JP7444126B2 - Internal combustion engine system control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine system that controls an internal combustion engine system that has a turbocharger and an EGR system that recirculates a portion of exhaust gas from an exhaust path to an intake path.

In recent years, vehicles equipped with internal combustion engines have been equipped with EGR systems that recirculate part of the exhaust gas to the intake path, lowering the combustion temperature and reducing the amount of NOx generated, in order to further reduce NOx in the exhaust gas. It is equipped. A typical EGR system has EGR piping that communicates the exhaust manifold and intake manifold, and uses an EGR valve installed in the EGR piping to adjust the opening degree of the EGR piping to adjust the EGR gas flow rate. Some of the gas is recirculated to the intake path.

In a naturally aspirated internal combustion engine without a supercharger, the pressure in the intake manifold is negative, lower than atmospheric pressure, and the pressure in the exhaust manifold is positive, higher than atmospheric pressure, so EGR gas flows in the EGR piping from the exhaust manifold side to the intake manifold side without any problem. However, in internal combustion engines with a supercharger, the pressure inside the intake manifold may be higher than atmospheric pressure, so EGR gas may not flow from the exhaust manifold side to the intake manifold side. . In order to ensure the controllability of the EGR system, a pressure difference across the EGR (pressure difference between the exhaust manifold internal pressure and the intake manifold internal pressure) of a certain level or higher is required to allow EGR gas to be recirculated. In order to ensure the differential pressure across the EGR, it is necessary to adjust the closing degree of the variable nozzle (or the closing degree of the wastegate valve) of the turbo supercharger to an appropriate degree (the closing degree of the variable nozzle (or The larger the wastegate valve (closed) is (the smaller the opening is), the more the exhaust resistance increases and the pressure in the exhaust manifold rises).

For example, in the turbocharger control device described in Patent Document 1, the supercharging pressure hardly changes in response to changes in the opening (closing) of the variable nozzle (mainly in the non-supercharging range (mainly at low rotation speeds such as idling speed).・The opening degree (closing degree) of the variable nozzle is appropriately adjusted to ensure EGR controllability in low load areas). This ensures EGR controllability in the non-supercharging region of the internal combustion engine (guarantees a pressure difference across EGR above a certain level that allows EGR gas to be recirculated).

JP 2019-157798 Publication

In the turbocharger control device described in Patent Document 1, a steady state at an idling rotation speed (steady state in a non-supercharging region), a steady state at a rotation speed higher than the idling rotation speed (a steady state in a supercharging region) , it is possible to guarantee a pressure difference across the EGR of a certain level or higher that allows EGR gas to be recirculated. In addition, in recent years, even in transient states where the rotational speed (and boost pressure) is fluctuating (transient states in the supercharging region and transient states in the non-supercharging region) (i.e., under any operating state), ), development is underway to ensure a pressure differential across the EGR that is above a certain level to allow EGR gas to be recirculated.

In this way, in order to reduce the amount of NOx generated, it is necessary to control the closing degree of the variable nozzle (or the closing degree of the waste gate valve) so as to guarantee the differential pressure across EGR above a certain level (guaranteeing EGR controllability). For example, even though the actual boost pressure is higher than the target boost pressure, it may be necessary to further control the closing degree of the variable nozzle (or the closing degree of the waste gate valve), and In this case, the actual boost pressure will increase further. In this case, the pressure of the exhaust gas in the exhaust manifold increases, which increases piston pumping loss and may slightly worsen fuel efficiency. For example, even if it is possible to obtain the target boost pressure with a lower exhaust manifold internal pressure than before using a turbocharger with higher efficiency than before, the required exhaust manifold The amount of increase in internal pressure becomes even larger, and the pumping loss of the piston further increases, which may further worsen fuel efficiency.

The present invention has been devised in view of these points, and provides an internal combustion engine system that can suppress deterioration in fuel efficiency due to ensuring a pressure difference across EGR above a certain level in which EGR gas can be recirculated. The object of the present invention is to provide a control device for the following.

In order to solve the above problems, a first aspect of the present invention is a control device for an internal combustion engine system, wherein the internal combustion engine system includes an internal combustion engine, one end of which is connected to an exhaust path of the internal combustion engine; an EGR pipe whose other end is connected to an intake path of an internal combustion engine and returns a portion of exhaust gas from the internal combustion engine to the intake path as EGR gas; an EGR valve capable of adjusting the opening degree of the EGR pipe; A turbo supercharger that supercharges the intake air of the internal combustion engine using a turbine disposed downstream of the EGR pipe connected to the exhaust route, and supercharging of the intake air by the turbo supercharger. The engine includes a boost pressure adjustment device that can adjust pressure, an injector that injects fuel into the internal combustion engine, and a control device that controls the boost pressure adjustment device, the EGR valve, and the injector. The control device detects the operating state of the internal combustion engine, sets a target boost pressure based on the detected operating state, and controls the boost pressure so that the boost pressure approaches the target boost pressure. a target supercharging pressure control related quantity calculation unit that calculates a target supercharging pressure control related quantity which is a control related quantity of the adjustment device; When the exhaust gas is returned from the exhaust path to the intake path, the pressure of the exhaust gas at the point in the exhaust path where the EGR piping is connected is higher than the pressure of the intake air at the point in the intake path where the EGR piping is connected. an EGR security control related amount calculation unit that calculates an EGR security control related amount that is a control related amount of the boost pressure adjustment device according to the operating state of the internal combustion engine, and the target excess A boost pressure adjustment that calculates a final boost pressure control related amount based on the boost pressure control related amount and the EGR security control related amount, and controls the boost pressure adjustment device based on the final boost pressure control related amount. A device control unit and a target EGR rate that is a target of an EGR rate that is an EGR gas amount with respect to a total intake air amount that is an intake air amount that is filled into a cylinder of the internal combustion engine based on the operating state of the internal combustion engine. and an EGR valve control unit that controls the opening degree of the EGR valve so that the EGR rate approaches the target EGR rate, and the fuel injected from the injector ignites based on the operating state of the internal combustion engine. The fuel injection timing control section sets a target ignition timing that is a timing target, and controls the timing of fuel injection from the injector so that ignition occurs at the target ignition timing. The control device further determines that when the actual boost pressure, which is the actual boost pressure, is higher than the target boost pressure by a predetermined pressure or more, the actual EGR rate, which is the actual EGR rate, is the target EGR rate. The intake/fuel coordination control section increases the EGR gas amount so that the amount is higher than the target ignition timing, and advances the fuel injection timing so that the fuel injection timing is ignited at a position advanced from the target ignition timing. , a control device for an internal combustion engine system.

Next, a second invention of the present invention is a control device for an internal combustion engine system according to the first invention, wherein the control device controls the actual boost pressure in the intake/fuel coordination control section. When determining the EGR gas increase amount that increases the EGR gas amount when the predetermined pressure or more is higher than the target boost pressure, the target boost pressure and the target EGR rate are determined as the target intake state according to the operating state. and the cylinder capacity of the internal combustion engine, the target amount of fresh air is calculated by subtracting the target EGR gas amount, which is the target amount of EGR gas, from the target total intake amount, which is the total amount of intake air filled into the cylinder. A certain target fresh air amount is determined, and the cylinder is filled based on the actual boost pressure, the target EGR rate, and the cylinder capacity as an actual intake state that is an actual intake state with respect to the target intake state. The present invention is a control device for an internal combustion engine system that calculates an actual fresh air amount that is the actual fresh air amount, and sets the difference between the actual fresh air amount and the target fresh air amount as the EGR gas increase amount.

