Control device for a compression self-ignition internal combustion engine

Abstract

To provide a controller for a compression self-ignition internal combustion engine whereby: for plural types of combustion in one combustion process in a compression self-ignition internal combustion engine: pre-combustion, first combustion following the pre-combustion to partially overlap the pre-combustion, and second combustion following the first combustion to partially overlap the first combustion, it is possible to properly control the pre-combustion, so that the timing of start of the first combustion can be precisely and stably controlled, reducing the amount of smoke and combustion noise.SOLUTION: At least one of jetting timing and jetting amount of at least one pilot jetting is adjusted so that a pre-combustion incidence area-related amount falls below a target pre-combustion area-related amount upper limit, where the pre-combustion incidence area-related amount is based on a pre-combustion incidence area Qp encircled by crank angle differential values of in-cylinder generated heat amounts for pre-combustion before the start of occurrence of crank angle differential values of in-cylinder generated heat amounts for first combustion, regarding pre-combustion, first combustion, and second combustion in one combustion process.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention relates to a control device for a compression ignition type internal combustion engine that controls a compression ignition type internal combustion engine.

Background Art

[0002] In a compression ignition type internal combustion engine (for example, a general diesel engine) that injects fuel into a combustion chamber where air is compressed and heated by a piston and self-ignites and burns, compared to a spark ignition type internal combustion engine (for example, a general gasoline engine) that ignites and burns by the spark of a spark plug in a combustion chamber where air and fuel are mixed, the combustion noise is large and the amount of smoke generated is also large.

[0003] Conventionally, in a compression ignition type internal combustion engine, a plurality of pilot injections that are pre-injections before the main injection are performed in one combustion cycle, and then the main injection is performed. Various methods have been devised to reduce combustion noise by causing the pressure waves of the first combustion generated by the pilot injection and the second combustion mainly generated by the main injection to interfere with each other.

[0004] For example, in the fuel injection control method and fuel injection control device for a compression ignition type engine described in Patent Document 1, a pre-injection (corresponding to a pilot injection) is performed before the main injection, and an after-injection is performed after the main injection. And in one combustion StrokeThe time difference between the peak position of the heat generation rate due to pre-combustion (corresponding to the first combustion), which is the combustion of the pre-injection, and the peak position of the heat generation rate due to the main combustion (corresponding to the second combustion), which is the combustion of the main injection, and the time difference between the peak position of the heat generation rate due to the main combustion and the peak position of the heat generation rate due to the after-combustion, which is the combustion of the after-injection, are controlled so as to be the target intervals even when the load and rotational speed (operating state of the internal combustion engine) of the internal combustion engine vary. By this control, among the plurality of resonance frequency bands of the engine's structural system, the resonance of the frequency band having a peak near the highest frequency of 3500 [Hz] is suppressed, and the knocking sounds having peaks at 1300 [Hz], 1700 [Hz], and 2500 [Hz] on the low-frequency side of the resonance frequency bands are reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Hereinafter, unless otherwise specified, the pilot injection and the pre-injection injected before the main injection are not distinguished, and the pilot injection and the pre-injection injected before the main injection are collectively referred to as "pilot injection". And it is assumed that a cancellation wave is formed to cancel and reduce the combustion noise by the pressure wave generated by the first combustion, which is the combustion by the pilot injection, and the pressure wave generated by the second combustion, which is mainly the combustion by the main injection.

[0007] Note that multiple combustions occur for one combustion Stroke These multiple combustions include pre-combustion, a first combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, and a second combustion generated following the first combustion so as to overlap a part of the first combustion, and the second combustion is mainly generated by the main injection.

[0008] The inventor of the present application has found through various experiments and simulations that the cancellation wave for further reducing combustion noise in a compression ignition internal combustion engine exists not only at the resonance frequency inherent to the compression ignition internal combustion engine, but also an optimal cancellation frequency exists according to the operating state of the compression ignition internal combustion engine. Further, at the optimal cancellation frequency, there exists an optimal cancellation amplitude. That is, there are factors other than the inherent resonance frequency that have a great influence on the combustion noise of a compression ignition internal combustion engine. Instead of forming a cancellation wave of a frequency limited to the resonance frequency, it has been found that the overall combustion noise can be further reduced by forming a cancellation wave with the frequency and amplitude adjusted according to the operating region.

[0009] Furthermore, the inventor of the present application has found that in order to stably obtain the optimal cancellation wave, it is necessary to make the start timing of the first combustion more accurately the target start timing, and for that purpose, it is necessary to appropriately control the pre-combustion generated immediately before the first combustion. It has been found that there are the required heat generation amount, the height of the heat generation rate, etc. in the pre-combustion, and when these deviate from the requirements, the start timing of the first combustion becomes unstable or the amount of smoke generation increases.

[0010] In Patent Document 1, the frequency of the cancellation wave is set so as to cancel the knocking sounds at 1300 [Hz], 1700 [Hz], and 2500 [Hz], which are the resonance frequencies specific to the engine. Specifically, the time difference between the peak position of the heat generation rate of pre-combustion (corresponding to the first combustion) and the peak position of the heat generation rate of main combustion (corresponding to the second combustion), and the time difference between the peak position of the heat generation rate of main combustion and the peak position of the heat generation rate of afterburning are controlled to the target intervals. That is, it focuses on the resonance frequency specific to the compression ignition type internal combustion engine and does not focus on the optimal cancellation frequency according to the operating state. Also, although the injection amount of pre-injection (corresponding to pilot injection) is increased according to the operating state of the compression ignition type internal combustion engine, it is an increase for generating pre-combustion (corresponding to the first combustion) at the target position in the operating region where combustion is difficult, and is not for achieving the optimal cancellation amplitude. Further, Patent Document 1 does not describe or suggest the point that appropriate control of combustion that occurs immediately before the first combustion, which is generated immediately before the second combustion (main combustion) corresponding to the main injection, is necessary.

[0011] The present invention was devised in view of such points, and in a compression ignition type internal combustion engine, in a plurality of combustions generated in one combustion Stroke including pre-combustion, first combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, and second combustion generated following the first combustion so as to overlap a part of the first combustion, by appropriately controlling the pre-combustion, it is an object to provide a control device for a compression ignition type internal combustion engine that can more accurately and stably control the start timing of the first combustion and further reduce the amount of smoke generation and combustion noise.

Means for Solving the Problems

[0012] To solve the above problems, a first invention of the present invention is a control device for a compression ignition type internal combustion engine that injects into the cylinder a main injection, which is a main fuel injection, and a pilot injection, which is a plurality of fuel injections that are pre-injections before the main injection, for one combustion in the compression ignition type internal combustion engine, and generates a plurality of combustions. For one combustion Stroke Stroke ​The plurality of the combustions with respect to [the combustion] are a pre-combustion, a first combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, and a second combustion generated following the first combustion so as to overlap a part of the first combustion, the second combustion being mainly generated by the main injection. One combustion Stroke With respect to [one combustion], in the in-cylinder heat generation amount or the in-cylinder pressure that changes with time, the time differential value of the in-cylinder heat generation amount corresponding to the first combustion or the time differential value of the in-cylinder pressure, or in the in-cylinder heat generation amount or the in-cylinder pressure that changes according to the crank angle which is the rotation angle of the crankshaft, the crank angle differential value of the in-cylinder heat generation amount corresponding to the first combustion or the crank angle differential value of the in-cylinder pressure, when the pre-combustion generation rate area surrounded by the time differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the time differential value of the in-cylinder pressure, or the crank angle differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the crank angle differential value of the in-cylinder pressure, before the start time of generation thereof, is defined as Qp, the control device has a fuel injection adjustment unit that adjusts at least one of the injection timing and the injection amount in at least one of the pilot injections so that a pre-combustion generation rate area-related quantity based on the pre-combustion generation rate area Qp is equal to or less than a preset target pre-combustion area-related quantity upper limit, and is a control device for a compression self-ignition type internal combustion engine.

[0013] Next, a second invention of the present invention is one combustion in a compression self-ignition type internal combustion engine Stroke With respect to [one combustion], a control device for a compression self-ignition type internal combustion engine that injects into the cylinder a main injection which is a main fuel injection and a plurality of pilot injections which are pre-stage injections of the main injection to generate a plurality of combustions. One combustion Stroke The plurality of the combustions with respect to [the combustion] are a pre-combustion, a first combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, and a second combustion generated following the first combustion so as to overlap a part of the first combustion, the second combustion being mainly generated by the main injection. One combustion StrokeFor the in-cylinder heat generation amount or the in-cylinder pressure that changes with time, the time differential value of the in-cylinder heat generation amount corresponding to the first combustion or the time differential value of the in-cylinder pressure, or, for the in-cylinder heat generation amount or the in-cylinder pressure that changes according to the crank angle which is the rotation angle of the crankshaft, the crank angle differential value of the in-cylinder heat generation amount corresponding to the first combustion or the crank angle differential value of the in-cylinder pressure, at the start time of generation, the time differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the time differential value of the in-cylinder pressure, or, the crank angle differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the crank angle differential value of the in-cylinder pressure, when the height of the pre-combustion generation rate, which is Hpre, the control device adjusts at least one of the injection timing and the injection amount in at least one of the pilot injections so that the pre-combustion generation rate related quantity based on Hpre, which is the pre-combustion generation rate height, is equal to or less than a preset target pre-combustion height related quantity upper limit. It is a control device for a compression self-ignition internal combustion engine having a fuel injection adjustment unit.

[0014] Next, a third invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the first invention, where one combustion Stroke When the total input heat amount, which is the heat amount converted from the total injection amount, which is the fuel amount by the pilot injection and the main injection, injected for one combustion, is Qall, the control device uses Qp / Qall as the pre-combustion generation rate area related quantity in the fuel injection adjustment unit. It is a control device for a compression self-ignition internal combustion engine.

[0015] Next, a fourth invention of the present invention is a control device for a compression self-ignition internal combustion engine according to the second invention, where one combustion Stroke When the total injection amount, which is the fuel amount by the pilot injection and the main injection, injected for one combustion, is Qv, the control device uses Hpre / Qv as the pre-combustion generation rate height related quantity in the fuel injection adjustment unit. It is a control device for a compression self-ignition internal combustion engine.

[0016] Next, a fifth invention of the present invention is a control device for a compression self-ignition type internal combustion engine according to any one of the first to fourth inventions described above, wherein the control device adjusts, at the fuel injection adjustment unit, the injection amount of the pilot injection two injections before at least the main injection in the pre-stage injection, and is a control device for a compression self-ignition type internal combustion engine.

