performed when the operation state of the engine 202 is relatively stable, and the correction amount is stored. When the engine 202 is in a sudden transient state, the stored correction amount is read. Can also be applied.

  Incidentally, the collective correction based on the indicated mean effective pressure and the collective correction based on the air-fuel ratio of the exhaust gas are controls that can be replaced with each other, and it is sufficient to execute either one. Therefore, the collective fuel injection amount correction unit 12 executes collective correction based on the air-fuel ratio of the exhaust gas when the λ sensor 221 is healthy, and executes collective correction based on the indicated mean effective pressure when the λ sensor 221 fails. You may do it. Further, only one of the controls may be configured according to the price setting of the vehicle type.

  In addition, in the pilot injection variation correction and main injection variation correction, the average value hr pilot ave of the heat generation amount by pilot injection of all cylinders and the average value imep ave of the indicated average effective pressure of all cylinders were calculated. In the calculation, the average value of the remaining values excluding the maximum value and the minimum value may be calculated instead of the average value of all the cylinders. For example, the average value for two cylinders is calculated for four cylinders, and the average value for two to four cylinders near the median value is calculated for six cylinders. When the maximum value and the minimum value are excluded in this way, the value of the cylinder that is extremely shifted is excluded, so that the drift is reduced. Thereby, even when the variation in the fuel injection amount is large, the variation can be corrected and the drift can be reduced.

  In this embodiment, as the target heat generation amount setting unit 7, the heat generation amount average value calculation unit 7a having the heat generation amount average value obtained by averaging the heat generation amounts in all cylinders as the target heat generation amount is used. The target heat generation amount may be set based on the above. For example, a target heat generation amount map 7b that is obtained in advance through experiments and stored in the ECU 16 is used. The target heat generation amount hr exp referred to in the target heat generation amount map 7b is expressed by Expression (19).

  The indices referring to the target heat generation amount map 7b are the command injection amount Qfin, the engine speed Ne, the command pilot injection amount Qpilot, and the common rail pressure Prail.

  As described above, according to the fuel injection control device 1 of the present invention, the injection amount is corrected so that each cylinder is equal to the average value of all the cylinders based on the heat generation amount obtained from the in-cylinder pressure and the indicated mean effective pressure. Therefore, correction can be made in response to changes in the characteristics of the fuel injection valve. At this time, the drift can be reduced by calculating the average value of the remaining values excluding the maximum value and the minimum value in the calculation of the average value.

  According to the fuel injection control device 1 of the present invention, the variation correction of the pilot injection amount that is relatively affected by the mechanical variation of the fuel injection valve is executed, and then the variation correction of the main injection amount is executed. Therefore, effective correction can be performed even with multi-injection.

  According to the fuel injection control device 1 of the present invention, the correction amount is calculated so that the difference between the actual fuel injection amount estimated by the indicated mean effective pressure and the target injection amount becomes small. Can be corrected to eliminate the effects of drift.

  According to the fuel injection control device 1 of the present invention, the correction is made so that the difference between the actual air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor and the estimated air-fuel ratio becomes small, so that the average value drifts temporarily. However, it is possible to correct the influence of drift.

DESCRIPTION OF SYMBOLS 1 Fuel injection control apparatus 2 In-cylinder pressure sensor 3 Crank angle sensor 4 Sampling part 5 Heat generation rate calculation part 6 Heat generation amount calculation part 7 Target heat generation amount setting part 7a Heat generation amount average value calculation part 7b Target heat generation amount map 8 Pilot injection amount correction unit 9 Graphical average effective pressure calculation unit 10 Graphical average effective pressure average value calculation unit 11 Main injection amount correction unit 12 Batch fuel injection amount correction unit 13 Target graphic average effective pressure map 14 Fuel injection amount estimation unit 15 Sky Fuel ratio calculation unit 16 ECU

Claims (3)

A sampling unit that samples the in-cylinder pressure detected by the in-cylinder pressure sensor in each of the plurality of cylinders at a constant crank angle interval based on a signal detected by the crank angle sensor, and stores an in-cylinder pressure data string of each cylinder;
A heat generation rate calculation unit that calculates a heat generation rate in each cylinder for each predetermined crank angle based on the in-cylinder pressure data sequence;
A heat generation amount calculation unit that calculates the heat generation amount by pilot injection in each cylinder by integrating the heat generation rate;
A target heat generation amount setting unit for setting a target heat generation amount that is a target value of the heat generation amount by pilot injection;
A pilot injection amount correction unit that corrects the fuel injection amount of pilot injection in each cylinder so that the difference between the heat generation amount and the target heat generation amount in each cylinder is reduced;
An indicated average effective pressure calculation unit that calculates an indicated average effective pressure in each cylinder based on the in-cylinder pressure data string,
An illustrated average effective pressure average value calculating unit that calculates the indicated average effective pressure average value by averaging the indicated average effective pressure for all cylinders;
A main injection amount correction unit that corrects the fuel injection amount of the main injection of each cylinder so that the difference between the indicated average effective pressure in each cylinder and the indicated average effective pressure average value of all cylinders is reduced; A fuel injection control device. A target indicated mean effective pressure map in which a relationship between a target fuel injection amount and a target indicated mean effective pressure that is an appropriate indicated mean effective pressure corresponding to the target fuel injection amount is set;
A fuel injection amount estimation unit that estimates an actual fuel injection amount by referring to the target indicated average effective pressure map based on the calculated indicated average effective pressure;
2. The fuel according to claim 1, further comprising a collective fuel injection amount correction unit that collectively corrects the fuel injection amounts of all the cylinders so that a difference between the actual fuel injection amount and the target fuel injection amount becomes small. Injection control device. An air-fuel ratio calculation unit that estimates and calculates the air-fuel ratio of the exhaust gas based on the intake air amount and the target fuel injection amount;
A collective fuel injection amount correction unit that collectively corrects the fuel injection amounts of all cylinders so that the difference between the actual air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor and the estimated air-fuel ratio becomes small; The fuel injection control device according to claim 1, wherein

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