JP4859731B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that controls the output of the internal combustion engine.

  Conventionally, as a control device for an internal combustion engine, for example, a device described in Patent Document 1 is known. In this internal combustion engine, a main throttle valve and a sub throttle valve are provided in the intake passage, and the intake air amount is changed by these throttle valves. The main throttle valve is mechanically connected to an accelerator pedal, and its opening degree changes in a linear relationship with the amount of depression of the accelerator pedal (hereinafter referred to as “accelerator opening degree”). On the other hand, the sub-throttle valve is connected to a stepping motor, and the opening degree is controlled by driving the stepping motor by a drive command signal from the control device.

  In this control device, based on the deviation between the average driving wheel speed and the average driven wheel speed, the road surface has a high road resistance (hereinafter referred to as “high μ road”) and a low road surface (hereinafter referred to as “low μ road”). When it is determined that the road is a low μ road, the target opening of the sub-throttle valve is calculated by searching a map for the low μ road. On the other hand, when it is determined that the road is a high μ road, two map search values are calculated by searching the maps for the high μ road and the low μ road, respectively. Set to the target opening of the throttle valve. Thereby, when the road surface is switched from the low μ road to the high μ road, the target opening of the sub-throttle valve gradually increases from the map search value for the low μ road toward the map search value for the high μ road. As a result, the intake air amount is controlled to gradually increase via the sub-throttle valve, so that the output of the internal combustion engine is controlled to gradually increase.

JP-A-6-330786

  According to the above-described conventional control device, the target opening of the sub-throttle valve is merely calculated based on the level of the frictional resistance of the road surface regardless of the actual operation state and actual output state of the internal combustion engine. Therefore, when the internal combustion engine shifts between the steady operation state and the transient operation state, there is a problem that the output of the internal combustion engine cannot be appropriately controlled. For example, when the accelerator opening changes suddenly due to the driver's operation and the internal combustion engine shifts from the steady operation state to the transient operation state, the main throttle valve opening changes suddenly with the sudden change of the accelerator opening, so that the internal combustion engine Sudden output fluctuations and rotation fluctuations may occur, and in this case, the drivability and stability of the internal combustion engine both decrease.

  The present invention has been made to solve the above-described problems, and can suppress the occurrence of output fluctuations, rotation fluctuations, and the like of an internal combustion engine even when the internal combustion engine transitions between a steady operation state and a transient operation state. Thus, an object of the present invention is to provide a control device for an internal combustion engine that can improve both drivability and stability.

In order to achieve the above object, the control device 1 for the internal combustion engine 3 according to claim 1, in one combustion cycle, fuel is injected divided into a pilot injection timing φINJ_P1 and a main injection timing φINJ_M1 after that. The control device 1 for the internal combustion engine 3 includes an in-cylinder pressure parameter detecting means (ECU 2, an in-cylinder pressure sensor 21) for detecting an in-cylinder pressure parameter (indicated mean effective pressure IMEP) indicating a pressure state in the cylinder 3a of the internal combustion engine 3. Step 3), target value calculation means (ECU2, step 12) for calculating a target value of the in-cylinder pressure parameter (target effective pressure IMEP_CMD), and the internal combustion engine 3 are in a steady operation state or a transient operation state. The operation state determination means (ECU2, steps 14-20 , 62 , 63 , 72 , 73) for determining whether And fruit, according to the deviation degree of the in-cylinder pressure parameters for the target value (effective pressure deviation DIMEP), calculated as an operation amount for changing the output of the internal combustion engine 3, the pilot injection timing φINJ_P and the main injection timing φINJ_M injection timing calculating means (ECU 2, steps 4 4,45) and comprises, injection timing calculating means, the operating condition determining means, when the internal combustion engine 3 is determined to be in the steady operating condition (step 53, 63, the question of the 73 time is YES), the pilot injection timing φINJ_P and the main injection timing steady operation for values of φINJ_M φ INJ_M1, steady operation for value calculating means for calculating a φINJ_P1 (ECU2, and step 6 4,74), when when the internal combustion engine 3 is determined to be in transient operation state (step 6 2,72 determination result is YES ), The pilot injection timing φINJ_P and the main injection timing transient operation for values of φINJ_M φ INJ_M2, value for steady operation of φINJ_P2 φ INJ_M1, transient operation for value calculating means for calculating a value different from φINJ_P1 (ECU2, Step 6 8, 78), when the degree of deviation of the cylinder inner pressure parameter for the target value is within a predetermined range (DI_1 ≦ DIMEP ≦ DI_2) (when the determination result of step 6 5,75 is NO), in accordance with the deviation degree, The pilot injection timing φINJ_P and the main injection timing φINJ_M are calculated by the weighted average calculation (equations (2) and (3)) of the steady operation values φINJ_M1, φINJ_P1 and the transient operation values φINJ_M2, φINJ_P2, and the degree of deviation is calculated. The smaller the value, the weight of the value for steady operation in the weighted average calculation Interpolation calculation means (ECU 2, steps 6 6,76) is set to a value greater than a, and having a.

