AU2021200546B2 - Controller for controlling compression self-ignition internal combustion engine - Google Patents

Abstract

At represents a time lag between a pilot peak angle position corresponding to a pilot combustion among peak positions of derivative value of the pressure within a cylinder (45A, 45B, 45C, 45D) and a main peak angle position corresponding to a main combustion. 5 Hp/Hm represents a peak height ratio, which are respective crank angle derivative values. A controller (50) includes an operation condition detecting unit (51A) and a fuel injection controlling unit (51B). The fuel injection controlling unit (51B) determines a target time lag (or target time lag associated amount) and the target peak height ratio in accordance with operation conditions. The fuel injection controlling unit (51B) controls at least an injection 0 timing and amount immediately before main injection and an injection timing and amount of the main injection, such that the time lag comes closer to the target time lag, and that the peak height ratio comes closer to the target peak height ratio. 17320977_1 (GHMatters) P115369.AU 1/8 Fue I 13 1042 1A 41 13 1 11 10 c 240 43A 42B 12A 45A 29 43B 42C 45B 11B 43C 42D - -12B 47V 45C0 47S 47 43D /16 45D- 24B26 28B 23 2A30 33 3 28A... 36....... ....... ... 11A 12C 61 24A Intake - 26BExhaust 35 31 32 51A L] 27 51 B 52 - -+ - ] 53 - -,50 54 - [-] +51 25 FIG. 1

Description

1/8

Fue I 13 1042 1A 41 13 1 11 10 c

240 43A 42B 12A 45A 29 43B 42C 45B 11B 43C 42D - -12B 47V 45C0 47S 47 43D /16 45D-

24B26

28B 23 2A30 33 3 28A... ....... ... 36....... 11A 12C 61

24A

Intake - 26BExhaust

35 31 32

51A L]

27

51 B 52 - -+ - ] 53 - -,50 54 - [-] +51

FIG. 1

CONTROLLER FOR CONTROLLING COMPRESSION SELF-IGNITION INTERNAL COMBUSTION ENGINE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese patent application serial numbers 2020-012280 filed January 29, 2020, the contents of which is incorporated herein by reference in its entirety for all purposes.

BACKGROUND

[0002] The present discloser relates to a controller for controlling a compression self-ignition internal combustion engine.

[0003] In compression self-ignition internal combustion engines (e.g., typical diesel engines), air is compressed and heated by pistons, and fuel is injected into a combustion chamber to cause the fuel to self-ignite and combust. In spark-ignition internal combustion engines (e.g., typical gasoline engines), air and fuel are mixed in a combustion chamber, and the air-fuel mixture is ignited and combusted by sparks generated by a spark plug. Since the noise generated during combustion in compression self-ignition internal combustion engines is greater than that in spark-ignition internal combustion engine, a reduction in combustion noise has been desired.

[0004] In a combustion cycle of a compression self-ignition internal combustion engine, a main injection is performed after more than one pilot injection, which function as pre-stage injections, have been performed. A pilot combustion is generated due to each pilot injection. The main combustion is generated due to the main injection. Various methods have been previously disclosed for reducing combustion noise by allowing the pressure wave of each combustion to interfere with one other.

17320977_1 (GHMatters) P115369.AU

[0005] For Example, Japanese Patent No. 6288066 discloses a method which includes performing a pre-injection prior to a main injection. An after-injection is performed after the main injection. During one combustion process, the heat generation rate due to the pre-combustion, which is the combustion of the pre-injection, achieves a peak position. The heat generation rate due to the main-combustion as a combustion of the main-injection also achieves the peak position. A time lag may be generated 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 serves as a combustion of the after-injection. An internal combustion engine is controlled such that this time lag will be a target length, even when a load or rotation speed of the internal combustion engine (operation conditions of the internal combustion engine) vary. A structural system of the engine creates noise. This noise includes a high frequency band having a peak near 3500 [Hz], which is the highest frequency among multiple resonance frequency bands. The structural system of the engine may generate knocking sound with a peak at 1300 [Hz], 1700 [Hz], and 2500 [Hz] on the low frequency side of the resonant frequency band. With appropriate control, high-frequency band resonance may be suppressed and also said knocking sound is reduced.

[0006] Post-pilot injections and pre-injection performed prior to main injection have been described above. However, in the present disclosure, unless otherwise specifically described, ,0 these injections will not be distinguished from each other and will be collectively referred to as "pilot injection(s)". A first pressure wave may be generated by the pilot combustion due to the pilot injections. A second pressure wave may be generated by the main combustion due to the main injections. It is assumed that the first pressure wave and the second pressure wave may be set so that they form an offset wave that cancels and reduces the combustion noise.

SUMMARY

[0007] One aspect of the present disclosure relates to a controller for a compression self-ignition internal combustion engine. The controller serves to inject a main injection into a cylinder that is a main fuel injection. The controller also servers to inject a pilot

17320977_1 (GHMatters) P115369.AU injection/pilot injections, which is/are a single or a multiple fuel injection(s), into a cylinder that are pre-stage injections of the main injection in one combustion process. A single or a multiple pilot fuel injections cause(s) a pilot combustion, which is a single combustion. The main injection causes a main combustion as a single combustion. At represents a time lag between the pilot peak time position and the main peak time position within one combustion process. A peak height ratio is represented by Hp/Hm. The pilot peak time position is the peak position corresponding to the pilot combustion among a plurality of peak positions represented by a derivative value of the pressure within the cylinder over the course of one combustion process. Instead, the pilot peak time position is a peak position corresponding to the pilot combustion among a plurality of peak positions of represented by a derivative value of the heat within the cylinder over the course of one combustion process. The main peak time position is the peak position of the main combustion among the plurality of peak positions represented by a derivative of either the pressure or heat within the cylinder over the course of one combustion process. Hp represents the derivative value of the pressure within the cylinder or a derivative value of the heat within the cylinder at the pilot peak time position. The Hm represents the derivative value of the pressure within the cylinder or the derivative value of the heat within the cylinder at the main peak time position. Alternatively, At may represents a time lag based on the crank angle difference and the rotation speed of the crankshaft in one combustion process. The peak height ratio in this situation is also represented by Hp/Hm. The crank angle difference is a difference between the pilot peak angle position and the main peak angle position. The pilot peak angle position is the peak position corresponding to the pilot combustion among a plurality of peak positions represented by the derivative value of the pressure within the cylinder that varies in accordance with the crank angle. The crank angle is a rotation angle of the crankshaft. Alternatively, the pilot peak angle position is the peak position corresponding to the pilot combustion among a plurality of peak positions represented by the derivative value of the heat within the cylinder that varies in accordance with the crank angle. The main peak angle position is the peak position corresponding to the main combustion among the plurality of peak positions represented by the derivative of the heat or pressure within the cylinder as it varies in accordance with the crank angle. Hp represents the derivative value of the pressure within the cylinder in the pilot peak angle position, or represents the derivative value of the