[0017] Next, a sixth invention of the present invention is a control device for a compression self-ignition type internal combustion engine according to any one of the first to fifth inventions described above, and in one combustion Stroke when the time difference between a first peak time position, which is a peak position corresponding to the first combustion, and a second peak time position, which is a peak position corresponding to the second combustion, among a plurality of peak positions based on the time differential value of the in-cylinder heat generation amount or the time differential value of the in-cylinder pressure is Δt, the time differential value of the in-cylinder heat generation amount or the time differential value of the in-cylinder pressure at the first peak time position is Hp, and the time differential value of the in-cylinder heat generation amount or the time differential value of the in-cylinder pressure at the second peak time position is Hm, and the peak height ratio is Hp / Hm, or in one combustion StrokeIn this case, among the plurality of peak positions based on the crank angle differential value of the in-cylinder heat generation amount or the crank angle differential value of the in-cylinder pressure, the first peak angle position which is the peak position corresponding to the first combustion, and the second peak angle position which is the peak position corresponding to the second combustion among the plurality of peak positions, the time difference Δt obtained by converting the difference in the crank angle between them into time based on the rotational speed of the crankshaft, the crank angle differential value of the in-cylinder heat generation amount or the crank angle differential value of the in-cylinder pressure at the first peak angle position is Hp, the crank angle differential value of the in-cylinder heat generation amount or the crank angle differential value of the in-cylinder pressure at the second peak angle position is Hm, and when the peak height ratio is Hp / Hm, the control device includes an operating state detection unit that detects the operating state of the compression self-ignition type internal combustion engine, a target time difference or a target time difference related quantity corresponding to the operating state of the compression self-ignition type internal combustion engine, and a target peak height ratio, and determines so that Δt approaches the target time difference or the time difference related quantity based on Δt approaches the target time difference related quantity, and Hp / Hm approaches the target peak height ratio, an injection timing and an injection amount of at least the pilot injection before at least one of the main injections in the pre-stage injection, and an injection timing and an injection amount of the main injection, and a fuel injection calculation unit that obtains them, and the control device for a compression self-ignition type internal combustion engine that adjusts the injection timing and the injection amount obtained by the fuel injection calculation unit by the fuel injection adjustment unit.

Effect of the Invention

[0018] According to the first invention, in the case where pre-combustion, first combustion, and second combustion are provided and the pre-combustion generation rate area before the start time of the occurrence of the first combustion with respect to one combustion is defined as Qp (corresponding to the heat generation amount (or pressure generation amount) of pre-heat), at least one of the injection timing and the injection amount in at least one pilot injection is adjusted so that the pre-combustion generation rate related quantity based on Qp becomes equal to or less than the upper limit of the target pre-combustion area related quantity. Thereby, by appropriately controlling the pre-combustion (in this case, the heat generation amount (or pressure generation amount) of the pre-combustion), the start time of the occurrence of the first combustion can be controlled more accurately and stably, and the smoke generation amount and combustion noise can be further reduced. Stroke ​

[0019] According to the second aspect of the present invention, the combustion apparatus includes a pre-combustion, a first combustion, and a second combustion, and is a single combustion. Stroke If the height of the pre-combustion occurrence rate at the start timing of the first combustion for the target is Hpre, then at least one of the injection timing and the injection amount of at least one pilot injection is adjusted so that the amount related to the pre-combustion occurrence rate height based on Hpre is equal to or less than the upper limit of the amount related to the target pre-combustion height. This makes it possible to more accurately and stably control the start timing of the first combustion, and further reduce the amount of smoke generation and combustion noise, by appropriately controlling the pre-combustion (in this case, the height of the heat release rate (or the height of the pressure release rate) of the pre-combustion).

[0020] According to the third invention, one combustion Stroke If the total input heat amount converted from the total injection amount in is Qall, then by using Qp / Qall as the amount related to the pre-combustion occurrence rate area, it is possible to appropriately eliminate the effects of differences in the displacement of compression ignition internal combustion engines, and generalize the equation.

[0021] According to the fourth invention, one combustion Stroke If the total injection amount in is Qv, then by setting Hpre / Qv as the amount related to the height of the pre-combustion occurrence rate, it is possible to appropriately eliminate the effects of differences in the displacement of compression ignition internal combustion engines, and generalize the equation.

[0022] According to the fifth aspect of the present invention, pre-combustion (amount of heat generation (or amount of pressure generation) and rate of heat generation (or rate of pressure generation)) can be more easily and appropriately controlled by simply adjusting the injection amount of the pilot injection that is two injections before the main injection.

[0023] According to the sixth invention, in the fuel injection calculation unit, at least the injection timing and injection amount of the pilot injection before at least one main injection and the injection timing and injection amount of the main injection are controlled so that the time difference Δt approaches the target time difference (or target time difference related quantity) according to the operating state of the compression ignition type internal combustion engine, whereby the frequency of the cancellation wave can be made to approach the optimum frequency according to the operating state. Further, at least the injection timing and injection amount of the pilot injection before at least one main injection and the injection timing and injection amount of the main injection are controlled so that the peak height ratio Hp / Hm approaches the target peak height ratio according to the operating state of the compression ignition type internal combustion engine, whereby the amplitude of the cancellation wave can be made to approach the optimum amplitude according to the operating state. Therefore, for a wide range of operating states, not only the knocking sound of the resonance frequency of the compression ignition type internal combustion engine but also the overall combustion noise can be appropriately reduced. And in the fuel injection adjustment unit, by adjusting at least one of the injection timing and injection amount in at least one pilot injection to appropriately control pre-combustion, the start timing of the first combustion can be more accurately controlled, and the smoke generation amount and combustion noise can be further reduced.

Brief Description of the Drawings

[0024]

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Embodiments for Carrying Out the Invention

[0025] ●[Example of the Schematic Configuration of the Internal Combustion Engine System 1 (FIG. 1)] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. First, with reference to FIG. 1, an example of the schematic configuration of the internal combustion engine system 1 will be described. In the description of this embodiment, as an example of a compression self-ignition type internal combustion engine, an internal combustion engine 10 (for example, a diesel engine) mounted on a vehicle will be used for explanation. Hereinafter, the internal combustion engine 10 refers to a compression self-ignition type internal combustion engine.

[0026] The following describes the entire system in order from the intake side to the exhaust side. An air cleaner (not shown) and an intake air flow detection device 21 (for example, an intake air flow sensor) are provided on the inflow side of the intake pipe 11A. The intake air flow detection device 21 outputs a detection signal corresponding to the flow rate of the air inhaled by the internal combustion engine 10 to the control device 50. The intake air flow detection device 21 is also provided with an intake air temperature detection device 28A (for example, an intake air temperature sensor) and an atmospheric pressure detection device 23 (for example, an atmospheric pressure sensor). The intake air temperature detection device 28A outputs a detection signal corresponding to the temperature of the intake air passing through the intake air flow detection device 21 to the control device 50. The atmospheric pressure detection device 23 outputs a detection signal corresponding to the ambient atmospheric pressure to the control device 50.

[0027] The outflow side of the intake pipe 11A is connected to the inflow side of the compressor 35, and the outflow side of the compressor 35 is connected to the inflow side of the intake pipe 11B. The compressor 35 of the turbocharger 30 is rotationally driven by a turbine 36 that is rotationally driven by the energy of the exhaust gas, and supercharges by pumping the intake air flowing in from the intake pipe 11A to the intake pipe 11B.

[0028] An upstream compressor pressure detection device 24A (for example, a pressure sensor) is provided in the intake pipe 11A upstream of the compressor 35. The upstream compressor pressure detection device 24A outputs a detection signal corresponding to the pressure in the intake pipe 11A to the control device 50. A downstream compressor pressure detection device 24B (for example, a pressure sensor) is provided in the intake pipe 11B downstream of the compressor 35 (at a position between the compressor 35 and the intercooler 16 in the intake pipe 11B). The downstream compressor pressure detection device 24B outputs a detection signal corresponding to the pressure in the intake pipe 11B to the control device 50.

[0029] An intercooler 16 is arranged on the upstream side of the intake pipe 11B, and a throttle device 47 is arranged on the downstream side of the intercooler 16. The intercooler 16 is arranged on the downstream side of the compressor downstream pressure detection device 24B. An intake air temperature detection device 28B (for example, an intake air temperature sensor) is provided between the intercooler 16 and the throttle device 47. The intake air temperature detection device 28B outputs a detection signal corresponding to the temperature of the intake air whose temperature has been lowered by the intercooler 16 to the control device 50.

[0030] The throttle device 47 can adjust the intake air flow rate by driving a throttle valve 47V that adjusts the opening degree of the intake pipe 11B based on a control signal from the control device 50. The control device 50 can output a control signal to the throttle device 47 to adjust the opening degree of the throttle valve 47V based on a detection signal from a throttle opening detection device 47S (for example, a throttle opening sensor) and a target throttle opening. For example, the control device 50 obtains a target throttle opening based on the depression amount of the accelerator pedal detected based on a detection signal from the accelerator pedal depression amount detection device 25 and the operating state of the internal combustion engine 10 and the like.

[0031] The accelerator pedal depression amount detection device 25 is, for example, an accelerator pedal depression angle sensor and is provided on the accelerator pedal. The control device 50 can detect the depression amount of the accelerator pedal by the driver based on a detection signal from the accelerator pedal depression amount detection device 25.

[0032] On the downstream side of the throttle device 47 in the intake pipe 11B, an intake manifold pressure detection device 24C (for example, a pressure sensor) is provided, and the outflow side of the EGR pipe 13 is connected thereto. And 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. The intake manifold pressure detection device 24C outputs a detection signal corresponding to the pressure of the intake air immediately before flowing into the intake manifold 11C to the control device 50. Also, from the outflow side (connection portion with the intake pipe 11B) of the EGR pipe 13, the EGR gas flowing in from the inflow side (connection portion with the exhaust pipe 12B) of the EGR pipe 13 is discharged into the intake pipe 11B.

[0033] The internal combustion engine 10 has a plurality of cylinders 45A to 45D, and injectors 43A to 43D are provided in the respective cylinders. Fuel is supplied to the injectors 43A to 43D via a common rail 41 and fuel pipes 42A to 42D, and the injectors 43A to 43D are driven by a control signal from the control device 50 to inject fuel into the respective cylinders 45A to 45D.

[0034] The internal combustion engine 10 is provided with a rotation detection device 22, a coolant temperature detection device 28C, etc. The rotation detection device 22 is, for example, a rotation sensor, and outputs a detection signal corresponding to the rotational speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotational speed) to the control device 50. The coolant temperature detection device 28C is, for example, a temperature sensor, and outputs a detection signal corresponding to the temperature of the coolant circulated in the internal combustion engine 10 to the control device 50.

[0035] On the exhaust side of the internal combustion engine 10, the inflow side of the exhaust manifold 12A is connected, and on the outflow side of the exhaust manifold 12A, the inflow side of the exhaust pipe 12B is connected. 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.

