JP4914807B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for an internal combustion engine capable of a premixed compression self-ignition operation.

  Conventionally, what was described in patent document 1 is known as a fuel-injection control apparatus of an internal combustion engine. This internal combustion engine is operated by premixed compression self-ignition operation, and includes a fuel injection valve, a knocking sensor, an engine speed sensor, a continuously variable transmission, a generator, and the like (see FIG. 1 of the publication). In this fuel injection control device, it is determined whether or not knocking has occurred based on the detection signal of the knocking sensor, and when knocking occurs, the engine speed is reduced by controlling the continuously variable transmission (see FIG. 2 steps 1-3).

  Next, it is determined whether or not the combination of the reduced engine speed and the engine torque is in a normal combustion region where knocking does not occur (step 4). It is determined whether or not the torque required in step 1 is insufficient (step 5). When the engine torque is insufficient, the fuel injection amount of the fuel injection valve is increased to increase only the engine torque within a range where the combination of the engine torque and the engine speed can be maintained in the normal combustion region. Controlled (step 6).

JP 2003-184624 A

  In general, in the case of an internal combustion engine that is operated by premixed compression self-ignition, the stability of the combustion state of the air-fuel mixture due to a large amount of EGR compared to an internal combustion engine that is operated by spark ignition or an internal combustion engine that is operated by diffusion combustion. Is low, and misfires, noises, vibrations, torque steps and the like are likely to occur. This disadvantage is particularly when the internal combustion engine is in a transient state, and the generated torque (or output) cannot achieve the torque corresponding to the operating load, that is, when the torque is insufficient (or insufficient output). , More prominently appear. On the other hand, according to the conventional fuel injection control device for an internal combustion engine, the fuel injection amount is controlled so that the combination of the engine speed and the engine torque is maintained in a normal combustion region where knocking does not occur. Therefore, when the internal combustion engine is in a transitional state, the combustion state of the air-fuel mixture becomes unstable, and the above-mentioned drawbacks may be remarkably exhibited, thereby reducing the merchantability, drivability, and exhaust gas characteristics. There is.

  The present invention has been made in order to solve the above problems, and in the case of premixed compression auto-ignition operation, even when the internal combustion engine is in a transient state, a stable combustion state can be ensured, and thereby, commerciality An object of the present invention is to provide a fuel injection control device for an internal combustion engine that can improve both drivability and exhaust gas characteristics.

  In order to achieve the above object, the invention according to claim 1 is configured such that the premixed compression auto-ignition operation is performed when the vehicle is in a predetermined operation region (when the determination result of steps 21, 31, 41 is YES), In the internal combustion engine 3 that can divide fuel into main injection and sub-injection after that during one combustion cycle during the premixed compression self-ignition operation, the fuel injection is performed in the cylinder 3a. A fuel injection control device 1 for an internal combustion engine 3 to be controlled, which includes an in-cylinder pressure detecting means (ECU 2, in-cylinder pressure sensor 21) for detecting an in-cylinder pressure PCYL of the internal combustion engine 3, and an internal combustion engine according to the detected in-cylinder pressure PCYL. An actual work parameter calculation means (ECU 2, steps 1 to 3) for calculating an actual work parameter (indicated mean effective pressure IMEP) representing an actual work of the engine 3 and an operation state parameter representing an operation state of the internal combustion engine 3 Operating state parameter detecting means (ECU 2, crank angle sensor 20, accelerator opening degree sensor 22) for detecting the engine (engine speed NE, accelerator pedal opening AP) and the internal combustion engine 3 according to the detected driving state parameter. Required work parameter calculation means (ECU 2, steps 10 and 11) for calculating a required work parameter (required torque TRQ) representing required work, and actual work calculated during the premixed compression self-ignition operation of the internal combustion engine 3 respectively. Index value calculation means (ECU2, steps 24, 35, 45) for calculating index values (ratio RTI, torque deviation DTRQ, pressure deviation DIMEP) representing the relative magnitude relationship between the parameters and the required work parameters; During the premixed compression self-ignition operation of the internal combustion engine 3, the fuel injection amount by the sub-injection (sub-injection) Sub-injection parameter calculating means for calculating at least one of a quantity QINJ2), a sub-injection timing (sub-injection timing φINJ2), and a fuel injection rate per unit time (sub-injection rate RINJ2) as a sub-injection parameter ( ECU2, steps 25, 36, and 46).

  According to the fuel injection control device for an internal combustion engine, the actual work parameter representing the actual work of the internal combustion engine is calculated according to the in-cylinder pressure, and the request representing the work required for the internal combustion engine according to the operating state parameter. A work parameter is calculated. Furthermore, using the actual work parameter and the required work parameter calculated during the premixed compression self-ignition operation of the internal combustion engine, an index value representing a relative magnitude relationship between the two is calculated, and according to the calculated index value At least one of the fuel injection amount by the sub injection, the timing of the sub injection, and the fuel injection rate per unit time in the sub injection is calculated as the sub injection parameter. In this case, since the actual work parameter is calculated according to the in-cylinder pressure that appropriately represents the combustion energy of the internal combustion engine, the actual work parameter appropriately represents the actual work of the internal combustion engine, and the required work parameter represents the operating state of the internal combustion engine. Since it is calculated according to the operating state parameter, the work required for the internal combustion engine at that time is appropriately expressed. Therefore, the index value representing the relative magnitude relationship between the actual work parameter and the required work parameter as described above appropriately represents whether or not the internal combustion engine is in a transient state at that time, and It represents the degree of achievement of the actual job corresponding to the requested job.

