JP7415868B2 - Control device for compression self-ignition internal combustion engine - Google Patents

Description

The present invention relates to a control device for a compression self-ignition internal combustion engine.

A compression self-ignition internal combustion engine (such as a typical diesel engine) injects fuel into a combustion chamber that compresses and heats air with a piston, ignites it, and burns it. Compared to internal combustion engines (in which air and fuel are mixed in a combustion chamber and ignited by a spark from an ignition plug to combust), combustion noise is louder, and it is desired to reduce combustion noise.

In a compression self-ignition internal combustion engine, a main injection and one or more pilot injections, which are pre-injections to the main injection, are performed for one combustion stroke. In the following, unless otherwise specified, pilot injection and pre-injection that are injected before main injection will not be distinguished, and pilot injection and pre-injection that are injected before main injection will be collectively referred to as "pilot injection." .

Combustion noise is caused by combustion chamber/bore resonance, where radial pressure pulsations are repeated in the combustion chamber and bore space, which is radiated from the engine surface by energy from the combustion (ignition) of fuel injected into the cylinder. The resonant frequency of combustion chamber/bore resonance is determined by the combustion chamber diameter, bore diameter, combustion gas temperature, oxygen concentration, etc., and in the case of a typical vehicle internal combustion engine, it is relatively low at around 4 to 5 [KHz]. It is a high frequency.

For example, in the fuel injection control device described in Patent Document 1, a combustion sound sensor is provided in each cylinder, and the signals from each combustion sound sensor are AD converted via a gate circuit and a high-speed AD converter, and then FFT is performed in an ECU. It has a configuration that performs processing to calculate the sound pressure level of each frequency component. Then, the resonant frequency component where the difference between the sound pressure when pilot injection is performed and the sound pressure when pilot injection is not performed is extracted, and the timing of pilot injection and injection are adjusted so as to cancel out the resonant frequency. The combustion noise experienced by the user is suppressed by controlling the amount.

Furthermore, for example, in the control device for an internal combustion engine described in Patent Document 2, a resonance frequency that resonates in the radial direction within the cylinder during combustion is calculated, and combustion occurs when the piston is near top dead center based on the resonance frequency. Combustion noise experienced by the user is suppressed by switching the combustion timing, or by causing combustion to occur when the piston moves a certain distance below top dead center.

Japanese Patent Application Publication No. 2001-234800 JP 2019-60264 Publication

In the fuel injection control device described in Patent Document 1, by adjusting the injection timing (injection timing) of pilot injection, the sound pressure in a specific frequency band that is easily audible to humans is offset and reduced. However, this method does not reduce the sound pressure of the resonant frequency itself, but rather slides the resonant frequency from a specific frequency band that is easy for humans to hear, and around the specific frequency band, the resonant frequency that has been slid Sound pressure may be amplified and new problems may occur. Furthermore, since the injection timing and injection amount of the pilot injection are changed relatively largely with emphasis on sliding the resonance frequency, it is possible that the amount of harmful components generated in the exhaust gas and the impact on fuel efficiency will be large.

Furthermore, the control device described in Patent Document 2 does not make major changes to the injection timing and injection amount of pilot injection, but adjusts the EGR rate, adjusts the intake air temperature, and changes the injection timing of main injection based on the resonance frequency. The combustion timing is changed by making adjustments. Similarly to the fuel injection control device described in Patent Document 1, the control device described in Patent Document 2 does not reduce the sound pressure itself of the resonant frequency, but rather reduces the resonance frequency from a specific frequency band that is easy for humans to hear. The sound pressure is amplified by the slid resonant frequency around a specific frequency band, which may cause new problems.

The present invention was devised in view of these points, and instead of sliding the resonant frequency of combustion noise generated in a compression self-ignition internal combustion engine from a specific frequency band, the sound pressure of the resonant frequency is An object of the present invention is to provide a control device for a compression self-ignition internal combustion engine that can suppress combustion noise by reducing combustion noise.

In order to solve the above problems, a first invention of the present invention uses an injector provided for each cylinder to perform main injection, which is the main fuel injection, and the main injection, which is the main fuel injection, for one combustion stroke . This is a control device for a compression self-ignition internal combustion engine that executes pilot injection, which is one or more fuel injections as a pre-injection. The internal combustion engine system including the internal combustion engine is provided with respective detection means for detecting respective states including the rotation speed, intake flow rate, boost pressure, and intake air temperature of the internal combustion engine, and the control device includes: The state is detected using each of the detection means, and the operating state including the state and the EGR rate and fuel injection amount determined based on the state is obtained. The control device stores a fuel injection rate characteristic indicating a fuel injection rate corresponding to a valve opening time of the injector. The control device controls the operation of the internal combustion engine from the start of the main injection based on the operating state of the internal combustion engine and the in-cylinder state quantities including the in-cylinder temperature, oxygen partial pressure, and fuel partial pressure based on the operating state. a main ignition delay time estimator that estimates a main ignition delay time that is the time until the start of main combustion, which is combustion corresponding to main injection, based on the fuel injection rate characteristic and the main ignition delay time; , an estimated premixed main fuel amount calculation unit that calculates an estimated premixed main fuel amount that is the fuel amount of the main injection injected during the main ignition delay time period, the rotation speed of the internal combustion engine, and the fuel a target premixed main fuel amount setting unit that sets a target premixed main fuel amount for the main injection using a map in which a target premixed main fuel amount is set according to the injection amount or the load of the internal combustion engine; If the estimated premixed main fuel amount exceeds the target premixed main fuel amount, the estimated premixed main fuel amount is adjusted so that the estimated premixed main fuel amount is equal to or less than the target premixed main fuel amount. This is a control device for a compression self-ignition internal combustion engine, which includes a premix main fuel amount adjustment section that controls a premix main fuel amount variable device that enables change of the premix main fuel amount.

Next, a second invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the first invention, wherein the premix main fuel amount variable device is capable of changing the fuel injection rate. The fuel injection rate variable device is a variable fuel injection rate device, and the control device adjusts the estimated premix main fuel amount in the premix main fuel amount adjustment section when the estimated premix main fuel amount exceeds the target premix main fuel amount. A compressor controller that controls the fuel injection rate variable device to reduce the fuel injection rate when controlling the premix main fuel amount variable device so that the main fuel amount is equal to or less than the target premix main fuel amount. This is a control device for an ignition-type internal combustion engine.

Next, a third invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the second invention, wherein the fuel pressure, which is the pressure of the fuel supplied to the injector, is the pressure of the fuel supplied to the injector. The injection rate can be changed by a fuel pressure adjustment device that is one of the injection rate variable devices, and the control device controls the premix main fuel amount so as to reduce the fuel injection rate in the premix main fuel amount adjustment section. The present invention is a control device for a compression self-ignition internal combustion engine that uses the fuel pressure adjustment device to reduce the pressure of fuel supplied to the injector when controlling variable equipment.

Next, a fourth invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the second or third invention, wherein the injector is one of the variable fuel injection rate devices. and has a fuel injection rate variable mechanism that makes the fuel injection rate variable, and the control device controls the premix main fuel amount adjustment section to reduce the fuel injection rate. The control device for a compression self-ignition internal combustion engine uses the variable fuel injection rate mechanism to reduce the fuel injection rate of the injector when controlling a mixed main fuel amount variable device.

Next, a fifth invention of the present invention is a control device for a compression self-ignition internal combustion engine according to any one of the second to fourth inventions, wherein the premixed main fuel amount is variable. The device further includes a main ignition delay time variable device that can change the main ignition delay time. The control device causes the premix main fuel amount adjusting section to adjust the estimated premix main fuel amount to the target premix main fuel amount when the estimated premix main fuel amount exceeds the target premix main fuel amount. When controlling the premix main fuel amount variable device so that the amount of premixed main fuel is equal to or less than the main fuel amount, the main ignition delay time variable device is further controlled so that the main ignition delay time is shortened. It is the engine control device.

Next, a sixth invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the fifth invention, wherein the internal combustion engine system having the internal combustion engine is supercharged by a supercharger. an intercooler temperature adjustment device that adjusts cooling fluid to an intercooler that cools the intake air; a supercharging pressure adjustment device that adjusts the supercharging pressure by the supercharger; It has at least one of the injector and an EGR valve that adjusts the opening degree of the EGR pipe that returns intake air, and each of the intercooler temperature adjustment device, the boost pressure adjustment device, and the EGR valve is the main ignition delay time variable device, and the injector can serve both as the fuel injection rate variable device and the main ignition delay time variable device. The control device controls the cooling fluid by the intercooler temperature adjustment device when the premix main fuel amount adjustment section controls the main ignition delay time variable device so that the main ignition delay time is shortened. reducing the flow rate of the fuel, increasing the boost pressure using the boost pressure regulator, reducing the EGR gas flow rate using the EGR valve, and increasing the injection amount of the pilot injection using the injector; This is a control device for a compression self-ignition internal combustion engine.

The inventor used various combustion analysis methods to develop a compression self-ignition internal combustion engine that performs main injection and pilot injection, which is a pre-injection to main injection, in one combustion stroke . The amount of premixed fuel, which is the amount of fuel injected into the cylinder but not yet combusted during the main ignition delay time period from the start of injection to the start of main combustion corresponding to main injection, causes a large amount of combustion noise. I found that it has an effect. The inventor believes that there is a premixed fuel amount threshold depending on the operating state of the internal combustion engine, and when the actual premixed fuel amount exceeds the premixed fuel amount threshold corresponding to the operating state at that time, main combustion occurs. It was discovered that the rate of increase in combustion heat (or combustion pressure) becomes excessive during combustion, leading to an increase in combustion noise. As a result, the inventor set a target premixed fuel amount according to the operating state, and controlled main injection so as not to exceed the target premixed fuel amount (so as not to exceed the premixed fuel amount threshold). It has been discovered that combustion noise can be suppressed by slowing down the rate of increase in combustion heat (or combustion pressure) during main combustion and reducing the sound pressure itself at the resonant frequency of combustion noise.