Next, a third invention of the present invention is a control device for an internal combustion engine system according to the second invention, wherein the control device controls the actual boost pressure in the intake/fuel coordination control section. When advancing the fuel injection timing when the predetermined pressure is higher than the target boost pressure, an ignition timing correction amount is determined based on the EGR gas increase amount, and the target ignition timing is set to the ignition timing correction amount. The present invention is a control device for an internal combustion engine system that advances the fuel injection timing so that the fuel injection timing is ignited at the ignition timing that is corrected to the advanced side.

Next, a fourth invention of the present invention is a control device for an internal combustion engine system according to the second invention, wherein the control device controls the actual boost pressure in the intake/fuel coordination control section. When advancing the fuel injection timing when the predetermined pressure is higher than the target boost pressure, an amount of NOx reduction is determined according to the amount of increase in EGR gas, and the amount of NOx increase is set to be less than or equal to the amount of NOx reduction. An internal combustion engine, wherein an ignition timing correction amount for the target ignition timing is determined, and the fuel injection timing is advanced so that the fuel injection timing is ignited at the ignition timing that is corrected to advance the target ignition timing by the ignition timing correction amount. It is the control device of the system.

Generally, when the amount of EGR gas (or EGR rate) is increased, the combustion temperature tends to decrease further, and the amount of NOx generated tends to decrease further. Further, if the ignition timing of the fuel is further advanced, the output torque increases more, but the combustion temperature tends to increase further, and the amount of NOx generated tends to increase. Furthermore, when the air-fuel ratio is made smaller (more rich), the amount of smoke generated tends to increase.

According to the first invention, the control device ensures EGR controllability with the target supercharging pressure control amount calculation section, the EGR security control amount calculation section, and the supercharging pressure adjustment device control section, and the EGR valve control section to bring the actual EGR rate closer to the target EGR rate. Further, the control device controls the fuel injection timing so that the ignition timing of the fuel becomes the target ignition timing. In this case, in order to ensure EGR controllability, the actual boost pressure, which is the actual boost pressure, may be higher than the target boost pressure, and in that case, the pump loss of the piston increases as described above. However, fuel efficiency may deteriorate slightly. When the actual boost pressure is higher than the target boost pressure by a predetermined pressure or more, more fresh air is being taken in than the target, and the air-fuel ratio is lower than the target air-fuel ratio. It should be lean. Therefore, in an overcharged state, smoke is reduced to a level lower than the target amount. Further, even in the overcharged state, the EGR rate is close to the target EGR rate, so the NOx generation amount is set to the target amount. Therefore, the amount of EGR gas is increased so that the air-fuel ratio approaches the target air-fuel ratio. Then, the amount of smoke generated approaches the target amount, and the amount of NOx generated decreases below the target amount. When the fuel ignition timing is advanced from the target ignition timing, the output torque increases, but the amount of NOx generated also increases. However, the increased amount of NOx generated is offset by the reduced amount of NOx due to the increased amount of EGR gas. As described above, the output torque can be increased without increasing the amount of smoke generation and the amount of NOx generation relative to the target, so it is possible to suppress deterioration of fuel efficiency.

According to the second invention, when the actual boost pressure is in an overcharged state higher than the target boost pressure by a predetermined pressure or more, an appropriate EGR gas increase amount can be determined.

According to the third invention, it is possible to obtain an appropriate ignition timing correction amount according to the amount of increase in EGR gas (corresponding to the amount of NOx reduction due to increase in EGR gas).

According to the fourth invention, it is possible to obtain an appropriate ignition timing correction amount in accordance with the amount of NOx reduction accompanying an increase in EGR gas.

FIG. 1 is a diagram illustrating an example of a schematic configuration of an entire internal combustion engine system. 2 is a flowchart illustrating an example of a processing procedure of [control of supercharging pressure adjustment device]. 2 is a flowchart illustrating an example of a processing procedure of [intake/fuel coordination control]. 4 is a flowchart illustrating details of [calculate target intake state] in the flowchart shown in FIG. 3. FIG. 4 is a flowchart illustrating details of [calculating actual intake state before coordination] in the flowchart shown in FIG. 3. FIG. 4 is a flowchart illustrating details of [calculating actual intake state after coordination] in the flowchart shown in FIG. 3. FIG. 2 is a flowchart illustrating an example of the processing procedure of [EGR valve control] 12 is a flowchart illustrating an example of a processing procedure for [calculation of fuel injection start timing]. FIG. 3 is a diagram illustrating an example of predetermined pressure characteristics. FIG. 6 is a diagram illustrating an example of EGR rate correction amount/ignition timing correction amount characteristics. FIG. 3 is a diagram illustrating a target intake state, an actual intake state before coordination by intake/fuel coordination control, and an actual intake state after coordination by intake/fuel coordination control. FIG. 3 is a diagram illustrating an example of EGR rate/NOx emission characteristics. FIG. 3 is a diagram illustrating an example of fuel ignition timing and NOx emission characteristics.

●[Example of schematic configuration of internal combustion engine system 1 (Figure 1)]
EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing. First, an example of a schematic configuration of an internal combustion engine system 1 will be described using FIG. 1. In the description of this embodiment, an internal combustion engine 10 (for example, a diesel engine) mounted on a vehicle will be used as an example of the internal combustion engine.

The entire system will be described below in order from the intake side to the exhaust side. An air cleaner (not shown) and an intake flow rate detection device 21 (for example, an intake flow rate sensor) are provided on the inflow side of the intake pipe 11A. The intake flow rate detection device 21 outputs a detection signal corresponding to the flow rate of air taken into the internal combustion engine 10 to the control device 50. The intake air flow rate detection device 21 is also provided with an intake air temperature detection device 28A (for example, an intake air temperature sensor) and an atmospheric pressure detection device 23 (for example, an atmospheric pressure sensor). The intake air temperature detection device 28A outputs a detection signal according to the temperature of the intake air passing through the intake air flow rate detection device 21 to the control device 50. The atmospheric pressure detection device 23 outputs a detection signal according to the surrounding atmospheric pressure to the control device 50.

The outflow side of the intake pipe 11A is connected to the inflow side of the compressor 35, and the outflow side of the compressor 35 is connected to the inflow side of the intake pipe 11B. The compressor 35 of the turbocharger 30 is rotationally driven by a turbine 36 that is rotationally driven by the energy of the exhaust gas, and performs supercharging by force-feeding intake air that has flowed in from the intake pipe 11A to the intake pipe 11B.

The intake pipe 11A on the upstream side of the compressor 35 is provided with a compressor upstream pressure detection device 24A (for example, a pressure sensor). The compressor upstream pressure detection device 24A outputs a detection signal to the control device 50 according to the pressure of intake air in the intake pipe 11A. A compressor downstream pressure detection device 24B (for example, a pressure sensor) is provided in the intake pipe 11B on the downstream side of the compressor 35 (a position between the compressor 35 and the intercooler 16 in the intake pipe 11B). The compressor downstream pressure detection device 24B outputs a detection signal to the control device 50 according to the pressure of the intake air in the intake pipe 11B.

In the intake pipe 11B, an intercooler 16 is arranged on the upstream side, and a throttle device 47 is arranged on the downstream side of the intercooler 16. Intercooler 16 is arranged downstream of compressor downstream pressure detection device 24B. An intake air temperature detection device 28B (for example, an intake air temperature sensor) is provided between the intercooler 16 and the throttle device 47. The intake air temperature detection device 28B outputs a detection signal corresponding to the temperature of the intake air whose temperature has been lowered by the intercooler 16 to the control device 50.

The throttle device 47 drives a throttle valve 47V that adjusts the opening degree of the intake pipe 11B based on a control signal from the control device 50, and can adjust the intake flow rate. The control device 50 can adjust the opening degree of the throttle valve 47V by outputting a control signal to the throttle device 47 based on the target throttle opening degree determined according to the operating state.