According to the control device for an internal combustion engine, when it is determined that the internal combustion engine is in a steady operation state, values for steady operation of the pilot injection timing and the main injection timing are calculated, and it is determined that the internal combustion engine is in a transient operation state. When the value is set, the transient operation values for the pilot injection timing and the main injection timing are calculated, and when the deviation degree of the in-cylinder pressure parameter with respect to the target value is within a predetermined range, the steady operation value and The pilot injection timing and the main injection timing are calculated by the weighted average calculation of the transient operation values. Therefore, when the internal combustion engine transitions between the steady operation state and the transient operation state, if the deviation degree of the in-cylinder pressure parameter with respect to the target value is within a predetermined range, the pilot injection timing and the main injection timing are the steady operation value and Since it is calculated so as to gradually change between the values for transient operation, by changing the output of the internal combustion engine using such pilot injection timing and main injection timing , output fluctuation and rotation fluctuation of the internal combustion engine, etc. Can be prevented from occurring. As a result, both the drivability and stability of the internal combustion engine can be improved. Further, since the in-cylinder pressure parameter represents the pressure state in the cylinder of the internal combustion engine, it is calculated so as to accurately represent the actual output state of the internal combustion engine. Therefore, the pilot injection timing and the main injection timing are accurately reflected on the actual output state of the internal combustion engine by executing the interpolation calculation of the steady operation value and the transient operation value in accordance with the in-cylinder pressure parameter. Can be calculated. As a result, the output of the internal combustion engine can be controlled with high accuracy. Further, as the degree of deviation is smaller, the weight of the steady operation value in the weighted average calculation is set to a larger value. In this case, a state where the deviation degree of the in-cylinder pressure parameter with respect to the target value is small indicates that the internal combustion engine is in a state close to a steady operation state. Therefore, according to this control apparatus, the closer the internal combustion engine is to the steady operation state, the larger the weight of the steady operation value in the weighted average calculation is set, whereas the internal combustion engine is closer to the transient operation state. The more the state is, the lower the weight of the steady operation value in the weighted average calculation is set. As a result, the pilot injection timing and the main injection timing can be calculated while accurately reflecting the actual operating state of the internal combustion engine, and the accuracy of the output control of the internal combustion engine can be further improved (this specification) “The detection of the in-cylinder pressure parameter” is not limited to the direct detection of the in-cylinder pressure parameter by a sensor or the like, but includes the calculation or estimation of the in-cylinder pressure parameter).

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

  The engine 3 is an in-line four-cylinder diesel engine mounted on a vehicle (not shown), 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 in FIG. 2).

  The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, 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.

  The in-cylinder pressure sensor 21 is of a piezoelectric element type integrated with a glow plug (not shown) provided for each cylinder 3a, and changes in the pressure in the corresponding cylinder 3a, that is, in-cylinder pressure PCYL. By bending, the detection signal indicating 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 parameter detection means, and the indicated mean effective pressure IMEP corresponds to the in-cylinder pressure parameter.

  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.

  On the other hand, in the intake passage 5 of the engine 3, an air flow sensor 22, a turbocharger 6, a supercharging pressure sensor 23, an intake throttle valve mechanism 7, and the like are provided in order from the upstream side. The air flow sensor 22 is composed of a hot-wire air flow meter, detects the flow rate of fresh air that passes through an intake throttle valve 7a described later, and outputs a detection signal representing it to the ECU 2. The ECU 2 calculates the actual fresh air amount QAIR based on the detection signal of the air flow sensor 22.

  The turbocharger 6 includes a compressor blade 6a provided on the downstream side of the air flow sensor 22 in the intake passage 5, a turbine blade 6b provided in the middle of the exhaust passage 9, and rotating integrally with the compressor blade 6a. Variable vanes 6c (only two are shown), a vane actuator 6d for driving the variable vanes 6c, and the like.

  In the turbocharger 6, when the turbine blade 6b is rotationally driven by the exhaust gas in the exhaust passage 9, the compressor blade 6a integrated with the turbine blade 6b is also rotated at the same time, so that the air in the intake passage 5 is pressurized. That is, the supercharging operation is executed.

  The variable vane 6c is for changing the supercharging pressure generated by the turbocharger 6, and is rotatably attached to the wall of the portion of the housing that houses the turbine blade 6b. The variable vane 6c is mechanically coupled to a vane actuator 6d connected to the ECU 2. The ECU 2 changes the rotational speed of the turbine blade 6b, that is, the rotational speed of the compressor blade 6a by changing the opening of the variable vane 6c via the vane actuator 6d and changing the amount of exhaust gas blown to the turbine blade 6b. Thereby, the supercharging pressure is controlled.

  On the other hand, the supercharging pressure sensor 23 is constituted by a semiconductor pressure sensor or the like, detects the pressure in the intake passage 5 pressurized by the turbocharger 6, that is, the supercharging pressure PC, and outputs a detection signal indicating it to the ECU 2. To do. The ECU 2 calculates the supercharging pressure PC based on the detection signal of the supercharging pressure sensor 23.

  The intake throttle valve mechanism 7 includes an intake throttle valve 7a and an ISV actuator 7b for driving the intake throttle valve 7a. The intake throttle valve 7a is rotatably provided in the middle of the intake passage 5, and changes the flow rate of the air passing through the intake throttle valve 7a by the change of the opening degree accompanying the rotation. The ISV actuator 7b is a combination of a motor and a reduction gear mechanism (both not shown), and is electrically connected to the ECU 2. The ECU 2 controls the opening degree of the intake throttle valve 7a via the ISV actuator 7b, thereby controlling the actual fresh air amount QAIR.