  On the other hand, when the fuel is divided into a main injection and a sub-injection after that during one combustion cycle in the premixed compression self-ignition operation as in this internal combustion engine, The actual work of the engine depends largely on the aforementioned sub-injection parameters. That is, when the fuel injection amount by the sub injection, the timing of the sub injection, the fuel injection rate per unit time in the sub injection, and the like change, the actual work of the internal combustion engine changes accordingly. Therefore, according to this fuel injection control device, the sub-injection parameters are appropriately calculated while reflecting the degree of achievement of the actual work corresponding to the work required for the internal combustion engine (in other words, the shortage of the actual work). Accordingly, even when the internal combustion engine is in a transient state, the actual work corresponding to the work required for the internal combustion engine can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

  According to a second aspect of the present invention, in the fuel injection control device 1 for the internal combustion engine 3 according to the first aspect, the actual work parameter calculation means includes an average effective pressure (the illustrated average effective pressure IMEP) and an average as the actual work parameter. One of the torque conversion values TRQ2 obtained by converting the effective pressure into torque is calculated, and the required work parameter calculation means converts the required torque TRQ required for the internal combustion engine 3 and the required torque TRQ into the average effective pressure as the required work parameters. One of the calculated pressure converted values IMEP2 is calculated, and the index value calculation means uses, as the index value, the ratio RTI between one and the other of the required torque TRQ and the average effective pressure (the indicated average effective pressure IMEP), the pressure converted value IMEP2 and the average The difference (pressure deviation DIMEP) between one and the other of the effective pressure (the indicated mean effective pressure IMEP), and the required torque And calculates one of the one and the other and the difference between the click TRQ and torque conversion value TRQ2 (torque deviation DTRQ).

  According to the fuel injection control device for an internal combustion engine, one of the average effective pressure and the torque converted value obtained by converting the average effective pressure into torque is calculated as the actual work parameter, and the request required for the internal combustion engine as the required work parameter One of the converted pressure values obtained by converting the torque and the required torque into the average effective pressure is calculated, and the ratio between one and the other of the required torque and the average effective pressure, and the difference between one and the other of the pressure converted value and the average effective pressure. , And the difference between one of the required torque and the torque converted value and the other is calculated as the index value. In this case, the required torque and pressure converted value appropriately represent work required for the internal combustion engine at that time, and the average effective pressure and torque converted value appropriately represent actual work of the internal combustion engine. Therefore, the ratio between one and the other of the required torque and the average effective pressure, the difference between one and the other of the pressure converted value and the average effective pressure, and the difference between one and the other of the required torque and the torque converted value are all It is calculated as representing whether or not the internal combustion engine is in a transient state at that time and representing the degree of achievement of actual work corresponding to the work required for the internal combustion engine at that time. As a result, the operation and effect of the invention according to claim 1 can be obtained with certainty.

  The invention according to claim 3 is the fuel injection control device 1 for the internal combustion engine 3 according to claim 2, wherein the index value calculation means controls the internal combustion engine 3 based on the required torque TRQ and the required torque TRQ. The index value is calculated using the average effective pressure (indicated average effective pressure IMEP) calculated during one combustion cycle.

  According to the fuel injection control device for an internal combustion engine, the index value is calculated using the required torque and the average effective pressure calculated during one combustion cycle when the internal combustion engine is controlled based on the required torque. Therefore, when the internal combustion engine is controlled based on the required torque, the sub-injection parameter can be calculated according to the actual work achievement level corresponding to the required torque, thereby controlling the fuel injection. The accuracy can be further improved.

  According to a fourth aspect of the present invention, in the fuel injection control device 1 for the internal combustion engine 3 according to the second or third aspect, the sub-injection parameter is a fuel injection amount by the sub-injection (sub-injection amount QINJ2). The calculation means calculates the fuel injection amount (sub-injection amount QINJ2) as the ratio RTI between the required torque TRQ and the average effective pressure (shown average effective pressure IMEP) increases, and the pressure conversion value IMEP2 and average effective pressure (shown average effective pressure). The larger the difference (pressure deviation DIMEP) from IMEP) or the larger the difference (torque deviation DTRQ) between the required torque TRQ and the torque converted value TRQ2, the larger the difference (steps 25, 36, 46). It is characterized by that.

  In this case, the ratio between the required torque and the average effective pressure, the difference between the required torque and the converted torque value, and the difference between the converted pressure value and the average effective pressure all represent an actual work shortage relative to the required torque. The larger these ratios and differences, the greater the actual work shortfall. On the other hand, when the fuel is divided into a main injection and a sub-injection after that during one combustion cycle in the premixed compression self-ignition operation as in this internal combustion engine, The greater the amount of fuel injected in the injection, the more work the internal combustion engine actually accomplishes. Therefore, according to the fuel injection control device for the internal combustion engine, the fuel injection amount in the sub-injection is controlled so that the work actually performed by the internal combustion engine becomes larger as the actual work shortage relative to the required torque becomes larger. As a result, the control accuracy can be further improved.

  According to a fifth aspect of the present invention, in the fuel injection control device 1 for the internal combustion engine 3 according to the second or third aspect, the sub-injection parameter is a sub-injection timing (sub-injection timing φINJ2), and the sub-injection parameter calculating means Indicates that the ratio of the sub-injection timing (sub-injection timing φINJ2) between the required torque TRQ and the average effective pressure (indicated average effective pressure IMEP) is larger, the pressure converted value IMEP2 and the average effective pressure (indicated average effective pressure IMEP). ), Or the greater the difference (torque deviation DTRQ) between the required torque TRQ and the torque conversion value TRQ2, the faster the timing is calculated (formulas (1) to ( 3)).

  As in this internal combustion engine, when fuel is divided into a main injection and a sub-injection after that during one combustion cycle in the premixed compression auto-ignition operation, The earlier the timing, the more work the internal combustion engine actually accomplishes. Therefore, according to the fuel injection control device for an internal combustion engine, the sub-injection timing is controlled so that the work actually achieved by the internal combustion engine becomes larger as the shortage of actual work with respect to the required torque becomes larger. As a result, the control accuracy can be further improved.

  The invention according to claim 6 is the fuel injection control device 1 for the internal combustion engine 3 according to claim 2 or 3, wherein the sub injection parameter is a fuel injection rate per unit time in the sub injection (sub injection rate RINJ2). The sub-injection parameter calculation means calculates the fuel-injection rate per unit time (sub-injection rate RINJ2) as the ratio RTI between the required torque TRQ and the average effective pressure (shown average effective pressure IMEP) increases. And the average effective pressure (the illustrated average effective pressure IMEP) are calculated so as to increase as the difference (pressure deviation DIMEP) increases or the difference between the required torque TRQ and the torque conversion value TRQ2 increases (torque deviation DTRQ). (FIGS. 7, 11, and 15).