In addition, the (estimated) premixed fuel amount is the fuel injection rate, which is the main ignition delay time from the start of main injection to the start of main combustion corresponding to main injection, and the fuel injection rate according to the injector opening time. determined by the rate characteristics. In order to reduce the (estimated) premixed fuel amount to the target premixed fuel amount or less, the fuel injection rate may be reduced or the main ignition delay time may be shortened. Further, the main ignition delay time changes depending on the in-cylinder temperature and in-cylinder oxygen concentration at the start of main injection.

According to the first invention, the control device has a premixed fuel amount adjustment section, and controls the premixed fuel amount variable device to adjust the estimated premixed fuel amount to be equal to or less than the target premixed fuel amount. change. Thereby, combustion noise can be suppressed by reducing the sound pressure of the resonance frequency itself, rather than by sliding the resonance frequency of combustion noise from a specific frequency band.

According to the second invention, the estimated premixed fuel amount is made equal to or less than the target premixed fuel amount by controlling the fuel injection rate variable device to reduce the fuel injection rate. Thereby, combustion noise can be suppressed by reducing the sound pressure of the resonance frequency itself, rather than by sliding the resonance frequency of combustion noise from a specific frequency band.

According to the third invention, the fuel injection rate can be appropriately reduced by reducing the pressure of the fuel supplied to the injector.

According to the fourth invention, the fuel injection rate can be appropriately reduced by controlling the injector having the variable fuel injection rate mechanism.

According to the fifth invention, the estimated premixed fuel amount is made equal to or less than the target premixed fuel amount by controlling the main ignition delay time variable device to shorten the main ignition delay time. Thereby, combustion noise can be suppressed by reducing the sound pressure of the resonance frequency itself, rather than by sliding the resonance frequency of combustion noise from a specific frequency band.

According to the sixth invention, the main ignition delay time can further be appropriately shortened by increasing the in-cylinder temperature or increasing the in-cylinder oxygen concentration.

FIG. 1 is a diagram illustrating an example of a schematic configuration of an entire compression self-ignition internal combustion engine system. FIG. 3 is a diagram illustrating an example of energization to an injector, fuel injection rate, heat release rate (first-order differential of cylinder heat), and second-order differential of cylinder heat during main injection. 2 is a flowchart illustrating an example of a processing procedure of [overall processing] of the control device in the first and second embodiments. 4 is a flowchart illustrating details of [calculating estimated premixed fuel amount] in the flowchart shown in FIG. 3 in the first embodiment. 4 is a flowchart illustrating details of [adjust estimated premixed fuel amount] in the flowchart shown in FIG. 3 in the first embodiment. 4 is a flowchart illustrating details of [setting the number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] in the flowchart shown in FIG. 3 in the first embodiment. 3 is a flowchart illustrating an outline of fuel pump control in the first embodiment. It is a figure explaining the example of the reduction effect of the combustion noise by this embodiment. FIG. 4 is a diagram illustrating details of "Calculate estimated premixed fuel amount" in the flowchart shown in FIG. 3 in the second embodiment. FIG. 3 is a diagram illustrating an example of an injection rate pattern of fuel injection rate characteristics. 4 is a diagram illustrating details of [adjustment of estimated premixed fuel amount] in the flowchart shown in FIG. 3 in the second embodiment. FIG. It is a flowchart explaining the outline of fuel pump control in a 2nd embodiment. 12 is a flowchart illustrating an example of a processing procedure of [overall processing] of the control device in the third embodiment. 14 is a flowchart illustrating details of [adjust estimated premixed fuel amount] in the flowchart shown in FIG. 13 in the third embodiment. 14 is a flowchart illustrating details of [setting the number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] in the flowchart shown in FIG. 13 in the third embodiment. It is a flowchart explaining the outline of fuel pump control in a 3rd embodiment. It is a flow chart explaining the outline of coolant pump control in a 3rd embodiment. It is a flowchart explaining the outline of supercharging pressure control in a 3rd embodiment. It is a flowchart explaining the outline of EGR valve control in a 3rd embodiment.

[Example of schematic configuration of internal combustion engine system 1 (Fig. 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 a compression self-ignition internal combustion engine. Hereinafter, the internal combustion engine 10 refers to a compression self-ignition internal combustion engine. In the following explanation, the "estimated premixed fuel amount" corresponds to the "estimated premixed main fuel amount", the "estimated premixed fuel calculation section" corresponds to the "estimated premixed main fuel amount calculation section", and the "estimated premixed main fuel amount calculation section" corresponds to the "target premixed main fuel amount". The "premixed fuel amount" corresponds to the "target premixed main fuel amount", the "target premixed fuel amount setting section" corresponds to the "target premixed main fuel amount setting section", and the "premixed fuel amount variable device" corresponds to the "premix main fuel amount variable device", and the "premix fuel amount adjustment section" corresponds to the "premix main fuel amount adjustment section".

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 means 21 (for example, an intake flow rate sensor) are provided on the inflow side of the intake pipe 11A. The intake flow rate detection means 21 outputs a detection signal corresponding to the flow rate of air taken in by the internal combustion engine 10 to the control device 50. Further, the intake air flow rate detection means 21 is provided with an intake air temperature detection means 28A (for example, an intake air temperature sensor) and an atmospheric pressure detection means 23 (for example, an atmospheric pressure sensor). The intake air temperature detection means 28A outputs a detection signal corresponding to the temperature of the intake air passing through the intake air flow rate detection means 21 to the control device 50. The atmospheric pressure detection means 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 turbo supercharger 30 (equivalent to a supercharger) is rotationally driven by a turbine 36 that is rotationally driven by the energy of exhaust gas, and compresses intake air flowing in from the intake pipe 11A to the intake pipe 11B. Supercharge with.

The intake pipe 11A on the upstream side of the compressor 35 is provided with a compressor upstream pressure detection means 24A (for example, a pressure sensor). The compressor upstream pressure detection means 24A outputs a detection signal to the control device 50 according to the pressure of the intake air in the intake pipe 11A. A compressor downstream pressure detection means 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 means 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. The intercooler 16 is arranged downstream of the compressor downstream pressure detection means 24B. An intake air temperature detection means 28B (for example, an intake air temperature sensor) is provided between the intercooler 16 and the throttle device 47. The intake air temperature detection means 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 intercooler 16 is connected to an intercooler radiator 16A via piping, and the piping is provided with a coolant pump 16B. The control device 50 controls the amount of coolant discharged from the coolant pump 16B (intercooler temperature adjustment device), circulates the coolant (cooling fluid) between the intercooler radiator 16A and the intercooler 16, and adjusts the intake air temperature. is adjustable.

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 outputs a control signal to the throttle device 47 to adjust the opening of the throttle valve 47V based on the detection signal from the throttle opening detection means 47S (for example, a throttle opening sensor) and the target throttle opening. It is possible. The control device 50 determines a target throttle opening based on the amount of accelerator pedal depression detected based on the detection signal from the accelerator pedal depression amount detection means 25, the operating state of the internal combustion engine 10, and the like.

The accelerator pedal depression amount detection means 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 means 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, downstream of the throttle device 47 in the intake pipe 11B (in the intake manifold 11C), an intake manifold pressure detection means 24C (for example, a pressure sensor) is provided, and the outflow side of the EGR pipe 13 is connected to the intake manifold pressure detection means 24C. The intake manifold pressure detection means 24C outputs a detection signal to the control device 50 according to the pressure of intake air 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 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 means 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 means 73 approaches the target fuel pressure.

The internal combustion engine 10 is provided with a crank angle detection means 22A, a cam angle detection means 22B, a coolant temperature detection means 28C, and the like. The crank angle detection means 22A is, for example, a rotation sensor, and outputs a detection signal corresponding to the rotation angle of the crankshaft of the internal combustion engine 10 to the control device 50. The cam angle detection means 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 stroke, rotation angle, etc. of each cylinder based on detection signals from the crank angle detection means 22A and the cam angle detection means 22B. Further, the coolant temperature detection means 28C is, for example, a temperature sensor, and outputs a detection signal according 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 exhaust pipe 12B. The EGR pipe 13 communicates the exhaust pipe 12B and the intake pipe 11B, and is capable of circulating part of the exhaust gas in the exhaust pipe 12B to the intake pipe 11B (returning part of the exhaust gas to the intake air). 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.

Exhaust gas temperature detection means 29 is provided in the exhaust pipe 12B. The exhaust gas temperature detection means 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 can control the flow rate of the exhaust gas that leads to the turbine 36 (the opening degree of the flow path that leads the exhaust gas to the turbine can be adjusted). The opening degree of the pressure adjusting device) is adjusted by the nozzle driving means 31. The control device 50 outputs a control signal to the nozzle drive means 31 to control the opening of the variable nozzle 33 based on the detection signal from the nozzle opening detection means 32 (for example, a nozzle opening sensor) and the target nozzle opening. Adjustable.

The exhaust pipe 12B on the upstream side of the turbine 36 is provided with a turbine upstream pressure detection means 26A (for example, a pressure sensor). The turbine upstream pressure detection means 26A outputs a detection signal to the control device 50 according to the pressure of the 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 means 26B (for example, a pressure sensor). The turbine downstream pressure detection means 26B outputs a detection signal to the control device 50 according to the pressure of the 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 means 27 is, for example, a vehicle speed detection sensor, and is provided on the wheels of the vehicle. The vehicle speed detection means 27 outputs a detection signal according to the rotational speed of the wheels of the vehicle to the control device 50.