17320977_1 (GHMatters) P115369.AU heat within the cylinder. Hm represents the derivative value of the pressure within the cylinder in the main peak angle position or represents the derivative value of the heat within the cylinder. In any of the above cases, an operation condition detecting unit of the controller detects operation conditions of the compression self-ignition internal combustion engine. A fuel injection controlling unit of the controller determines a target time lag or a target time lag associated amount in accordance with the operation conditions of the compression self-ignition internal combustion engine. The fuel injection controlling unit also determines a target peak height ratio. The operation condition detecting unit is configured to control at least an injection timing and an injection volume of the pilot injection immediately before the main injection in the pre-stage injection and an injection timing and an injection volume of the main injection such that the At comes closer to the target time lag. Alternatively, they may be controlled such that the time lag associated amount based on At comes closer to the target time lag associated amount. In either situation, they may be controlled such that the Hp/Hm comes closer to the target peak height ratio.

[0008] More specifically, at least an injection timing and an injection volume of the pilot injection immediately before the main injection and an injection timing and an injection volume of the main injection are controlled such that the time lag At comes closer to the target time lag (or target time lag associated amount) in accordance with the operation conditions of ,0 the compression self-ignition internal combustion engine. As a result, a frequency of an offset sound wave may be allowed to approach the optimum frequency in accordance with the specific operating conditions. At least the injection timing and the injection volume of a pilot injection immediately before the main injection and the injection timing of the injection volume of the main injection are controlled such that the peak height ratio Hp/Hm comes closer to the target peak height ratio in accordance with the specific operation condition of the compression self-ignition internal combustion engine. This allows the amplitude of the offset sound wave to approach the optimum amplitude in accordance with the specific operation condition. Therefore, it is possible to reduce the overall combustion noise. This reduction is not limited to knocking sound at a specific resonance frequency of the compression self-ignition internal combustion engine, but instead covers a wide range of different operation conditions.

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[0009] According to another aspect of the present disclosure, the fuel injection controlling unit of the controller may change the target time lag or the target time lag associated amount such that the At will increase. The fuel injection controlling unit of the controller may also change the target peak height ratio such that the Hp/Hm will decrease when the rotation speed of the compression self-ignition internal combustion engine is substantially constant while the load of the compression self-ignition internal combustion engine is increased from a low load to a high load. As a result, the overall combustion noise may be properly reduced.

[0010] According to another aspect of the present disclosure, the target time/target peak height ratio corresponding to each of various preset rotation speed are saved in the controller. A vertical axis representing the target time/target peak height ratio represents one of the following (1) or (2), and a horizontal axis represents the other (1) or (2). (1) is a target offset center frequency, which is a frequency at substantially the center of an offset frequency band that serves to cancel and reduce the combustion noise due to the pilot combustions and the main combustion, the target offset center frequency representing the target time lag associated amount determined based on the target time lag or the target time lag. (2) is the target peak height ratio. For the target time/target peak height ratio, positions are set in accordance with loads of the compression self-ignition internal combustion engine with respect to the preset rotation speed. The fuel injection controlling unit of the controller selects the target time/target peak height ratio in accordance with the rotation speed of the compression self-ignition internal combustion engine. The fuel injection controlling unit determines the target time lag associated amount or the target time lag and determines the target peak height ratio based on the selected target time/target peak height ratio and the load of the compression self-ignition internal combustion engine. The fuel injection controlling unit determines the target time lag associated amount or the target time lag in accordance with the rotation speed and the load of the compression self-ignition internal combustion engine, and determines the target peak height ratio based on these operation conditions. The fuel injection controlling unit controls at least the injection timing and the injection volume of the pilot injection immediately before the main injection and controls the injection timing and the injection volume of the main injection such that the offset center frequency, which is the time lag 17320977_1 (GHMatters) P115369.AU associated amount based on the At, comes closer to the target center frequency, which is the target time lag associated amount, or that the At comes closer to the target time lag. The fuel injection controlling unit controls these such that the Hp/Hm comes closer to the target peak height ratio. The fuel injection controlling unit controls at least the injection timing and the injection volume of the pilot injection immediately before the main injection of the pre-stage injection and the injection timing and the injection volume of the main injection such that the offset center frequency comes closer to the target offset center frequency and such that the At comes closer to the target time lag and such that the Hp/Hm comes closer to the target peak height ratio. The offset center frequency is the time lag associated amount based on the At. The target offset center frequency is the target time lag associated amount.

[0011] With this configuration, the optimum target offset center frequency (target time lag associated amount) or target time lag/target peak height ratio in accordance with the operation conditions may be easily determined based on the target time/target peak height ratio and the operation conditions (rotation speed and the load (injection volume)) of the compression self-ignition internal combustion engine.