[0036] The inflow side of the EGR pipe 13 is connected to the exhaust pipe 12B. The EGR pipe 13 communicates the exhaust pipe 12B with the intake pipe 11B, and it is possible to recirculate a part of the exhaust gas in the exhaust pipe 12B (corresponding to the exhaust path) to the intake pipe 11B (corresponding to the intake path). Further, an EGR cooler 15 and an EGR valve 14 are provided in the EGR pipe 13. The EGR valve 14 adjusts the flow rate of the EGR gas flowing in the EGR pipe 13 by adjusting the opening degree of the EGR pipe 13 based on a control signal from the control device 50.

[0037] An exhaust temperature detection device 29 is provided in the exhaust pipe 12B. The exhaust temperature detection device 29 is, for example, an exhaust temperature sensor, and outputs a detection signal corresponding to the exhaust temperature to the control device 50.

[0038] 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 capable of controlling the flow velocity of the exhaust gas guided to the turbine 36 (capable of adjusting the opening degree of the flow path guiding the exhaust gas to the turbine), and the opening degree of the variable nozzle 33 is adjusted by the nozzle drive device 31. The control device 50 can adjust the opening degree of the variable nozzle 33 by outputting a control signal to the nozzle drive device 31 based on a detection signal from a nozzle opening degree detection device 32 (for example, a nozzle opening degree sensor) and a target nozzle opening degree.

[0039] An exhaust pipe 12B upstream of the turbine 36 is provided with a turbine upstream pressure detection device 26A (for example, a pressure sensor). The turbine upstream pressure detection device 26A outputs a detection signal corresponding to the pressure in the exhaust pipe 12B to the control device 50. An exhaust pipe 12C downstream of the turbine 36 is provided with a turbine downstream pressure detection device 26B (for example, a pressure sensor). The turbine downstream pressure detection device 26B outputs a detection signal corresponding to the pressure in the exhaust pipe 12C to the control device 50.

[0040] An exhaust gas 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 gas purification device 61 includes an oxidation catalyst, a particulate filter, a selective reduction catalyst, and the like.

[0041] The vehicle speed detection device 27 is, for example, a vehicle speed detection sensor and is provided on a wheel or the like of the vehicle. The vehicle speed detection device 27 outputs a detection signal corresponding to the rotational speed of the vehicle wheel to the control device 50.

[0042] 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 devices 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 and output of the control device 50 are not limited to the above detection devices and actuators. Also, the temperature, pressure, etc. of each part may be calculated by estimation calculation without mounting a sensor. The control device 50 detects the operating state of the internal combustion engine 10 based on detection signals from various detection devices including the above detection devices, and controls various actuators including the above 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 and performing self-diagnosis. Further, the control device 50 (CPU 51) has an operating state detection unit 51A, a fuel injection calculation unit 51B, a fuel injection adjustment unit 51C, etc., and details thereof will be described later.

[0043] Based on the operating state of the internal combustion engine 10, the control device 50 Stroke performs, for one combustion, a main injection which is the main fuel injection and one or a plurality of pilot injections which are fuel injections before the main injection, and injects them into the cylinder in which air is compressed and heated. In the description of the present embodiment, all injections before the main injection in one combustion Stroke are collectively referred to as "pilot injection". Also, the number and injection amount of the pilot injection, the injection amount of the main injection, etc. are appropriately calculated based on the total fuel injection amount in one combustion Stroke and the operating state of the internal combustion engine.

[0044] ●[Pilot injection, main injection, in-cylinder pressure generation rate (Fig. 2), and heat generation rate (Fig. 3)] Next, in the cylinder (e.g., cylinder No. 1) of the internal combustion engine 10, for one combustion Stroke the in-cylinder pressure generation rate (Fig. 2) and the in-cylinder heat generation rate (Fig. 3) corresponding to the crank angle will be described for the pilot injection and the main injection. In the examples of Figs. 2 and 3, the control device 50 performs three pilot injections slightly before the position of the compression top dead center (the position where the crank angle = 0 [deg]) of the target cylinder, and performs one main injection slightly after the position of the compression top dead center, showing an example.

[0045] Fig. 2 shows the results of an experiment or simulation when the horizontal axis is the crank angle, which is the rotation angle of the crankshaft, and the vertical axis is the in-cylinder pressure generation rate. In the example of Fig. 2, fuel is injected by three pilot injections into the combustion chamber where the intake air is compressed and heated by the piston for self-ignition, and fuel is injected by the main injection for self-ignition. One pilot combustion (corresponding to the first combustion) occurs by the three pilot injections, and the in-cylinder pressure due to the pilot combustion changes as shown by the pilot combustion pressure Pp indicated by the dotted line in Fig. 2. Also, one main combustion (corresponding to the second combustion) occurs by the one main injection, and the in-cylinder pressure due to the main combustion overlaps with the pilot combustion pressure Pp and changes as shown by the main combustion pressure Pm indicated by the dashed-dotted line in Fig. 2.

[0046] The pressure generation rate f(θ) shown by the solid line in Fig. 2 is the crank angle differential value of the in-cylinder pressure that changes according to the crank angle in one combustion Stroke (the slope of the change in the total in-cylinder pressure of the pilot combustion pressure Pp and the main combustion pressure Pm). As shown in Fig. 2, among the multiple peak positions in the pressure generation rate f(θ) of one combustion Stroke the peak position corresponding to the pilot combustion (corresponding to the first combustion) is defined as the pilot peak angle position Pap (corresponding to the first peak angle position). Similarly, in one combustion StrokeAmong the multiple peak positions in the pressure generation rate f(θ), the peak position corresponding to the main combustion (equivalent to the second combustion) is defined as the main peak angle position Pam (equivalent to the second peak angle position). As shown in Figure 2, let the crank angle of the pilot peak angle position Pap be θp, and the crank angle differential value of the in-cylinder pressure at the pilot peak angle position Pap be Hp. Similarly, let the crank angle of the main peak angle position Pam be θm, and the crank angle differential value of the in-cylinder pressure at the main peak angle position Pam be Hm. Then, the crank angle difference Δθ (Δθ = θm - θp) between the main peak angle position Pam and the pilot peak angle position Pap is converted into a time difference (the time difference corresponding to Δθ) Δt based on the difference in crank angle and the rotational speed of the crankshaft. Also, let the crank angle differential value of the in-cylinder pressure (i.e., the value of the pressure generation rate) at the pilot peak angle position Pap be Hp, and the crank angle differential value of the in-cylinder pressure (i.e., the value of the pressure generation rate) at the main peak angle position Pam be Hm, and further, the peak height ratio is Hp / Hm.

[0047] Although not shown in the figure, the horizontal axis shown in Figure 2 may be changed from the crank angle [deg] to time [sec], and the vertical axis may be changed from the pressure generation rate [MPa / deg] to the pressure generation rate [MPa / sec]. In this case, the pressure generation rate (in this case, the time differential value of the in-cylinder pressure) is the same as the pressure generation rate f(θ) in Figure 2. Among the multiple peak positions in the pressure generation rate, the peak positions corresponding to the pilot combustion and the main combustion are defined as the pilot peak time position PtP (equivalent to the first peak time position) and the main peak time position Ptm (equivalent to the second peak time position), respectively. When the main peak time position is Ptm (tm, Hm) and the pilot peak time position is Ptp (tp, Hp), the time difference is represented by Δt = tm - tp, and the peak height ratio is represented by Hp / Hm.

[0048] Figure 3 shows the case when focusing on the heat inside the cylinder, as opposed to Figure 2 which focuses on the pressure inside the cylinder. Figure 3 shows the case when the same pilot injection and main injection as in Figure 2 are executed. The horizontal axis is the crank angle as in Figure 2, and the vertical axis is different in that it is the heat generation rate (the crank angle differential value of the in-cylinder heat generation amount). Figure 3 is the result of an experiment or simulation when the horizontal axis is the crank angle which is the rotation angle of the crankshaft, and the vertical axis is the in-cylinder heat generation rate.

[0049] The heat generation rate g(θ) shown by the solid line in Figure 3 is the crank angle differential value of the in-cylinder heat generation amount that changes according to the crank angle in one combustion Stroke (the slope of the change in the total in-cylinder heat generation amount of the pilot combustion heat Ep and the main combustion heat Em). As shown in Figure 3, in one combustion Stroke Among the multiple peak positions in the heat generation rate g(θ), the peak position corresponding to the pilot combustion (corresponding to the first combustion) is defined as the pilot peak angle position Eap (corresponding to the first peak angle position). Similarly, among the multiple peak positions in the heat generation rate g(θ) of one combustion Stroke the peak position corresponding to the main combustion (corresponding to the second combustion) is defined as the main peak angle position Eam (corresponding to the second peak angle position). And as shown in Figure 3, let the crank angle of the pilot peak angle position Eap be θp, and the crank angle differential value of the in-cylinder heat generation amount at the pilot peak angle position Eap be Hp. Similarly, let the crank angle of the main peak angle position Eam be θm, and the crank angle differential value of the in-cylinder heat generation amount at the main peak angle position Eam be Hm. Then, the crank angle difference Δθ (Δθ = θm - θp) between the main peak angle position Eam and the pilot peak angle position Eap is defined as the time difference Δt obtained by converting to time based on the difference in crank angle and the rotational speed of the crankshaft (the time difference corresponding to Δθ). Also, taking the crank angle differential value of the in-cylinder heat generation amount (i.e., the value of the heat generation rate) at the pilot peak angle position Eap as Hp, and the crank angle differential value of the in-cylinder heat generation amount (i.e., the value of the heat generation rate) at the main peak angle position Eam as Hm, further define the peak height ratio as Hp / Hm.

[0050] Although not shown, the horizontal axis shown in FIG. 3 may be changed from the crank angle [deg] to time [sec], and the vertical axis may be changed from the heat generation rate [J / deg] to the heat generation rate [J / sec]. In this case, the heat generation rate (in this case, the time derivative value of the in-cylinder heat generation amount) is the same as the heat generation rate g(θ) in FIG. 3. Among the plurality of peak positions in the heat generation rate, the peak positions corresponding to pilot combustion and main combustion are defined as the pilot peak time position EtP (corresponding to the first peak time position) and the main peak time position Etm (corresponding to the second peak time position), respectively. When the main peak time position is Etm (tm, Hm) and the pilot peak time position is Etp (tp, Hp), the time difference is represented by Δt = tm - tp, and the peak height ratio is represented by Hp / Hm.