  The engine 3 is provided with an exhaust gas recirculation mechanism 8. The exhaust gas recirculation mechanism 8 recirculates a part of the exhaust gas in the exhaust passage 9 to the intake passage 5 side, and includes an EGR passage 8a connected between the intake passage 5 and the exhaust passage 9, and the EGR passage 8a. And an EGR control valve 8b that opens and closes. One end of the EGR passage 8a opens to a portion of the exhaust passage 9 upstream of the turbine blade 6b, and the other end opens to a portion of the intake passage 5 downstream of the intake throttle valve 7a.

  The EGR control valve 8b is a linear electromagnetic valve whose lift changes linearly between a maximum value and a minimum value, and is electrically connected to the ECU 2. The ECU 2 controls the recirculation amount of exhaust gas, that is, the EGR amount, by changing the opening degree of the EGR passage 8a via the EGR control valve 8b.

  An upstream EGR pressure sensor 24 and an EGR temperature sensor 26 are provided on the upstream side of the EGR control valve 8b in the EGR passage 8a (that is, the exhaust passage 9 side), and on the downstream side of the EGR control valve 8b, A downstream EGR pressure sensor 25 is provided. The upstream EGR pressure sensor 24 detects a pressure (hereinafter referred to as “upstream EGR pressure”) PEGRU in the EGR passage 8 a on the upstream side of the EGR control valve 8 b, and outputs a detection signal representing it to the ECU 2.

  Further, the EGR temperature sensor 26 detects the temperature (hereinafter referred to as “EGR temperature”) TEGR in the EGR passage 8a, and outputs a detection signal representing the detected temperature to the ECU 2, and the downstream EGR pressure sensor 25 includes the EGR control valve. The pressure in the EGR passage 8a on the downstream side of 8b (hereinafter referred to as “downstream EGR pressure”) PEGRD is detected, and a detection signal indicating it is output to the ECU 2.

  On the other hand, as shown in FIG. 2, an accelerator opening sensor 27 and four wheel speed sensors 28 (only one is shown) are connected to the ECU 2. The accelerator opening sensor 27 detects a depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle and outputs a detection signal representing the detected AP to the ECU 2.

  Each of the four wheel speed sensors 28 detects the rotational speed of the four wheels of the vehicle, and outputs a detection signal representing it to the ECU 2. The ECU 2 calculates the vehicle speed VP based on the detection signals of these wheel speed sensors 28.

  On the other hand, the ECU 2 is composed of a microcomputer including a CPU, RAM, ROM, I / O interface and drive circuit (none of which are shown), and corresponds to the detection signals of the various sensors 20 to 28 described above. Then, various control processes such as a determination process of the operating state of the engine 3, a calculation process of the indicated mean effective pressure IMEP, a fuel injection control process, and an intake air amount control process are executed. Thereby, the output of the engine 3 is controlled.

In this embodiment, the ECU 2 corresponds to in-cylinder pressure parameter detection means, target value calculation means, operation state determination means, injection timing calculation means, steady operation value calculation means, transient operation value calculation means, and interpolation calculation means. To do.

  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 calculates the indicated mean effective pressure IMEP in the combustion cycle for each cylinder 3a, and is executed at a predetermined cycle (for example, a cycle at a crank angle of 1 °). In addition, the various values calculated in the following description shall be memorize | stored in RAM of ECU2. 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.

  Next, the driving state determination process executed by the ECU 2 will be described with reference to FIG. As described below, this process calculates the required torque TRQ and the target effective pressure IMEP_CMD and determines whether or not the engine 3 is in a transient operation state. The first TDC signal in one combustion cycle is determined in this process. It is executed in synchronization with the occurrence. That is, it is executed only once during one combustion cycle.

  In this process, first, in step 10, various data such as the engine speed NE, the actual fresh air amount QAIR, the accelerator opening AP, the vehicle speed VP, and the supercharging pressure PC, which are stored in the RAM, are read.

  Next, the routine proceeds to step 11 where the required torque TRQ is calculated. Specifically, the required torque TRQ is calculated as shown in FIG. First, in step 30, the basic torque TRQ_BASE is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP. This basic torque TRQ_BASE is a value representing an output required for the engine 3 due to the driver's accelerator pedal operation or the like.

  In this map, the basic torque TRQ_BASE is set to a larger value as the accelerator opening AP is larger. This is because the output required for the engine 3 increases as the accelerator opening AP increases. Further, in this map, the basic torque TRQ_BASE is set to a larger value as the engine speed NE is higher in the low / medium speed range, for the reason described above. Furthermore, the basic torque TRQ_BASE is set to a smaller value as the engine speed NE is higher in the high speed range. This is to suppress the occurrence of knocking.

  Next, the routine proceeds to step 31, where a limit value TRQ_LMT is calculated by searching a map (not shown) according to the engine speed NE and the actual fresh air amount QAIR. This limit value TRQ_LMT represents the upper limit value of the torque that can be output by the engine 3 with respect to the current values of the engine speed NE and the actual fresh air amount QAIR.

  In this map, the limit value TRQ_LMT is set to a larger value as the actual fresh air amount QAIR increases. This is because the torque that the engine 3 can output increases as the actual fresh air amount QAIR increases. Further, in this map, the limit value TRQ_LMT is set to a larger value as the engine speed NE is higher in the low / medium speed range. This is because the engine speed NE is higher in the low / medium speed range. This is because the torque that the engine 3 can output increases. Further, limit value TRQ_LMT is set to a smaller value in the high engine speed range as engine speed NE is higher. This is to suppress the occurrence of knocking as described above.