The control device 50 includes a CPU 51, a RAM 52, a storage device 53, a timer 54, and the like. Detection signals from the various detection means described above are input to the control device 50 (CPU 51), and the control device 50 (CPU 51) 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 means and actuator. Further, the temperature, pressure, etc. of each part may be calculated by estimation calculation without installing a sensor. The control device 50 detects the operating state of the internal combustion engine 10 based on detection signals from various detection means including the above-mentioned detection means, and controls various actuators including the above-mentioned actuators. 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 (CPU 51) includes a main ignition delay time estimation section 51A, an estimated premixed fuel amount calculation section 51B, a target premixed fuel amount setting section 51C, a premixed fuel amount adjustment section 51D, etc. Details of these will be described later.

Based on the operating state of the internal combustion engine 10, the control device 50 controls, for one combustion stroke , a main injection that is a main fuel injection, and one or more fuel injections that are a pre-injection of the main injection. A pilot injection is carried out into a cylinder in which air is compressed and heated. In the description of this embodiment, all injections before the main injection in one combustion stroke are collectively referred to as "pilot injection." Further, the number and injection amount of pilot injections, the injection amount of main injection, etc. are calculated as appropriate based on the total fuel injection amount in one combustion stroke , the operating state of the internal combustion engine, etc.

The injectors 43A to 43D correspond to premixed fuel quantity variable devices, and also correspond to fuel injection rate variable devices that can change the fuel injection rate and main ignition delay time variable devices that can change the main ignition delay time. (can be used both as a fuel injection rate variable device and a main ignition delay time variable device). Further, the fuel pump 72 corresponds to a premixed fuel amount variable device, and also corresponds to a fuel injection rate variable device. The coolant pump 16B (intercooler temperature adjustment device) corresponds to a premixed fuel amount variable device, and also corresponds to a main ignition delay time variable device. Further, the variable nozzle 33 (supercharging pressure adjustment device) corresponds to a premixed fuel amount adjustment device, and also corresponds to a main ignition delay time variable device. Further, the EGR valve 14 corresponds to a premixed fuel amount variable device, and also corresponds to a main ignition end time variable device.

[Overview of causes of combustion noise (Figure 2)]
Next, the cause of combustion noise will be explained using the schematic diagram shown in FIG. 2. FIG. 2 shows each state for main injection, and the horizontal axis shows time. FIG. 2 shows, in order from the top, the injector energization state, fuel pressure, fuel injection rate, heat release rate (first-order differential of cylinder heat), and second-order differential of cylinder heat. In each figure, the dotted line indicates the case where the fuel pressure is high (fuel pressure Pa), and the actual line indicates the case where the fuel pressure is low (fuel pressure Pb).

"Injector energization" means that when the same amount of fuel is injected when the fuel pressure is Pa and when the fuel pressure is Pb, the valve opening time Ta for the fuel pressure Pa is longer than the valve opening time Tb for the fuel pressure Pb. It also shows that it becomes shorter. In the case of fuel pressure Pa, electricity is applied (valve opened) from time T1 to time T3, and in the case of fuel pressure Pb, electricity is applied (valve opened) from time T1 to time T4.

"Fuel injection rate" indicates the fuel injection rate corresponding to the valve opening time, and the fuel injection rate of the injector in this case is the fuel injection rate Ha when the fuel pressure is Pa, and the fuel injection rate when the fuel pressure is Pb. This indicates that the fuel injection rate is Hb. The area surrounded by the fuel injection rate Ha is the amount of fuel injected at the fuel injection rate Ha, and the area surrounded by the fuel injection rate Hb is the amount of fuel injected at the fuel injection rate Hb. In this case, since the amount of fuel is the same, the area is the same.

The "heat release rate" indicates a value obtained by differentiating the in-cylinder heat that changes over time with respect to time (indicates the slope of the in-cylinder heat that changes over time). It is shown that when the fuel pressure is Pa, the heat release rate is Ja, and when the fuel pressure is Pb, the heat release rate is Jb. Note that ignition does not occur for a while (until time T2) from time T1 when the injector starts energizing, and ignition occurs at time T2, indicating that combustion has started. In the description of this embodiment, the time from time T1 when fuel injection is started to time T2 when ignition occurs is referred to as "main ignition delay time (τ)."

"Second differential of cylinder heat" indicates the value obtained by differentiating the heat release rate (first differential of cylinder heat) once again with respect to time. It shows the change in the slope of . In the case of fuel pressure Pa, the second-order differential of the cylinder heat is Da, and in the case of the fuel pressure Pb, the second-order differential of the cylinder heat is Db.

As shown in FIG. 2, when the fuel pressure is high (fuel pressure Pa), the amount of fuel injected during the main ignition delay time period (from time T1 to time T2) is This is the area Sa surrounded by the fuel injection rate Ha in the period. When the fuel pressure is low (fuel pressure Pb), the amount of fuel injected during the main ignition delay time period (from time T1 to time T2) is equal to the fuel injection rate Hb during the period from time T1 to time T2. The area surrounded by is Sb. In this case, area Sa is larger than area Sb. As a result, when ignition occurs at time T2, more fuel is rapidly combusted at heat release rate Ja, so the in-cylinder heat second derivative Da, which is the rising rate of heat release rate Ja from time T2, is It becomes larger than the second-order differential of the cylinder heat, Db, which is the rate of rise of the heat generation rate Jb from time T2. In the case of the fuel pressure Pa, the combustion noise increases due to the sudden rise of the second-order differential of cylinder heat Da at time T2 (at the start of ignition of main injection).

Hereinafter, the amount of fuel injected during the main ignition delay time period (period from time T1 to time T2) and not yet ignited will be referred to as "premixed fuel amount." In the example of FIG. 2, the "premixed fuel amount (area Sa surrounded by the fuel injection rate Ha)" in the case of the fuel pressure Pa is different from the "premixed fuel amount (the area Sa surrounded by the fuel injection rate Hb)" in the case of the fuel pressure Pb. Since the area surrounded by the fuel is larger than the area Sb), the amount of fuel when ignited at time T2 is large, and the combustion noise is large.

The inventor used various combustion analysis methods and found that the "premixed fuel amount" has a large effect on combustion noise, as described above. The inventor also discovered that there is a premixed fuel amount threshold depending on the operating state of the internal combustion engine, and that when the actual premixed fuel amount exceeds the premixed fuel amount threshold corresponding to the operating state at that time, the main combustion It was discovered that the rate of increase in cylinder heat (or cylinder pressure) at the time of combustion becomes excessive, leading to an increase in combustion noise. As a result, the inventor set a target premixed fuel amount according to the operating state, and controlled main injection so as not to exceed the target premixed fuel amount (so as not to exceed the premixed fuel amount threshold). It has been discovered that combustion noise can be suppressed by slowing down the rate of increase in cylinder heat (or cylinder pressure) when main combustion occurs and reducing the sound pressure itself at the resonant frequency of combustion noise.

Next, first to third embodiments of the processing procedure of the control device 50 based on the above idea will be described. The "premixed fuel amount" can be adjusted by increasing or decreasing the fuel injection rate, by increasing or decreasing the main ignition delay time, or by adjusting both the fuel injection rate and the main ignition delay time. There are three possible ways. In the first and second embodiments described below, an example of a method of adjusting the fuel injection rate is shown, and in the third embodiment, an example of a method of adjusting both the fuel injection rate and the main ignition delay time is shown. show.

[Processing procedure of control device 50 in first embodiment (FIGS. 3 to 8)]
Next, an example of the processing procedure of the control device 50 in the first embodiment will be described using the flowcharts shown in FIGS. 3 to 8. In the first embodiment, the fuel injection rate is adjusted by adjusting the fuel pressure by the fuel pump 72. The control device 50 (CPU 51) starts the [overall process] shown in FIG. 3, for example, at every predetermined crank angle (timing at which the fuel injection amount should be calculated), and advances the process to step S110. Note that the control device 50 calculates and stores the injection amount for the next combustion stroke in a separate process.

In step S110, the control device 50 sets (calculates) a target in-cylinder temperature that is the target in-cylinder temperature at the start of main injection, and advances the process to step S120. The control device 50 calculates and stores a target in-cylinder temperature that is set in advance according to the operating state of the internal combustion engine. For example, the control device 50 stores a map in which a target in-cylinder temperature is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and calculates the target in-cylinder temperature using the map. and memorize it. The target cylinder temperature is set to an appropriate value that has been confirmed through experiments using actual vehicles, simulations, and the like.

In step S120, the control device 50 calculates and stores an in-cylinder state quantity, which is a state quantity in the cylinder, based on the operating state of the internal combustion engine, and advances the process to step S130. For example, the control device 50 controls internal combustion engine rotational speed, intake flow rate, supercharging pressure, etc., such as in-cylinder state quantities such as in-cylinder temperature, oxygen partial pressure based on in-cylinder oxygen concentration, and fuel partial pressure based on injection amount. , the intake air temperature, the EGR rate, etc., are calculated and stored.

In step S130, the control device 50 sets (calculates) a target main ignition timing based on the operating state of the internal combustion engine and stores it. The target main ignition timing is a target crank angle at which main combustion is started, and is an angle set within a range of about 5 [°] before compression top dead center to about 5 [°] after compression top dead center. For example, the control device 50 stores a map in which the target main ignition timing is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and calculates the target main ignition timing using the map. and memorize it. The control device 50 also estimates (calculates) the main ignition delay time based on the operating state of the internal combustion engine and the in-cylinder state quantities (in-cylinder temperature, oxygen partial pressure, fuel partial pressure, etc.), and The time is memorized and the process proceeds to step S140. For example, the control device 50 calculates the main ignition delay time τ using the following (Equation 1).
τ=1/{A[Fuel] ^B [O ₂ ] ^C exp(-D/T)} (Formula 1)
A, B, C, D: Constant [Fuel]: Fuel partial pressure [O ₂ ]: Oxygen partial pressure T: In-cylinder temperature at injection time

The control device 50 (CPU 51) executing the process of step S130 determines the time from the start of main injection to the start of main combustion, which is combustion corresponding to the main injection, based on the operating state of the internal combustion engine. This corresponds to the main ignition delay time estimation section 51A (see FIG. 1) that estimates the main ignition delay time.