The accelerator pedal depression amount detection device 25 is, for example, an accelerator pedal depression angle sensor, and is provided on the accelerator pedal. The control device 50 is capable of detecting the amount of depression of the accelerator pedal by the driver based on the detection signal from the accelerator pedal depression amount detection device 25.

The outflow side of the intake pipe 11B is connected to the inflow side of the intake manifold 11C, and the outflow side of the intake manifold 11C is connected to the inflow side of the internal combustion engine 10. Further, an intake manifold pressure detection device 24C (for example, a pressure sensor) is provided downstream of the throttle device 47 in the intake pipe 11B (in the intake manifold 11C), and is connected to the outflow side of the EGR pipe 13. The intake manifold pressure detection device 24C outputs a detection signal to the control device 50 according to the pressure of intake air (supercharging pressure) immediately before flowing into the intake manifold 11C. Further, from the outflow side of the EGR pipe 13 (connection with the intake pipe 11B), EGR gas that has flowed in from the inflow side of the EGR pipe 13 (connection with the exhaust pipe 12B) is discharged into the intake pipe 11B. . The EGR pipe 13 has one end connected to the exhaust path and the other end connected to the intake path.

The internal combustion engine 10 has a plurality of cylinders 45A to 45D (cylinders), and injectors 43A to 43D are provided in each cylinder. Fuel is supplied to the injectors 43A to 43D via the common rail 41 and fuel pipes 42A to 42D, and the injectors 43A to 43D are driven by control signals from the control device 50 and are injected into the respective cylinders 45A to 45D. Inject fuel. The common rail 41 is provided with a fuel pressure detection device 73, and is filled with fuel adjusted to a target fuel pressure by a fuel pump 72. The control device 50 controls the fuel pump 72 so that the fuel pressure detected using the fuel pressure detection device 73 approaches the target fuel pressure.

The internal combustion engine 10 is provided with a crank angle detection device 22A, a cam angle detection device 22B, a coolant temperature detection device 28C, and the like. The crank angle detection device 22A is, for example, a rotation sensor, and outputs a detection signal according to the rotation angle of the crankshaft of the internal combustion engine 10 to the control device 50. The cam angle detection device 22B is, for example, a rotation sensor, and outputs a detection signal according to the rotation angle of the camshaft of the internal combustion engine 10 to the control device 50. The control device 50 can detect the process, rotation angle, etc. of each cylinder based on detection signals from the crank angle detection device 22A and the cam angle detection device 22B. Further, the coolant temperature detection device 28C is, for example, a temperature sensor, and outputs a detection signal corresponding to the temperature of the cooling coolant circulating within the internal combustion engine 10 to the control device 50.

The inflow side of an exhaust manifold 12A is connected to the exhaust side of the internal combustion engine 10, and the inflow side of an exhaust pipe 12B is connected to the outflow side of the exhaust manifold 12A. The outflow side of the exhaust pipe 12B is connected to the inflow side of the turbine 36, and the outflow side of the turbine 36 is connected to the inflow side of the exhaust pipe 12C.

The inflow side of the EGR pipe 13 is connected to the upstream side of the exhaust pipe 12B. The EGR pipe 13 corresponds to an EGR flow path, communicates the exhaust pipe 12B and the intake pipe 11B, and allows part of the exhaust gas in the exhaust pipe 12B to be returned to the intake pipe 11B as EGR gas (part of the exhaust gas is returned to the intake pipe 11B). It is possible to return some of the gas to the intake air as EGR gas). Further, the EGR pipe 13 is provided with an EGR cooler 15 and an EGR valve 14. The control device 50 can adjust the flow rate of EGR gas flowing through the EGR pipe 13 by adjusting the opening degree of the EGR valve 14.

Further, an exhaust manifold pressure detection device 26C (for example, a pressure sensor) is provided on the upstream side of the exhaust pipe 12B (in the exhaust manifold 12A). The exhaust manifold pressure detection device 26C outputs a detection signal to the control device 50 according to the pressure of exhaust gas in the exhaust manifold 12A.

An exhaust gas temperature detection device 29 is provided in the exhaust pipe 12B. The exhaust gas temperature detection device 29 is, for example, an exhaust gas temperature sensor, and outputs a detection signal according to the exhaust gas temperature to the control device 50.

The outflow side of the exhaust pipe 12B is connected to the inflow side of the turbine 36, and the outflow side of the turbine 36 is connected to the inflow side of the exhaust pipe 12C. The turbine 36 is provided with a variable nozzle 33 that is capable of controlling the flow rate of the exhaust gas guided to the turbine 36 (the amount related to the degree of closure related to the degree of closure of the flow path that guides the exhaust gas to the turbine can be adjusted). The closing degree (opening degree) of the variable nozzle 33 (corresponding to a supercharging pressure adjusting device) is adjusted by the nozzle driving device 31. The control device 50 outputs a control signal to the nozzle drive device 31 to control the variable nozzle 33 based on the detection signal from the nozzle closure detection device 32 (for example, a nozzle closure sensor) and the target nozzle closure (opening). The boost pressure can be adjusted by adjusting the degree of closure (degree of opening). Note that the turbine 36 is arranged on the exhaust downstream side of the EGR pipe 13 connected to the exhaust path.

The exhaust pipe 12B on the upstream side of the turbine 36 is provided with a turbine upstream pressure detection device 26A (for example, a pressure sensor). The turbine upstream pressure detection device 26A outputs a detection signal to the control device 50 according to the pressure of exhaust gas in the exhaust pipe 12B. The exhaust pipe 12C on the downstream side of the turbine 36 is provided with a turbine downstream pressure detection device 26B (for example, a pressure sensor). The turbine downstream pressure detection device 26B outputs a detection signal to the control device 50 according to the pressure of exhaust gas in the exhaust pipe 12C.

An exhaust purification device 61 is connected to the outflow side of the exhaust pipe 12C. For example, when the internal combustion engine 10 is a diesel engine, the exhaust purification device 61 includes an oxidation catalyst, a particulate filter, a selective reduction catalyst, and the like.

The vehicle speed detection device 27 is, for example, a vehicle speed detection sensor, and is provided on the wheels of the vehicle. Vehicle speed detection device 27 outputs a detection signal according to the rotational speed of the wheels of the vehicle to control device 50.

The control device 50 includes a CPU 51, a RAM 52, a storage device 53, a timer 54, and the like. The control device 50 (CPU 51) receives detection signals from the various detection devices described above, and outputs control signals to the various actuators described above. Note that the input/output of the control device 50 is not limited to the above-mentioned detection device and actuator. Further, the temperature, pressure, etc. of each part may be calculated by estimation calculation without installing a sensor. The control device 50 is capable of detecting the operating state of the internal combustion engine 10 based on detection signals from various detection devices including the above-mentioned detection device, and controls various actuators including the above-mentioned actuator based on the operating state. do. The storage device 53 is a storage device such as a Flash-ROM, and stores programs, data, etc. for controlling the internal combustion engine, performing self-diagnosis, and the like. Further, the control device 50 (CPU51) includes a target boost pressure control related amount calculation section 51A, an EGR security control related amount calculation section 51B, a boost pressure adjustment device control section 51C, an EGR valve control section 51D, and a fuel injection timing control section 51E. , an intake/fuel coordination control section 51F, etc., the details of which will be described later.

The control device 50 calculates the EGR rate etc. based on the operating state of the internal combustion engine 10, adjusts the opening degree of the EGR valve 14 based on the calculated EGR rate etc., and controls EGR from the exhaust pipe 12B (exhaust manifold 12A). A part of the exhaust gas is recirculated as EGR gas to the intake pipe 11B (intake manifold 11C) via the pipe 13, EGR cooler 15, and EGR valve 14. Note that at this time, the differential pressure across the EGR, which is the pressure difference between the pressure on the upstream side of the EGR piping 13 (on the exhaust manifold 12A side) and the pressure on the downstream side of the EGR piping 13 (on the intake manifold 11C side), is set to a predetermined value. If the differential pressure is not higher than that, EGR gas will not be recirculated. In an internal combustion engine system having a supercharger, depending on the supercharging state, the differential pressure across the EGR may become less than a predetermined differential pressure. Includes 'processing'.