[0012] According to another aspect of the present disclosure, the fuel injection controlling unit of the controller controls the Hp/Hm such that the deviation amount from the target peak height ratio falls within a tolerance height ratio when at least the injection timing and the injection volume of the pilot injection immediately before the main injection of the pre-stage injection and the injection timing and the injection volume of the main injection are controlled such that the Hp/Hm comes closer to the target peak height ratio. The tolerance height ratio is set at a tolerance height ratio reference value when the load of the compression self-ignition internal combustion engine is in the vicinity of the predetermined load. The tolerance height ratio is set to be greater than the tolerance height ratio reference value as the load of the compression self-ignition internal combustion engine becomes smaller than the predetermined load. The tolerance height ratio is set to be smaller than the tolerance height ratio reference value as the load of the compression self-ignition internal combustion engine increases to become greater than the predetermined load.

17320977_1 (GHMatters) P115369.AU

[0013] The accuracy that the actual peak height ratio Hp/Hm must be brought to the target peak height ratio in order to achieve a reduction effect in combustion noise can be made clear by clarifying the tolerable deviation range of the actual peak height ratio Hp/Hm relative to the target peak height ratio. Therefore, this is useful when the actual peak ratio Hp/Hm cannot be easily matched to the target peak height ratio, due to various factors.

[0014] According to another aspect of the present disclosure, the fuel injection controlling unit of the controller controls such that the deviation amount of the offset center frequency from the target offset center frequency falls within the tolerance frequency when at least the injection timing and the injection volume of the pilot injection immediately before the main injection of the pre-stage injection and the injection timing and the injection volume of the main injection are controlled such that the offset center frequency comes closer to the target offset center frequency. When the load of the compression self-ignition internal combustion engine is in the vicinity of the predetermined load, the tolerance frequency is set at the tolerance frequency reference value. The tolerance frequency is set to be greater than the tolerance frequency reference value as the load of the compression self-ignition internal combustion engine becomes smaller than the predetermined load. The tolerance frequency is set to be smaller than the tolerance frequency reference value as the load of the compression self-ignition internal combustion engine is increased to become greater than the predetermined load.

[0015] The proximity that the actual offset center frequency must be brought to the target offset center frequency in order to achieve a reduction effect in combustion noise can be made clear by clarifying the tolerable deviation range of the actual offset center frequency relative to the target offset center frequency. Therefore, this is useful when the actual offset center frequency cannot be easily matched the offset center frequency due to various factors.

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BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a schematic view of a compression self-ignition internal combustion engine system.

[0017] FIG. 2 is a diagram illustrating an example of a relationship, among a pilot injection and a main injection, a pilot combustion pressure, a main combustion pressure, a pressure generation rate due to the pilot combustion, a pressure generation rate due to the main combustion, and a crank angle during one combustion process.

[0018] FIG. 3 is a diagram illustrating a heat generation rate due to the pilot combustion and a heat generation rate due to the main combustion for the example of FIG. 2.

[0019] FIG. 4 is a diagram illustrating an example of simulation results at a rotation speed of the compression self-ignition internal combustion engine of Ne=1600 [rpm] and an injection volume of Qv=30 [mm/st].

[0020] FIG. 5 is a diagram illustrating an example of simulation results at a rotation speed of the compression self-ignition internal combustion engine of Ne=1600 [rpm] and an injection volume of Qv=55 [mm/st].

[0021] FIG. 6 is a diagram illustrating an example of simulation results at a rotation speed of the compression self-ignition internal combustion engine of Ne=2400 [rpm] and an injection volume of Qv=30 [mm/st].

[0022] FIG. 7 is a diagram illustrating how the results of FIG. 4 to FIG. 6 are applied to the positions of the compression self-ignition internal combustion engine during operation, shown in terms of rotation speed and injection volume (load).

[0023] FIG. 8 is a diagram illustrating the pressure generation rate at each of data points Si and S2 of FIG. 4.

[0024] FIG. 9 is a diagram illustrating the combustion noise at each of data points S Iand S2 of FIG. 4.

[0025] FIG. 10 is a diagram illustrating the pressure generation rate at each of data points S3 and S4 of FIG. 5.

[0026] FIG. 11 is a diagram illustrating the combustion noise at each of data points S3 and

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S4 of FIG. 5.

[0027] FIG 12 is a diagram illustrating an example of target-time/target-peak-height ratio characteristics.

[0028] FIG. 13 is a diagram illustrating the tolerable deviation range of the target-time/target-peak-height ratio characteristics.

[0029] FIG. 14 is a flowchart illustrating an example of processing procedure of a controller.

DETAILED DESCRIPTION

[0030] The present inventors have found following features by various experiments and simulations: An offset wave for reducing the combustion noise of a compression self-ignition internal combustion engine is present. The compression self-ignition internal combustion engine has a specific resonant frequency at certain operation conditions. The offset wave may not be limited to only a specific resonant frequency, but may also include an optimum offset frequency depending on said operation conditions. At the optimum offset frequency, an optimum offset amplitude is present. In other words, there may be properties that provide a great impact on the combustion noise of the compression self-ignition internal combustion engine other than the specific resonant frequency. Instead of forming an offset wave focused only on the resonance frequency, the offset wave may be formed with frequency and amplitude adjusted depending on operating regions. This enables an overall reduction in the combustion noise. This had not been previously known.

[0031] It was previously known that a frequency of an offset wave cancels knocking sounds having resonance frequencies of 1300 [Hz], 1700[Hz], and 2500[Hz]. These frequencies are specific for knocking sounds for engines. An internal combustion engine is controlled such that the time lag between the peak position of the heat generation rate due to the pre-combustion (pilot combustion) and the peak position of the heat generation rate due to the main combustion will become a target interval. The internal combustion engine is also controlled such that the time lag 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

17320977_1 (GHMatters) P115369.AU combustion will become a target interval. That is, only the resonance frequency specific for knocking sound of the compression self-ignition internal combustion engine was previously focused on. There was no focus on an optimum offset wave based on specific operation conditions. Although the injection volume during the pre-injection (pilot injection) step may be increased in accordance with the operation conditions of the compression self-ignition internal combustion engine, this increase was for allowing pre-combustions (pilot-combustion) to be generated in the operation region where combustion is difficult. There was previously no consideration for achieving an optimum offset amplitude.