  As in this internal combustion engine, when fuel is divided into a main injection and a sub-injection after that during one combustion cycle in the premixed compression self-ignition operation, The greater the fuel injection rate per unit time, the more work the internal combustion engine actually accomplishes. Therefore, according to the fuel injection control device for the internal combustion engine, the larger the shortage of the actual work with respect to the required torque, the greater the work that the internal combustion engine actually achieves. The fuel injection rate can be controlled, and as a result, the control accuracy can be further improved.

  Hereinafter, a fuel injection control device for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a fuel injection control device 1 of the present embodiment and an internal combustion engine (hereinafter referred to as “engine”) 3 to which the fuel injection control device 1 is applied. As shown in FIG. An ECU 2 is provided. As will be described later, the ECU 2 executes various control processes such as a fuel injection control process in accordance with the operating state of the engine 3.

  The engine 3 is an in-line four-cylinder diesel engine mounted on the vehicle 10, and includes four sets of cylinders 3a and pistons 3b (only one set is shown), a crankshaft 3c, and the like. The engine 3 is provided with a crank angle sensor 20 and four in-cylinder pressure sensors 21 (only one is shown).

  The crank angle sensor 20 includes a magnet rotor 20a and an MRE pickup 20b, and outputs a CRK signal and a TDC signal, both of which are pulse signals, to the ECU 2 as the crankshaft 3c rotates.

  The CRK signal is output at one pulse every predetermined crank angle (for example, 1 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly ahead of the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle. In the present embodiment, the crank angle sensor 20 corresponds to the driving state parameter detecting means, and the engine speed NE corresponds to the driving state parameter.

  The in-cylinder pressure sensor 21 is a piezoelectric element type integrated with a glow plug (not shown) provided for each cylinder 3a, and bends in accordance with a change in the pressure in the corresponding cylinder 3a, that is, the in-cylinder pressure PCYL. Thus, a detection signal representing the in-cylinder pressure PCYL is output to the ECU 2. As will be described later, the ECU 2 calculates the in-cylinder pressure PCYL and the indicated mean effective pressure IMEP based on the voltage value (hereinafter referred to as “detection voltage”) VCPS of the detection signal of the in-cylinder pressure sensor 21. In the present embodiment, the in-cylinder pressure sensor 21 corresponds to the in-cylinder pressure detecting means.

  Further, the engine 3 is provided with a fuel injection valve 4 for each cylinder 3a (only one is shown), and each fuel injection valve 4 is electrically connected to the ECU 2. The fuel injection valve 4 is controlled in its opening / closing timing by the ECU 2, thereby controlling the fuel injection amount and the injection timing, as will be described later.

  Further, an accelerator opening sensor 22 is connected to the ECU 2, and this accelerator opening sensor 22 detects a depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle. Is output to the ECU 2. In the present embodiment, the accelerator opening sensor 22 corresponds to the driving state parameter detecting means, and the accelerator opening AP corresponds to the driving state parameter.

  On the other hand, the ECU 2 is composed of a microcomputer comprising a CPU, RAM, ROM, I / O interface and drive circuit (all not shown), and responds to the detection signals of the various sensors 20 to 22 described above. Various control processes are executed.

  Specifically, the ECU 2 executes a process for calculating the indicated mean effective pressure IMEP, a process for calculating the required torque TRQ, a fuel injection control process, and the like, as will be described later, in accordance with the operating state of the engine 3. By these control processes, when the operating state of the engine 3 is in the predetermined PCCI operating range, the premixed compression auto-ignition operation of the engine 3 is executed, and in the other operating ranges, the normal compression auto-ignition operation is executed. The Further, as will be described later, when a predetermined operating condition is satisfied (when RTI> R2 is satisfied) during the premixed compression self-ignition operation, the fuel is injected into the main injection timing and the sub-injection timing later than that. It is divided and injected twice.

  In the present embodiment, the ECU 2 corresponds to an in-cylinder pressure detecting means, an actual work parameter calculating means, an operating state parameter detecting means, a required work parameter calculating means, an index value calculating means, and a sub injection parameter calculating means.

  Next, the calculation process of the indicated mean effective pressure IMEP executed by the ECU 2 will be described with reference to FIG. This process is to calculate the indicated mean effective pressure IMEP in the combustion cycle in each cylinder 3a, and is executed at a predetermined cycle (for example, a cycle at a crank angle of 1 °). Here, the processing content in one cylinder 3a is described as an example, and various values calculated in the following description are stored in the RAM of the ECU 2. In this process, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), the detection voltage VCPS of the in-cylinder pressure sensor 21 is read.

  Next, the process proceeds to step 2, and the in-cylinder pressure PCYL is calculated by the present applicant using the detection voltage VCPS by the method described in Japanese Patent Application Laid-Open No. 2006-233798. Specifically, the in-cylinder pressure PCYL is calculated so that the deviation between the estimated value of the in-cylinder pressure estimated from the motoring pressure and the calculated value calculated from the detection voltage VCPS of the in-cylinder pressure sensor 21 is minimized.

  In step 3 following step 2, the present applicant calculates the indicated mean effective pressure IMEP using the in-cylinder pressure PCYL calculated in step 2 by the method described in Japanese Patent Laid-Open No. 2006-52647. Thereafter, this process is terminated. In the present embodiment, the indicated mean effective pressure IMEP corresponds to the actual work parameter and the mean effective pressure.

  Next, the required torque TRQ calculation process executed by the ECU 2 will be described with reference to FIG. As will be described below, this process calculates the torque required for the engine 3 as the required torque TRQ, and is executed in synchronism with the generation timing of the first TDC signal in one combustion cycle.

  In this process, first, in step 10, data of the engine speed NE and the accelerator pedal opening AP stored in the RAM are read.

  Next, the routine proceeds to step 11 where a required torque TRQ is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP. In this map, the required torque TRQ is set to a larger value as the engine speed NE is higher or the accelerator pedal opening AP is larger. This is because a higher engine output is required as the engine speed NE is higher or the accelerator pedal opening AP is larger. Thereafter, this process is terminated.