●[Processing procedure of control device 50 (Figs. 2 to 8)]
Next, examples of each process of the control device 50 will be explained in order using the flowcharts shown in FIGS. 2 to 8.

●[Control of supercharging pressure regulator (Figure 2)]
The control device 50 (CPU 51) starts [control of supercharging pressure adjustment device] shown in FIG. 2 at predetermined time intervals (several [ms] to several tens [ms]), and executes the process in step S010. Proceed. In addition, in the [control of the supercharging pressure adjustment device] shown in FIG. With the above, "processing to ensure EGR controllability" is included.

In step S010, the control device 50 calculates a target boost pressure based on the operating state of the internal combustion engine, and advances the process to step S020. Note that the operating state of the internal combustion engine includes the flow rate, temperature, pressure, rotation speed, etc. detected using the various detection devices described above, and the operating state of various actuators, and the control device 50 is not shown. The operating state is detected (obtained) by another process.

In step S020, the control device 50 determines the first target nozzle closing degree, which is the target closing degree of the variable nozzle 33 so that the boost pressure detected using the intake manifold pressure detection device 24C approaches the target boost pressure. is calculated using a map or the like based on the driving state, and the process proceeds to step S030. Note that since the process of step S020 is an existing process, detailed explanation will be omitted.

In step S030, the control device 50 sets the second target nozzle closing degree, which is the target closing degree of the variable nozzle 33 to ensure EGR controllability (to make the differential pressure before and after the EGR equal to or higher than a predetermined pressure difference). It is calculated using a map or the like based on the driving state, and the process proceeds to step S040. Note that since the process of step S030 is an existing process, detailed explanation will be omitted.

In step S040, the control device 50 determines whether the first target nozzle closure degree is greater than or equal to the first target nozzle closure degree. If the first target nozzle closing degree is greater than or equal to the second target nozzle closing degree (Yes), the control device 50 advances the process to step S050A, and if the first target nozzle closing degree is less than the second target nozzle closing degree. (No), the process advances to step S050B.

When proceeding to step S050A, the control device 50 substitutes and stores the first target nozzle closure degree as the final target nozzle closure degree, and proceeds to step S060.

When proceeding to step S050B, the control device 50 substitutes and stores the second target nozzle closure degree as the final target nozzle closure degree, and proceeds to step S060. In steps S040, S050A, and S050B, "EGR controllability is ensured" by setting the larger of the first target nozzle closing degree and the second target nozzle closing degree as the final target nozzle closing degree.

When the process proceeds to step S060, the control device 50 performs feedback control on the nozzle drive device (supercharging pressure adjustment device) so that the (actual) nozzle closure degree of the variable nozzle 33 approaches the final target nozzle closure degree. Then, the process shown in FIG. 2 ends.

Note that the control device 50 (CPU 51) executing the processing in steps S010 and S020 sets a target boost pressure based on the detected operating state, and adjusts the boost pressure so that the boost pressure approaches the target boost pressure. It corresponds to the target boost pressure control related amount calculation unit 51A (see FIG. 1) that calculates the target boost pressure control related amount (in this case, the first target nozzle closing degree) which is the control related amount of the adjustment device.

Further, the control device 50 (CPU 51) executing the process of step S030 opens the EGR valve and converts a portion of the exhaust gas into EGR gas through the EGR piping to intake air from the exhaust route (exhaust manifold 12A, exhaust pipe 12B). When returning the gas to the path (intake manifold 11C, intake pipe 11B), the pressure of the exhaust gas at the point in the exhaust path where the EGR piping is connected is higher than the pressure of the intake air at the point in the intake path where the EGR piping is connected. The EGR security control-related quantity (in this case, the EGR security control-related quantity, which is a control-related quantity of the boost pressure adjustment device), is This corresponds to the EGR security control related amount calculation unit 51B (see FIG. 1) that calculates the target nozzle closing degree).

Further, the control device 50 (CPU 51) executing the processes of steps S040, S050A, S050B, and S060 controls the target boost pressure control related amount (in this case, the first target nozzle closing degree) and the EGR security control related amount ( In this case, the final boost pressure control-related quantity (in this case, the final target nozzle closure degree) is determined based on the second target nozzle closure degree), and the boost pressure adjustment device is controlled based on the final boost pressure control-related quantity. This corresponds to the supercharging pressure adjustment device control section 51C (see FIG. 1).

●[Intake/fuel coordination control (Figure 3)]
The control device 50 (CPU 51) starts the [intake/fuel coordination control] shown in FIG. 3, for example, at predetermined time intervals (several [ms] to several tens [ms]), and advances the process to step S110.

In step S110, the control device 50 calculates a predetermined pressure depending on the operating state, and advances the process to step S120. For example, the storage device 53 of the control device 50 stores predetermined pressure characteristics shown in FIG. The predetermined pressure characteristics include the actual predetermined pressures (P11, P12...) that correspond to the rotational speed (N1, N2, N3...) of the internal combustion engine and the fuel injection amount (Q1, Q2, Q3...). It has been set based on experiments and simulations using several vehicles. Note that the predetermined pressure is not limited to the map shown in the example of FIG. 9, and may be set to a constant value, or may be set according to other operating conditions, not limited to the rotation speed or fuel injection amount. Good too.

In step S120, the control device 50 determines whether "actual boost pressure - target boost pressure" is equal to or higher than a predetermined pressure. If "actual boost pressure - target boost pressure" is equal to or higher than the predetermined pressure (Yes), the control device 50 advances the process to step S130, and if "actual boost pressure - target boost pressure" is less than the predetermined pressure. If there is (No), the process advances to step S160B.

When proceeding to step S130, the control device 50 executes a process of [calculating target intake state] and proceeds to step S140. Note that the details of the process (FIG. 4) for [calculating the target intake state] will be described later.

In step S140, the control device 50 executes a process of [calculating the actual intake state before coordination] and advances the process to step S150. The details of the process (FIG. 5) for [calculating the actual intake state before coordination] will be described later.

In step S150, the control device 50 executes a process of [calculating the actual intake state after coordination] and advances the process to step S160A. The details of the process (FIG. 6) for [calculating the actual intake state after coordination] will be described later.

In step S160A, the control device 50 subtracts the target EGR rate (calculated in [EGR valve control] described later) from the actual EGR rate after coordination obtained in step S150, and substitutes the value obtained by subtracting it into the EGR rate correction amount. memorize it. Further, the control device 50 calculates and stores the ignition timing correction amount based on the EGR rate correction amount, and ends the process shown in FIG. 3. For example, the storage device 53 of the control device 50 stores the EGR rate correction amount and ignition timing correction amount characteristics shown in FIG. The ignition timing correction amount is calculated based on the amount.

When the process proceeds to step S160B, the control device 50 initializes the EGR rate correction amount to 0 (zero), initializes the ignition timing correction amount to 0 (zero), and ends the process shown in FIG. 3.

●[Calculate target intake state (Fig. 4, Fig. 11)]
Next, using FIG. 4, details of the process of [calculating target intake state] in step S130 of the flowchart shown in FIG. 3 will be described. When executing the process in step S130 of the flowchart shown in FIG. 3, the control device 50 advances the process to step S210 shown in FIG. The process of [calculating target intake state] shown in FIG. 4 is a process of calculating each value of [target intake state] shown in FIG. 11.