In step S140, the control device 50 calculates the main injection start timing, which is the timing to start main injection, based on the target main ignition timing, the main ignition delay time, and the rotation speed of the internal combustion engine, and advances the process to step S150. .

In step S150, the control device 50 sets (calculates) and stores a target premixed fuel amount based on the operating state of the internal combustion engine, and advances the process to step S160. For example, the control device 50 stores a map in which a target premixed fuel amount is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and uses the map to determine the target premixed fuel amount. Calculate and store. The target premixed fuel amount is set to an appropriate value that reduces combustion noise, which has been confirmed through experiments and simulations using actual vehicles.

The control device 50 (CPU 51) executing the process of step S150 sets a target premixed fuel amount setting section 51C (see FIG. (see).

In step S160, the control device 50 executes a process of [calculating estimated premixed fuel amount], and advances the process to step S170. Note that details of the process (FIG. 4) for [calculating estimated premixed fuel amount] will be described later.

In step S170, the control device 50 executes a process of [adjusting the estimated premixed fuel amount] and advances the process to step S180. The details of the process (FIG. 5) for [adjusting the estimated premixed fuel amount] will be described later.

In step S180, the control device 50 executes a process of [setting the number of pilot injection stages, injection amount, injection timing, and main injection injection amount and injection timing], and ends the process shown in FIG. 3. Note that the details of the process (FIG. 6) for [setting the number of stages, injection amount, and injection timing of pilot injection, and the injection amount and injection timing of main injection] will be described later.

[Process for calculating the estimated premixed fuel amount in the first embodiment (FIG. 4)]
Next, using FIG. 4, details of the process of [calculating estimated premixed fuel amount] in step S160 of the flowchart shown in FIG. 3 in the first embodiment will be described. When executing the process of step S160 of the flowchart shown in FIG. 3, the control device 50 advances the process to step SA120 shown in FIG.

In step SA120, control device 50 determines whether the premix adjustment request flag is ON. Note that the "premix adjustment flag" is a flag that is set to ON in step SB130 shown in FIG. 5, and is set to ON when the estimated premix fuel amount exceeds the target premix fuel amount. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SA130, and if the premix adjustment request flag is not ON (No), the control device 50 advances the process to step SA160.

When proceeding to step SA130, the control device 50 determines whether the "fuel pressure reduction amount" is equal to or higher than a predetermined pressure. Note that the "fuel pressure reduction amount" is the amount by which the pressure of the fuel discharged from the fuel pump is reduced from the target fuel pressure, as shown in step SB140 etc. shown in FIG. If the fuel pressure reduction amount is equal to or higher than a predetermined pressure (for example, a relatively small pressure of about several tens [KPa] and a pressure of ΔP2 or more) (Yes), the control device 50 advances the process to step SA140, and reduces the fuel pressure. If the amount of reduction is less than the predetermined pressure (No), the process advances to step SA150.

When proceeding to step SA140, control device 50 updates and stores the value obtained by subtracting ΔP2 from the current fuel pressure reduction amount as a new fuel pressure reduction amount, and proceeds to step SA160.

When proceeding to step SA150, control device 50 sets the premix adjustment request flag to OFF, initializes the fuel pressure reduction amount to zero, and proceeds to step SA160.

When the process proceeds to step SA160, the control device 50 acquires the current fuel pressure, acquires the fuel injection rate characteristic according to the fuel pressure, and proceeds to step SA170. As for the fuel injection rate characteristics, the graph-like characteristics shown in FIG. 2 may be prepared for each fuel pressure and stored in the storage device, or the fuel injection rate may be calculated according to the valve opening time. You can.

In step SA170, the control device 50 uses the main ignition delay time for the next main injection and the fuel injection rate characteristics to estimate the estimated amount of fuel that is injected and not burned within the main ignition delay time period. The amount of mixed fuel is calculated (estimated) and stored, the process shown in FIG. 4 is ended, and the process returns to step S170 shown in FIG.

Based on the fuel injection rate characteristics and the main ignition delay time, the control device 50 (CPU 51) executing the process of step SA170 calculates the estimated premixed fuel, which is the amount of fuel to be injected during the main ignition delay time. This corresponds to the estimated premixed fuel amount calculation unit 51B (see FIG. 1) that calculates the amount.

[Processing for adjusting the estimated premixed fuel amount in the first embodiment (FIG. 5)]
Next, using FIG. 5, details of the process of [adjusting the estimated premixed fuel amount] in step S170 of the flowchart shown in FIG. 3 in the first embodiment will be described. When executing the process of step S170 of the flowchart shown in FIG. 3, the control device 50 advances the process to step SB120 shown in FIG.

At step SB120, control device 50 determines whether the estimated premixed fuel amount for the next main injection is less than or equal to the target premixed fuel amount. If the estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 proceeds to step SB170, and if the estimated premixed fuel amount is not less than or equal to the target premixed fuel amount (No), the control device 50 proceeds to step SB170. The process advances to SB125.

When proceeding to step SB170, the control device 50 determines whether the premix adjustment request flag is ON. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SB175, and if the premix adjustment request flag is not ON (No), it ends the process shown in FIG. The process returns to step S180 shown in FIG.

When the process proceeds to step SB175, the control device 50 controls the fuel pump 72 so that the fuel pressure (detected using the fuel pressure detection means 73) approaches "target fuel pressure - fuel pressure reduction amount", and The process shown in FIG. 5 is completed and the process returns to step S180 shown in FIG.

When proceeding to step SB125, the control device 50 determines whether the premix adjustment request flag is ON. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SB140, and if the premix adjustment request flag is not ON (No), the control device 50 advances the process to step SB130.

When proceeding to step SB130, the control device 50 sets the fuel pressure reduction amount to ΔP1 (predetermined fuel pressure, relatively small pressure), sets the premix adjustment request flag to ON, and proceeds to step SB140. Proceed with the process.

When the process proceeds to step SB140, the control device 50 controls the fuel pump 72 (using the fuel pressure adjustment device) so that the fuel pressure (detected using the fuel pressure detection means 73) approaches "target fuel pressure - fuel pressure reduction amount". (corresponding to a variable fuel injection rate device), and the process proceeds to step SB145.

In step SB145, the control device 50 acquires a new fuel injection rate characteristic corresponding to "target fuel pressure - fuel pressure reduction amount" and advances the process to step SB150.

In step SB150, control device 50 updates and stores the estimated premixed fuel amount based on the main ignition delay time and the new fuel injection rate characteristic, and proceeds to step SB155. Note that since the fuel injection rate has been reduced by reducing the fuel pressure below the target fuel pressure in step SB140, the estimated premixed fuel amount updated in step SB150 is equal to the estimated premixed fuel amount used in step SB120. The amount of fuel is reduced compared to the amount of mixed fuel.

Based on the fuel injection rate characteristics and the main ignition delay time, the control device 50 (CPU 51) executing the process of step SB150 calculates the estimated premixed fuel, which is the amount of fuel to be injected during the main ignition delay time. This corresponds to the estimated premixed fuel amount calculation unit 51B (see FIG. 1) that calculates the amount.

In step SB155, control device 50 determines whether the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount. If the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 ends the process shown in FIG. 5 and returns the process to step S180 shown in FIG. If the mixed fuel amount is not less than the target premixed fuel (No), the process advances to step SB160.

When the process proceeds to step SB160, the control device 50 adds ΔP1 to the current fuel pressure reduction amount, updates and stores the fuel pressure reduction amount, and returns the process to step SB140.

If the estimated premixed fuel amount exceeds the target premixed fuel amount, the control device 50 (CPU 51) executing the process of step SB140 controls the estimated premixed fuel amount to be equal to or less than the target premixed fuel amount. This corresponds to the premixed fuel amount adjusting section 51D (see FIG. 1) that controls a premixed fuel amount variable device (in this case, the fuel pump 72) that allows changing the estimated premixed fuel amount.

[Processing for setting the number of pilot injection stages, injection amount, injection timing, and main injection injection amount and injection timing in the first embodiment (FIG. 6)]
Next, using FIG. 6, details of the process of [setting the number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] in the flowchart shown in FIG. 3 in the first embodiment will be explained. explain. When executing the process of step S180 in the flowchart shown in FIG. 3, the control device 50 advances the process to step SC120 shown in FIG.

In step SC120, the control device 50 sets the number of stages (number of times) of pilot injection based on the operating state of the internal combustion engine. For example, the storage device stores a map in which the number of stages of pilot injection (for example, 1 to 3) is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and the control device 50 The number of pilot injection stages is calculated using the map. Further, the control device 50 calculates the total pilot injection amount that can achieve the target in-cylinder temperature at the crank angle at which main injection is started, based on the main injection start timing and the target in-cylinder temperature. Then, the control device 50 divides the total pilot injection amount according to the number of stages, calculates and stores the pilot injection amount for each stage. Further, the control device 50 sets (calculates) and stores the injection start timing of the pilot injection for each stage, and advances the process to step SC130.