  When the required torque TRQ is calculated as described above, the fuel injection amount and the intake air amount of all the cylinders 3a are controlled based on the required torque TRQ in the current combustion cycle, whereby the engine corresponding to the required torque TRQ. The engine 3 is controlled so that an output can be obtained. In the present embodiment, the required torque TRQ corresponds to the required work parameter.

  Next, the fuel injection control process executed by the ECU 2 will be described with reference to FIG. In this process, as will be described below, the main injection amount QINJ1, the main injection timing φINJ1, the sub injection amount QINJ2, and the sub injection timing φINJ2 are calculated for each cylinder 3a, and are executed in synchronization with the generation timing of the TDC signal. Is done.

  In this process, first, in step 20, various data such as the engine speed NE, the required torque TRQ, and the indicated mean effective pressure IMEP stored in the RAM are read. In this case, the current value, that is, the latest calculated value is read as the indicated mean effective pressure IMEP, and the previous value, that is, the value calculated at the previous control timing is read as the required torque TRQ. In other words, a value calculated during one combustion cycle when the internal combustion engine 3 is controlled based on the required torque TRQ is used as the indicated mean effective pressure IMEP. The reason will be described later.

  Next, the routine proceeds to step 21 where it is determined whether or not the premixed compression self-ignition operation mode flag F_PCCI is “1”. The premixed compression self-ignition operation mode flag F_PCCI is set based on operation state parameters such as the engine speed NE, the engine water temperature, and the required torque TRQ. Specifically, these operation state parameters are set in the engine. 3 is set to “1” when it is in a predetermined PCCI operating region in which premixed compression self-ignition operation is to be performed, and is set to “0” otherwise.

  When the determination result in step 21 is YES and F_PCCI = 1, it is determined that the engine 3 should be premixed compression self-ignition operation, and the process proceeds to step 22 in accordance with the engine speed NE and the required torque TRQ. The main injection amount QINJ1 is calculated by searching a map (not shown).

  Next, at step 23, a main injection timing φINJ1 is calculated by searching a map (not shown) according to the engine speed NE and the main injection amount QINJ1. The main injection timing φINJ1 is the injection start timing of the main injection amount QINJ1, and is set to a crank angle (for example, BTDC 20 ° to 30 °) within a predetermined range before the TDC position of the intake stroke.

  In step 24 following step 23, a value TRQ / IMEP obtained by dividing the required torque TRQ by the indicated mean effective pressure IMEP is set as the ratio RTI. In the present embodiment, the ratio RTI corresponds to the index value and the ratio of one of the actual work parameter and the required work parameter to the other.

  Next, the routine proceeds to step 25, where the sub injection quantity QINJ2 is calculated by searching the table shown in FIG. 5 according to the ratio RTI. In the present embodiment, the sub injection amount QINJ2 corresponds to the fuel injection amount by the sub injection. In the drawing, R2 is a predetermined threshold value of the ratio RTI, and when RTI <R2 is established, it represents that the actual work of the engine 3 exceeds the work required for the engine 3, When RTI = R2, it represents that both are equal, and when RTI> R2 is established, it represents that the actual work of the engine 3 is less than the work required for the engine 3. Q2_B is a basic value of the auxiliary injection amount QINJ2, and is set to a value of 0 in this embodiment.

  As shown in the figure, in this table, the sub-injection amount QINJ2 is set to the basic value Q2_B (= 0) in the region of RTI ≦ R2, and therefore, sub-injection is not executed when RTI ≦ R2. Only the main injection is executed. This is because when RTI ≦ R2 holds, the actual work of the engine 3 exceeds the work required for the engine 3 or they are equal, and it is not necessary to perform the sub-injection. Note that the basic value Q2_B may be set to a positive predetermined value, and the sub-injection may be performed even in the region of RTI ≦ R2.

  In addition, in the region of RTI> R2, that is, in the region where the actual work of the engine 3 is less than the work required for the engine 3, in order to compensate for the shortage of the actual work of the engine 3, in addition to the main injection Since the sub-injection needs to be executed, the sub-injection amount QINJ2 is set so that QINJ2> 0. Further, in this region, the sub injection amount QINJ2 is set to a larger value as the ratio RTI is larger. This is because the sub-injection amount QINJ2 needs to be set to a larger value in order to compensate for the greater lack of actual work of the engine 3.

  Next, the process proceeds to step 26, where a sub-injection timing φINJ2 is calculated by searching a map (not shown) according to the sub-injection amount QINJ2 and engine speed NE calculated in step 25. This sub injection timing φINJ2 is an injection start timing of the sub injection amount QINJ2, and is set to a crank angle (for example, ATDC 0 ° to 30 °) within a predetermined range after the TDC position of the intake stroke. Thereafter, this process is terminated.

  On the other hand, when the determination result in step 21 is NO and F_PCCI = 0, it is determined that the engine 3 should be operated in a normal compression self-ignition operation, the process proceeds to step 27, and the normal control process is executed. In this normal control process, a fuel injection control process for normal compression self-ignition operation is executed. Thereafter, this process is terminated.

  As described above, according to the fuel injection control device 1 of the present embodiment, the indicated mean effective pressure IMEP is calculated according to the in-cylinder pressure PCYL, and the required torque TRQ according to the engine speed NE and the accelerator pedal opening AP. Is calculated. Further, by dividing this required torque TRQ by the indicated mean effective pressure IMEP calculated during one combustion cycle when the internal combustion engine 3 is controlled based on the required torque TRQ, the ratio RTI is calculated. A sub-injection amount QINJ2 is calculated according to the ratio RTI.

  In this case, since the indicated mean effective pressure IMEP is calculated according to the in-cylinder pressure PCYL that appropriately represents the combustion energy of the engine 3, the actual work of the engine 3 is appropriately represented, and the required torque TRQ is equal to the engine speed NE. Since it is calculated according to the accelerator opening AP, the work required for the engine 3 at that time is appropriately represented. Further, the ratio RTI is calculated by dividing the required torque TRQ by the indicated mean effective pressure IMEP calculated during one combustion cycle when the engine 3 is controlled based on the required torque TRQ. When controlled according to the torque TRQ, it appropriately represents how much work corresponding to the required torque TRQ has actually been achieved.