[0032] In view of the above, it has been desired to provide a controller that is configured to properly reduce the overall combustion noise generated for a wide range of operation conditions of a compression self-ignition internal combustion engine.

[Schematic Structure of Internal Combustion Engine System 1 (FIG. 1)]

[0033] Hereinafter, one exemplary embodiment of the present disclosure will be described with reference to the drawings. First of all, a schematic structural example of the internal combustion engine system will be described with reference to FIG. 1. In the present embodiment, an internal combustion engine 10 (e.g., diesel engine) mounted in a vehicle will be described as an example of a compression self-ignition internal combustion engine.

[0034] Hereinafter, an entire system will be described in order from an intake side to an exhaust side. An air cleaner (not shown), an intake flow rate detecting means 21 (e.g., an intake flow rate sensor) may be provided on an inlet side of an intake pipe 11A. The intake flow rate detecting means 21 outputs a detected signal, which corresponds to the air flow rate inhaled by the internal combustion engine 10, to a controller 50. An intake air temperature detecting means 28A (e.g., an intake air temperature sensor) and an atmospheric pressure detecting means 23 (e.g., an atmospheric pressure sensor) may be provided on the intake air flow rate detecting means 21. The intake air temperature detecting means 28Ais configured to output a detected signal corresponding to a temperature of the intake air flowing through

17320977_1 (GHMatters) P115369.AU the intake air flow rate detecting means 21. The atmospheric air detecting means 23 is configured to output a detected signal corresponding to the ambient atmospheric pressure to the controller 50.

[0035] As shown in FIG. 1, an outlet side of the exhaust pipe 11A is connected to an inlet side of a compressor 35. The outlet side of the compressor 35 is connected to the inlet side of the intake pipe 11B. The compressor 35 may be a part of a turbocharger 30. The compressor 35 of a turbocharger 30 is driven to rotate by a turbine 36. The turbine 36 is driven to rotate by the exhaust gas. The compressor 35 feeds the intake air drawn through the intake pipe 11A to the intake pipe 11B under pressure to supercharge the intake air.

[0036] As shown in FIG. 1, the intake pipe 11A upstream of the compressor 35 is provided with a compressor-upstream pressure detecting means 24A (e.g., a pressure sensor). The compressor upstream-pressure detecting means 24A is configured to output a detected signal corresponding to a pressure within the intake pipe 11A to the controller 50. The intake pipe 11B downstream of the compressor 35 is provided with a compressor-downstream pressure detecting means 24B (e.g., a pressure sensor). Specifically, the compressor-downstream pressure detecting means 24B is located between the compressor 35 and an intercooler 16 located in the intake pipe 11B. The compressor-downstream pressure detecting means 24B outputs the detected signal corresponding to the pressure within the intake pipe 11B to the controller 50.

[0037] As shown in FIG. 1, the intercooler 16 is disposed upstream of the intake pipe 11B. A throttle device 47 is disposed downstream of the intercooler 16. The intercooler 16 is disposed downstream of the compressor-downstream pressure detecting means 24B. An intake air temperature detecting means 28B (e.g., an intake air temperature sensor) is provided between the intercooler 16 and the throttle device 47. The intake air temperature detecting means 28B outputs the detected signal corresponding to the temperature of the intake air at a temperature cooled by the intercooler 16.

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[0038] As shown in FIG. 1, the throttle device 47 drives a throttle valve 47V for adjusting an opening of the intake pipe 11B based on a control signal from the controller 50. Thethrottle device 47 is also capable of adjusting the intake air flow rate. The controller 50 outputs a control signal to the throttle device 47 based on the detected signal detected by the throttle opening detecting means 47S (e.g., a throttle opening sensor) and based on a target throttle opening. The throttle device 47 is capable of adjusting the opening of the throttle valve 47V. The controller 50 serves to determine a target throttle opening based on an accelerator pedal depressing amount detected based on a detected signal from an accelerator pedal depressing amount detecting means 25 and based an operation conditions of the internal combustion engine 10, etc.

[0039] As shown in FIG. 1, the accelerator pedal depressing amount detecting means 25 may be, for example, an accelerator pedal depressing angle sensor, and may be provided on an accelerator pedal. The controller 50 is able to detect the accelerator pedal depressing amount by a driver based on a detected signal from the accelerator pedal depressing amount detecting means 25.

[0040] As shown in FIG. 1, an intake manifold pressure detecting means 24C (e.g., a pressure sensor) may be provided at the intake pipe 11B downstream of the throttle device 47. An outlet side of an exhaust gas recirculation (EGR) line 13 is connected to the intake pipe 11B. An outlet side of the intake pipe 11B is connected to an inlet side of the intake manifold11C. An outlet side of the intake manifold 11C is connected to an inlet side of the internal combustion engine 10. The intake manifold pressure detecting means 24C outputs a detected signal to the controller 50 corresponding to the pressure of the intake air immediately before flowing into the intake manifold 11C. The EGR line 13 serves to connect the exhaust pipe 12B to the intake pipe 1lB. The exhaust gas within the EGR line 13 is exhausted into the intake pipe 11B via a connection between the outlet sides of the EGR line 13 and the intake pipe IB.

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[0041] As shown in FIG. 1, the internal combustion engine 10 includes a plurality of cylinders 45A to 45D. Injectors 43A to 43D are provided to the respective cylinders. The injectors 43A to 43D are supplied with fuel via a common rail 41 and fuel lines 42A to 42D. The injectors 43A to 43D are driven by control signals from the controller 50 and inject the fuel into the respective cylinders 45A to 45D.

[0042] As shown in FIG. 1, the internal combustion engine 10 is provided with a rotation detecting means 22, a coolant temperature detecting means 28C, etc. The rotation detecting means 22 may be, for example, a rotation sensor and is configured to output detected signals corresponding to the rotation speed of the crankshaft of the internal combustion engine 10 (i.e., the rotation speed of an engine). The coolant temperature detecting means 28C may be, for example, a temperature sensor and is configured to output detected signals corresponding to a temperature of the cooling coolant circulating in the internal combustion engine 10.