In step SC130, the control device 50 sets (calculates) and stores the main injection amount based on the injection amount of the next combustion stroke and the total pilot injection amount (in this case, the control device 50 (The main injection amount is calculated and stored by subtracting the total pilot injection amount from the injection amount.) The control device 50 also stores the main injection start timing calculated in step S140 shown in FIG. 3, returns to the end point of step S180 shown in FIG. 3, and ends the process shown in FIG. 3.

In a pilot injection control process (this is an existing process and the details are omitted) that is executed at a different timing, the control device 50 controls the pilot injection based on the number of stages of pilot injection, the pilot injection start timing of each stage, and the pilot injection amount. Execute injection. Further, the control device 50 executes main injection based on the main injection start timing and the main injection amount in a main injection control process (this is an existing process and the details are omitted) that is executed at a different timing.

[Fuel pump control processing in the first embodiment (FIG. 7)]
Next, [fuel pump control] of the first embodiment will be explained using FIG. 7. [Fuel Pump Control] shown in FIG. 7 has step SP130 added to the existing [Fuel Pump Control] process.

After setting the target fuel pressure in the existing process of step SP120, the control device 50 determines whether the premix adjustment request flag is ON in step SP130. When the premix adjustment request flag is ON (Yes), the control device 50 ends the process shown in FIG. 7, and when the premix adjustment request flag is not ON (No), the process proceeds to step SP140, and the fuel pressure is The fuel pump 72 is controlled so that the pressure approaches the target fuel pressure, and the process shown in FIG. 7 ends.

[Effects of this embodiment (FIG. 8)]
Next, the effects of this embodiment will be explained using FIG. 8. In FIG. 8, the horizontal axis shows frequency and the vertical axis shows the sound pressure level of combustion noise. The combustion noise characteristic G1 indicated by the dotted line shows an example where no measures are taken to suppress combustion noise. Note that the specific frequency band W1 is a frequency band that is easily audible to humans, and is a frequency band in which the sound pressure level of combustion noise should be reduced. In this case, since the resonant frequency (high sound pressure part) of the combustion noise is within the specific frequency band W1 that is easy for people to hear, the user can hear the combustion noise that bothers him.

Combustion noise characteristic G2 indicated by a two-dot chain line shows an example in which the combustion noise in the specific frequency band W1 is reduced by taking the measures described in Patent Document 1 or Patent Document 2 mentioned above. In Patent Document 1 or Patent Document 2, the resonant frequency of combustion noise is slid from within a specific frequency band W1 that is easily audible to humans. In this case, there is no resonant frequency within the specific frequency band W1, but a new resonant frequency (portion with high sound pressure) appears around the specific frequency band W1. As a result, combustion noise that is bothersome to the user becomes less audible, but since the sound pressure level of the slid resonance frequency is high, new problems may occur.

Combustion noise characteristic G3 shown by a solid line shows an example in which combustion noise is reduced by taking the measures described in this embodiment. In this embodiment, instead of sliding the resonance frequency as in Patent Document 1 and Patent Document 2, the sound pressure level of combustion noise itself is reduced. Therefore, it becomes difficult for the user to hear the combustion noise that bothers him, and no new problems arise due to the sliding of the resonant frequency.

[Processing procedure of control device 50 in second embodiment (FIGS. 9 to 12)]
Next, an example of the processing procedure of the control device 50 in the second embodiment will be described using flowcharts shown in FIGS. 9 to 12. In the second embodiment, the fuel injection rate is adjusted by using an injector having a variable fuel injection rate mechanism. Note that the [overall processing] shown in FIG. 3 is common to the first and second implementations.

The control device 50 (CPU 51) starts the process shown in FIG. 3 ([overall process]), for example, at every predetermined crank angle (timing at which the fuel injection amount should be calculated), and advances the process to step S110. Note that the control device 50 calculates and stores the injection amount for the next combustion stroke in a separate process.

[Overall processing] shown in FIG. 3 is the same in the first and second embodiments, so the explanation will be omitted. Further, the process of [setting the number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] in step S180 in FIG. 3 is also the same in the first and second embodiments. The explanation will be omitted. The process of [calculating the estimated premixed fuel amount] in step S160 of FIG. 3 and the process of [adjusting the estimated premixed fuel amount] of step S170 of FIG. 3 are different in the second embodiment, so they will be described below. The details of the process of [calculating the estimated premixed fuel amount] (FIG. 9) and the process of [adjusting the estimated premixed fuel amount] (FIG. 11) will be described.

[Process for calculating estimated premixed fuel amount in second embodiment (FIGS. 9 and 10)]
Next, details of the process of [calculating estimated premixed fuel amount] in step S160 of the flowchart shown in FIG. 3 in the second embodiment will be explained using FIGS. 9 and 10. When executing the process of step S160 of the flowchart shown in FIG. 3, the control device 50 advances the process to step SA220 shown in FIG.

In step SA220, control device 50 determines whether the premix adjustment request flag is ON. Note that the "premix adjustment flag" is a flag that is set to ON in step SB230 shown in FIG. 11, and is set to ON when the estimated premix fuel amount exceeds the target premix fuel amount. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SA230, and if the premix adjustment request flag is not ON (No), the control device 50 advances the process to step SA260.

When the process proceeds to step SA230, the control device 50 determines whether the "injection rate pattern" is the standard pattern R0 (see FIG. 10). For example, the injection rate pattern is a pattern of fuel injection rate characteristics set in advance for an injector having a variable fuel injection rate mechanism, and as shown in FIG. A pattern R1 with a low injection rate, a pattern R2 with one more low injection rate, and a pattern Rn with one more low injection rate are set in advance and stored in the storage device. If the stored injection rate pattern is the standard pattern R0 (Yes), the control device 50 advances the process to step SA250, and if it is not the standard pattern R0 (No), the control device 50 advances the process to step SA240.

When the process proceeds to step SA240, the control device 50 stores an injection rate pattern changed from the current injection rate pattern to a pattern on the one-step increase side, and proceeds to step SA245. For example, when the currently stored injection rate pattern is pattern R2, the control device 50 stores pattern R1 on the one-stage increase side as the injection rate pattern. Note that the injection rate pattern is initialized to the standard pattern R0 when the control device 50 is started.

In step SA245, the control device 50 determines whether the "injection rate pattern" is the standard pattern R0 (see FIG. 10). If the injection rate pattern is the standard pattern R0 (Yes), the control device 50 advances the process to step SA250, and if the injection rate pattern is not the standard pattern R0 (No), the control device 50 advances the process to step SA260.

When proceeding to step SA250, control device 50 sets the premix adjustment request flag to OFF and proceeds to step SA260.

When proceeding to step SA260, control device 50 obtains the current fuel pressure, obtains the fuel injection rate characteristic according to the pattern stored in the injection rate pattern, and proceeds to step SA270. The control device 50 also corrects the fuel injection rate characteristics based on the fuel pressure, if necessary.

In step SA270, the control device 50 calculates the estimated premixed fuel amount, which is the amount of fuel injected and not burned within the period of the main ignition delay time, based on the main ignition delay time and the fuel injection rate characteristics. The process shown in FIG. 9 is ended, and the process returns to step S170 shown in FIG. 3.

Based on the fuel injection rate characteristics and the main ignition delay time, the control device 50 (CPU 51) executing the process of step SA270 calculates the estimated premixed fuel, which is the amount of fuel to be injected during the main ignition delay time. This corresponds to the estimated premixed fuel amount calculation unit 51B (see FIG. 1) that calculates the amount.

[Processing for adjusting estimated premixed fuel amount in second embodiment (FIG. 11)]
Next, using FIG. 11, details of the process of [adjusting the estimated premixed fuel amount] in step S170 of the flowchart shown in FIG. 3 in the second embodiment will be described. When executing the process of step S170 of the flowchart shown in FIG. 3, the control device 50 advances the process to step SB220 shown in FIG. 11.

At step SB220, control device 50 determines whether the estimated premixed fuel amount is less than or equal to the target premixed fuel amount. If the estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 ends the process shown in FIG. 11 and returns the process to step S180 shown in FIG. If it is not below the target premixed fuel amount (No), the process advances to step SB225.

When proceeding to step SB225, the control device 50 determines whether the premix adjustment request flag is ON. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SB245, and if the premix adjustment request flag is not ON (No), the control device 50 advances the process to step SB230.

When the process proceeds to step SB230, the control device 50 stores a pattern that is one step lower than the standard pattern (pattern R1 in this case) as the injection rate pattern, and sets the premix adjustment request flag to ON. Then, the process advances to step SB245.

When the process proceeds to step SB245, the control device 50 acquires new fuel injection rate characteristics according to the patterns stored in the injection rate patterns of the injectors 43A to 43D (corresponding to variable fuel injection rate devices). The process advances to step SB250.

At step SB250, control device 50 updates and stores the estimated premixed fuel amount based on the main ignition delay time and the new fuel injection rate characteristic, and proceeds to step SB255. Note that by acquiring the reduced fuel injection rate characteristic in step SB245, the estimated premixed fuel amount updated in step SB250 is smaller than the estimated premixed fuel amount used in step SB220.

Based on the fuel injection rate characteristics and the main ignition delay time, the control device 50 (CPU 51) executing the process of step SB250 calculates the estimated premixed fuel, which is the amount of fuel to be injected during the main ignition delay time. This corresponds to the estimated premixed fuel amount calculation unit 51B (see FIG. 1) that calculates the amount.

In step SB255, control device 50 determines whether the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount. If the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 ends the process shown in FIG. 11 and returns the process to step S180 shown in FIG. If the mixed fuel amount is not less than the target premixed fuel (No), the process advances to step SB260.

When the process proceeds to step SB260, the control device 50 stores a pattern that is one step lower than the pattern stored in the current injection rate pattern as an injection rate pattern, and returns the process to step SB245. For example, when the currently stored injection rate pattern is pattern R1, the control device 50 stores pattern R2 on the one-stage reduction side as the injection rate pattern.