  On the other hand, when the premixed compression auto-ignition operation is performed as in the engine 3, the fuel is divided into two main injections and sub-injections after that in one combustion cycle. When the fuel is injected, the actual work of the engine 3 greatly depends on the sub-injection amount QINJ2. That is, the actual work of the engine 3 is determined by the auxiliary injection amount QINJ2. Therefore, according to this fuel injection control device, the sub-injection amount QINJ2 is appropriately set while reflecting the degree of achievement of actual work corresponding to the work required for the engine 3 (in other words, the shortage of actual work). Accordingly, even when the engine 3 is in a transient state, a stable combustion state can be ensured by appropriately securing an actual work corresponding to the work required for the engine 3. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

  Further, the sub-injection amount QINJ2 is set to a larger value as the ratio RTI is larger when RTI> R2, that is, when the actual work of the engine 3 is less than the work required for the engine 3. In other words, as the actual work shortage of the engine 3 increases, the sub-injection amount QINJ2 is set to a larger value, so that the actual work shortage of the engine 3 can be appropriately compensated.

  The embodiment is an example in which the indicated mean effective pressure IMEP is used as the actual work parameter. However, the actual work parameter of the present invention is not limited to this, and may be anything that represents the actual work of the internal combustion engine. For example, the net average effective pressure BMEP may be used as the actual work parameter instead of the indicated average effective pressure IMEP. Furthermore, as the actual work parameter, a value obtained by converting the indicated average effective pressure IMEP or the net average effective pressure BMEP into work (joule) may be used.

  Further, the embodiment is an example in which the required torque TRQ is used as the required work parameter. However, the actual work parameter of the present invention is not limited to this, and may be anything that represents the work required for the internal combustion engine. For example, a value obtained by converting the required torque TRQ into work (joule) may be used as the required work parameter.

  Furthermore, the embodiment is an example in which the ratio RTI (= TRQ / IMEP) is used as an index value representing the relative magnitude relationship between the actual work parameter and the required work parameter, but the index value of the present invention is not limited to this. Instead, it only needs to represent the relative magnitude relationship between the actual work parameter and the required work parameter. For example, the ratio IMEP / TRQ may be used instead of the ratio RTI of the embodiment. Furthermore, instead of the ratio RTI, the ratio between the required torque TRQ and one of the torque converted value TRQ2 described later and the other (TRQ / TRQ2 or TRQ2 / TRQ) may be used. The ratio of one of IMEP to the other (IMEP / IMEP2 or IMEP2 / IMEP) may be used.

  The above five ratios IMEP / TRQ, TRQ / TRQ2, TRQ2 / TRQ, IMEP / IMEP2, and IMEP2 / IMEP are all the same as the ratio RTI of the embodiment, and the engine 3 actually performs work corresponding to the required torque TRQ. Since the degree of achievement is appropriately expressed, even when any of these ratios is used, the same effect as the fuel injection control device 1 of the embodiment can be obtained. That is, even when the engine 3 is in a transient state, the actual work corresponding to the work required for the engine 3 can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

Further, instead of steps 25 and 26 in FIG. 4 described above, the sub injection amount QINJ2 and the sub injection timing φINJ2 may be calculated as described below. First, when RTI ≦ R2, the secondary injection amount QINJ2 is set to a value of 0, and when RTI> R2, the secondary injection amount QINJ2 is set to a positive predetermined value. Next, the sub injection timing φINJ2 is calculated by the following equation (1).
φINJ2 = φINJ2_B−Dφ2_RTI (1)

  Here, φINJ2_B is a basic value of the sub injection timing φINJ2, and is set to a value corresponding to a predetermined crank angle position after the TDC position of the intake stroke. Dφ2_RTI is a correction term for correcting the basic value φINJ2_B to the advance side, and is calculated by searching the table shown in FIG. 6 according to the ratio RTI.

  As shown in the figure, the correction term Dφ2_RTI is set to 0 in the region of RTI ≦ R2. In the region of RTI> R2, that is, in the region where the actual work of the engine 3 is less than the work required for the engine 3, the correction term Dφ2_RTI is set so that Dφ2_RTI> 0 holds. This is because, in the region of RTI> R2, it is necessary to advance the secondary injection timing φINJ2 from the basic value φINJ2_B in order to increase the actual work of the engine 3 in order to compensate for the shortage of the actual work of the engine 3. Because there is something (ie it needs to be changed at an earlier timing). Therefore, the correction term Dφ2_RTI is set to a larger value to compensate for the larger ratio RTI, that is, the greater the actual work shortage of the engine 3.

  As described above, even when the sub-injection amount QINJ2 and the sub-injection timing φINJ2 are calculated, the same operational effects as in the embodiment can be obtained. That is, even when the engine 3 is in a transient state, the actual work corresponding to the work required for the engine 3 can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved. In this case, the sub injection timing φINJ2 may be calculated by the above method, and the sub injection amount QINJ2 may be calculated by the same method as in Step 25.

  When a fuel injection valve 4 that can change the injection rate per unit time is used, instead of steps 25 and 26 in FIG. 4 described above, as described below, the sub-injection timing φINJ2 and The sub-injection rate RINJ2 (injection rate per unit time at the time of sub-injection) may be calculated. First, the sub injection timing φINJ2 is set to a predetermined crank angle position after the TDC position of the intake stroke.

  Next, the sub injection rate RINJ2 is calculated by searching the table shown in FIG. 7 according to the ratio RTI. In the figure, R2_B is a basic value of the sub-injection rate RINJ2, and is set to 0 in the present embodiment. As shown in the figure, in the region of RTI ≦ R2, the sub injection rate RINJ2 is set to the basic value R2_B. This is because when RTI ≦ R2, the actual work of the engine 3 exceeds the work required for the engine 3 or they are equal, and it is not necessary to execute the sub-injection. Note that the basic value R2_B may be set to a predetermined positive value, and the sub-injection may be performed even in the region of RTI ≦ R2.

  Further, in the region of RTI> R2, that is, in the region where the actual work of the engine 3 is less than the work required for the engine 3, the sub-injection rate RINJ2 increases as the ratio RTI increases, that is, the actual work of the engine 3 increases. In order to increase the actual work of the engine 3 to compensate for the shortage, it is set to a larger value.