[0051] The inventor has found through various experiments and simulations that there are an optimal time difference Δt and an optimal peak height ratio Hp / Hm for reducing the combustion noise of an internal combustion engine according to the operating state of the internal combustion engine. The time difference Δt and the peak height ratio Hp / Hm may be any of the crank angle - pressure generation rate shown in FIG. 2, the crank angle - heat generation rate shown in FIG. 3, the time - pressure generation rate (not shown), and the time - heat generation rate (not shown). However, the following description of this embodiment will be based on the crank angle - pressure generation rate shown in FIG. 2.

[0052] ● [Results of simulation (or experiment) in each operating state (FIGS. 4 to 7)] Next, using FIGS. 4 to 7, the results of simulations (or experiments) are shown when the time difference Δt and the peak height ratio Hp / Hm are changed to various values in each operating state of the internal combustion engine. The cancellation center frequencies shown in FIGS. 4 to 6 are time difference-related quantities based on the time difference Δt, are frequencies calculated based on the time difference Δt, are frequencies with a half cycle of the time difference Δt, and are f = 1 / (2*Δt). For example, when the time difference Δt = 0.26 [ms], the frequency = 1 / (0.00026 [sec]*2) ≒ 1.923 [KHz]. The cancellation center frequency is the frequency that is approximately the center of the cancellation frequency band (f = 0.3 / Δt to f = 0.7 / Δt) that cancels and reduces the combustion noise caused by the pilot combustion and the main combustion.

[0053] FIG. 4 shows the case where the engine speed Ne of the internal combustion engine is 1600 [rpm] and the injection amount (load) Qv injected in one combustion Stroke is 30 [mm 3 / st]. The results of simulations (or experiments) are shown in which the time difference Δt and the peak height ratio Hp / Hm are set to various values (the positions of the circles in FIG. 4). The cancellation center frequency is the frequency converted from the time difference Δt as described above. In the idling state of this internal combustion engine, the engine speed Ne = approximately 700 [rpm] and the injection amount (load) Qv = approximately 5 [mm 3 / st]. The "injection amount (load) Qv" corresponds to the "total injection amount", which is the amount of fuel injected by the pilot injection and the main injection for one combustion. Stroke

[0054] ​In Fig. 4, the curves of combustion noise levels D1 to D5 shown by the dashed-dotted line indicate the overall combustion noise levels integrated in the range of 0.9 to 5.6 [KHz] of the observed combustion noise as a result of simulation (or experiment), and the combustion noise levels are D5 > D4 > D3 > D2 > D1. Note that the region where the peak height ratio Hp / Hm exceeds 1.0 is not realistic because the peak position of the pilot combustion is higher than the peak position of the main combustion. Also, since the pilot combustion is too small when the peak height ratio Hp / Hm is less than 0.2 and it is not realistic, values of 0.2 or more are considered. Therefore, the peak height ratio Hp / Hm is considered for values of 1.0 or less and 0.2 or more. Also, the region where the cancellation center frequency exceeds 2.2 [KHz] is a region where the time difference Δt becomes shorter than about 0.227 [msec] and is close to the limits of the injector and control, and is not realistic. Also, the region where the cancellation center frequency is less than 0.6 [KHz] is a region where the time difference Δt becomes longer than about 0.833 [msec], the interval between the pilot injection and the main injection is too long, the width of the cancellation frequency band becomes short, and the cancellation effect cannot be obtained, so values of 0.6 [KHz] or more are considered. Therefore, the cancellation center frequency is considered for values of 2.2 [KHz] or less and 0.6 [KHz] or more (the same applies to Figs. 5 and 6).

[0055] The operating state (rotation speed = 1600 [rpm], fuel injection amount (load) = 30 [mm 3 / st]) shown in Fig. 4 is indicated by U1 in Fig. 7 showing the operating state with the rotation speed on the horizontal axis and the fuel injection amount (load) on the vertical axis. In this operating state U1, as shown in Fig. 4, in order to make the combustion noise level D1 or less, it can be seen that the cancellation center frequency should be set to about 1.9 [KHz] to about 2.2 [KHz] (that is, the time difference Δt should be set to about 0.227 [msec] to about 0.263 [msec]), and the peak height ratio Hp / Hm should be set to about 0.85 to about 1.0.

[0056] Fig. 5 shows the rotation speed Ne = 1600 [rpm] of the internal combustion engine and the injection amount (load) Qv = 55 [mm Stroke injected per combustion 3 / st], the results of simulations (or experiments) are shown where the time difference Δt and the peak height ratio Hp / Hm are set to various values (the positions of the circles in Fig. 5). Note that the cancellation center frequency is the frequency converted from the time difference Δt as described above.

[0057] In Fig. 5, the curves of the combustion noise levels D1 to D5 indicated by the dashed-dotted line show the overall observed combustion noise levels, similar to the case of Fig. 4, and the combustion noise levels are D5 > D4 > D3 > D2 > D1. Also, regarding the peak height ratio Hp / Hm, it is considered for values of 1.0 or less and 0.2 or more, and regarding the cancellation center frequency, it is considered for values of 2.2 [KHz] or less and 0.6 [KHz] or more in the same way. However, the injection quantity Qv is increased compared to the fuel injection quantity in the operating state of Fig. 4, and it is realistic to consider the cancellation center frequency for about 0.9 [KHz] or less.

[0058] The operating state (rotation speed = 1600 [rpm], fuel injection quantity (load) = 55 [mm 3 / st]) shown in Fig. 5 is indicated by U2 in Fig. 7 showing the operating state with the rotation speed on the horizontal axis and the fuel injection quantity (load) on the vertical axis. In this operating state U2, in order to make the combustion noise level D2 or less in Fig. 5 and the realistic cancellation center frequency = about 0.9 [KHz] or less, it can be seen that the cancellation center frequency should be about 0.9 [KHz] or more (that is, the time difference Δt should be about 0.556 [msec] or less), and the peak height ratio Hp / Hm should be about 0.2 to about 0.5.

[0059] Fig. 6 shows the case where the rotation speed Ne of the internal combustion engine is 2400 [rpm] and the injection quantity (load) Qv injected in one combustion Stroke is 30 [mm 3 / st]. The results of simulations (or experiments) are shown where the time difference Δt and the peak height ratio Hp / Hm are set to various values (the positions of the circles in Fig. 6). Note that the cancellation center frequency is the frequency converted from the time difference Δt as described above.

[0060] In FIG. 6, the curves of combustion noise levels D2 to D5 indicated by the dashed-dotted line show the observed combustion noise levels, similar to the case of FIG. 4, and the combustion noise levels are such that D5 > D4 > D3 > D2. Also, regarding the peak height ratio Hp / Hm, consideration is given for values of 1.0 or less and 0.2 or more, and regarding the cancellation center frequency, consideration is given for values of 2.2 [KHz] or less and 0.6 [KHz] or more in the same way. However, the rotational speed Ne has been increased compared to the rotational speed in the operating state of FIG. 4, and the combustion noise level has not decreased to D1.

[0061] The operating state (rotational speed = 2400 [rpm], fuel injection amount (load) = 30 [mm 3 / st]) shown in FIG. 6 is indicated by U3 in FIG. 7 showing the operating state with the rotational speed on the horizontal axis and the fuel injection amount (load) on the vertical axis. In this operating state U3, as shown in FIG. 6, in order to make the combustion noise level D2 or less, it can be seen that the cancellation center frequency should be set to approximately 1.22 [KHz] to approximately 2.2 [KHz] (that is, the time difference Δt should be set to approximately 0.227 [msec] to approximately 0.410 [msec]), and the peak height ratio Hp / Hm should be set to approximately 0.75 to approximately 1.0.

[0062] As described above, as shown in FIG. 7, when the rotational speed is substantially constant and the load (fuel injection amount) increases from a low load to a high load, it can be seen that increasing the time difference Δt and decreasing the peak height ratio Hp / Hm are effective in reducing combustion noise. Also, when the load (fuel injection amount) is substantially constant and the rotational speed increases from a low rotation to a high rotation, it can be seen that the allowable range of the time difference Δt is expanded to the longer side, and the allowable range of the peak height ratio Hp / Hm is expanded to the lower side.

[0063] As described above, the time difference Δt (or the cancellation center frequency (time difference-related quantity) converted from the time difference Δt) and the peak height ratio Hp / Hm greatly affect the reduction of combustion noise, and there exist an optimal time difference Δt and an optimal peak height ratio Hp / Hm according to the operating state.

[0064] ● [Optimal time difference Δt and optimal peak height ratio Hp / Hm in each operating state (FIGS. 8 to 11)] Figure 8 shows the crank angle - pressure generation rate fs1(θ) in the case of data S1(1.9 [KHz], 0.88) in Figure 4 and the crank angle - pressure generation rate fs2(θ) in the case of data S2(1.9 [KHz], 0.58) in Figure 4. Since the frequencies converted from the time difference Δt are both 1.9 [KHz], the crank angle difference Δθ is the same. Also, the peak height ratio Hp(H) / Hm(H) of fs1(θ) is 0.88, and the peak height ratio Hp(L) / Hm(L) of fs2(θ) is 0.58. The observation results of the frequency - combustion noise spectrum in this case are shown in Figure 9.

[0065] As shown in Figure 9, for the same time difference Δt (converted frequency = 1.9 [KHz]), the combustion noise with a peak height ratio Hp / Hm = 0.88 (combustion noise by fs1(θ) (solid - line graph in Figure 9)) is relatively more greatly reduced in the frequency band from about 1.2 [KHz] to about 2.5 [KHz] compared to the combustion noise with a peak height ratio Hp / Hm = 0.58 (combustion noise by fs2(θ) (dotted - line graph in Figure 9)).

[0066] Figure 10 shows the crank angle - pressure generation rate fs3(θ) in the case of data S3(0.83 [KHz], 0.75) in Figure 5 and the crank angle - pressure generation rate fs4(θ) in the case of data S4(0.83 [KHz], 0.26) in Figure 5. Since the frequencies converted from the time difference Δt are both 0.83 [KHz], the crank angle difference Δθ is the same. Also, the peak height ratio Hp(H) / Hm(H) of fs3(θ) is 0.75, and the peak height ratio Hp(L) / Hm(L) of fs4(θ) is 0.26. Because it is a condition where the main injection amount is larger than the condition in Figure 8, the time from the start of the main injection to the main peak becomes longer, and due to the constraint of the injection interval between the pilot and the main injection, it becomes difficult to shorten the time difference Δt (crank angle difference Δθ) from the pilot peak. The observation results of the frequency - combustion noise spectrum in this case are shown in Figure 11.