  In step 32 following step 31, it is determined whether or not the basic torque TRQ_BASE is smaller than the limit value TRQ_LMT. When the determination result is YES, the process proceeds to step 33, the required torque TRQ is set to the basic torque TRQ_BASE, and the process is terminated.

  On the other hand, if the determination result in step 32 is NO and TRQ_BASE ≧ TRQ_LMT, the process proceeds to step 34, and the requested torque TRQ is set to the limit value TRQ_LMT.

  Returning to FIG. 4, after calculating the required torque TRQ as described above in step 11, the process proceeds to step 12 to calculate the target effective pressure IMEP_CMD. This target effective pressure IMEP_CMD is a target value that is a target of the indicated mean effective pressure IMEP, and is specifically calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ.

  In this map, the target effective pressure IMEP_CMD is set to a larger value as the required torque TRQ is larger. This is because the amount of work required for the engine 3 increases as the required torque TRQ increases. Further, in this map, the target effective pressure IMEP_CMD is set to a larger value as the engine speed NE is higher in the low / medium speed range, for the reason described above. Further, the target effective pressure IMEP_CMD is set to a smaller value as the engine speed NE is higher in the high speed range. This is to suppress the occurrence of knocking as described above.

  Next, at step 13, the effective pressure deviation DMIEP is set to the absolute value | IMEP_CMD-IMEP | of the deviation between the target effective pressure and the indicated mean effective pressure. Thereafter, the process proceeds to step 14 to determine whether NE1 <NE <NE2 is satisfied. These values NE1 and NE2 are predetermined values of the engine speed NE such that NE1 <NE2 is satisfied.

  When the determination result of this step 14 is YES, it progresses to step 15 and it is determined whether VP1 <VP <VP2 is materialized. These values VP1 and VP2 are predetermined values of the vehicle speed VP that satisfy VP1 <VP2.

  When the determination result of this step 15 is YES, it progresses to step 16, and it is determined whether TRQ1 <TRQ <TRQ2 is materialized. These values TRQ1, TRQ2 are predetermined values of the required torque TRQ that satisfies TRQ1 <TRQ2.

  When the determination result of this step 16 is YES, it progresses to step 17, and it is determined whether the EGR amount deviation DQEGR is smaller than a predetermined value DQEGR1. This EGR amount deviation DQEGR corresponds to the absolute value | QEGR_CMD-QEGR | of the deviation between the target EGR amount QEGR_CMD and the actual EGR amount QEGR. The The predetermined value DQEGR1 is set to a positive constant value.

  When the determination result of this step 17 is YES, it progresses to step 18, and it is determined whether the supercharging pressure deviation DPC is smaller than the predetermined value DPC1. This supercharging pressure deviation DPC corresponds to the absolute value | QPC_CMD−QPC | of the deviation between the target supercharging pressure PC_CMD and the supercharging pressure PC, and the target supercharging pressure PC_CMD is a supercharging pressure control process to be described later. Is calculated in

  When the determination result of step 18 is YES, that is, when all the determination results of steps 14 to 18 are YES, it is determined that the engine 3 is not in a transient operation state, and the process proceeds to step 19 to represent it. After the transient operation flag F_TRANS is set to “0”, this process is terminated.

  On the other hand, when the determination result in any one of steps 14 to 18 is NO, it is determined that the engine 3 is in a transient operation state, and the process proceeds to step 20, in which the transient operation flag F_TRANS is set to “1”. After setting, this process is terminated.

  Next, the fuel injection control process executed by the ECU 2 will be described with reference to FIG. This control process calculates the main injection amount QINJ_M, the pilot injection amount QINJ_P, the main injection timing φINJ_M, and the pilot injection timing φINJ_P for each cylinder 3a as described below, and is executed in synchronization with the generation of the TDC signal. Is done. In the present embodiment, the pilot injection amount QINJ_P, the main injection timing φINJ_M, and the pilot injection timing φINJ_P correspond to the manipulated variables.

  In this process, first, in step 40, 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.

  Next, the routine proceeds to step 41, where the total injection amount QINJ is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ.

  This total injection amount QINJ represents the total amount of fuel to be injected into the corresponding cylinder 3a in one combustion cycle. In this map, the total injection amount QINJ corresponds to a larger required torque TRQ. It is set to a larger value. Further, the total injection amount QINJ is set to a larger value as the engine speed NE is higher in the low / medium speed range, and is set to a smaller value in the high speed range as the engine speed NE is higher. Has been. This is to suppress the occurrence of knocking as described above.

  Next, at step 42, a pilot injection amount QINJ_P is calculated. Specifically, the pilot injection amount QINJ_P is calculated as shown in FIG. First, at step 50, a steady operation value QINJ_P1 of the pilot injection amount is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ.

  The steady operation value QINJ_P1 represents the amount of fuel to be injected at the pilot injection timing when the engine 3 is in the steady operation state. In this map, the steady operation value QINJ_P1 is injected at the main injection timing. It is set to slow down the combustion of the fuel and suppress the combustion noise. Specifically, on the high load side (high rotation side), the combustion noise is loud and pilot injection is not required, so the steady operation value QINJ_P1 is set to a value of zero. In the low speed range, the steady operation value QINJ_P1 is set to a larger value as the engine speed NE is lower. This is because in the low speed range, if the pilot injection amount is small, the temperature in the combustion chamber becomes low, and diffusion combustion at the time of main injection becomes inactive, so that good ignitability of the air-fuel mixture cannot be secured. In order to cope with it.