[0043] As shown in FIG. 1, the inlet side of the exhaust manifold 12A is connected to the exhaust side of the internal combustion engine 10. The inlet side of the exhaust pipe 12B is connected to the outlet side of the exhaust manifold 12A. The outlet side of the exhaust pipe 12B is connected to the inlet side of the turbine 36. The outlet side of the turbine 36 is connected to the inlet side of the exhaust pipe 12C.

[0044] As shown in FIG. 1, the inlet side of the EGR line 13 is connected to the exhaust pipe 12B. The EGR line 13 communicates the exhaust pipe 12B with the inlet pipe 1lB. This enables the EGR line 13 to allow a portion of the exhaust gas of the exhaust pipe 12B (corresponding to an exhaust path) to recirculate to the intake pipe 1lB (corresponding to an intake path). The EGR line 13 is provided with an EGR cooler 15 and an EGR valve 14. The EGR valve 14 adjusts a flow rate of the EGR gas flowing through the EGR line 13 by adjusting the opening of the EGR line 13 based on the control signal from the controller 50.

[0045] As shown in FIG. 1, the exhaust pipe 12B is provided with an exhaust temperature

17320977_1 (GHMatters) P115369.AU detecting means 29. The exhaust temperature detecting means 29 may be, for example, an exhaust temperature sensor and is configured to output a detected signal corresponding to an exhaust temperature to the controller 50.

[0046] As shown in FIG. 1, the outlet side of the exhaust pipe 12B is connected to the inlet side of the turbine 36. The outlet side of the turbine 36 is connected to the inlet 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 to be led to the turbine 36. The variable nozzle 33 can adjust the opening of the flow path leading the exhaust gas to the turbine 36. The opening of the variable nozzle 33 is adjusted by a nozzle driving means 31. The controller 50 outputs a control signal to the nozzle driving means 31 based on a detected signal from the nozzle opening detecting means 32 (e.g., a nozzle opening sensor) and a target nozzle opening so as to allow the opening of the variable nozzle 33 to be adjusted.

[0047] As shown in FIG 1, the exhaust pipe 12B is located upstream of the turbine 36. The exhaust pipe 12B is provided with a turbine upstream pressure detecting means 26A (e.g., a pressure sensor). The turbine upstream pressure detecting means 26A outputs a detected signal corresponding the pressure within the exhaust pipe 12B to the controller 50. The exhaust pipe 12C is located downstream of the turbine 36. The exhaust pipe 12C is provided with a turbine downstream pressure detecting means 26B (e.g., a pressure sensor). The turbine downstream pressure detecting means 26B outputs a detected signal corresponding to the pressure within the exhaust pipe 12C to the controller 50.

[0048] As shown in FIG. 1, an exhaust gas purifier 61 is connected to the outlet side of the exhaust pipe 12C. For example, when the internal combustion engine 10 is a diesel engine, the exhaust gas purifier 62 may include an oxidation catalyst, a fine particle collection filter, a selective reduction catalyst, etc.

[0049] A vehicle speed detecting means 27 may be, for example, a vehicle speed detecting

17320977_1 (GHMatters) P115369.AU sensor and may be provided on a wheel(s) of a vehicle, etc. The vehicle speed detecting means 27 outputs detected signals corresponding to a rotation speed of the wheel(s) of the vehicle to the controller 50.

[0050] As shown in FIG. 1, the controller 50 includes a CPU 51, a RAM 52, a memory device 53, a timer 54, etc. The detected signals from the above-described various detecting means are input to the controller 50 (e.g., the CPU 51), and the controller 50 (e.g., the CPU 51) outputs control signals to the above-described various actuators, etc. The input/output of the controller 50 shall not be limited to the above-described detecting means and/or the actuator. Temperatures and pressures at each part may be calculated by estimated calculation, without the need for mounted sensors. The controller 50 is configured to detect operation conditions of the internal combustion engine 10 based on the detected signals from the various detecting means (e.g., the sensors), including the above detecting means, so as to control various actuators, etc., including the above-described actuator(s). The memory device 53 may be, for example, a memory such as a Flash-ROM, etc., in which programs, data, etc. for executing a control of the internal combustion engine, a self-diagnosis, or the like are saved. The controller 50 (e.g., the CPU 51) includes an operation condition detecting unit 51A, a fuel injection controlling unit 51B, and the like, some of the details of which will be described later.

[0051] The controller 50 injects a main injection and pilot injection(s) into the cylinder, in which the air has been compressed and heated, in order to complete one combustion process in accordance with the operation condition of the internal combustion engine 10. The main injection is a main fuel injection. The pilot injection(s) is/are single or a multiple fuel injections that is/are pre-stage injections of the main injection. In the description according to the present embodiment, all injections prior to the main injection of one combustion process will be referred to as a "pilot injection." The number and injection volume of the pilot injections, the injection volume of the main injection, etc. may be appropriately calculated based on the total fuel injection volume, the operation condition of the internal combustion engine, etc. in one combustion process.

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[0052] FIG 2 illustrates the pressure generation rate within a cylinder due to the pilot injections and the main injection. FIG. 3 illustrates the heat generation rate due to the pilot injections and the main injection. A cylinder is a cylinder for the internal combustion engine, for example, a first cylinder. In FIG.2 and FIG. 3, the pressure generation rate and the heat generation rate in one combustion process are illustrated. In the examples of FIG. 2 and FIG. 3, the controller 50 performs three pilot injections slightly before the piston is at the compression top dead center of the target cylinder. One main injection is performed in a position slightly after the piston has reached the compression top dead center. The compression top dead center corresponds to a position when the crank angle=0 [deg].