  As described above, even when the sub-injection timing φINJ2 and the sub-injection rate RINJ2 are calculated, the same operational effects as in the embodiment can be obtained. That is, even when the engine 3 is in a transient state, the actual work corresponding to the work required for the engine 3 can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

  When the fuel injection valve 4 that can change the injection rate per unit time is used as in the above example, the injection rate of the fuel injection valve 4 is changed to the sub injection start in one sub injection. The time may be set to a small value, and may be variably controlled so as to become a larger value from the start to the end of the sub-injection. When controlled in this way, the injection rate is set to a small value at the start of the sub-injection, so that noise and noise associated with combustion can be suppressed.

  Furthermore, instead of the fuel injection control process of FIG. 4 described above, a fuel injection control process shown in FIG. 8 may be executed. The process of FIG. 8 is also executed in synchronization with the generation timing of the TDC signal, similarly to the process of FIG. This fuel injection control process is different from the process of FIG. 4 only in steps 34 to 36, and the others are the same. Therefore, the description below will focus on the different points, and the other description will be omitted. .

  First, after executing Steps 30 to 33 in the same manner as Steps 20 to 23 described above, in Step 34, the product KTRQ · IMEP of the conversion coefficient KTRQ and the indicated mean effective pressure IMEP is set as the torque conversion value TRQ2. This torque conversion value TRQ2 is obtained by converting the indicated mean effective pressure IMEP into torque, and the conversion coefficient KTRQ is preset based on the stroke volume or the like.

  Next, in step 35, the difference TRQ-TRQ2 between the required torque TRQ and the torque converted value TRQ2 is set as the torque deviation DTRQ. In this example, the torque deviation DTRQ corresponds to the index value and the difference between one of the required torque and the torque conversion value and the other.

  Next, the routine proceeds to step 36, where the sub injection quantity QINJ2 is calculated by searching the table shown in FIG. 9 according to the torque deviation DTRQ calculated at step 35. As shown in the figure, in this table, the sub-injection amount QINJ2 is set to the above-described basic value Q2_B (= 0) in the region of DTRQ ≦ 0. Therefore, when DTRQ ≦ 0, sub-injection is executed. Instead, only the main injection is executed. This is because when DTRQ ≦ 0 is established, the actual work of the engine 3 exceeds the work required for the engine 3 or they are equal, so that it is not necessary to perform the sub-injection. Also in this example, as described above, the basic value Q2_B may be set to a predetermined positive value, and the sub-injection may be performed even in the region where DTRQ ≦ 0.

  In the region where DTRQ> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the sub-injection amount QINJ2 is set to a larger value as the torque deviation DTRQ is larger. Yes. This is because the sub-injection amount QINJ2 needs to be set to a larger value in order to compensate for the greater lack of actual work of the engine 3.

  Next, the process proceeds to step 37, and the sub injection timing φINJ2 is calculated by the same method as in step 26 described above, and then the present process is terminated.

  As described above, even when the fuel injection control process of FIG. 8 is executed, the same effects as those of the fuel injection control process of FIG. 4 described above can be obtained. That is, even when the engine 3 is in a transient state, the actual work corresponding to the work required for the engine 3 can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

  8 is an example using the difference TRQ−TRQ2 (= torque deviation DTRQ) between the required torque TRQ and the torque converted value TRQ2 as the difference between one and the other of the required torque and the torque converted value. However, instead of this, the difference TRQ2-TRQ, the absolute value of the difference | TRQ-TRQ2 |, or the absolute value of the difference | TRQ2-TRQ | may be used. In that case, the horizontal axis of the table of FIG. 9 described above is set to the absolute value of the difference | TRQ−TRQ2 | or | TRQ2−TRQ |, and the sub table is searched according to these absolute values. What is necessary is just to comprise so that the injection quantity QINJ2 may be calculated. Even when configured as described above, the same effects as the fuel injection control process of FIG. 8 can be obtained.

Further, instead of steps 36 and 37 in FIG. 8 described above, the sub injection amount QINJ2 and the sub injection timing φINJ2 may be calculated as described below. First, when DTRQ ≦ 0, the secondary injection amount QINJ2 is set to a value of 0, and when DTRQ> 0, the secondary injection amount QINJ2 is set to a positive predetermined value. Next, the sub injection timing φINJ2 is calculated by the following equation (2).
φINJ2 = φINJ2_B−Dφ2_DTRQ (2)

  Here, Dφ2_DTRQ is a correction term for correcting the basic value φINJ2_B to the advance side, and is calculated by searching the table shown in FIG. 10 according to the torque deviation DTRQ.

  As shown in the figure, the correction term Dφ2_DTRQ is set to a value of 0 in the region where DTRQ ≦ 0. Further, in the region where DTRQ> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the correction term Dφ2_DTRQ increases as the ratio DTRQ increases, that is, the actual work of the engine 3 is insufficient. The larger the minute, the larger the value is set to compensate for it.

  As described above, even when the sub-injection amount QINJ2 and the sub-injection timing φINJ2 are calculated, the same effects as the fuel injection control process of FIG. 8 can be obtained.

  Further, when the fuel injection valve 4 that can change the injection rate per unit time is used, instead of the steps 36 and 37 in FIG. 8 described above, the sub-injection timing φINJ2 and The sub-injection rate RINJ2 may be calculated. First, the sub injection timing φINJ2 is set to a predetermined crank angle position after the TDC position of the intake stroke.

  Next, the sub injection rate RINJ2 is calculated by searching the table shown in FIG. 11 according to the torque deviation DTRQ. As shown in the figure, the sub-injection rate RINJ2 is set to the aforementioned basic value R2_B (= 0) in the region where DTRQ ≦ 0. This is because when DTRQ ≦ 0 is established, the actual work of the engine 3 exceeds the work required for the engine 3 or they are equal, and it is not necessary to execute the sub-injection. Also in this example, as described above, the basic value R2_B may be set to a predetermined positive value, and the sub-injection may be performed even in the region where DTRQ ≦ 0.

  Further, in the region where DTRQ> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the sub-injection rate RINJ2 increases as the torque deviation DTRQ increases, that is, the actual work of the engine 3. In order to compensate for the larger deficiency of the engine 3, the larger value is set to increase the actual work of the engine 3.