[0067] As shown in FIG. 11, although the time difference Δt is the same (converted frequency = 0.83 [KHz]), for the peak height ratio Hp / Hm = 0.75 (combustion noise by fs3(θ) (dotted line graph in FIG. 11)), the peak height ratio Hp / Hm = 0.26 (combustion noise by fs4(θ) (solid line graph in FIG. 11)) has less noise reduction effect in the cancellation frequency band of about 0.5 [KHz] to about 1.2 [KHz], but the noise amplification effect in the amplification frequency band of about 1.2 [KHz] to about 2.2 [KHz] centered around about 1.7 [KHz] is suppressed. It can be seen that the maximum value of the spectrum in the integration range of 0.9 [KHz] to 5.6 [KHz] of the overall combustion noise value is low, and the combustion noise is relatively greatly reduced.

[0068] ● [Setting of [Target Time · Target Peak Height Ratio Characteristics (FIGS. 12 and 13)]] From the above results, according to the operating state of the internal combustion engine (specifically, the rotational speed and load (injection amount)), an optimal target time difference (or an optimal target time difference related quantity (target cancellation center frequency)) and an optimal target peak height ratio are set, and a target time · target peak height ratio characteristic (see FIG. 12) is created and stored in the storage device 53 of the control device 50. The target time · target peak height ratio characteristic is set corresponding to each of a plurality of preset rotational speeds with one of the target cancellation center frequency (or target time difference), which is a target time difference related quantity obtained based on the target time difference, and the target peak height ratio as the vertical axis and the other as the horizontal axis.

[0069] The target time · target peak height ratio characteristic is represented by a graph-like characteristic for each rotational speed as shown in the example of FIG. 12. In FIG. 12, the characteristic for the case of Ne = 1600 [rpm] is represented by h(1600), the characteristic for the case of Ne = 2000 [rpm] is represented by h(2000), and the characteristic for the case of Ne = 2400 [rpm] is represented by h(2400).

[0070] Also, for example, in the characteristic of h(1600) (Ne = 1600 [rpm]) in FIG. 12, the injection amount (load) Qv = 30 [mm 3The position in the case of / st is expressed by the position of M11 (Ne1600, Qv30), and the injection quantity (load) Qv = 40 [mm 3 The position in the case of / st is expressed by the position of M12 (Ne1600, Qv40), and the injection quantity (load) Qv = 55 [mm 3 The position of / st is expressed by the position of M13 (Ne1600, Qv55). Similarly, in the characteristic of h(2000) (Ne = 2000 [rpm]) in FIG. 12, the injection quantity (load) Qv = 40 [mm 3 The position of / st is expressed by the position of M22 (Ne2000, Qv40), and the injection quantity (load) Qv = 55 [mm 3 The position of / st is expressed by the position of M23 (Ne2000, Qv55). Similarly, in the characteristic of h(2400) (Ne = 2400 [rpm]) in FIG. 12, the injection quantity (load) Qv = 30 [mm 3 The position of / st is expressed by the position of M31 (Ne2400, Qv30), and the injection quantity (load) Qv = 40 [mm 3 The position of / st is expressed by the position of M32 (Ne2400, Qv40). The dashed-dotted line shown in FIG. 12 indicates an equal-load line passing through the positions of the same load. As shown in FIG. 12, when the rotational speed of the internal combustion engine is substantially constant and the load of the internal combustion engine increases from a low load to a high load, the target time difference related quantity is changed so that the time difference (Δt) becomes longer (changed so that the target cancellation center frequency becomes lower), and the target peak height ratio is changed so that the peak height ratio (Hp / Hm) becomes smaller.

[0071] For example, the control device 50 can obtain the target time difference related quantity (in this case, the target cancellation center frequency) and the target peak height ratio corresponding to the operating state (rotational speed, load) of the internal combustion engine by using the detected operating state (rotational speed, load) of the internal combustion engine and the target time·target peak height ratio characteristic (FIG. 12) stored in the storage device 53.

[0072] Figure 13 shows an example of the upper tolerance limit (Max) h(1600) and an example of the lower tolerance limit (Min) h(1600) in the characteristics of h(1600) in Figure 12. In the example of M11 in Figure 13, based on the data S1 in Figure 4, if ±0.15 is achieved with respect to the target peak height ratio and ±0.2 [KHz] is achieved with respect to the target cancellation center frequency, it can be contained within approximately the target noise level of ±1 [dBA]. Note that, as shown by the upper tolerance limit (Max) h(1600) and the lower tolerance limit (Min) h(1600) in Figure 13, in the example of M11, even if it is a value slightly larger than ±0.15 with respect to the target peak height ratio, or even if it is a value slightly larger than ±0.2 [KHz] with respect to the target cancellation center frequency, it can be contained within approximately the target noise level of ±1 [dBA].

[0073] Also, in the example of M12 with a higher load than M11 in Figure 13, if ±0.15 is achieved with respect to the target peak height ratio and ±0.2 [KHz] is achieved with respect to the target cancellation center frequency, it can be contained within approximately the target noise level of ±1 [dBA]. Further, in the example of M13 with an even higher load than M12 in Figure 13, based on the data S4 in Figure 5, the inventor confirmed from the results of various simulations and experiments that if a value slightly smaller than ±0.15 is achieved with respect to the target peak height ratio and ±0.1 [KHz] is achieved with respect to the target cancellation center frequency, it can be contained within approximately the target noise level of ±1 [dBA]. As shown by the upper tolerance limit (Max) h(1600) and the lower tolerance limit (Min) h(1600) in Figure 13, in the example of M13, by setting it to a value slightly smaller than ±0.15 with respect to the target peak height ratio and ±0.1 [KHz] which is slightly smaller than ±0.2 [KHz] with respect to the target cancellation center frequency, it can be contained within approximately the target noise level of ±1 [dBA].

[0074] That is, it is preferable to control Hp / Hm so that the deviation amount is within the allowable height ratio with respect to the target peak height ratio. And the "allowable height ratio" is set to 0.15 (allowable height ratio reference value) when the load (Qv) is in the vicinity of the predetermined load (in this case, in the vicinity of Qv = 40 [mm 3 / st]). Also, when the load (Qv) is the predetermined load (in this case, Qv = 40 [mm3 As it becomes smaller than / st], the allowable height ratio is set to be larger than the allowable height ratio reference value (set to a value slightly larger than 0.15). Also, when the load (Qv) is larger than a predetermined load (in this case, Qv = 40 [mm 3 / st]), the allowable height ratio is set to be smaller than the allowable height ratio reference value (set to a value slightly smaller than 0.15). Therefore, in Fig. 13, the interval in the direction of the target peak height ratio between the allowable upper limit (Max) h(1600) and the allowable lower limit (Min) h(1600) is set to become narrower as the load (Qv) increases, and set to become wider as the load (Qv) decreases.

[0075] Similarly for the target cancellation center frequency, it is preferable to control so that the actual cancellation center frequency has a deviation amount within the allowable frequency with respect to the target cancellation center frequency. And the "allowable frequency" is set to 0.2 [KHz] (allowable frequency reference value) when the load (Qv) is in the vicinity of a predetermined load (in this case, in the vicinity of Qv = 40 [mm 3 / st]). Also, as the load (Qv) becomes smaller than a predetermined load (in this case, Qv = 40 [mm 3 / st]), the allowable frequency is set to be larger than the allowable frequency reference value (set to a value slightly larger than 0.2 [KHz]). Also, as the load (Qv) becomes larger than a predetermined load (in this case, Qv = 40 [mm 3 / st]), the allowable frequency is set to be smaller than the allowable frequency reference value (set to a value slightly smaller than 0.2 [KHz]). Therefore, in Fig. 13, the interval in the direction of the target cancellation center frequency between the allowable upper limit (Max) h(1600) and the allowable lower limit (Min) h(1600) is set to become narrower as the load (Qv) increases, and set to become wider as the load (Qv) decreases.

[0076] In the above description, the reduction of combustion noise based on the time difference Δt and the peak height ratio Hp / Hm has been explained. Hereinafter, in addition to adjusting the above-described time difference Δt and peak height ratio Hp / Hm, the generation amount of smoke will be further reduced by appropriately controlling pre-combustion that occurs before the above-described pilot combustion (corresponding to the first combustion).

[0077] ●[Examples of differences in combustion due to differences in pre-combustion (Figs. 14 to 16)] Fig. 14 shows examples of experimental results of five types of combustion, g1(θ) to g5(θ), with the crank angle [deg] on the horizontal axis and the heat generation rate [J / deg] (the crank angle differential value of the in-cylinder heat generation amount) on the vertical axis. g1(θ) to g5(θ) are all obtained by performing three pilot injections indicated by "P1, P2, P3" and one main injection indicated by "M". In g1(θ) to g5(θ), the injection timing (injection start crank angle position) and injection amount of each pilot injection (P1, P2, P3) and main injection (M) are as shown in Fig. 15, and only the injection amount of the pilot injection (the second pilot injection P2) two before the main injection M is different. The injection amount of the second pilot injection P2 is (Qb + β2) > (Qb + β1) > Qb > (Qb - α1) > (Qb - α2).

[0078] Fig. 16 is a schematic diagram representing g1(θ) shown in Fig. 14. As shown in Fig. 16, one combustion StrokeMultiple combustions (pre-combustion, first combustion, second combustion) are occurring. Also, the multiple combustions (combustion occurrence rates) have a pre-combustion occurrence rate (first, main pre-combustion occurrence rate), a first combustion occurrence rate, and a second combustion occurrence rate. In FIG. 16, the first pre-combustion (the first pre-combustion occurrence rate in FIG. 16) is mainly generated by the first pilot injection P1, and the main pre-combustion (the main pre-combustion occurrence rate in FIG. 16) is mainly generated by the second pilot injection P2. Also, the first combustion (the first combustion occurrence rate in FIG. 16) is mainly generated by the third pilot injection P3, and the second combustion (the second combustion occurrence rate in FIG. 16) is mainly generated by the main injection M. The first combustion (first combustion occurrence rate) occurs following the pre-combustion (in this case, the main pre-combustion occurrence rate) so as to overlap a part of the pre-combustion (main pre-combustion occurrence rate). The second combustion (second combustion occurrence rate) occurs following the first combustion (first combustion occurrence rate) so as to overlap a part of the first combustion (first combustion occurrence rate). In FIGS. 14 and 16, the vertical axis is the "heat generation rate" (the crank angle differential value (or time differential value) of the in-cylinder heat generation amount), but it may also be the "pressure generation rate" (the crank angle differential value (or time differential value) of the in-cylinder pressure). In either case, as a name that can be used, it is the "combustion occurrence rate".