[0053] FIG. 2 shows the results of experiments or simulations where the horizontal axis represents the crank angle, which is the rotation angle of the crankshaft, and the vertical axis represents the pressure generation rate in the cylinder. In the example of FIG 2, the intake air (air) is compressed and heated by pistons in a combustion chamber. Fuel is injected during the three pilot injections into the combustion chamber. During these pilot injections, the fuel is self-ignited. The fuel is also injected during the main injection and is self-ignited. The three pilot injections are considered to together cause a single pilot combustion, in essence causing a single combustion. The pressure within the cylinder due to the pilot combustion varies as shown as the pilot combustion pressure Pp indicated by a broken line in FIG 2. A single main combustion is generated by one main injection. The pressure within the cylinder due to the main combustion overlaps with that due to the pilot combustion pressure Pp. Therefore, the pressure within the cylinder varies as shown as the main combustion pressure Pm indicated by, a dot-chain line in FIG. 2.

[0054] The pressure generation rate f (0) is indicated by a solid line in FIG 2. The pressure generation rate f (0) represents the derivative value of the pressure within the cylinder based on the crank angle. The derivative value of the pressure within the cylinder varies in accordance with the crank angle during a single combustion process. The derivative value of the pressure is a slope of variations in the total pressure within the cylinder, due to the pilot

17320977_1 (GHMatters) P115369.AU combustion pressure Pp and the main combustion pressure Pm. As shown in FIG. 2, the pressure generation rate f (0) in one combustion process has multiple peak positions. For instance, the peaks of the pressure generation rate f (0) may be located at positions where the derivative of the pressure generation rate f (0), or the double derivative of the pressure, is zero. One peak position is the peak position corresponding to a pilot combustion and another peak position is a pilot peak angle position Pap. One of the other peak positions is a main peak angle position Pam corresponding to the main combustion. As shown in FIG. 2, the crank angle of the pilot peak angle position Pap is represented by Op, and the derivative value of the pressure within the cylinder at the pilot peak angle position Pap is represented by Hp. Similarly, the crank angle of the main peak angle position Pam is represented by Om, and the derivative value of the pressure within the cylinder at the main peak angle position Pam is represented by Hm. A crank angle difference A (AO = Om - Op) is present between the main peak angle position Pam and the pilot peak angle position Pap. A lag (a lag corresponding to A) converted to time based on the crank angle difference and the rotation speed of the crankshaft is represented by At. The derivative value of the pressure within the cylinder at the pilot peak angle position Pap (i.e., pressure generation rate value) is represented by Hp. The derivative value of the pressure within the cylinder at the main peak angle position Pam (i.e., pressure generation rate value) is represented by Hm. The peak height ratio is represented by Hp/Hm.

[0055] Although not shown in the drawings, the horizontal axis shown in FIG. 2 may be changed from the crank angle [deg] to a time [sec]. The vertical axis may be changed from the pressure generation rate based on the crank angle [Mpa/deg] to a pressure generation rate based on time [Mpa/sec]. In this case, the pressure generation rate (specifically, the derivative value of the pressure within the cylinder) is essentially the same as the pressure generation rate f (0) shown in FIG. 2. For instance, the pressure generation rate has a plurality of the peak positions. The peak position due to the pilot combustions represents the pilot peak time position Ptp. The peak position due to the main combustion represents the main peak time position Ptm. When the main peak time position represents Ptm (tm, Hm) and the pilot peak time position represents Ptp (tp, Hp), the time lag may be represented by At=tm-tp and the peak height ratio may be represented by Hp/Hm.

17320977_1 (GHMatters) P115369.AU

[0056] FIG 2 focuses on the pressure within the cylinder. On the other hand, FIG. 3 focuses on the heat within the cylinder. The horizontal axis in FIG. 3 represents crank angles, similar to the horizontal axis in FIG. 2. The vertical axis in FIG. 3 represents heat generation rate, and, more specifically, a derivative values of the heat within the cylinder based on the crank angle. In FIG. 3, results of experiments or simulations are shown.

[0057] The heat generation rate g() is indicated by a solid line in FIG 3. The heat generation rate g() indicates the derivative value of the heat within the cylinder based on the crank angle. The derivative value of the heat within the cylinder varies depending on the crank angle during one combustion process. The derivative value is a slope of the variations in the total heat within the cylinder, due to the pilot combustion heat Ep and the main combustion heat Em. As shown in FIG 3, the heat generation rate g() in one combustion process has multiple peak positions. For instance, the peaks of the heat generation rate g(O) may be located at positions where the derivative of the heat generation rate g(O), or the double derivative of the heat, is zero. The peak position corresponding to the pilot combustion is represented by the pilot peak angle position Eap. Similarly, the peak position corresponding to the main combustion is represented by the main peak angle position Eam. As shown in FIG 3, the crank angle of the pilot peak angle position Eap is represented by Op, and the derivative value of the heat within the cylinder at the pilot peak angle position Eap is represented by Hp. Similarly, the crank angle of the main peak angle position Eam is represented by Om, the derivative value of the heat within the cylinder at the main peak angle position Eam is represented by Hm. The difference between the main peak angle position Eam and the pilot peak angle position Eap is represented by the crank angle difference A (AO = Om - Op). Time lag (a lag corresponding to AG), which is converted to time based on the crank angle difference and the rotation speed of the crankshaft, is represented by At. The derivative value of the heat within the cylinder at the pilot peak angle position Eap, i.e., heat generation rate value, is represented by Hp. The derivative value of the heat within the cylinder at the main peak angle position Eam, i.e., heat generation rate value, is represented by Hm. The peak height ratio is represented by Hp/Hm.

17320977_1 (GHMatters) P115369.AU

[0058] Although not shown in the drawings, the horizontal axis shown in FIG. 3 may be changed from the crank angle [deg] to time [sec]. The vertical axis may be changed from the heat generation rate based on crank angle [J/deg] to heat generation rate based on time

[J/sec]. In this case, the heat generation rate (the derivative value of the heat within the cylinder) is essentially the same as the heat generation rate g(O) in FIG. 3. For instance, the peak positions among the plurality of the peak positions of the heat generation rate corresponding to the pilot combustion and the main combustion are represented by a pilot peak time position EtP and a main peak time position Etm, respectively. When the main peak time position is represented by Etm (tm, Hm) and the pilot peak time position is represented by an Etp (tp, Hp), the time lag is represented by At-tm-tp and the peak height ratio is represented by Hp/Hm.