[Target intake condition] is the intake condition that makes the output torque, NOx generation amount, smoke generation amount, etc. reach the target values for the current driving condition, and is based on experiments using actual vehicles. It is determined in advance through simulation, etc. [Target intake state] is the target fuel injection amount Qv1 and target ignition timing to obtain the targeted output torque, and the target fresh air amount Gn1 (target air-fuel ratio A target fresh air amount Gn1) to achieve the desired NOx generation amount, a target EGR rate and a target ignition timing to achieve the targeted NOx generation amount are set. Note that, in general, the amount of NOx generated tends to decrease as the EGR rate increases, and increase as the fuel ignition timing advances. Furthermore, the output torque tends to increase as the fuel ignition timing advances. Furthermore, the amount of smoke generated tends to decrease as the air-fuel ratio increases (leans).

[Target intake state] is the operating state at that time, (actual) boost pressure = target boost pressure, (actual) EGR rate = target EGR rate, (actual) fuel injection amount = target fuel injection amount. Qv1, (actual) air-fuel ratio = target air-fuel ratio, (actual) fuel ignition timing = target ignition timing, is the intake state when the following conditions are achieved. Note that the cylinder capacity C1 is known in advance and stored in the storage device 53.

When the control device 50 detects the operating state, the control device 50 sets the target supercharging pressure (calculated in the process of FIG. 2), the target EGR rate (calculated in the process of FIG. 7), and the target fuel injection amount Qv1 ( (not shown) and target ignition timing (calculated in the process of FIG. 8) are set (calculated), respectively. Therefore, in the [target intake state] shown in FIG. 11, the control device 50 calculates the remaining target EGR gas amount Ge1, the target fresh air amount Gn1, and the target air-fuel ratio.

In step S210, the control device 50, based on the preset cylinder capacity C1, the target boost pressure found in step S010 of FIG. 2, and the target EGR rate found in step S510 of FIG. 7, which will be described later, The target EGR gas amount Ge1 and the target fresh air amount Gn1 are calculated and stored, and the process proceeds to step S220.

As shown in [Cylinder capacity] and [Target intake state] in FIG. Target EGR gas amount Ge1+target fresh air amount Gn1) is calculated. Then, the control device 50 calculates the target EGR gas amount Ge1 using the target total intake air amount G1 (target EGR gas amount Ge1+target fresh air amount Gn1) and the target EGR rate, and calculates the target fresh air amount Gn1. Target EGR gas amount Ge1=target total intake air amount G1*target EGR rate, and target new air amount Gn1=target total intake air amount G1−target EGR gas amount Ge1.

In step S220, the control device 50 calculates and stores the target air-fuel ratio based on the target fresh air amount Gn1 and the target fuel injection amount Qv1, ends the process shown in FIG. 4, and proceeds to step S140 shown in FIG. 3. Return processing.

The control device 50 calculates the target air-fuel ratio using the target fresh air amount Gn1 and the target fuel injection amount Qv1. Target air-fuel ratio=target fresh air amount Gn1/target fuel injection amount Qv1.

From the above, in the case of [target intake state], as shown in FIG. 11, total intake air amount = target total intake air amount G1, boost pressure = target boost pressure, EGR rate = target EGR gas amount Ge1/ (Target fresh air amount Gn1 + target EGR gas amount Ge1) = target EGR rate, EGR gas amount = target EGR gas amount Ge1, fresh air amount = target fresh air amount Gn1, fuel injection amount = target fuel injection amount Qv1, air-fuel ratio = Target fresh air amount Gn1/target fuel injection amount Qv1=target air-fuel ratio, fuel ignition timing=target ignition timing, and each value is known as described above.

●[Calculate the actual intake state before coordination (Fig. 5, Fig. 11)]
Next, using FIG. 5, details of the process of [calculating the actual intake state before coordination] in step S140 of the flowchart shown in FIG. 3 will be described. When executing the process in step S140 of the flowchart shown in FIG. 3, the control device 50 advances the process to step S310 shown in FIG. The process of [calculating actual intake state before coordination] shown in FIG. 5 is a process of calculating each value of [actual intake state before coordination] shown in FIG. 11 .

As shown in FIG. 11, the [actual intake state before coordination] is the closing degree of the variable nozzle in order to ensure EGR controllability with respect to the [target intake state] where boost pressure = target boost pressure. As a result of increasing the pressure in the exhaust manifold by increasing the pressure, the actual boost pressure is higher than the target boost pressure (actual boost pressure - target boost pressure ≧ predetermined pressure). This is the state before executing the [intake/fuel coordination control] shown in FIG.

In the [actual intake state before coordination], as shown in FIG. 11, the actual EGR rate before coordination = target EGR rate, the fuel injection amount = target fuel injection amount Qv1, and the fuel ignition timing = target ignition timing. . However, since boost pressure>target boost pressure, total intake air amount before coordination G2>target total intake air amount G1, actual EGR gas amount before coordination Ge2>target EGR gas amount Ge1, actual fresh air amount before coordination Gn2>target Fresh air amount Gn1, and actual air-fuel ratio before coordination=actual fresh air amount before coordination Gn2/target fuel injection amount Qv1>target air-fuel ratio.

In the [actual intake state before coordination] shown in FIG. 11, boost pressure=actual boost pressure, and actual EGR rate before coordination=target EGR rate. In the [actual intake state before coordination], the actual EGR gas amount before coordination Ge2 > the target EGR gas amount Ge1 with respect to the [target intake state], but since the actual EGR rate before coordination = the target EGR rate, the EGR The amount of NOx generated according to the rate is equivalent to the [target intake state]. Furthermore, since the actual fresh air amount before coordination Gn2>target fresh air amount Gn1, the actual air-fuel ratio before coordination>target air-fuel ratio, and the smoke generation amount is reduced compared to the [target intake state]. Also, since the points that fuel injection amount = target fuel injection amount Qv1 and fuel ignition timing = target ignition timing are the same as [target intake state], the NOx generation amount according to the fuel ignition timing is [target intake state] is equivalent to However, in order to ensure EGR controllability, the variable nozzle is closed to a greater degree (as a result, the boost pressure becomes higher than the target boost pressure), increasing the pressure in the exhaust manifold. The pump loss of the piston increases, the output torque is slightly reduced compared to the [target intake state], and the fuel efficiency may deteriorate slightly.

[Actual intake state before coordination]: (actual) boost pressure (>target boost pressure), actual EGR rate before coordination (=target EGR rate), fuel injection amount (=target fuel injection amount Qv1), fuel The ignition timing (=target ignition timing) is already known. Therefore, in the [actual intake state before coordination] shown in FIG. 11, the control device 50 calculates the remaining pre-coordination actual EGR gas amount Ge2, pre-coordination actual fresh air amount Gn2, and pre-coordination actual air-fuel ratio.

In step S310, the control device 50 determines the pre-coordination actual EGR gas amount Ge2, based on the preset cylinder capacity C1, the actual boost pressure, and the target EGR rate obtained in step S510 of FIG. The pre-coordination actual fresh air amount Gn2 is calculated and stored, and the process proceeds to step S320.

As shown in [Cylinder capacity] and [Actual fresh air state before coordination] in FIG. The intake air amount G2 (pre-coordination actual EGR gas amount Ge2+pre-coordination actual fresh air amount Gn2) is calculated. Then, the control device 50 calculates the actual EGR gas amount Ge2 before coordination using the total intake air amount G2 before coordination (actual EGR gas amount Ge2 before coordination + actual fresh air amount Gn2 before coordination) and the target EGR rate, and calculates the actual EGR gas amount Ge2 before coordination. Calculate the actual fresh air amount Gn2. Actual EGR gas amount before cooperation Ge2 = total intake air amount before cooperation G2 * target EGR rate, and actual new air amount before cooperation Gn2 = total intake amount before cooperation G2 - actual EGR gas amount before cooperation Ge2. Note that the pre-coordination actual fresh air amount Gn2 may be determined based on the intake air amount detected using the intake air flow rate detection device 21, the rotational speed of the internal combustion engine, and the like.