If the estimated premixed fuel amount exceeds the target premixed fuel amount, the control device 50 (CPU 51) executing the process of changing the injection rate pattern in steps SB230 and SB260 determines that the estimated premixed fuel amount is the target premixed fuel amount. A premixed fuel amount adjustment unit 51D (see FIG. 1) controls a premixed fuel amount variable device (in this case, injectors 43A to 43D) that enables changing the estimated premixed fuel amount so that it is equal to or less than the premixed fuel amount. ).

[Fuel pump control processing in the second embodiment (FIG. 12)]
Next, [fuel pump control] of the second embodiment will be explained using FIG. 12. In the [fuel pump control] shown in FIG. 12, step SP130 is omitted from the process of the [fuel pump control] of the first embodiment shown in FIG.

After setting the target fuel pressure in the existing process of step SP120, the control device 50 advances the process to step SP140, controls the fuel pump so that the fuel pressure approaches the target fuel pressure, and performs the process shown in FIG. finish.

Note that the effects of the second embodiment are similar to those of the first embodiment described using FIG. 8, and instead of sliding the resonance frequency, the sound pressure level of combustion noise itself is reduced. . Therefore, it becomes difficult for the user to hear the combustion noise that bothers him, and no new problems arise due to the sliding of the resonant frequency.

[Processing procedure of control device 50 in third embodiment (FIGS. 13 to 19)]
Next, an example of the processing procedure of the control device 50 in the third embodiment will be described using flowcharts shown in FIGS. 13 to 19. In the third embodiment, the fuel injection rate is adjusted by the fuel pump, and the main ignition delay time is adjusted by the coolant pump 16B, the EGR valve 14, the variable nozzle 33, and the injector (pilot injection).

The [overall processing] shown in FIG. 13 is different from the [overall processing] shown in FIG. 3 in the first and second embodiments. In addition, the processing of [Calculate estimated premixed fuel amount], [Adjust estimated premixed fuel amount], and [Set number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] can also be performed. This is different from the first and second embodiments. The control device 50 (CPU 51) starts the [overall process] shown in FIG. 13, for example, at every predetermined crank angle (timing at which the fuel injection amount should be calculated), and advances the process to step S310. Note that the control device 50 calculates and stores the injection amount for the next combustion stroke in a separate process.

In step S310, the control device 50 determines whether the in-cylinder state correction request flag is ON. Note that the "in-cylinder state correction request flag" is set to ON in step SB333 shown in FIG. 14, and is set to ON when the estimated premixed fuel amount exceeds the target premixed fuel amount. If the in-cylinder state correction request flag is ON (Yes), the control device 50 advances the process to step S311, and if the in-cylinder state correction request flag is not ON (No), the control device 50 advances the process to step S313.

When the process proceeds to step S311, the control device 50 determines whether the in-cylinder correction maintenance timer is longer than a predetermined time (for example, several seconds). Note that the "in-cylinder correction maintenance timer" is initialized (zero) and activated in step SB333 shown in FIG. 14, and is activated when the estimated premixed fuel amount exceeds the target premixed fuel amount. If the in-cylinder correction maintenance timer is longer than the predetermined time (Yes), the control device 50 advances the process to step S312, and if the in-cylinder correction maintenance timer is less than the predetermined time (No), the control device 50 advances the process to step S313. .

When proceeding to step S312, the control device 50 sets the in-cylinder state correction request flag to OFF and proceeds to step S313.

When proceeding to step S313, the control device 50 sets (calculates) a target in-cylinder temperature base that is the base of the target in-cylinder temperature at the start of main injection, and proceeds to step S314. The control device 50 calculates and stores a target in-cylinder temperature base set in advance according to the operating state of the internal combustion engine. For example, the control device 50 stores a map in which a target in-cylinder temperature base is set according to the rotational speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and uses the map to set the target in-cylinder temperature base. Calculate and store. The target in-cylinder temperature base is set to an appropriate value that has been confirmed through experiments and simulations using actual vehicles.

In step S314, the control device 50 determines whether the in-cylinder state correction request flag is set to ON. If the in-cylinder state correction request flag is ON (Yes), the control device 50 advances the process to step S315, and if the in-cylinder state correction request flag is not ON (No), the control device 50 advances the process to step S316.

When proceeding to step S315, the control device 50 stores the temperature obtained by adding ΔTh to the target in-cylinder temperature base as the target in-cylinder temperature, and proceeds to step S320. Note that ΔTh is a relatively small temperature that does not affect the increase in harmful components of the exhaust gas of the internal combustion engine or the deterioration of fuel efficiency, and is set to an appropriate value confirmed through experiments, simulations, etc. The control device 50 can shorten the main ignition delay time by increasing the target in-cylinder temperature.

When proceeding to step S316, the control device 50 stores the target in-cylinder temperature base as the target in-cylinder temperature, and proceeds to step S320.

The process in step S320 is the same as the process in step S120 shown in FIG. The process advances to S330. For example, the control device 50 controls internal combustion engine rotational speed, intake flow rate, supercharging pressure, etc. as in-cylinder state quantities such as in-cylinder temperature, oxygen partial pressure based on in-cylinder oxygen concentration, and fuel partial pressure based on injection amount. , the intake air temperature, the EGR rate, etc., are calculated and stored.

The process in step S330 is the same as the process in step S130 shown in FIG. 3, and the control device 50 sets (calculates) the target main ignition timing based on the operating state of the internal combustion engine and stores it. The target main ignition timing is a target crank angle at which main combustion is started, and is an angle set within a range of about 5 [°] before compression top dead center to about 5 [°] after compression top dead center. For example, the control device 50 stores a map in which the target main ignition timing is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and calculates the target main ignition timing using the map. and memorize it. The control device 50 also estimates (calculates) the main ignition delay time based on the operating state of the internal combustion engine and the in-cylinder state quantities (in-cylinder temperature, oxygen partial pressure, fuel partial pressure, etc.), and The time is memorized and the process proceeds to step S340. For example, the control device 50 calculates the main ignition delay time τ using the above-mentioned (Equation 1).

The control device 50 (CPU 51) executing the process in step S330 determines the time from the start of main injection to the start of main combustion, which is combustion corresponding to the main injection, based on the operating state of the internal combustion engine. This corresponds to the main ignition delay time estimation section 51A (see FIG. 1) that estimates the main ignition delay time.

The process in step S340 is the same as the process in step S140 shown in FIG. 3, and the control device 50 calculates the main injection start timing based on the target main ignition timing, the main ignition delay time, and the rotation speed of the internal combustion engine, The process advances to step S350.

The process in step S350 is the same as the process in step S150 shown in FIG. proceed. For example, the control device 50 stores a map in which a target premixed fuel amount is set according to the rotation speed of the internal combustion engine and the fuel injection amount (load of the internal combustion engine), and uses the map to determine the target premixed fuel amount. Calculate and store. The target premixed fuel amount is set to an appropriate value that reduces combustion noise confirmed through experiments and simulations using actual vehicles.

The control device 50 (CPU 51) executing the process of step S350 sets a target premixed fuel amount setting section 51C (see FIG. (see).

In step S360, the control device 50 executes a process of [calculating estimated premixed fuel amount], and advances the process to step S370. Note that the process of [calculating the estimated premixed fuel amount] is the same as the process of [calculating the estimated premixed fuel amount] shown in FIG. 4, so a description thereof will be omitted.

In step S370, the control device 50 executes a process of [adjusting the estimated premixed fuel amount] and advances the process to step S380. The details of the process (FIG. 14) for [adjusting the estimated premixed fuel amount] will be described later.

In step S380, the control device 50 executes a process of [setting the number of pilot injection stages, injection amount, injection timing, and main injection injection amount and injection timing], and ends the process shown in FIG. 13. The details of the process (FIG. 15) for [setting the number of pilot injection stages, injection amount, injection timing, and main injection injection amount and injection timing] will be described later.

[Process for adjusting estimated premixed fuel amount in third embodiment (FIG. 14)]
Next, using FIG. 14, details of the process of [adjusting the estimated premixed fuel amount] in step S370 of the flowchart shown in FIG. 13 in the third embodiment will be described. When executing the process of step S370 of the flowchart shown in FIG. 13, the control device 50 advances the process to step SB320 shown in FIG. 14.

At step SB320, control device 50 determines whether the estimated premixed fuel amount is less than or equal to the target premixed fuel amount. If the estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 advances the process to step SB370, and if the estimated premixed fuel amount is not less than or equal to the target premixed fuel amount (No), the control device 50 proceeds to step SB370. The process advances to SB325.

When proceeding to step SB370, the control device 50 determines whether the in-cylinder state correction request flag is ON. If the in-cylinder state correction request flag is ON (Yes), the control device 50 advances the process to step SB372, and if the in-cylinder state correction request flag is not ON (No), the control device 50 advances the process to step SB380.

When the process proceeds to step SB372, the control device 50 controls the coolant pump 16B so that the coolant flow rate approaches "target coolant flow rate - ΔWh", and proceeds to step SB373. Note that ΔWh, which is the amount of reduction in coolant flow rate, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and is an appropriate amount that has been confirmed through experiments and simulations. Value is set. The control device 50 can increase the in-cylinder temperature by reducing the target coolant flow rate and increasing the intake air temperature, thereby shortening the main ignition delay time.

In step SB373, the control device 50 controls the opening degree (closed degree) of the variable nozzle 33 of the turbocharger 30 so that the boost pressure approaches "target boost pressure + ΔPh", and proceeds to step SB374. . Note that ΔPh, which is the amount of increase in the target boost pressure, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and has been confirmed through experiments and simulations. Appropriate values are set. By increasing the target boost pressure, the control device 50 can increase the oxygen concentration in the cylinder and the temperature in the cylinder, thereby shortening the main ignition delay time.