  As described above, even when the sub-injection timing φINJ2 and the sub-injection rate RINJ2 are calculated, the same operational effects as the fuel injection control process of FIG. 8 can be obtained.

  Furthermore, instead of the fuel injection control process of FIG. 4 described above, the fuel injection control process shown in FIG. 12 may be executed. The process of FIG. 12 is also executed in synchronization with the generation timing of the TDC signal, similarly to the process of FIG. This fuel injection control process is different from the process of FIG. 4 only in steps 44 to 46, and the others are the same. Therefore, the following description will focus on the different points, and the other description will be omitted. .

  First, after executing Steps 40 to 43 in the same manner as Steps 20 to 23 described above, in Step 44, the product KIMEP · TRQ of the conversion coefficient KIMEP and the required torque TRQ is set as the pressure conversion value IMEP2. This pressure conversion value IMEP2 is obtained by converting the required torque TRQ into the indicated mean effective pressure IMEP, and the conversion coefficient KIMEP is preset based on the stroke volume and the like.

  Next, in step 45, the difference IMEP2-IMEP between the pressure converted value IMEP2 and the indicated mean effective pressure IMEP is set as the pressure deviation DIMEP. In this example, the pressure deviation DIMEP corresponds to the index value and the difference between one of the average effective pressure and the pressure converted value and the other.

  Next, the process proceeds to step 46, and the sub injection amount QINJ2 is calculated by searching the table shown in FIG. 13 according to the pressure deviation DIMEP calculated in step 45. As shown in the figure, in this table, the sub-injection amount QINJ2 is set to the aforementioned basic value Q2_B (= 0) in the region of DIMEP ≦ 0. Therefore, when DIMEP ≦ 0, the sub-injection is performed. Only the main injection is executed without being executed. This is because when DIMEP ≦ 0 is satisfied, the actual work of the engine 3 exceeds the work required for the engine 3 or they are equal, and it is not necessary to perform the sub-injection. Also in this example, as described above, the basic value Q2_B may be set to a positive value, and the sub-injection may be performed even in the region of DIMEP ≦ 0.

  In the region of DIMEP> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the sub-injection amount QINJ2 is set to a larger value as the pressure deviation DIMEP is larger. Yes. This is because the sub-injection amount QINJ2 needs to be set to a larger value in order to compensate for the greater lack of actual work of the engine 3.

  Next, the process proceeds to step 47, and the sub-injection timing φINJ2 is calculated by the same method as in step 26 described above, and then the present process is terminated.

  As described above, even when the fuel injection control process of FIG. 12 is executed, the same effects as those of the fuel injection control process of FIG. 4 described above can be obtained. That is, even when the engine 3 is in a transient state, the actual work corresponding to the work required for the engine 3 can be appropriately ensured, thereby ensuring a stable combustion state. As a result, the exhaust gas characteristics can be improved, and the occurrence of misfires, noise, and torque steps can be avoided, so that the merchantability and operability can be improved.

  In the above-described processing of FIG. 12, the difference IMEP2−IMEP (= pressure deviation DIMEP) between the pressure converted value IMEP2 and the indicated average effective pressure IMEP is used as the difference between one of the average effective pressure and the pressure converted value. As an example, instead of this, the difference IMEP-IMEP2, the absolute value of the difference | IMEP2-IMEP |, or the absolute value of the difference | IMEP2-IMEP | may be used. In that case, the horizontal axis of the table of FIG. 13 described above is set to the absolute value of the difference | IMEP2-IMEP | or | IMEP2-IMEP |, and the table is searched according to these absolute values. What is necessary is just to comprise so that the injection quantity QINJ2 may be calculated. Even when configured as described above, the same effects as the fuel injection control process of FIG. 12 can be obtained.

Further, instead of the above-described steps 46 and 47 in FIG. 12, the sub injection amount QINJ2 and the sub injection timing φINJ2 may be calculated as described below. First, when DIMEP ≦ 0, the sub-injection amount QINJ2 is set to the value 0, and when DIMEP> 0, the sub-injection amount QINJ2 is set to the positive predetermined value. Next, the sub injection timing φINJ2 is calculated by the following equation (3).
φINJ2 = φINJ2_B−Dφ2_DIMEP (3)

  Here, Dφ2_DIMEP is a correction term for correcting the basic value φINJ2_B to the advance side, and is calculated by searching the table shown in FIG. 14 according to the pressure deviation DIMEP.

  As shown in the figure, the correction term Dφ2_DIMEP is set to a value of 0 in the region of DIMEP ≦ 0. Further, in the region where DIMEP> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the correction term Dφ2_DIMEP increases as the ratio DIMEP increases, that is, the lack of actual work of the engine 3 The larger the minute, the larger the value is set to compensate for it.

  As described above, even when the sub-injection amount QINJ2 and the sub-injection timing φINJ2 are calculated, the same effects as the fuel injection control process of FIG. 12 can be obtained.

  When the fuel injection valve 4 that can change the injection rate per unit time is used, instead of the steps 46 and 47 in FIG. 12 described above, the sub-injection timing φINJ2 and The sub-injection rate RINJ2 may be calculated. First, the sub injection timing φINJ2 is set to a predetermined crank angle position after the TDC position of the intake stroke.

  Next, the sub injection rate RINJ2 is calculated by searching the table shown in FIG. 15 according to the pressure deviation DIMEP. As shown in the figure, the sub-injection rate RINJ2 is set to the aforementioned basic value R2_B (= 0) in the region of DIMEP ≦ 0. As described above, when DIMEP ≦ 0 is established, it is necessary to execute the sub-injection because the actual work of the engine 3 exceeds or is equal to the work required for the engine 3. By not. In this example, as described above, the basic value R2_B may be set to a positive value, and the sub-injection may be performed even in the region of RTI ≦ R2.

  In the region where DIMEP> 0, that is, the region where the actual work of the engine 3 is less than the work required for the engine 3, the sub-injection rate RINJ2 increases as the pressure deviation DIMEP increases, that is, the actual work of the engine 3. In order to compensate for the larger deficiency of the engine 3, the larger value is set to increase the actual work of the engine 3.

  As described above, even when the sub-injection timing φINJ2 and the sub-injection rate RINJ2 are calculated, the same effects as the fuel injection control process of FIG. 12 can be obtained.