In step S320, the control device 50 calculates and stores a pre-coordination actual air-fuel ratio based on the pre-coordination actual fresh air amount Gn2 and target fuel injection amount Qv1, ends the process shown in FIG. 5, and returns to FIG. The process returns to step S150 shown in FIG.

The control device 50 calculates the actual air-fuel ratio before coordination using the actual fresh air amount Gn2 before coordination and the target fuel injection amount Qv1. Actual air-fuel ratio before coordination=actual fresh air amount before coordination Gn2/target fuel injection amount Qv1 (>target air-fuel ratio).

From the above, in the case of [actual intake state before coordination], as shown in FIG. 11, total intake air amount = total intake air amount before coordination G2 > target total intake air amount G1, boost pressure = actual boost pressure >Target boost pressure, actual EGR rate before coordination = actual EGR gas amount before coordination Ge2/(actual fresh air amount before coordination Gn2 + actual EGR gas amount before coordination Ge2) = target EGR rate, actual EGR gas amount before coordination Ge2>Target EGR gas amount Ge1, actual fresh air amount before coordination Gn2 > target fresh air amount Gn1, fuel injection amount = target fuel injection amount Qv1, actual air-fuel ratio before coordination = actual fresh air amount before coordination Gn2/target fuel injection amount Qv1 > target The air-fuel ratio and fuel ignition timing = target ignition timing, and each value is known as described above.

●[Calculate the actual intake state after coordination (Fig. 6, Fig. 11)]
Next, using FIG. 6, details of the process of [calculating the actual intake state after coordination] in step S150 of the flowchart shown in FIG. 3 will be described. When executing the process of step S150 of the flowchart shown in FIG. 3, the control device 50 advances the process to step S410 shown in FIG. The process of [calculating the actual intake state after coordination] shown in FIG. 6 is the process of calculating each value of the [actual intake state after coordination] shown in FIG. 11 .

As shown in Fig. 11, [actual intake state after coordination] is the same as [actual intake state before coordination]: boost pressure = actual boost pressure > target boost pressure, and the total after coordination The intake air amount G3=pre-coordination total intake air amount G2, the total intake air amount is the same, and the fuel injection amount=target fuel injection amount Qv1. However, the difference is that after coordination actual EGR gas amount Ge3>pre-coordination actual EGR gas amount Ge2, and after coordination actual fresh air amount Gn3=target fresh air amount Gn1<pre-coordination actual fresh air amount Gn2.

Due to this difference, [actual intake state after coordination] is different from [actual intake state before coordination]: actual EGR rate after coordination = actual EGR gas amount after coordination Ge3/(target fresh air amount Gn1 + actual EGR after coordination). Gas amount Ge3) = "target EGR rate + EGR rate correction amount" > target EGR rate. Also, [actual intake state after coordination] is the same as [actual intake state before coordination] in that fuel injection amount = target fuel injection amount Qv1, but fuel ignition timing = "target ignition timing". - Ignition timing correction amount" and is advanced compared to the [actual intake state before coordination]. Note that the actual air-fuel ratio after coordination=target air-fuel ratio.

[Actual intake state after coordination] The actual boost pressure is lower than the target boost pressure as a result of increasing the closing degree of the variable nozzle and increasing the pressure in the exhaust manifold to ensure EGR controllability. This is the state after executing the [intake/fuel coordination control] shown in FIG. 3 for the [actual intake state before coordination] in which the fuel consumption has also increased.

In [actual intake state after coordination], as shown in FIG. 11, actual EGR rate after coordination = "target EGR rate + EGR rate correction amount" > target EGR rate, fuel injection amount = target fuel injection amount Qv1, Fuel ignition timing = target ignition timing - ignition timing correction amount (advanced than target ignition timing). Then, actual EGR gas amount after coordination Ge3 > actual EGR gas amount Ge2, actual fresh air amount after coordination Gn3 = target fresh air amount Gn1 < actual fresh air amount before coordination Gn2, so air-fuel ratio = actual fresh air after coordination Amount Gn3/Target fuel injection amount Qv1=Target fresh air amount Gn1/Target fuel injection amount Qv1=Target air-fuel ratio.

In the [actual intake state after coordination] shown in FIG. 11, with respect to the [actual intake state before coordination], the actual EGR gas amount after coordination Ge3 > the actual EGR gas amount before coordination Ge2, and the actual EGR rate after coordination = Since "target EGR rate + EGR rate correction amount" > target EGR rate, the amount of NOx generated according to the EGR rate is reduced compared to the [actual intake state before coordination]. Further, since the actual fresh air amount after coordination Gn3=the target fresh air amount Gn1, the air-fuel ratio=the target air-fuel ratio, and the amount of smoke generated is equal to the [target intake state]. Also, although the fuel injection amount = target fuel injection amount Qv1 is the same, the fuel ignition timing is advanced by the target ignition timing - ignition timing correction amount, and NOx is generated according to the fuel ignition timing. Although the amount increases from the [actual intake state before coordination], it is offset by the decrease in NOx generation amount due to the following: actual EGR rate after coordination > target EGR rate (the amount of increase in NOx only needs to be less than the amount of decrease in NOx) ). Since the fuel ignition timing is advanced, the output torque is increased compared to the [actual intake state before coordination], and deterioration of fuel efficiency is suppressed.

In [actual intake state after coordination], (actual) boost pressure (>target boost pressure), actual fresh air amount after coordination Gn3 (= target fresh air amount Gn1), fuel injection amount (= target fuel injection amount) Qv1) is already known. Therefore, in the [actual intake state after coordination] shown in FIG. 11, the control device 50 calculates the actual EGR gas amount Ge3 after coordination, the actual EGR rate after coordination, and the actual air-fuel ratio after coordination.

In step S410, the control device 50 controls the preset cylinder capacity C1, the actual boost pressure, the target fresh air amount Gn1 (=actual fresh air amount Gn3 after coordination) obtained in step S210 of FIG. 4 described above, Based on this, the actual EGR gas amount Ge3 after coordination and the actual EGR rate after coordination are calculated and stored, and the process proceeds to step S420.

As shown in [Cylinder capacity] and [Actual fresh air state after coordination] in FIG. The intake air amount G3 (actual EGR gas amount Ge3 after coordination + actual fresh air amount Gn3 after coordination) is calculated. Then, the control device 50 uses the total intake air amount after coordination G3 (actual EGR gas amount after coordination Ge3+actual fresh air amount after coordination Gn3) and the actual fresh air amount after coordination Gn3=target fresh air amount Gn1. The EGR gas amount Ge3 is calculated, and the actual EGR rate after coordination is calculated. Actual EGR gas amount after coordination Ge3 = total intake air amount after coordination G3 - target fresh air amount Gn1, and actual EGR rate after coordination = actual EGR gas amount after coordination Ge3/(target fresh air amount Gn1 + actual EGR gas amount after coordination Ge3 ).

In step S420, the control device 50 calculates and stores the actual air-fuel ratio after coordination (=target air-fuel ratio) based on the actual fresh air amount after coordination Gn3 (=target fresh air amount Gn1) and the target fuel injection amount Qv1. Then, the process shown in FIG. 6 is ended and the process returns to step S160A shown in FIG.

The control device 50 calculates the actual air-fuel ratio after coordination using the actual fresh air amount after coordination Gn3=target fresh air amount Gn1 and the target fuel injection amount Qv1. Actual air-fuel ratio after coordination=actual fresh air amount after coordination Gn3/target fuel injection amount Qv1=target fresh air amount Gn1/target fuel injection amount Qv1=target air-fuel ratio.