  In step 51 following step 50, a transient operation value QINJ_P2 of the pilot injection amount is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ.

  This transient operation value QINJ_P2 indicates the amount of fuel to be injected at the pilot injection timing when the engine 3 is in the transient operation state in order to slow down the combustion of the fuel injected at the main injection timing and suppress the combustion noise. In this map, the transient operation value QINJ_P2 is generally set to a larger value than the above-described steady operation value QINJ_P1. This is because in the transient operation state, the combustion noise of the engine 3 becomes larger than that in the steady operation state, so that it corresponds to that. Specifically, the transient operation value QINJ_P2 is set to a value of 0 because the combustion noise is loud on the high load side (high rotation side) and pilot injection is unnecessary. In the low speed range, the transient operation value QINJ_P2 is set to a larger value as the engine speed NE is lower. This is because in the low speed range, if the pilot injection amount is small, the temperature in the combustion chamber becomes low, and diffusion combustion at the time of main injection becomes inactive, so that good ignitability of the air-fuel mixture cannot be secured. In order to cope with it.

  Next, in step 52, it is determined whether or not the above-described transient operation flag F_TRANS is “1”. When the determination result is YES and the engine 3 is in the transient operation state, the process proceeds to step 59, and the pilot injection amount QINJ_P is set to the transient operation value QINJ_P2. Thereafter, this process is terminated.

  On the other hand, when the determination result of step 52 is NO, the process proceeds to step 53, where it is determined whether or not the effective pressure deviation DIMEP is smaller than the steady determination value DI_1. The steady state determination value DI_1 is set to a positive constant value.

  When the determination result in step 53 is YES, it is determined that the engine 3 is in the steady operation state, the process proceeds to step 54, and the pilot injection amount QINJ_P is set to the steady operation value QINJ_P1. Thereafter, this process is terminated.

  On the other hand, when the determination result of step 53 is NO, the process proceeds to step 55 to determine whether or not the effective pressure deviation DIMEP is larger than the transient determination value DI_2. The transient determination value DI_2 is set to a positive constant value that satisfies DI_1 <DI_2.

  If the determination result in step 55 is YES and DIMEP> DI_2 is satisfied, it is determined that the engine 3 is in the transient operation state, and the process proceeds to step 59 described above, and the pilot injection amount QINJ_P is set to the transient operation value QINJ_P2. After setting to, this process ends.

  On the other hand, when the determination result of step 55 is NO and DI_1 ≦ DIMEP ≦ DI_2 is established, it is determined that the engine 3 is in the middle of transition between the transient operation state and the steady operation state. Proceeding to 56, the weight K is calculated by searching the table shown in FIG. 8 according to the effective pressure deviation DIMEP.

  As shown in the figure, in this table, the weight K is set to a value of 1.0 when DIMEP = DI_1, and to a value of 0 when DIMEP = DI_2, and in the range of DI_1 <DIMEP <DI_2, The smaller the effective pressure deviation DIMEP is, the larger the value is set. The reason for this will be described later. In the present embodiment, the effective pressure deviation DIMEP corresponds to the degree of deviation of the in-cylinder pressure parameter from the target value, and DI_1 <DIMEP <DI_2 corresponds to the predetermined range.

In step 57 following step 56, a pilot injection amount transition value QINJ_P3 is calculated by the following equation (1).
QINJ_P3 = K.QINJ_P1 + (1-K) .QINJ_P2 (1)

  As shown in the above equation (1), the transition time value QINJ_P3 is calculated by the weighted average calculation of the steady operation value QINJ_P1 and the transient operation value QINJ_P2 using the two weights K, 1-K (reflection degree). Therefore, as the weight K increases, the ratio of the steady operation value QINJ_P1 reflected in the transition value QINJ_P3 increases. In this case, the smaller the effective pressure deviation DIMEP is, the closer the engine 3 is to a steady operation state. Therefore, the weight K is increased to increase the ratio of the steady operation value QINJ_P1 reflected in the transition value QINJ_P3. Must be set to a value. For the above reason, in the table of FIG. 8 described above, the weight K is set to a larger value as the effective pressure deviation DIMEP is smaller in the region of DI_1 <DIMEP <DI_2.

  Next, the routine proceeds to step 58, where the pilot injection amount QINJ_P is set to the transition time value QINJ_P3, and then this processing is terminated.

  Returning to FIG. 6, after calculating the pilot injection amount QINJ_P as described above in step 42, the process proceeds to step 43, where the main injection amount QINJ_M is set to a value QINJ−QINJ_P obtained by subtracting the pilot injection amount QINJ_P from the total injection amount QINJ. To do.

  Next, the routine proceeds to step 44, where the main injection timing φINJ_M is calculated. The calculation process of the main injection timing φINJ_M is specifically executed as shown in FIG. First, in step 60, a steady operation value φINJ_M1 of the main injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ. In this map, the steady operation value φINJ_M1 is set to a predetermined crank angle near the TDC of the compression stroke.

  In step 61 following step 60, a transient operation value φINJ_M2 of the main injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ. In this map, the transient operation value φINJ_M2 is a predetermined crank angle in the vicinity of the TDC of the compression stroke and is different from the above-described steady operation value φINJ_M1, specifically, more than the steady operation value φINJ_M1. The value is set on the retard side. As described above, this is because the combustion noise of the engine 3 becomes larger in the transient operation state than in the steady operation state, and this is to cope with it.