[0059] The inventors have conducted various experiments and simulations. As a result, it was found that there is an optimum time lag At and an optimum peak height ratio Hp/Hm that reduces the combustion noise of the internal combustion engine. The crank angle/pressure generation rate shown in FIG. 2 may be used for both the time lag At and the peak height ratio Hp/Hm. Alternatively, the crank angle/heat generation rate and time lag shown in FIG. 3 may be used for both the time lag At and the peak height ratio Hp/Hm. Alternatively, a time/pressure generation rate (not shown) or a time/heat generation rate (not shown) may be used for the lag time At and peak height ratio Hp/Hm. In the following description of the present embodiment, time lag At and peak height ratio Hp/Hm will be described based on the crank angle/pressure generation rate, an example of which is shown in FIG. 2.

[Results of Simulations and/or Experiments (FIG. 4 to FIG. 7)]

[0060] The results of simulations or experiments are illustrated when the time lag At and the peak height ratio Hp/Hm are changed to various values for various operation condition of the internal combustion engine. Some of the results will be discussed with reference to FIG. 4 to FIG. 7. The offset center frequency shown in FIG. 4 to FIG. 6 represents a time lag associated amount based on the time lag At. For instance, the offset center frequency may 17320977_1 (GHMatters) P115369.AU correspond to the offset (e.g., difference in phase) of the frequencies of the pressure waves generated by the pilot combustion and the main combustion. The offset center frequency is calculated based on the time lag At. The offset center frequency may be, for example, a frequency in which the time lag At [sec] is a time in which it takes the frequency to complete half of a cycle, feq=/(2*At). Said another way, twice the time lag At [sec] is the time it takes to complete an entire cycle of the offset center frequency. For example, when the time lag is represented by At=0.26[ms], the frequency is represented by 1/(0.00026[sec]*2)~1.923[KHz]. The offset center frequency is a frequency at substantially the center of the offset frequency band (e.g., f=0.3/At to f=0.7/At) that serves to cancel or reduce the combustion noise due to the pilot combustions and the main combustion.

[0061] In some embodiments, the main combustion may generate a certain pressure wave, which may then cause generation of noise. The frequency and amplitude of these pressure waves may vary based on the rotational speed of the internal combustion engine and the fuel injection volume corresponding to the main combustion. In order to reduce the noise generated by the main combustion, the pilot combustion may be used. For instance, the pilot combustion may be configured to generate another pressure wave, which may also generate a noise. The pilot pressure wave may also have a frequency and amplitude based on the rotational speed of the internal combustion engine and the fuel injection volume ,0 corresponding to the pilot combustion. In order to reduce the noise, it may be beneficial to set the time between the pilot combustion and the main combustion such that the frequencies due to the corresponding pressure waves are out of phase with each other. That is, it may be beneficial to set the frequencies to interfere with each other to cause destructive interference.

[0062] FIG. 4 shows results when the rotation speed of the internal combustion engine is represented by Ne=1600[rpm] and injection volume (load) injected in one combustion process is represented by Qv=30[mm 3/st]. FIG. 4 shows the results of simulations or experiments when the time lag At and the peak height ratio Hp/Hm are set at various values. The results of the simulations or experiments are indicated by solid circles in FIG. 4. The offset center frequency is a frequency converted from the time lag At, as described above. That is, one

17320977_1 (GHMatters) P115369.AU cycle of the offset center frequency is completed in twice the time of the time lag At. When this internal combustion engine is in an idling condition, the rotation speed Ne is about 700[rpm] and the injection volume (load) Qv is about 5[mm 3 /st].

[0063] In FIG. 4, the curves of combustion noise levels D1 to D5 resulting from the simulations or experiments are indicated by dot-chain lines. D1 to D5 indicates the overall combustion noise levels (e.g., as measured in decibels) integrated in the audio frequency range of 0.9 to 5.6 [KHz] of the observed combustion noise. There is a relationship among the combustion noise levels, which is D5>D4>D3>D2>D1. That is, D5 has a louder noise than D4, D4 is louder than D3, etc. A region where the peak height ratio Hp/Hm exceeds 1.0 is unrealistic because this is a region where the peak position of the pilot combustion Pp is higher than the peak position of the main combustion Pm. The peak height ratio Hp/Hn of less than 0.2 will not be considered in these experiments or simulations because it would result in the pilot combustion being too small to be realistic. Therefore, the peak height ratio Hp/Hm will be considered to be less than or equal to 1.0 and more than or equal to 0.2. A region where the offset center frequency exceeds 2.2 [KHz] is unrealistic because this is a region near the injection frequency limit of the injector and requires control where the time lag At is shorter than about 0.227 [ms]. A region where the offset center frequency is less than 0.6 [KHz] is the region where the time lag At is longer than about 0.833[m]. Therefore, ,0 since the interval between the pilot injection and the main injection is too long, the width of the offset frequency band becomes too narrow to achieve the offset effect. Accordingly, an offset center frequency of less than or equal to 2.2[KHz] and more than or equal to 0.6 [KHz] will be considered (and similarly in FIG. 5 and FIG. 6).

[0064] FIG 4 shows an operation condition at a rotation speed is at 1600 [rpm] and a fuel injection volume (load) at 30[mm 3 /st]. The horizontal axis in FIG 7 represents the rotation speed, while the vertical axis represents the fuel injection volume (load). The operation condition in FIG 4 is indicated by Ul in FIG 7. In the operation condition Ul, the offset center frequency may be set between about 1.9 [KHz] and about 2.2 [KHz] to keep the combustion noise level below D1, as shown in FIG 4. In other words, the time lag At may

17320977_1 (GHMatters) P115369.AU be set between about 0.227 [ms] and about 0.263 [ms] for these operation conditions. At the combustion noise level D1, the peak height ratio Hp/Hm is between about 0.85 and about 1.0.