From the above, in the case of [actual intake state after coordination], as shown in FIG. 11, total intake amount = total intake amount after coordination G3 = total intake amount before coordination G2, boost pressure = actual supercharging pressure > target boost pressure, actual EGR rate after coordination = actual EGR gas amount after coordination Ge3/(target new air amount Gn1 + actual EGR gas amount after coordination Ge3) = "target EGR rate + EGR rate correction amount" > target EGR rate, Actual EGR gas amount after coordination Ge3 > Actual EGR gas amount before coordination Ge2, Actual fresh air amount after coordination Gn3 = Target fresh air amount Gn1, Fuel injection amount = Target fuel injection amount Qv1, Actual air-fuel ratio after coordination = Target fresh air amount Gn1/target fuel injection amount Qv1 = target air-fuel ratio, fuel ignition timing = target ignition timing - ignition timing correction amount, and except for the EGR rate correction amount and ignition timing correction amount, each value is as described above. know. Note that the EGR rate correction amount and the ignition timing correction amount are calculated by the control device 50 in step S160A shown in FIG.

● [EGR valve control (Figure 7)]
The control device 50 (CPU 51) starts the EGR valve control shown in FIG. 7 at, for example, predetermined time intervals (several [ms] to several tens of [ms]), and advances the process to step S510. [EGR valve control] shown in Fig. 7 includes a part of intake/fuel cooperative control using the "EGR rate correction amount" calculated in [intake/fuel cooperative control] shown in Fig. 3. .

In step S510, the control device 50 calculates a target EGR rate based on the driving state, and advances the process to step S520. Note that since the calculation of the target EGR rate is an existing process, the details will be omitted.

In step S520, the control device 50 adds the EGR rate correction amount to the target EGR rate, calculates and stores the final target EGR rate, and advances the process to step S530.

In step S530, the control device 50 determines the actual EGR rate based on the intake air amount detected using the intake flow rate detection device 21, the boost pressure detected using the intake manifold pressure detection device 24C, the cylinder capacity, etc. The actual EGR rate is calculated and stored, and the process advances to step S540.

In step S540, the control device 50 performs feedback control on the opening degree of the EGR valve so that the actual EGR rate approaches the final target EGR rate, and ends the process shown in FIG. 7.

The control device 50 (CPU 51) executing the process shown in FIG. This corresponds to the EGR valve control unit 51D (see FIG. 1) that sets a target EGR rate, which is a target EGR rate, and controls the opening degree of the EGR valve so that the EGR rate approaches the target EGR rate.

●[Calculation of fuel injection start timing (Figure 8)]
The control device 50 (CPU 51) starts [Calculation of fuel injection start timing] shown in FIG. 8, for example at a predetermined crank angle timing, and advances the process to step S610. [Calculation of fuel injection start timing] shown in Fig. 8 includes a part of the intake/fuel coordinated control using the "ignition timing correction amount" calculated in the [intake/fuel coordinated control] shown in Fig. 3. ing.

In step S610, control device 50 calculates a target ignition timing based on the operating state, and advances the process to step S620. Note that the calculation of the target ignition timing is an existing process, so the details will be omitted.

In step S620, the control device 50 subtracts the ignition timing correction amount from the target ignition timing, calculates and stores the final target ignition timing, and advances the process to step S630.

In step S630, the control device 50 calculates the fuel injection start timing based on the operating state so that the fuel ignites at the final target ignition timing, and controls the fuel injection to start from the fuel injection start timing, The process shown in FIG. 8 ends. Note that since this process is an existing process, the details will be omitted.

The control device 50 (CPU 51) that executes the process in FIG. 8 sets a target ignition timing, which is a target timing for igniting the fuel injected from the injector, based on the operating state of the internal combustion engine, and ignites at the target ignition timing. This corresponds to a fuel injection timing control section 51E that controls the timing of fuel injection from the injector so that the timing of fuel injection from the injector is controlled.

In addition, the control device 50 (CPU 51) executing the process of FIG. 3, step S520 of FIG. 7, and step S620 of FIG. When the pressure is higher than a predetermined value, the amount of EGR gas is increased so that the actual EGR rate is higher than the target EGR rate, and the ignition is ignited at a position that is more advanced than the target ignition timing. This corresponds to the intake/fuel coordination control section 51F (see FIG. 1) that advances the fuel injection start timing. As shown in FIG. 11, EGR gas increase amount = Actual fresh air amount before coordination Gn2 - Actual fresh air amount after coordination Gn3 = Actual fresh air amount before coordination Gn2 - Target fresh air amount Gn1 (Actual fresh air amount before coordination (difference between Gn2 and target fresh air amount Gn1).

●[Another method for determining the ignition timing correction amount (Fig. 12, Fig. 13)]
Next, another method for determining the ignition timing correction amount will be explained using FIGS. 12 and 13. In step S160A of FIG. 3 described above, using the EGR rate correction amount/ignition timing correction amount characteristics shown in FIG. Although the ignition timing correction amount corresponding to the increase in the amount of the ignition timing correction amount was calculated, the ignition timing correction amount may be calculated using the following procedure.

The storage device 53 stores EGR rate/NOx emission characteristics shown in FIG. 12 and fuel ignition timing/NOx emission characteristics shown in FIG. 13. As shown in FIG. 12, the EGR rate/NOx emission characteristics show that as the EGR rate increases, the NOx emission decreases. Furthermore, the fuel ignition timing/NOx emission characteristics show that as the fuel ignition timing is advanced, the NOx emission increases, as shown in FIG.

After determining the EGR rate correction amount in step S160A, the control device 50 uses the EGR rate/NOx emission characteristics shown in FIG. 12 and the target EGR rate to calculate the NOx emission amount (QN1) at the target EGR rate. demand. Then, the control device 50 uses the EGR rate/NOx emission characteristics shown in FIG. 12 and the actual EGR rate after coordination to determine the NOx emission amount (QN3) in the case of the actual EGR rate after coordination. Then, the control device 50 calculates ΔQN, which is the reduction in NOx emissions by subtracting the NOx emissions (QN3) for the actual EGR rate after coordination from the NOx emissions (QN1) for the target EGR rate.

Next, the control device 50 uses the fuel ignition timing/NOx emission characteristics shown in FIG. 13 and the target ignition timing to determine the NOx emission amount (QT1) in the case of the target ignition timing. Then, the control device 50 uses the fuel ignition timing and NOx emission characteristics shown in FIG. do. Then, the control device 50 sets the ignition timing correction amount to be the target ignition timing - the post-cooperative ignition timing (ignition timing correction amount = target ignition timing - post-cooperative ignition timing). That is, the amount of NOx generated is offset by the decrease in the amount of NOx generated due to the increase in the EGR rate=the increase in the amount of NOx generated due to the advance of the ignition timing (the amount of increase in NOx only needs to be equal to or less than the amount of decrease in NOx).

As explained above, in the intake/fuel coordination control explained in this embodiment, by changing the [actual intake state before coordination] to the [actual intake state after coordination] shown in FIG. Actual EGR rate = target EGR rate + EGR rate correction amount, and the EGR rate is increased to reduce the NOx generation amount. At the same time, the fuel ignition timing is advanced as follows: fuel ignition timing = target ignition timing - ignition timing correction amount, thereby increasing the amount of NOx generated, but also increasing the generated torque. Note that the increase in the amount of NOx generated due to the advance of the fuel ignition timing is offset by the decrease in the amount of NOx generated due to the increase in the EGR rate. Further, regarding the amount of smoke generated, since the actual air-fuel ratio after coordination in the [actual intake state after coordination]=target air-fuel ratio, it is equivalent to the [target intake state]. Therefore, even if fuel efficiency deteriorates slightly in the [actual intake state before coordination], by changing to the [actual intake state after coordination], the generated torque can be increased without deteriorating the exhaust gas condition. Deterioration of fuel efficiency can be suppressed.