In step SB374, the control device 50 controls the opening degree of the EGR valve 14 so that the EGR rate approaches "target EGR rate - ΔEh" and advances the process to step SB375. Note that ΔEh, which is the reduction amount of the target EGR rate, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and is an appropriate amount that has been confirmed through experiments and simulations. A value is set. By reducing the target EGR rate, the control device 50 can increase the oxygen concentration in the cylinder and shorten the main ignition delay time.

In step SB375, the control device 50 stores the temperature obtained by adding ΔTh to the target in-cylinder temperature base as the target in-cylinder temperature, and advances the process to step SB380. Note that the target in-cylinder temperature raised here is reflected in the injection amount of pilot injection, etc. in step SC320 shown in FIG. 15, and the main ignition delay time is shortened.

At step SB380, control device 50 determines whether the premix adjustment request flag is ON. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SB382, and if the premix adjustment request flag is not ON (No), it ends the process shown in FIG. The process returns to step S380 shown in FIG.

When proceeding to step SB325, the control device 50 determines whether the premix adjustment request flag is ON. If the premix adjustment request flag is ON (Yes), the control device 50 advances the process to step SB332, and if the premix adjustment request flag is not ON (No), the control device 50 advances the process to step SB330.

When proceeding to step SB330, the control device 50 sets the fuel pressure reduction amount to ΔP1 (a predetermined fuel pressure, which is a relatively small pressure), sets the premix adjustment request flag to ON, and proceeds to step SB332. Proceed with the process.

When proceeding to step SB332, the control device 50 determines whether the in-cylinder state correction request flag is ON. If the in-cylinder state correction request flag is ON (Yes), the control device 50 advances the process to step SB334, and if the in-cylinder state correction request flag is not ON (No), the control device 50 advances the process to step SB333.

When proceeding to step SB333, the control device 50 initializes (zero) and starts the in-cylinder correction maintenance timer, sets the in-cylinder state correction request flag to ON, and proceeds to step SB334.

When the process proceeds to step SB334, the control device 50 operates the coolant pump 16B (which is an intercooler temperature adjustment device and corresponds to the main ignition delay time variable device) so that the coolant flow rate approaches "target coolant flow rate - ΔWh". The process is then controlled to proceed to step SB335. In this case, the control device 50 reduces the flow rate of coolant (cooling fluid) by the coolant pump 16B (intercooler temperature adjustment device). Note that ΔWh, which is the amount of reduction in coolant flow rate, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and is an appropriate amount that has been confirmed through experiments and simulations. Value is set. The control device 50 can increase the in-cylinder temperature by reducing the target coolant flow rate and increasing the intake air temperature, thereby shortening the main ignition delay time.

In step SB335, the control device 50 controls the variable nozzle 33 of the turbocharger 30 (which is a boost pressure adjustment device and corresponds to a main ignition delay time variable device) so that the boost pressure approaches "target boost pressure + ΔPh". ) is controlled, and the process proceeds to step SB336. In this case, the control device 50 increases the boost pressure by the variable nozzle 33 (supercharging pressure adjustment device). Note that ΔPh, which is the amount of increase in the target boost pressure, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and has been confirmed through experiments and simulations. Appropriate values are set. By increasing the target boost pressure, the control device 50 can increase the oxygen concentration and the in-cylinder temperature, thereby shortening the main ignition delay time.

In step SB336, the control device 50 controls the opening degree of the EGR valve 14 (corresponding to the main ignition delay time variable device) so that the EGR rate approaches "target EGR rate - ΔEh", and proceeds to step SB337. In this case, the control device 50 reduces the EGR gas flow rate by the EGR valve 14. Note that ΔEh, which is the amount of reduction in the target EGR rate, is a relatively small amount that does not affect the increase in harmful components of the internal combustion engine exhaust or the deterioration of fuel efficiency, and is an appropriate amount that has been confirmed through experiments and simulations. A value is set. By reducing the target EGR rate, the control device 50 can increase the oxygen concentration and shorten the main ignition delay time.

In step SB337, the control device 50 stores the temperature obtained by adding ΔTh to the target in-cylinder temperature base as the target in-cylinder temperature, and advances the process to step SB340. Note that ΔTh is a relatively small temperature that does not affect the increase in harmful components of the exhaust gas of the internal combustion engine or the deterioration of fuel efficiency, and is set to an appropriate value confirmed through experiments, simulations, etc. The control device 50 increases the target in-cylinder temperature, increases pilot injection from the injectors 43A to 43D (corresponding to main ignition delay time variable devices), increases the increase in the in-cylinder temperature, and changes the main ignition delay time. Can be shortened.

When the process proceeds to step SB340, the control device 50 controls the fuel pump 72 so that the fuel pressure (detected using the fuel pressure detection means 73) approaches "target fuel pressure - fuel pressure reduction amount", and controls the fuel pump 72 to step SB345. Proceed to processing.

In step SB345, the control device 50 acquires a new fuel injection rate characteristic according to "target fuel pressure - fuel pressure reduction amount" and advances the process to step SB350.

In step SB350, control device 50 updates and stores the estimated premixed fuel amount based on the main ignition delay time and the new fuel injection rate characteristic, and proceeds to step SB355. Note that since the fuel injection rate has been reduced by reducing the fuel pressure below the target fuel pressure in step SB340, the estimated premixed fuel amount updated in step SB350 is the estimated predicted amount used in step SB320. The amount of fuel is reduced compared to the amount of mixed fuel.

Based on the fuel injection rate characteristics and the main ignition delay time, the control device 50 (CPU 51) executing the process of step SB350 calculates the estimated premixed fuel, which is the amount of fuel to be injected during the main ignition delay time. This corresponds to the estimated premixed fuel amount calculation unit 51B (see FIG. 1) that calculates the amount.

In step SB355, control device 50 determines whether the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount. If the updated estimated premixed fuel amount is less than or equal to the target premixed fuel amount (Yes), the control device 50 ends the process shown in FIG. 14, returns the process to step S180 shown in FIG. 13, and updates the updated estimated premixed fuel amount. If the mixed fuel amount is not less than the target premixed fuel (No), the process advances to step SB360.

If the process proceeds to step SB360, the control device 50 adds ΔP1 to the current fuel pressure reduction amount, updates and stores the fuel pressure reduction amount, and returns the process to step SB340.

If the estimated premixed fuel amount exceeds the target premixed fuel amount, the control device 50 (CPU 51) executing the processing in steps SB334, SB335, SB336, SB337, and SB340 determines that the estimated premixed fuel amount exceeds the target premixed fuel amount. Premixed fuel amount variable equipment that allows changing the estimated premixed fuel amount so that it is equal to or less than the mixed fuel amount (in this case, coolant pump 16B, variable nozzle 33, EGR valve 14, injectors 43A to 43D, fuel pump 72) This corresponds to the premixed fuel amount adjusting section 51D (see FIG. 1) that controls the amount of premixed fuel.

[Processing for setting the number of pilot injection stages, injection amount, injection timing, and main injection injection amount and injection timing in the third embodiment (FIG. 15)]
Next, using FIG. 15, details of the process of [setting the number of stages of pilot injection, injection amount, injection timing, injection amount and injection timing of main injection] of the flowchart shown in FIG. 13 in the third embodiment will be explained. explain. When executing the process in step S380 of the flowchart shown in FIG. 13, the control device 50 advances the process to step SC320 shown in FIG. 15.

Note that each process in steps SC320 and SC330 is the same as each process in steps SC120 and SC130 in FIG. 6 of the first embodiment, so a description thereof will be omitted. Note that, if the target in-cylinder temperature has been increased to the target in-cylinder temperature base +ΔTh, the injection amount of the pilot injection determined in step SC320 is increased by that amount.

[Fuel pump control processing in the third embodiment (FIG. 16)]
Next, [fuel pump control] of the third embodiment will be described using FIG. 16. [Fuel Pump Control] shown in FIG. 16 has step SP330 added to the existing [Fuel Pump Control] process.

After setting the target fuel pressure in the existing process of step SP320, the control device 50 determines whether the premix adjustment request flag is ON in step SP330. When the premix adjustment request flag is ON (Yes), the control device 50 ends the process shown in FIG. 16, and when the premix adjustment request flag is not ON (No), the process proceeds to step SP340, and the fuel pressure is The fuel pump 72 is controlled so that the pressure approaches the target fuel pressure, and the process shown in FIG. 16 ends.

[Coolant pump control processing in the third embodiment (FIG. 17)]
Next, [coolant pump control] of the third embodiment will be explained using FIG. 17. [Coolant Pump Control] shown in FIG. 17 has step SF330 added to the existing [Coolant Pump Control] process.

After setting the target coolant flow rate in the existing process of step SF320, the control device 50 determines whether the in-cylinder state correction request flag is ON in step SF330. If the cylinder condition correction request flag is ON (Yes), the control device 50 ends the process shown in FIG. 17, and if the cylinder condition correction request flag is not ON (No), the control device 50 advances the process to step SF340. The coolant pump 16B is controlled so that the coolant flow rate approaches the target coolant flow rate, and the process shown in FIG. 17 is completed.

[Processing of boost pressure control in the third embodiment (FIG. 18)]
Next, [supercharging pressure control] of the third embodiment will be explained using FIG. 18. [Supercharging pressure control] shown in FIG. 18 has step ST330 added to the existing process of [supercharging pressure control].