  Next, the routine proceeds to step 62, where it is determined whether or not the transient operation flag F_TRANS described above is “1”. When the determination result is YES and the engine 3 is in the transient operation state, the process proceeds to step 68, and the main injection timing φINJ_M is set to the transient operation value φINJ_M2. Thereafter, this process is terminated.

  On the other hand, when the determination result in step 62 is NO, it is determined in step 63 whether or not the effective pressure deviation DIMEP described above is smaller than the steady determination value DI_1 described above. When the determination result is YES, it is determined that the engine 3 is in a steady operation state, the process proceeds to step 64, and the main injection timing φINJ_M is set to a steady operation value φINJ_M1. Thereafter, this process is terminated.

  On the other hand, when the determination result of step 63 is NO, the process proceeds to step 65, where it is determined whether or not the effective pressure deviation DIMEP is larger than the transient determination value DI_2 described above. When the determination result is YES, it is determined that the engine 3 is in a transient operation state, the process proceeds to step 68 described above, and the main injection timing φINJ_M is set to the transient operation value φINJ_M2, and then this process is terminated.

On the other hand, when the determination result in step 65 is NO and DI_1 ≦ DIMEP ≦ DI_2 is established, it is determined that the engine 3 is in the middle of transition between the transient operation state and the steady operation state. Proceeding to 66, a value φINJ_M3 for transition of the main injection timing is calculated by the following equation (2).
φINJ_M3 = K · φINJ_M1 + (1-K) · φINJ_M2 (2)

  As shown in the above equation (2), the transition time value φINJ_M3 is calculated by the weighted average calculation of the steady operation value φINJ_M1 and the transient operation value φINJ_M2 using the two weights K and 1-K.

  Next, the routine proceeds to step 67, where the main injection timing φINJ_M is set to the transition time value φINJ_M3, and then this processing is terminated.

  Returning to FIG. 6, after calculating the main injection timing φINJ_M as described above in step 44, the process proceeds to step 45 to calculate the pilot injection timing φINJ_P. Specifically, the pilot injection timing φINJ_P is calculated as shown in FIG.

  First, in step 70, a steady operation value φINJ_P1 of the pilot injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ. In this map, the steady operation value φINJ_P1 is set to a crank angle that is more advanced than the aforementioned steady operation value φINJ_M1 of the main injection timing.

  In step 71 subsequent to step 70, a transient operation value φINJ_P2 of the pilot injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque TRQ. In this map, the transient operation value φINJ_P2 is different from the above-described steady operation value φINJ_P1, and is set to a crank angle that is more advanced than the transient operation value φINJ_M2 of the main injection timing described above. .

  Next, in step 72, it is determined whether or not the above-described transient operation flag F_TRANS is “1”. If the determination result is YES and the engine 3 is in a transient operation state, the routine proceeds to step 78, where the pilot injection timing φINJ_P is set to the transient operation value φINJ_P2. Thereafter, this process is terminated.

  On the other hand, when the determination result in step 72 is NO, it is determined in step 73 whether or not the effective pressure deviation DIMEP described above is smaller than the steady determination value DI_1 described above. When the determination result is YES, it is determined that the engine 3 is in a steady operation state, the process proceeds to step 74, and the pilot injection timing φINJ_P is set to a steady operation value φINJ_P1. Thereafter, this process is terminated.

  On the other hand, when the determination result of step 73 is NO, the process proceeds to step 75 to determine whether or not the effective pressure deviation DIMEP is larger than the above-described transient determination value DI_2. If the determination result is YES, it is determined that the engine 3 is in a transient operation state, the process proceeds to step 78 described above, and the pilot injection timing φINJ_P is set to the transient operation value φINJ_P2, and then this process is terminated.

On the other hand, when the determination result in step 75 is NO and DI_1 ≦ DIMEP ≦ DI_2 is established, it is determined that the engine 3 is in the middle of transition between the transient operation state and the steady operation state. Proceeding to 76, a value φINJ_P3 for transition of the pilot injection timing is calculated by the following equation (3).
φINJ_P3 = K · φINJ_P1 + (1-K) · φINJ_P2 (3)

  As shown in the above equation (3), the transition time value φINJ_P3 is calculated by the weighted average calculation of the steady operation value φINJ_P1 and the transient operation value φINJ_P2 using the two weights K and 1-K.

  Next, the routine proceeds to step 77, where the pilot injection timing φINJ_P is set to the transition time value φINJ_P3, and then this processing is terminated.

  Returning to FIG. 6, after calculating the pilot injection timing φINJ_P as described above in step 45, the present process is terminated.

  Next, an intake air amount control process executed by the ECU 2 will be described with reference to FIG. As will be described below, this process controls the amount of fresh air and EGR drawn into the cylinder 3a by executing various control processes, and is executed at a predetermined control cycle.

  In this process, first, in step 80, it is determined whether or not the above-described transient operation flag F_TRANS is “1”. When the determination result is NO, in steps 81 to 83 below, the intake air amount control process for steady operation is executed.

  First, in step 81, an EGR control process for steady operation is executed. Specifically, first, the actual EGR amount QEGR is calculated based on the above-described upstream EGR pressure PEGRU, downstream EGR pressure PEGRD, and EGR temperature TEGR. Next, a target EGR amount QEGR_CMD for steady operation is calculated by searching a map (not shown) according to the required torque TRQ and the engine speed NE. Then, the control input to the EGR control valve 8b is calculated by an algorithm based on a model that defines the relationship between the actual EGR amount QEGR and the target EGR amount QEGR_CMD, and then the drive signal corresponding to the control input is output to the EGR control valve 8b. 8b. Thereby, the EGR amount is controlled via the EGR control valve 8b.