[0079] In FIG. 16, the start time of occurrence of the first combustion occurrence rate (in this case, the crank angle differential value of the in-cylinder heat generation amount that changes according to the crank angle) is the time (position) indicated by "θs1". Also, g1(θ) to g5(θ) in FIG. 14 are the angle difference and the time difference Δt converted from the rotational speed between the peak position (first peak angle position) of the first combustion occurrence rate (see FIG. 16) and the peak position (second peak angle position) of the second combustion occurrence rate (see FIG. 16), and Hp / Hm which is the height Hp of the first peak angle position with respect to the height Hm of the second peak angle position, are adjusted as described above, and the combustion noise is reduced. In addition to this, as will be described later, by appropriately adjusting the pre-combustion (the first pre-combustion occurrence rate and the main pre-combustion occurrence rate in FIG. 16), the amount of smoke generation can be reduced. As the adjustment of the pre-combustion occurrence rate for reducing the amount of smoke generation, there are an adjustment of the area of the pre-combustion occurrence rate and an adjustment of the height of the pre-combustion occurrence rate, which will be described in order below.

[0080] ●[Adjustment of pre-combustion generation rate area Qp (Figs. 16 and 17)] In Fig. 16, the pre-combustion generation rate area Qp is the area surrounded by the pre-combustion generation rate (the first pre-combustion generation rate, the main pre-combustion generation rate) before the start time θs1 of the generation of the first combustion generation rate, and is the area indicated by the filled area “Qp”. Note that the pre-combustion generation rate is the time differential value of the in-cylinder heat generation amount or the in-cylinder pressure, or the crank angle differential value of the in-cylinder heat generation amount or the in-cylinder pressure.

[0081] Note that since the pre-combustion generation rate area Qp (heat generation amount) varies according to the amount of fuel injection corresponding to the size of the exhaust volume of the internal combustion engine, in order to eliminate and generalize these effects, for one combustion Stroke Qp / Qall is calculated by dividing by the total input heat amount Qall, which is the heat amount converted from the total fuel injection amount Qv, which is the fuel amount by the pilot injection and the main injection injected for one combustion. Note that the total input heat amount Qall can be calculated, for example, by the total fuel injection amount Qv [mm 3 * fuel density [g / mm 3 * lower calorific value [MJ / Kg].

[0082] Fig. 17 is a graph with the horizontal axis set to Qp / Qall and the vertical axis set to the smoke generation amount, and plots the respective (Qp / Qall, smoke generation amount) of g1(θ) to g5(θ) shown in Fig. 14. In the example shown in Fig. 17, g1(θ), g2(θ), and g3(θ) are below the allowable upper limit of the smoke generation amount, but g4(θ) and g5(θ) exceed the allowable upper limit. From Fig. 17, in order to keep the smoke generation amount below the allowable upper limit, it is necessary to make Qp / Qall about 10.5 [%] or less (below the upper limit of the target pre-combustion area related quantity). Note that since g1(θ) to g5(θ) only differ in the injection amount of the second pilot injection, by adjusting at least the injection amount of the second pilot injection, Qp / Qall can be relatively easily adjusted to about 10.5 [%] or less (below the upper limit of the target pre-combustion area related quantity).

[0083] Also, as shown in FIG. 14, the pre-combustion generation rate areas Qp of g4(θ) and g5(θ) are much larger than the pre-combustion generation rate areas Qp of g1(θ) to g3(θ), and the generation start times of the first combustion generation rates of g4(θ) and the generation start time of the first combustion generation rate of g5(θ) are advanced positions compared to θs1 (the first combustion occurs earlier than the target). Therefore, in g4(θ) and g5(θ), since the generation start time of the first combustion becomes unstable and advances, the time difference Δt becomes slightly longer, which is not very preferable also in terms of suppressing combustion noise.

[0084] ● [Adjustment of pre-combustion generation rate height Hpre (FIGS. 16 and 18)] In FIG. 16, the pre-combustion generation rate height Hpre is the height of the pre-combustion generation rate (main pre-combustion generation rate) at the generation start time θs1 of the first combustion generation rate, and is the height indicated by "Hpre". The pre-combustion generation rate is the time differential value of the in-cylinder heat generation amount or the in-cylinder pressure, or the crank angle differential value of the in-cylinder heat generation amount or the in-cylinder pressure.

[0085] Note that since the pre-combustion generation rate height Hpre (heat generation amount height) varies according to the magnitude of the fuel injection amount according to the displacement of the internal combustion engine, in order to eliminate these effects and generalize, for one combustion Stroke divide by the total injection amount Qv, which is the fuel amount by the pilot injection and the main injection injected for one combustion, to calculate Hpre / Qv.

[0086] FIG. 18 is a graph in which the horizontal axis is set to Hpre / Qv and the vertical axis is set to the amount of smoke generation, and each (Hpre / Qv, amount of smoke generation) of g1(θ) to g5(θ) shown in FIG. 14 is plotted. In the example shown in FIG. 18, g1(θ), g2(θ), and g3(θ) are below the upper limit of the allowable amount of smoke generation, but g4(θ) and g5(θ) exceed the upper limit. From FIG. 17, in order to keep the amount of smoke generation below the upper limit, it is necessary to make Hpre / Qv about 1.3 or less (below the upper limit of the target pre-combustion height related quantity). Note that since g1(θ) to g5(θ) only differ in the injection amount of the second pilot injection, by adjusting at least the injection amount of the second pilot injection, Hpre / Qv can be relatively easily adjusted to about 1.3 or less (below the upper limit of the target pre-combustion height related quantity).

[0087] Also, as shown in FIG. 14, the pre-combustion generation rate height Hpre of g4(θ) and g5(θ) is much higher than the pre-combustion generation rate height Hpre of g1(θ) to g3(θ), and the start timing of the first combustion generation rate of g4(θ) and the start timing of the first combustion generation rate of g5(θ) are advanced positions compared to θs1 (the first combustion occurs earlier than the target). For this reason, in g4(θ) and g5(θ), the start timing of the first combustion becomes unstable and advances, so the time difference Δt becomes slightly longer, which is not very preferable also in terms of suppressing combustion noise.

[0088] ●[Processing Procedure of Control Device 50 (FIGS. 19 to 23)] Next, an example of the processing procedure (first and second embodiments) by the control device 50 will be described using the flowcharts shown in FIGS. 19 to 23. The first embodiment is control using the above-mentioned "adjustment of the pre-combustion generation rate area Qp", and the second embodiment is control using the above-mentioned "adjustment of the pre-combustion generation rate height Hpre".

[0089] ●[First Embodiment (FIGS. 19 to 21)] First, using the flowcharts shown in FIGS. 19 to 21, the processing procedure of the control device 50 in the first embodiment using "adjustment of the pre-combustion generation rate area Qp" will be described. The control device 50 (CPU 51) starts the processing shown in FIG. 19, for example, at every predetermined crank angle (for example, every 180 [°CA] in the case of a 4-cylinder engine), and proceeds to step S010.

[0090] In step S010, the control device 50 detects various operating states of the internal combustion engine and proceeds to step S015. For example, the control device 50 detects the rotational speed of the internal combustion engine, the intake air amount, the intake manifold pressure, the variable nozzle opening amount, the accelerator pedal depression amount, the fuel injection amount, etc., based on the detection signals from various detection devices shown in FIG. 1 and the control amount (previous fuel injection amount) of the injector. The control device 50 (CPU 51) executing the processing in step S010 corresponds to the operating state detection unit 51A (see FIG. 1) that detects the operating state of the internal combustion engine.

[0091] In step S015, the control device 50 calculates the required torque from the driver based on the detected operating state and proceeds to step S020. For example, the control device 50 calculates the required torque based on a map stored in the storage device, a calculation formula, etc., based on the rotational speed of the internal combustion engine and the accelerator pedal depression amount.

[0092] In step S020, the control device 50 calculates the total injection amount (Qv) (for the next time) based on the calculated required torque and the operating state of the internal combustion engine, and proceeds to step S025. The details of the calculation procedure of the total injection amount (Qv) will be omitted.

[0093] In step S025, the control device 50 obtains the target time difference related amount (target cancellation center frequency) and the target peak height ratio based on the operating state of the internal combustion engine (rotational speed, load (total injection amount)) and the target time·target peak height ratio characteristic (see FIG. 12) stored in the storage device, and proceeds to step S030. For example, the control device 50, when (rotational speed, load (injection amount)) is (1600 [rpm], 30 [mm 3In the case of / st], h(1600) is selected from the target time - target peak height ratio characteristics shown in FIG. 12, and 30 [mm at the selected h(1600) 3 Based on the position of M11(Ne1600, Qv30) corresponding to the position of / st], the target time difference related quantity (target cancellation center frequency) and the target peak height ratio are obtained.

[0094] In step S030, the control device 50 determines, based on the (next) total injection amount (Qv), the target time difference related quantity (target cancellation center frequency), the target peak height ratio, and the operating state of the internal combustion engine, the provisional number of pilot injections, the provisional injection timing and provisional injection amount of each pilot injection, the provisional injection timing and provisional injection amount of the main injection in the next fuel injection, and proceeds to step S040. Note that in one combustion Stroke injection, the number of pilot injections is one or more, and the number of main injections is one.

[0095] At this time, the provisional injection timing of the main injection and the provisional injection timing of the pilot injection immediately before the main injection are set based on the target time difference related quantity (target cancellation center frequency). For example, in the storage device, a target time interval corresponding to the target time difference related quantity (target cancellation center frequency) is stored in the form of a map or the like, and the control device 50 uses the target time difference related quantity and the map to obtain the provisional injection timing of the main injection and the provisional injection timing of the pilot injection immediately before the main injection so as to be the target time interval. Note that the above - mentioned map is created using simulations, experiments, etc. and stored in the storage device.

[0096] Also, the provisional total pilot injection amount, which is the sum of the provisional injection amounts of a plurality of pilot injections, and the provisional injection amount of the main injection are obtained by a predetermined calculation formula, a map, or the like based on the target peak height ratio. For example, the control device 50 divides the (next) total injection amount (Qv) according to the target peak height ratio into a provisional total pilot injection amount and a provisional main injection amount to obtain the provisional total pilot injection amount and the provisional main injection amount. Note that the above - mentioned predetermined calculation formula and map are created using simulations, experiments, etc. and stored in the storage device.

[0097] In step S040, the control device 50 executes [pre-combustion adjustment] and proceeds with the process to step S050. The details of [pre-combustion adjustment] will be described later.

[0098] In step S050, the control device 50 determines the final number of pilot injections, the final injection timing and the final injection amount of each pilot injection, and the final injection timing and the final injection amount of the main injection in the next fuel injection, and ends the process shown in FIG. 19. In one combustion Stroke injection, the number of pilot injections is plural (plural times to generate pre-combustion and first combustion respectively), and the number of main injections is one.

[0099] As described above, if the final number of pilot injections, the final injection timing and the final injection amount of each pilot injection, and the final injection timing and the final injection amount of the main injection are set, although not shown in the figure, by the control device 50, in the existing pilot injection scheduling process and the existing main injection scheduling process, the processes of each injection are executed at the targeted timing.