After setting the target boost pressure in the existing process of step ST320, the control device 50 determines whether the in-cylinder state correction request flag is ON in step ST330. If the cylinder condition correction request flag is ON (Yes), the control device 50 ends the process shown in FIG. 18, and if the cylinder condition correction request flag is not ON (No), the control device 50 advances the process to step ST340. The opening degree (closing degree) of the variable nozzle 33 is controlled so that the boost pressure approaches the target boost pressure, and the process shown in FIG. 18 is completed.

[Processing of EGR valve control in the third embodiment (FIG. 19)]
Next, [EGR valve control] of the third embodiment will be explained using FIG. 19. [EGR valve control] shown in FIG. 19 has step SG330 added to the existing [EGR valve control] process.

After setting the target EGR rate in the existing process of step SG320, the control device 50 determines whether the in-cylinder state correction request flag is ON in step SG330. If the cylinder condition correction request flag is ON (Yes), the control device 50 ends the process shown in FIG. 19, and if the cylinder condition correction request flag is not ON (No), the control device 50 advances the process to step SG340. The opening degree of the EGR valve 14 is controlled so that the EGR rate approaches the target EGR rate, and the process shown in FIG. 19 ends.

In the third embodiment, the main ignition delay time variable equipment (coolant pump 16B, EGR valve 14, variable nozzle 33, injectors 43A to 43D (pilot injection amount)) changes a small amount that does not affect exhaust gas or fuel efficiency. Therefore, the amount of reduction in main ignition delay time is relatively small. Furthermore, increases in the cylinder temperature and oxygen concentration caused by the coolant pump 16B, the EGR valve 14, and the variable nozzle 33 change relatively slowly. Therefore, with this alone, there is a possibility that the estimated premixed fuel amount cannot be made equal to or less than the target premixed fuel amount. Therefore, it is preferable to combine this with adjustment using a fast-acting variable fuel injection rate device (the fuel pump 72 or the injectors 43A to 43D (variable fuel injection rate mechanism)). In the third embodiment described above, an example was explained in which the fuel pump 72 was used as the variable fuel injection rate device, but the injectors 43A to 43D equipped with a variable fuel injection rate mechanism may also be used as the variable fuel injection rate device. good.

Note that the effects of the third embodiment are similar to those of the first embodiment described using FIG. 8, and instead of sliding the resonance frequency, the sound pressure level of combustion noise itself is reduced. . Therefore, it becomes difficult for the user to hear the combustion noise that bothers him, and no new problems arise due to the sliding of the resonant frequency.

The control device for a compression self-ignition internal combustion engine of the present invention is not limited to the configuration, structure, processing procedure (flowchart), etc. described in this embodiment, and various modifications and changes may be made without departing from the gist of the present invention. Can be added or deleted.

Furthermore, the control device for a compression self-ignition internal combustion engine of the present invention is not limited to diesel engines, but can also be applied to compression self-ignition gasoline engines.

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. Further, the numerical values used in the description of this embodiment are merely examples, and the present invention is not limited to these numerical values.

In the description of the third embodiment, in order to shorten the main ignition delay time, the coolant pump 16B is controlled so that the coolant flow rate approaches "target coolant flow rate - ΔWh", and the boost pressure is controlled to "target boost pressure + ΔPh". The variable nozzle 33 is controlled so that the EGR rate approaches "Target EGR rate - ΔEh", and the EGR valve 14 is controlled so that the in-cylinder temperature approaches "Target in-cylinder temperature base + ΔTh". Although an example has been described in which all four of the following are executed: 43D pilot injection control, at least one of these four may be executed.

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 (main ignition delay time variable device)
15 EGR cooler 16 Intercooler 16A Radiator for intercooler 16B Coolant pump (main ignition delay time variable device)
21 Intake flow rate detection means 22A Crank angle detection means 22B Cam angle detection means 23 Atmospheric pressure detection means 24A Compressor upstream pressure detection means 24B Compressor downstream pressure detection means 24C Intake manifold pressure detection means 25 Accelerator pedal depression amount detection means 26A Turbine upstream pressure detection means Means 26B Turbine downstream pressure detection means 27 Vehicle speed detection means 28A, 28B Intake air temperature detection means 28C Coolant temperature detection means 29 Exhaust temperature detection means 30 Turbo supercharger 31 Nozzle drive means 32 Nozzle opening detection means 33 Variable nozzle (main ignition delay time variable equipment)
35 Compressor 36 Turbine 41 Common rail 43A to 43D Injector (combined as fuel injection rate variable device and main ignition delay time variable device)
45A to 45D Cylinder 47 Throttle device 47S Throttle opening detection means 47V Throttle valve 50 Control device 51 CPU
51A Main ignition delay time estimation section 51B Estimated premixed fuel amount calculation section 51C Target premixed fuel amount setting section 51D Premixed fuel amount adjustment section 53 Storage device 61 Exhaust purification device 72 Fuel pump (fuel injection rate variable device)
73 Fuel pressure detection means τ Main ignition delay time

Claims (6)

Using an injector provided for each cylinder, for one combustion stroke , there is a main injection which is the main fuel injection, and a pilot injection which is one or more fuel injections which are the preceding injections of the main injection. , a control device for a compression self-ignition internal combustion engine,
The internal combustion engine system including the internal combustion engine is provided with respective detection means for detecting respective states of the internal combustion engine including the rotation speed, intake air flow rate, boost pressure, and intake air temperature,
The control device detects the state using each of the detection means, and obtains the state and an operating state including an EGR rate and a fuel injection amount determined based on the state,
The control device includes:
A fuel injection rate characteristic indicating a fuel injection rate corresponding to a valve opening time of the injector is stored,
The control device includes:
Combustion corresponding to the main injection from the start of the main injection based on the operating state of the internal combustion engine and the in-cylinder state quantities including the in-cylinder temperature, oxygen partial pressure, and fuel partial pressure based on the operating state. a main ignition delay time estimator that estimates a main ignition delay time that is the time until the start of main combustion;
an estimated premix main fuel amount that is a fuel amount of the main injection injected during the main ignition delay time based on the fuel injection rate characteristic and the main ignition delay time; A fuel amount calculation unit,
A target premixed main fuel amount for the main injection is set using a map in which a target premixed main fuel amount is set according to the rotational speed of the internal combustion engine and the fuel injection amount or the load of the internal combustion engine . , a target premix main fuel amount setting section;
If the estimated premixed main fuel amount exceeds the target premixed main fuel amount, changing the estimated premixed main fuel amount so that the estimated premixed main fuel amount is equal to or less than the target premixed main fuel amount. a premix main fuel amount adjustment section that controls a premix main fuel amount variable device that enables
has,
Control device for compression self-ignition internal combustion engine. A control device for a compression self-ignition internal combustion engine according to claim 1,
The premix main fuel amount variable device is a fuel injection rate variable device that can change the fuel injection rate,
The control device includes:
In the premix main fuel amount adjustment section, when the estimated premix main fuel amount exceeds the target premix main fuel amount, the estimated premix main fuel amount becomes equal to or less than the target premix main fuel amount. When controlling the premix main fuel amount variable device, controlling the fuel injection rate variable device to reduce the fuel injection rate,
Control device for compression self-ignition internal combustion engine. A control device for a compression self-ignition internal combustion engine according to claim 2,
The fuel pressure, which is the pressure of the fuel supplied to the injector, can be changed by a fuel pressure adjustment device that is one of the fuel injection rate variable devices,
The control device includes:
When the premix main fuel amount adjustment section controls the premix main fuel amount variable device to reduce the fuel injection rate, the fuel pressure adjustment device is used to control the pressure of the fuel supplied to the injector. reduce,
Control device for compression self-ignition internal combustion engine. A control device for a compression self-ignition internal combustion engine according to claim 2 or 3,
The injector is one of the variable fuel injection rate devices, and has a variable fuel injection rate mechanism that varies the fuel injection rate,
The control device includes:
When the premix main fuel amount adjustment section controls the premix main fuel amount variable device to reduce the fuel injection rate, the fuel injection rate variable mechanism is used to adjust the fuel injection rate of the injector. reduce,
Control device for compression self-ignition internal combustion engine. A control device for a compression self-ignition internal combustion engine according to any one of claims 2 to 4,
The premix main fuel amount variable device further includes a main ignition delay time variable device capable of changing the main ignition delay time,
The control device includes:
In the premix main fuel amount adjustment section, when the estimated premix main fuel amount exceeds the target premix main fuel amount, the estimated premix main fuel amount becomes equal to or less than the target premix main fuel amount. When controlling the premix main fuel amount variable device so as to further control the main ignition delay time variable device so that the main ignition delay time is shortened,
Control device for compression self-ignition internal combustion engine. A control device for a compression self-ignition internal combustion engine according to claim 5,
An internal combustion engine system having the internal combustion engine,
an intercooler temperature adjustment device that adjusts cooling fluid to an intercooler that cools intake air supercharged by the supercharger;
a supercharging pressure adjustment device that adjusts supercharging pressure by the supercharger;
an EGR valve that adjusts the opening degree of an EGR pipe that returns part of the exhaust gas of the internal combustion engine to the intake;
the injector;
has at least one of the following;
Each of the intercooler temperature adjustment device, the boost pressure adjustment device, and the EGR valve is the main ignition delay time variable device,
The injector can serve both as the fuel injection rate variable device and the main ignition delay time variable device,
The control device includes:
When controlling the main ignition delay time variable device in the premix main fuel amount adjustment section so that the main ignition delay time is shortened,
reducing the flow rate of the cooling fluid by the intercooler temperature adjustment device;
an increase in supercharging pressure by the supercharging pressure adjustment device;
Reducing the EGR gas flow rate by the EGR valve;
increasing the injection amount of the pilot injection using the injector;
perform at least one of the following;
Control device for compression self-ignition internal combustion engine.

Images