  Next, the routine proceeds to step 82 where the ISV control process for steady operation is executed. Specifically, a target fresh air amount QAIR_CMD for steady operation is calculated by searching a map (not shown) according to the required torque TRQ and the engine speed NE. Then, the control input to the ISV actuator 7b is calculated by an algorithm based on a model that defines the relationship between the actual fresh air amount QAIR and the target fresh air amount QAIR_CMD, and then the drive signal corresponding to the control input is sent to the ISV actuator 7b. 7b. Thereby, the amount of fresh air is controlled via the intake throttle valve 7a.

  Next, in step 83, a boost pressure control process for steady operation is executed. Specifically, a target boost pressure PC_CMD for steady operation is calculated by searching a map (not shown) according to the required torque TRQ and the engine speed NE, and the target boost pressure PC_CMD for steady operation is calculated. A corresponding drive signal is supplied to the vane actuator 6d. Thereby, the supercharging pressure PC is controlled via the turbocharger 6. Thereafter, this process is terminated.

  On the other hand, if the decision result in the step 80 is YES and the engine 3 is in a transient operation state, the intake air amount control process for the transient operation is executed in the following steps 84 to 86.

  First, in step 84, an EGR control process for transient operation is executed. Specifically, the actual EGR amount QEGR and the target EGR amount QEGR_CMD for transient operation are calculated by the same method as in step 81 described above. Then, after calculating the control input to the EGR control valve 8b by the method described above, a drive signal corresponding to the control input is supplied to the EGR control valve 8b. Thereby, the EGR amount is controlled via the EGR control valve 8b.

  Next, the process proceeds to step 85, and the ISV control process for transient operation is executed. Specifically, the target fresh air amount QAIR_CMD for transient operation is calculated by the same method as in step 82 described above. Then, after calculating the control input to the ISV actuator 7b by the method described above, a drive signal corresponding to the control input is supplied to the ISV actuator 7b. Thereby, the amount of fresh air is controlled via the intake throttle valve 7a.

  Next, in step 86, a boost pressure control process for transient operation is executed. Specifically, the target boost pressure PC_CMD for transient operation is calculated by the same method as in step 83 described above, and a drive signal corresponding to the target boost pressure PC_CMD for transient operation is supplied to the vane actuator 6d. . Thereby, the supercharging pressure PC is controlled via the turbocharger 6. Thereafter, this process is terminated.

  As described above, according to the control apparatus 1 for an internal combustion engine of the present embodiment, it is determined that the engine 3 is in a transient operation state as calculated values of the pilot injection amount QINJ_P, the main injection timing φINJ_M, and the pilot injection timing φINJ_P. Sometimes, the transient operation values QINJ_P2, φINJ_M2, and φINJ_P2 are used, and when it is determined that the engine 3 is in the steady operation state, the steady operation values QINJ_P1, φINJ_M1, and φINJ_P1 are used. Further, when it is determined that the state is not in the transient operation state, when DI_1 ≦ DIMEP ≦ DI_2 is established, the weight K is calculated according to the effective pressure deviation DIMEP, and the value for steady operation is calculated using the weight K. Three values QINJ_P, φINJ_M, and φINJ_P are calculated by interpolation calculation of QINJ_P1, φINJ_M1, φINJ_P1, and transient operation values QINJ_P2, φINJ_M2, and φINJ_P2, respectively.

  Accordingly, when the engine 3 shifts between the steady operation state and the transient operation state, when DI_1 ≦ DIMEP ≦ DI_2, the three values QINJ_P, φINJ_M, and φINJ_P are the steady operation value and the transient operation value. Therefore, by controlling the output of the engine 3 using such three values QINJ_P, φINJ_M, and φINJ_P, output fluctuation and rotation fluctuation of the engine 3 occur. Can be suppressed. As a result, both the drivability and stability of the engine 3 can be improved.

  Further, the indicated mean effective pressure IMEP accurately represents the actual output state of the engine 3, and therefore, the interpolation operation of the steady operation value and the transient operation value is performed according to the indicated mean effective pressure IMEP. By executing, the three values QINJ_P, φINJ_M, and φINJ_P can be calculated while accurately reflecting the actual output state in the engine 3. As a result, the output of the engine 3 can be controlled with high accuracy.

  The embodiment is an example in which the indicated mean effective pressure IMEP is used as the in-cylinder pressure parameter. However, the in-cylinder pressure parameter of the present invention is not limited to this, and the in-cylinder pressure PCYL or a predetermined crank angle (for example, 1 °) is used. Anything that represents the pressure state in the cylinder of the internal combustion engine, such as a change in the in-cylinder pressure PCYL, may be used. For example, when the in-cylinder pressure PCYL is used as the in-cylinder pressure parameter, when a deviation (or an absolute value thereof) between the maximum value of the in-cylinder pressure PCYL during one combustion cycle of the cylinder and the target value is within a predetermined range, Interpolation calculation may be executed according to the deviation. In this case, since the indicated mean effective pressure IMEP used in the embodiment is calculated as an integral value of the in-cylinder pressure PCYL, higher control accuracy can be ensured than in the case of using the in-cylinder pressure PCYL and its change. it can.