[0100] Note that the target time difference related quantity (target cancellation center frequency) in the above description may be changed to a target time difference. The target time difference is the time of half a cycle (half wavelength) at the target cancellation center frequency. For example, the target time·target peak height ratio characteristic with the horizontal axis of the target time·target peak height ratio characteristic shown in FIG. 12 changed from the target cancellation center frequency (target time difference related quantity) to the target time difference is stored in the storage device. Then in step S025, the control device 50 obtains the target time difference and the target peak height ratio based on the operating state (rotation speed, load (injection amount)) of the internal combustion engine and the target time·target peak height ratio characteristic stored in the storage device. Then in step S030, the control device 50 sets the injection timing of the main injection and the injection timing of the pilot injection immediately before the main injection based on the target time difference.

[0101] The control device 50 (CPU 51) that executes the processes of steps S025 and S030 described above obtains a target time difference or a target time difference-related quantity according to the operating state of the internal combustion engine, and a target peak height ratio, and causes the time difference (Δt) to approach the target time difference (or causes the time difference-related quantity based on the time difference (Δt) to approach the target time difference-related quantity), and causes the peak height ratio (Hp / Hm) to approach the target peak height ratio, and obtains the injection timing and injection amount of at least one pilot injection before the main injection in the pre-injection and the injection timing and injection amount of the main injection, corresponding to the fuel injection calculation unit 51B (see FIG. 1).

[0102] ●[Details of pre-combustion adjustment 1-1 (FIG. 20) and details 1-2 (FIG. 21)] Next, with reference to FIG. 20, the details (details 1-1) of [pre-combustion adjustment] in step S040 of FIG. 19 will be described. When the control device 50 proceeds to the process in step S040 shown in FIG. 19, it proceeds to the process in step S110 shown in FIG. 20.

[0103] In step S110, the control device 50 predicts the state of each pre-combustion occurrence rate (the first pre-combustion occurrence rate and the main pre-combustion occurrence rate in FIG. 16), and proceeds to the process in step S115. For example, based on the operating state of the internal combustion engine, the temporary number of pilot injections, the temporary injection timing and temporary injection amount of each pilot injection, the control device 50 predicts the occurrence position (crank angle) and magnitude (height) of the first pre-combustion occurrence rate, the occurrence position (crank angle) and magnitude (height) of the main pre-combustion occurrence rate, the occurrence position (crank angle) and magnitude (height) of the first combustion occurrence rate, etc. as shown in FIG. 16.

[0104] In step S115, the control device 50 predicts the occurrence start time θs1 of the first combustion occurrence rate (see FIG. 16), and proceeds to the process in step S120. For example, based on the prediction performed in step S110, the control device 50 predicts the occurrence start time θs1 of the first combustion occurrence rate.

[0105] In step S120, the control device 50 predicts the pre-combustion generation rate area Qp before the generation start time θs1, and proceeds to step S125. For example, the control device 50 calculates the pre-combustion generation rate area Qp based on the generation position and size (height) of the first pre-combustion generation rate predicted in step S110, the generation position and size (height) of the main pre-combustion generation rate, and the generation start time θs1.

[0106] In step S125, the control device 50 calculates the total input heat amount Qall from the (next) total injection amount Qv and proceeds to step S130. As described above, for example, the control device 50 calculates the total input heat amount Qall using the total injection amount Qv [mm 3 * fuel density [g / mm 3 * lower calorific value [MJ / Kg].

[0107] In step S130, the control device 50 determines whether Qp / Qall is less than or equal to the target pre-combustion area related quantity upper limit. When Qp / Qall is less than or equal to the target pre-combustion area related quantity upper limit (Yes), the control device 50 ends the process shown in FIG. 20, returns the process to step S050 shown in FIG. 19, and when Qp / Qall is greater than the target pre-combustion area related quantity upper limit (No), proceeds to step S135.

[0108] When proceeding to step S135, the control device 50, for example, reduces the tentative injection amount of the pilot injection two before the main injection according to the value of Qp / Qall, ends the process shown in FIG. 20, and returns the process to step S050 shown in FIG. 19. For example, in the storage device 53, a reduction map in which a reduction value (or reduction ratio, etc.) according to Qp / Qall is set is stored, and the control device 50 reduces the tentative injection amount of the pilot injection two before the main injection based on Qp / Qall and the reduction map. The reduction map is determined through various experiments and simulations, etc. The reduced injection amount may be allocated to the main injection and the pilot injection one before the main injection according to the peak height ratio Hp / Hm.

[0109] Alternatively, instead of the [pre - combustion adjustment] (detail 1 - 1) shown in FIG. 20, the [pre - combustion adjustment] (detail 1 - 2) shown in FIG. 21 may be used. When the control device 50 proceeds to the process of step S040 shown in FIG. 19, it proceeds to step S110A shown in FIG. 21.

[0110] In step S110A, the control device 50 extracts an appropriate pattern from the pre - prepared patterns according to the operating state of the internal combustion engine, the total injection amount Qv, the provisional number of pilot injections, the provisional injection timing and provisional injection amount of each pilot injection, the provisional injection timing and provisional injection amount of the main injection, etc., reads out the final number of pilot injections, the final injection timing and final injection amount of each pilot injection, the final injection timing and final injection amount of the main injection, ends the process shown in FIG. 21, and returns the process to step S050 shown in FIG. 19. For example, in the storage device 53, a plurality of patterns in which the final number of pilot injections, the final injection timing and final injection amount of each pilot injection, the final injection timing and final injection amount of the main injection are set according to the operating state and the representative total injection amount Qv are stored.

[0111] Also, not limited to the above example, in the [pre - combustion adjustment], the control device 50 may adjust at least one of the injection timing and injection amount in at least one pilot injection so that the pre - combustion generation rate related quantity (in the above example, Qp / Qall) based on the pre - combustion generation rate area Qp is equal to or less than a preset target pre - combustion area related quantity upper limit (in the above example, about 10.5 [%] (see FIG. 17)). The control device 50 (CPU 51) that executes the process of this [pre - combustion adjustment] corresponds to the fuel injection adjustment unit 51C (see FIG. 1).

[0112] ●[Second Embodiment (FIGS. 19, 22, 23)] Next, using the flowcharts shown in FIGS. 19, 22, and 23, the processing procedure of the control device 50 in the second embodiment using the "adjustment of the pre - combustion generation rate height Hpre" will be described. Since the flowchart shown in FIG. 19 is the same as that of the first embodiment, the description is omitted. The second embodiment is different in the details of the [pre - combustion adjustment] in step S040 in the flowchart shown in FIG. 19.

[0113] ●[Pre - combustion adjustment details 2 - 1 (Fig. 22) and details 2 - 2 (Fig. 23)] Next, using Fig. 22, the details (details 2 - 1) of the [pre - combustion adjustment] in step S040 of Fig. 19 will be described. When the control device 50 proceeds to the process of step S040 shown in Fig. 19, it proceeds to the process of step S210 shown in Fig. 22.

[0114] In step S210, the control device 50 predicts the state of the main pre - combustion generation rate (the pre - combustion generation rate one before the first pre - combustion generation rate in Fig. 16) and proceeds to the process of step S215. For example, based on the operating state of the internal combustion engine, the tentative number of pilot injections, the tentative injection timing and injection amount of each pilot injection, the control device 50 predicts the generation position (crank angle) and magnitude (height) of the main pre - combustion generation rate, the generation position (crank angle) and magnitude (height) of the first combustion generation rate, etc., as shown in Fig. 16.

[0115] In step S215, the control device 50 predicts the generation start time θs1 of the first combustion generation rate (see Fig. 16) and proceeds to the process of step S220. For example, the control device 50 predicts the generation start time θs1 of the first combustion generation rate based on the prediction performed in step S210.

[0116] In step S220, the control device 50 predicts the pre - combustion generation rate height Hpre at the generation start time θs1 and proceeds to the process of step S230. For example, the control device 50 calculates the pre - combustion generation rate height Hpre based on the generation position and magnitude (height) of the first pre - combustion generation rate predicted in step S210, the generation position and magnitude (height) of the main pre - combustion generation rate, and the generation start time θs1.

[0117] In step S230, the control device 50 determines whether Hpre / Qv is the target pre - combustion HeightIt is determined whether it is below the upper limit of the related quantity. Note that Qv is the total injection quantity. When Hpre / Qv is below the upper limit of the target pre-combustion height related quantity (Yes), the control device 50 ends the process shown in FIG. 22, returns the process to step S050 shown in FIG. 19, and when Hpre / Qv is greater than the upper limit of the target pre-combustion height related quantity (No), the process proceeds to step S235.

[0118] When the process proceeds to step S235, the control device 50 reduces the provisional injection quantity of the pilot injection two injections before the main injection according to, for example, the value of Hpre / Qv, ends the process shown in FIG. 22, and returns the process to step S050 shown in FIG. 19. For example, in the storage device 53, a reduction map in which a reduction value (or reduction ratio, etc.) according to Hpre / Qv is set is stored, and the control device 50 reduces the provisional injection quantity of the pilot injection two injections before the main injection based on Hpre / Qv and the reduction map. The reduction map is determined through various experiments, simulations, etc. The reduced injection quantity may be allocated to the main injection and the pilot injection one injection before the main injection according to the peak height ratio Hp / Hm.

[0119] Also, instead of [Pre-combustion adjustment] (Detail 2-1) shown in FIG. 22, [Pre-combustion adjustment] (Detail 2-2) shown in FIG. 23 may be used. When the control device 50 proceeds to step S040 shown in FIG. 19, the process proceeds to step S210A shown in FIG. 23.

[0120] In step S210A, the control device 50 extracts an appropriate pattern from the pre-prepared patterns according to the operating state of the internal combustion engine, the total injection amount Qv, the provisional number of pilot injections, the provisional injection timing and provisional injection amount of each pilot injection, the provisional injection timing and provisional injection amount of the main injection, etc., reads out the final number of pilot injections, the final injection timing and final injection amount of each pilot injection, the final injection timing and final injection amount of the main injection, ends the process shown in FIG. 23, and returns the process to step S050 shown in FIG. 19. For example, in the storage device 53, a plurality of patterns in which the final number of pilot injections, the final injection timing and final injection amount of each pilot injection, the final injection timing and final injection amount of the main injection are set according to the operating state and the representative total injection amount Qv are stored.

[0121] Also, not limited to the above example, in [premixed combustion adjustment], the control device 50 adjusts at least one of the injection timing and injection amount in at least one pilot injection so that the premixed combustion generation rate related quantity (in the above example, Hpre / Qv) based on the premixed combustion generation rate height Hpre becomes equal to or less than a preset target premixed combustion height related quantity upper limit (in the above example, about 1.3 (see FIG. 18)). The control device 50 (CPU 51) that executes the process of this [premixed combustion adjustment] corresponds to the fuel injection adjustment unit 51C (see FIG. 1).