The control device 50 for an internal combustion engine system of the present invention is not limited to the configuration, processing procedures, etc. described in this embodiment, and various changes, additions, and deletions can be made without changing the gist of the present invention.

Furthermore, the control device for an internal combustion engine system of the present invention is not limited to diesel engines, but can also be applied to gasoline engines.

In the description of this embodiment, an example has been described in which the boost pressure adjustment device includes the variable nozzle 33, the nozzle drive device 31, and the nozzle closure detection device 32. However, instead of these, an exhaust bypass that bypasses the turbine 36 is used. The supercharging pressure adjustment device may be configured by the passage and a waste gate valve that adjusts the degree of closure of the exhaust bypass passage.

Further, terms such as greater than or equal to (≧), less than or equal to (≦), greater than (>), less than (less than) (<), etc. may or may not include an equal sign.

1 Internal combustion engine system 10 Internal combustion engine 11A, 11B Intake pipe 11C Intake manifold 12A Exhaust manifold 12B, 12C Exhaust pipe 13 EGR piping 14 EGR valve 15 EGR cooler 16 Intercooler 21 Intake flow rate detection device 22A Crank angle detection device 22B Cam angle detection device 23 Atmospheric pressure detection device 24A Compressor upstream pressure detection device 24B Compressor downstream pressure detection device 24C Intake manifold pressure detection device 25 Accelerator pedal depression amount detection device 26A Turbine upstream pressure detection device 26B Turbine downstream pressure detection device 26C Exhaust manifold pressure detection device 27 Vehicle speed Detection device 28A, 28B Intake air temperature detection device 28C Coolant temperature detection device 29 Exhaust temperature detection device 30 Turbo supercharger 31 Nozzle drive device 32 Nozzle closure degree detection device 33 Variable nozzle (supercharging pressure adjustment device)
35 Compressor 36 Turbine 41 Common rail 43A to 43D Injector 45A to 45D Cylinder 47 Throttle device 47S Throttle opening detection means 47V Throttle valve 50 Control device 51 CPU
51A Target supercharging pressure control related amount calculation section 51B EGR security control related amount calculation section 51C Supercharging pressure adjustment device control section 51D EGR valve control section 51E Fuel injection timing control section 51F Intake/fuel coordination control section 53 Storage device 61 Exhaust purification Device 72 Fuel pump 73 Fuel pressure detection device C1 Cylinder capacity G1 Target total intake air amount G2 Total intake air amount before coordination G3 Total intake air amount after coordination Ge1 Target EGR gas amount Ge2 Actual EGR gas amount before coordination Ge3 Actual EGR gas amount after coordination Gn1 Target Fresh air amount Gn2 Actual new air amount before coordination Gn3 Actual new air amount after coordination

Claims (4)

A control device for an internal combustion engine system,
The internal combustion engine system includes:
internal combustion engine;
EGR piping, one end of which is connected to an exhaust path of the internal combustion engine, the other end of which is connected to an intake path of the internal combustion engine, and returns a portion of exhaust gas from the internal combustion engine to the intake path as EGR gas;
an EGR valve that can adjust the opening degree of the EGR pipe;
a turbo supercharger that supercharges intake air of the internal combustion engine using a turbine disposed downstream of the exhaust route than the EGR pipe connected to the exhaust route;
a supercharging pressure adjustment device capable of adjusting the supercharging pressure of intake air by the turbo supercharger;
an injector that injects fuel into the internal combustion engine;
the control device that controls the boost pressure adjustment device, the EGR valve, and the injector;
It has
The control device includes:
detecting the operating state of the internal combustion engine, setting a target supercharging pressure based on the detected operating state, and controlling a control related variable of the supercharging pressure adjustment device so that the supercharging pressure approaches the target supercharging pressure. a target boost pressure control related quantity calculation unit that calculates a target boost pressure control related quantity;
When the EGR valve is opened and a part of the exhaust gas is returned as the EGR gas from the exhaust path to the intake path via the EGR pipe, the amount of exhaust gas at the point in the exhaust path to which the EGR pipe is connected is A control-related variable of the boost pressure adjustment device is adjusted according to the operating state of the internal combustion engine so that the pressure of the intake air is higher than the pressure of the intake air at a point in the intake path to which the EGR pipe is connected. an EGR collateral control related amount calculation unit that calculates a certain EGR collateral control related amount;
determining a final boost pressure control related amount based on the target boost pressure control related amount and the EGR security control related amount, and controlling the boost pressure adjustment device based on the final boost pressure control related amount; A supply pressure regulator control unit;
Based on the operating state of the internal combustion engine, a target EGR rate is set, which is an EGR rate that is an EGR gas amount with respect to a total intake air amount that is an intake air amount that is filled into a cylinder of the internal combustion engine, and the EGR rate is set. an EGR valve control unit that controls the opening degree of the EGR valve so that the EGR rate approaches the target EGR rate;
Based on the operating state of the internal combustion engine, a target ignition timing, which is a target timing for igniting the fuel injected from the injector, is set, and the fuel injection timing from the injector is controlled so that the fuel is ignited at the target ignition timing. a fuel injection timing control section;
It has
The control device further includes:
When the actual boost pressure, which is the actual boost pressure, is higher than the target boost pressure by a predetermined pressure or more, the EGR is adjusted such that the actual EGR rate, which is the actual EGR rate, is higher than the target EGR rate. an intake/fuel coordination control unit that increases the amount of gas and advances the fuel injection timing so that the fuel injection timing is ignited at a position advanced from the target ignition timing;
Control device for internal combustion engine system. A control device for an internal combustion engine system according to claim 1,
The control device includes:
When the intake/fuel coordination control unit calculates an EGR gas increase amount to increase the EGR gas amount when the actual boost pressure is higher than the target boost pressure by the predetermined pressure or more,
As the target intake state according to the operating state, based on the target boost pressure, the target EGR rate, and the cylinder capacity of the internal combustion engine, from the target total intake air amount that is the total intake air amount filled into the cylinder. Determining a target fresh air amount that is a target of fresh air amount excluding the target EGR gas amount that is a target of the EGR gas amount,
As an actual intake state that is an actual intake state with respect to the target intake state, the actual amount of new air filled into the cylinder based on the actual boost pressure, the target EGR rate, and the cylinder capacity. Find the actual fresh air volume,
The difference between the actual fresh air amount and the target fresh air amount is the EGR gas increase amount;
Control equipment for internal combustion engine systems. A control device for an internal combustion engine system according to claim 2,
The control device includes:
When the intake/fuel coordination control unit advances the fuel injection timing when the actual boost pressure is higher than the target boost pressure by at least the predetermined pressure,
determining an ignition timing correction amount based on the EGR gas increase amount, and advancing the fuel injection timing so that the fuel injection timing is ignited at an ignition timing that is corrected to advance the target ignition timing by the ignition timing correction amount;
Control equipment for internal combustion engine systems. A control device for an internal combustion engine system according to claim 2,
The control device includes:
When the intake/fuel coordination control unit advances the fuel injection timing when the actual boost pressure is higher than the target boost pressure by at least the predetermined pressure,
Determining the NOx reduction amount according to the EGR gas increase amount,
An ignition timing correction amount for the target ignition timing is determined so that the NOx increase amount is less than the NOx reduction amount, and ignition is performed at an ignition timing that is corrected to advance the target ignition timing by the ignition timing correction amount. advancing the fuel injection timing to;
Control equipment for internal combustion engine systems.

Images