  The embodiment is an example in which the effective pressure deviation DIMEP (= | IMEP_CMD−IMEP |) is used as the deviation degree of the in-cylinder pressure parameter with respect to the target value. However, the deviation degree of the present invention is not limited to this, and both It only needs to represent the degree of deviation. For example, a relative ratio (IMEP_CMD / IMEP or IMEP / IMEP_CMD) between the indicated mean effective pressure IMEP and the target effective pressure IMEP_CMD may be used as the degree of deviation of the in-cylinder pressure parameter from the target value. Further, when the in-cylinder pressure PCYL is used as the in-cylinder pressure parameter, a relative ratio between the maximum value of the in-cylinder pressure PCYL in one combustion cycle and its target value may be used.

  Furthermore, although the pilot injection amount QINJ_P, the main injection timing φINJ_M, and the pilot injection timing φINJ_P are calculated as operation amounts for changing the output of the internal combustion engine, the operation amount of the present invention is not limited to this, and the internal combustion engine Any value for changing the output of. For example, when the control device of the present invention is applied to a gasoline engine, the ignition timing may be used as the operation amount.

  On the other hand, in the embodiment, when the transient operation flag F_TRANS = 0 and it is determined that the engine 3 is not in the transient operation state, when DI_1 ≦ DMEP ≦ DI_2 is satisfied, the steady operation value and the transient operation value are satisfied. This is an example in which value interpolation calculation is performed. However, the present invention is not limited to this, and regardless of the value of the transient operation flag F_TRANS, when DI_1 ≦ DMEP ≦ DI_2 holds, You may comprise so that the interpolation calculation of the value for driving | running | working may be performed.

  Moreover, although embodiment is an example which applied the control apparatus of this invention to the diesel engine as an internal combustion engine, this invention is applicable not only to this but internal combustion engines, such as a gasoline engine.

  Furthermore, the embodiment is an example in which the in-cylinder pressure sensor 21 is provided for each cylinder 3a, and the in-cylinder pressure PCYL and the indicated mean effective pressure IMEP are calculated for each cylinder 3a. However, in one of the four cylinders 3a, one cylinder 3a is provided. In-cylinder pressure sensor 21 is provided, and the in-cylinder pressure PCYL and the indicated mean effective pressure IMEP in this one cylinder 3a are calculated. Using this indicated mean effective pressure IMEP, three values QINJ_P, φINJ_M, and φINJ_P are calculated for each cylinder 3a May be.

It is a figure which shows schematic structure of the internal combustion engine to which the control apparatus which concerns on one Embodiment of this invention is applied. It is a block diagram which shows schematic structure of a control apparatus. It is a flowchart which shows the calculation process of illustrated mean effective pressure IMEP. It is a flowchart which shows a driving | running state determination process. 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 flowchart which shows the calculation process of pilot injection quantity QINJ_P. It is a figure which shows an example of the table used for calculation of the weight K. It is a flowchart which shows the calculation process of main injection timing (phi) INJ_M. It is a flowchart which shows the calculation process of pilot injection time (phi) INJ_P. 6 is a flowchart showing an intake air amount control process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 ECU (In-cylinder pressure parameter detection means, target value calculation means, operation state determination means, injection timing calculation means, steady operation value calculation means, transient operation value calculation means, interpolation calculation means)
3 Internal combustion engine 3a Cylinder 21 In-cylinder pressure sensor (in-cylinder pressure parameter detecting means)
IMEP Indicated mean effective pressure (In-cylinder pressure parameter)
IMEP_CMD Target effective pressure (Target value)
DIMEP effective pressure deviation (degree of deviation)
DI_1 Steady state judgment value (value that defines a predetermined range)
DI_2 Transient judgment value (value that defines a predetermined range)
φINJ_M main injection period when φINJ_M1 steady operation for value φINJ_M2 transient operation for value φINJ_P pilot injection period when φINJ_P1 steady operation for value φINJ_P2 transient operation for value
K weight (reflection level)

Claims (1)

A control apparatus for an internal combustion engine, in which fuel is divided and injected into a pilot injection timing and a main injection timing after that during one combustion cycle,
And the cylinder inner pressure parameter detecting means for detecting a cylinder inner pressure parameter representative of the pressure conditions in the cylinder of the internal combustion engine,
Target value calculating means for calculating a target value that is a target of the in-cylinder pressure parameter;
An operation state determination means for determining whether the internal combustion engine is in a steady operation state or a transient operation state;
The pilot injection timing and the main injection timing are used as operation amounts for changing the output of the internal combustion engine according to the determination result of the operating state determination means and the degree of deviation of the in-cylinder pressure parameter with respect to the target value. Injection timing calculating means for calculating;
With
The injection timing calculation means is
A steady operation value calculating means for calculating a steady operation value of the pilot injection timing and the main injection timing when the operation state determination means determines that the internal combustion engine is in the steady operation state; and the internal combustion engine When it is determined that the engine is in the transient operation state, transient operation value calculation means for calculating the transient operation value of the pilot injection timing and the main injection timing to a value different from the steady operation value;
When the deviation degree of the in-cylinder pressure parameter with respect to the target value is within a predetermined range, according to the deviation degree, the pilot injection timing and the steady injection value and the transient operation value are calculated by weighted average calculation . Interpolation calculation means for calculating the main injection timing and setting the weight of the value for steady operation in the weighted average calculation to a larger value as the divergence degree is smaller ;
A control apparatus for an internal combustion engine, comprising:

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