[0122] In the description of this embodiment, the time difference Δt and the peak height ratio Hp / Hm are adjusted to suppress combustion noise, and the premixed combustion generation rate area Qp or the premixed combustion generation rate height Hpre is adjusted to suppress the smoke generation amount. However, another method may be used to suppress combustion noise.

[0123] The control device of the compression self-ignition type internal combustion engine of the present invention is not limited to the configuration, structure, processing procedure, etc. described in this embodiment, and various changes, additions, and deletions are possible without changing the gist of the present invention.

[0124] In the description of this embodiment, in FIGS. 2, 3, 8, and 10, an example of obtaining the crank angle difference Δθ with the horizontal axis being the crank angle has been described. However, the horizontal axis may be the time and the time difference Δt may be obtained. Also, in FIGS. 4, 5, 6, 12, and 13, an example of setting the horizontal axis as the cancellation center frequency f (time difference related quantity) has been described. However, the horizontal axis of these figures may be the time difference Δt (f = 1 / (Δt * 2)). Further, in FIGS. 14 and 16, an example of setting the horizontal axis as the crank angle has been described. However, the horizontal axis may be the time, and although the vertical axis is the heat generation rate, the vertical axis may be the pressure generation rate.

[0125] Also, in the description of this embodiment, an example of setting the pre - combustion generation rate area related quantity as Qp / Qall has been described. However, it is not limited to this. For example, Qp or Qp / Qv (Qv = total injection amount) may be used as the pre - combustion generation rate area related quantity. Similarly, in the description of this embodiment, an example of setting the pre - combustion generation rate height related quantity as Hpre / Qv has been described. However, it is not limited to this. For example, Hpre or Hpre / Qall may be used as the pre - combustion generation rate height related quantity.

[0126] Further, the control device for the compression self - ignition type internal combustion engine of the present invention is not limited to a diesel engine and can also be applied to a compression self - ignition type gasoline engine.

[0127] Also, the above (≧), below (≦), greater than (>), less than (<), etc. may or may not include the equal sign. Also, the numerical values used in the description of this embodiment are examples and are not limited to these numerical values.

Explanation of Reference Numerals

[0128] 10 Internal combustion engine 11A, 11B Intake pipe 11C Intake manifold 12A Exhaust manifold 12B, 12C Exhaust pipe 13 EGR pipe 14 EGR valve 15 EGR cooler 21 Intake air flow rate detection device 22 Rotation detection device 23 Atmospheric pressure detection device 24A Compressor upstream pressure detection device 24B Compressor downstream pressure detection device 24C Intake manifold pressure detection device 25 Accelerator pedal depression amount detection device 26A Turbine upstream pressure detection device 26B Turbine downstream pressure detection device 27 Vehicle speed detection device 28A, 28B Intake air temperature detection device 28C Coolant temperature detection device 29 Exhaust gas temperature detection device 30 Turbocharger 31 Nozzle drive device 32 Nozzle opening degree detection device 33 Variable nozzle 35 Compressor 36 Turbine 41 Common rail 43A~43D Injector 45A~45D Cylinder 47 Throttle device 47S Throttle opening degree detection device 47V Throttle valve 50 Control device 51 CPU 51A Operating state detection section 51B Fuel injection calculation section 51C Fuel injection adjustment section 53 Memory device 61 Exhaust gas purification device f(θ) Pressure generation rate Pam Main peak angle position (second peak angle position) Pap Pilot peak angle position (first peak angle position) Pm Main combustion pressure Pp Pilot combustion pressure g(θ) Heat generation rate Eam Main peak angle position (second peak angle position) Eap Pilot Peak Angle Position (First Peak Angle Position) Em Main Combustion Heat Ep Pilot Combustion Heat Hp / Hm Peak Height Ratio Hpre Pre-Combustion Generation Rate Height Qall Total Input Heat Qp Pre-Combustion Generation Rate Area Qv Total Injection Quantity θs1 Generation Start Time Δt Time Difference Δθ Crank Angle Difference

Claims

1. In a compression ignition internal combustion engine, for one combustion stroke, main injection which is the main fuel injection and pilot injection which is a plurality of fuel injections that are pre-stage injections of the main injection are injected into the cylinder to generate a plurality of combustions. A control device for a compression ignition internal combustion engine, The plurality of combustions for one combustion stroke are, Pre-combustion, First combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, Second combustion generated following the first combustion so as to overlap a part of the first combustion, and the second combustion mainly generated by the main injection, And have, For one combustion stroke, In the in-cylinder heat generation amount or in-cylinder pressure that changes according to time, the time differential value of the in-cylinder heat generation amount corresponding to the first combustion or the time differential value of the in-cylinder pressure, Or, in the in-cylinder heat generation amount or the in-cylinder pressure that changes according to the crank angle which is the rotation angle of the crankshaft, the crank angle differential value of the in-cylinder heat generation amount corresponding to the first combustion or the crank angle differential value of the in-cylinder pressure, Before the start of generation of, The time differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the time differential value of the in-cylinder pressure, Or, the crank angle differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the crank angle differential value of the in-cylinder pressure, The pre-combustion generation rate area surrounded by is Qp, When, The control device, The injection timing and at least one of the injection amounts in at least one of the pilot injections are adjusted so that the pre-combustion generation rate area related quantity based on Qp which is the pre-combustion generation rate area is below the upper limit of the target pre-combustion area related quantity set so that the smoke generation amount is below the allowable upper limit. It has a fuel injection adjustment unit, When the total injection amount which is the fuel amount by the pilot injection and the main injection injected for one combustion stroke is Qv, and the total input heat amount which is the heat amount converted from the total injection amount is Qall, When, The control device, In the fuel injection adjustment unit, Qp / Qall or Qp / Qv is set as the pre-combustion generation rate area related quantity, A control device for a compression ignition internal combustion engine.

2. For one combustion stroke in a compression ignition internal combustion engine, a main injection which is the main fuel injection and a pilot injection which is a plurality of fuel injections that are pre-stage injections of the main injection are injected into the cylinder to generate a plurality of combustions. A control device for a compression ignition internal combustion engine, The plurality of combustions for one combustion stroke are, a pre-combustion, a first combustion generated following the pre-combustion so as to overlap a part of the pre-combustion, a second combustion generated following the first combustion so as to overlap a part of the first combustion, and the second combustion is mainly generated by the main injection, and have, For one combustion stroke, In the in-cylinder heat generation amount or the in-cylinder pressure that changes according to time, the time differential value of the in-cylinder heat generation amount corresponding to the first combustion or the time differential value of the in-cylinder pressure, Or, in the in-cylinder heat generation amount or the in-cylinder pressure that changes according to the crank angle which is the rotation angle of the crankshaft, the crank angle differential value of the in-cylinder heat generation amount corresponding to the first combustion or the crank angle differential value of the in-cylinder pressure, At the start time of the generation of, The time differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the time differential value of the in-cylinder pressure, Or, the crank angle differential value of the in-cylinder heat generation amount corresponding to the pre-combustion or the crank angle differential value of the in-cylinder pressure, The pre-combustion generation rate height which is the height of is Hpre, When, The control device, The control device has a fuel injection adjustment unit that adjusts at least one of the injection timing and the injection amount in at least one of the pilot injections so that the pre-combustion generation rate height related quantity based on Hpre, which is the pre-combustion generation rate height, is equal to or less than the target pre-combustion height related quantity upper limit set so that the smoke generation amount is equal to or less than the allowable upper limit. When the total injection amount Qv which is the fuel amount by the pilot injection and the main injection injected for one combustion stroke, and the total input heat amount Qall which is the heat amount converted from the total injection amount, When, The control device, In the fuel injection adjustment unit, Hpre / Qv or Hpre / Qall is used as the pre-combustion generation rate height related quantity. A control device for a compression ignition internal combustion engine.

3. A control device for a compression ignition internal combustion engine according to claim 1, When the pre-combustion generation rate area related quantity is Qp / Qall, the value equal to or less than the target pre-combustion area related quantity upper limit is set to 10.5 or less. A control device for a compression ignition internal combustion engine.

4. A control device for a compression ignition type internal combustion engine according to claim 2, wherein when the pre-combustion generation rate related quantity is Hpre / Qv, a value equal to or less than the upper limit of the target pre-combustion height related quantity is set to 1.3 or less. A control device for a compression ignition type internal combustion engine.

5. A control device for a compression ignition type internal combustion engine according to any one of claims 1 to 4, wherein the control device, adjusts an injection amount of at least the pilot injection two times before the main injection in the pre-stage injection at the fuel injection adjustment unit. A control device for a compression ignition type internal combustion engine.

6. A control device for a compression ignition type internal combustion engine according to any one of claims 1 to 5, in one combustion stroke, when a time difference between a first peak time position which is a peak position corresponding to the first combustion among a plurality of peak positions based on a time differential value of the in-cylinder heat generation amount or a time differential value of the in-cylinder pressure and a second peak time position which is a peak position corresponding to the second combustion among the plurality of peak positions is Δt, a time differential value of the in-cylinder heat generation amount or a time differential value of the in-cylinder pressure at the first peak time position is Hp, and a time differential value of the in-cylinder heat generation amount or a time differential value of the in-cylinder pressure at the second peak time position is Hm, and a peak height ratio is Hp / Hm; alternatively, in one combustion stroke, when a time difference between a first peak angle position which is a peak position corresponding to the first combustion among a plurality of peak positions based on a crank angle differential value of the in-cylinder heat generation amount or a crank angle differential value of the in-cylinder pressure and a second peak angle position which is a peak position corresponding to the second combustion among the plurality of peak positions is Δt obtained by converting a difference in the crank angle into time based on the rotational speed of the crankshaft, a crank angle differential value of the in-cylinder heat generation amount or a crank angle differential value of the in-cylinder pressure at the first peak angle position is Hp, and a crank angle differential value of the in-cylinder heat generation amount or a crank angle differential value of the in-cylinder pressure at the second peak angle position is Hm, and a peak height ratio is Hp / Hm; the control device, has an operating state detection unit that detects an operating state of the compression ignition type internal combustion engine. Determine a target time difference or a target time-difference related quantity according to the operating state of the compression ignition type internal combustion engine, and a target peak height ratio, and cause at least one of the injection timing and the injection amount of the pilot injection before the main injection in the pre-stage injection, and the injection timing and the injection amount of the main injection to approach the target peak height ratio such that Δt approaches the target time difference or a time-difference related quantity based on Δt approaches the target time-difference related quantity. A fuel injection calculation unit; having; adjust the injection timing and the injection amount obtained by the fuel injection calculation unit by the fuel injection adjustment unit; A control device for a compression ignition type internal combustion engine.

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