  The embodiment is an example in which the fuel injection control device 1 of the present invention is applied to a diesel engine using light oil as a fuel as the internal combustion engine 3, but the internal combustion engine to which the fuel injection control device of the present invention can be applied Not limited to this, any premixed compression self-ignition operation is possible. For example, the fuel injection control device of the present invention may be applied to an internal combustion engine using gasoline or natural gas as fuel.

1 is a diagram schematically illustrating a schematic configuration of a fuel injection control device according to an embodiment of the present invention and an internal combustion engine to which the fuel injection control device is applied. FIG. It is a flowchart which shows the calculation process of illustrated mean effective pressure IMEP. It is a flowchart which shows the calculation process of request | requirement torque TRQ. It is a flowchart which shows a fuel-injection control process. It is a figure which shows an example of the table used for calculation of the sub injection amount QINJ2. It is a figure which shows an example of the table used for calculation of correction | amendment term Dphi2_RTI. It is a figure which shows an example of the table used for calculation of sub injection rate RINJ2. It is a flowchart which shows the modification of a fuel-injection control process. It is a figure which shows the modification of the table used for calculation of sub injection amount QINJ2. It is a figure which shows an example of the table used for calculation of correction | amendment term Dphi2_DTRQ. It is a figure which shows the modification of the table used for calculation of sub injection rate RINJ2. It is a flowchart which shows the other modification of a fuel-injection control process. It is a figure which shows the other modification of the table used for calculation of sub injection amount QINJ2. It is a figure which shows an example of the table used for calculation of correction | amendment term Dphi2_DIMEP. It is a figure which shows the other modification of the table used for calculation of sub injection rate RINJ2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection control apparatus 2 ECU (In-cylinder pressure detection means, Actual work parameter calculation means, Operating state parameter detection means, Required work parameter calculation means, Index value calculation means, Sub injection parameter calculation means)
3 Internal combustion engine 3a Cylinder 20 Crank angle sensor (operating state parameter detecting means)
21 In-cylinder pressure sensor (in-cylinder pressure detection means)
22 Accelerator opening sensor (operating state parameter detection means)
PCYL In-cylinder pressure IMEP Graphical mean effective pressure (actual work parameter, mean effective pressure)
NE Engine speed (operating condition parameter)
AP accelerator opening (operating condition parameter)
TRQ Required torque (Required work parameter)
RTI ratio (index ratio, required torque and average effective pressure ratio between one and the other)
QINJ2 Sub-injection amount (fuel injection amount by sub-injection)
φINJ2 Sub injection timing (Sub injection timing)
TRQ2 Torque conversion value DTRQ Torque deviation (difference between one and the other of index value, required torque and torque conversion value)
IMEP2 Pressure conversion value DIMEP Pressure deviation (difference between one and the other of index value, pressure conversion value and average effective pressure)
RINJ2 Sub-injection rate (fuel injection rate per unit time in sub-injection)

Claims (6)

The premixed compression self-ignition operation is performed when in the predetermined operation region, and the fuel is injected into the main injection and the sub-injection after that during one combustion cycle during the premixed compression self-ignition operation. A fuel injection control device for an internal combustion engine that controls fuel injection in an internal combustion engine that can be divided into
In-cylinder pressure detecting means for detecting the in-cylinder pressure of the internal combustion engine;
An actual work parameter calculating means for calculating an actual work parameter representing an actual work of the internal combustion engine according to the detected in-cylinder pressure;
An operating state parameter detecting means for detecting an operating state parameter representing an operating state of the internal combustion engine;
Requested work parameter calculating means for calculating a required work parameter representing work required for the internal combustion engine according to the detected operating state parameter;
Index value calculation means for calculating an index value representing a relative magnitude relationship between the actual work parameter and the required work parameter calculated during the premixed compression auto-ignition operation of the internal combustion engine,
During the premixed compression auto-ignition operation of the internal combustion engine, the fuel injection amount by the sub-injection, the timing of the sub-injection, and the fuel injection rate per unit time in the sub-injection according to the calculated index value Sub-injection parameter calculating means for calculating at least one of the sub-injection parameters,
A fuel injection control device for an internal combustion engine, comprising: The actual work parameter calculating means calculates one of an average effective pressure and a torque converted value obtained by converting the average effective pressure into torque as the actual work parameter,
The required work parameter calculating means calculates, as the required work parameter, one of a required torque required for the internal combustion engine and a pressure converted value obtained by converting the required torque into an average effective pressure,
The index value calculation means includes, as the index value, a ratio between one and the other of the required torque and the average effective pressure, a difference between the pressure converted value and one and the other of the average effective pressure, and the required torque and 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein one of the differences between the torque converted value and the other is calculated.   The index value calculation means calculates the index value using the required torque and the average effective pressure calculated during one combustion cycle when the internal combustion engine is controlled based on the required torque. The fuel injection control device for an internal combustion engine according to claim 2, wherein: The sub injection parameter is the fuel injection amount by the sub injection,
The sub-injection parameter calculating means determines the fuel injection amount as the ratio between the required torque and the average effective pressure is larger, as the difference between the pressure converted value and the average effective pressure is larger, or as the required torque. The fuel injection control apparatus for an internal combustion engine according to claim 2 or 3, wherein the calculation is performed such that the larger the difference from the torque conversion value, the larger the difference. The secondary injection parameter is the timing of the secondary injection,
The sub-injection parameter calculating means determines the timing of the sub-injection as the ratio between the required torque and the average effective pressure increases, the difference between the pressure converted value and the average effective pressure increases, or the required torque. 4. The fuel injection control device for an internal combustion engine according to claim 2, wherein the calculation is performed so that the timing becomes earlier as the difference between the torque conversion value and the torque conversion value increases. The secondary injection parameter is a fuel injection rate per unit time in the secondary injection,
The sub-injection parameter calculating means determines the fuel injection rate per unit time as the ratio between the required torque and the average effective pressure is larger, the difference between the pressure converted value and the average effective pressure is larger, or 4. The fuel injection control device for an internal combustion engine according to claim 2, wherein the calculation is performed such that the difference between the required torque and the torque converted value increases as the difference increases. 5.

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