[0065] For the operation condition of FIG. 5, the rotation speed of the internal combustion engine Ne is 1600 [rmp] and the injection volume (load) injected in one combustion process Qv is 55[mm 3/st]. FIG. 5 shows the results of the simulations (or experiments) of the time lag At and the peak height ratio Hp/Hm set at various values (positions indicated by solid circles in FIG. 5), based on this operation condition. The offset center frequency is a frequency converted from the time lag At, as described above.

[0066] In FIG. 5, curves of the combustion noise levels D1 to D5 are indicated by dot-chain lines and represent the observed overall combustion noise levels, similar to FIG. 4. The combustion noise levels are arranged in order, D5>D4>D3>D2>D1. That is, D5 has a louder noise than D4, D4 is louder than D3, etc. Only the realistic operation conditions are to be considered for these experiments or simulations. That is, a peak height ratio Hp/Hm of less than or equal to 1.0 and more than or equal to 0.2 will only be considered. Also, an offset center frequency of less than or equal to 2.2 [KHz] and more than or equal to 0.6 [KHz] will be considered. The fuel injection volume Qv is increased as compared to that of the operation conditions of FIG. 4. Also, an offset frequency of less than or equal to about 0.9

[KHz] will be considered.

[0067] Under the operation condition shown in FIG. 5, the rotation speed is 1600[rpm] and the fuel injection volume (load) is 55 [mm 3/st]. The horizontal axis in FIG. 7 represents the rotation speed and the vertical axis represents the fuel injection volume (load). The operation condition of FIG. 5 is indicated by U2 in FIG. 7. In order to keep the combustion noise level below D2 when operating under the operation condition U2, the offset center frequency may be set to approximately equal to or more than 0.9 [KHz], that is the time lag At may be set between less than or equal to about 0.556 [ms], while the peak height ratio Hp/Hm may be set between about 0.2 to about 0.5. The conditions under the combustion noise level of D2 are the conditions of FIG. 5 where the realistic offset frequency is less than or equal to 17320977_1 (GHMatters) P115369.AU

0.9 [KHz].

[0068] Under the operation condition of FIG. 6, the rotation speed of the internal combustion engine Ne is 2400 [rmp] and the injection volume (load) injected in one combustion process Qv is 30[mm 3/st]. FIG. 6 shows the results of the simulations (or experiments) of the time lag At and the peak height ratio Hp/Hm set at various values (positions indicated by solid circles in FIG. 6) under this condition. The offset center frequency is a frequency converted from the time lag At, as described above.

[0069] In FIG. 6, curves of the combustion noise levels D2 to D5 are indicated by dot-chain lines. Similar to FIG. 4, FIG. 6 shows the observed combustion noise levels. The combustion noise levels are D5>D4>D3>D2. Peak height ratios Hp/Hm of less than or equal to 1.0 and more than or equal to 0.2 are considered. An offset center frequencies of less than or equal to 2.2 [KHz] and more than or equal to 0.6 [KHz] are considered. The rotation speed Ne is increased as compared to the operation conditions of FIG. 4. Under the operation conditions of FIG. 6, it was not possible to reduce the combustion noise level to D1.

[0070] Under the operation conditions shown in FIG. 6, the rotation speed is 2400[rpm] and the fuel injection volume (load) is 30 [mm 3/st]. The horizontal axis of FIG. 7 represents the rotation speed and the vertical axis represents the fuel injection volume (load). The operation conditions of FIG. 6 are indicated by U3 in FIG. 7. In order to keep the combustion noise level below D2 under the operation condition U3, as shown in FIG. 6, the offset center frequency may be set in the range of about 1.22 [KHz] to about 2.2 [KHz], that is the time lag At may be set to between about 0.227 [ms] and about 0.410 [ms], while the peak height ratio Hp/Hm may be set to between about 0.75 and about 1.0.

[0071] As described above, when the rotation speed is substantially constant and the load (fuel injection volume) is increased from a low load to a high load, the beneficial time lag At range is elongated and set later, while the entire preferred peak height ratio Hp/Hm range is

17320977_1 (GHMatters) P115369.AU reduced. This is effective for reducing the combustion noise. When the load (fuel injection volume) is substantially constant and the rotation speed is increased from low speed to high speed, both a beneficial range of the time lag At a beneficial range of the peak height ratio Hp/Hm are extended low.

[0072] As described above, the time lag At (or the offset center frequency converted from the time lag At (time lag associated amount)) and the peak height ratio Hp/Hm significantly affect a reduction in combustion noise. An optimum time lag At and an optimum peak height ratio Hp/Hm are also present.

[Optimum Time Lag At and Optimum Peak Height Ratio Hp/Hm under each Operation Condition (FIG. 8 to FIG. 11)]

[0073] FIG 8 shows a crank angle/pressure generation rate fsl (0) for the data Si in FIG 4. In the data S, the offset center frequency is 1.9 [KHz] and the peak height ratio Hp(H)/Hm(H) is 0.88. FIG 8 further shows a crank angle/pressure generation rate fs2 (0) for the data S2 in FIG 4. In the data S2, the offset center frequency is 1.9 [KHz] and the peak height ratio Hp(H)/Hm(H) is 0.58. Since the frequencies, which are converted from the time lag At, are both 1.9 [KHz], the crank angle differences AO are identical. The peak height ratio of fsl (0) is Hp(H)/Hm(H)=0.88, while the peak height ratio of fs2(0) is Hp(L)/Hm(L)=0.58. The observation results of the audio frequency/combustion noise level spectrum of this example are shown in FIG 9.

[0074] FIG 9 shows the results of the combustion audio frequency and the combustion noise level of fsl(0) and fs2(0). The time lags At by fsl() and fs2() are identical (converted frequency is 1.9 [KHz]). The peak height ratio Hp/Hm of fsl(0) is 0.88. The combustion noise at fs1(0) is indicated by a solid line in FIG 9. The peak height ratio Hp/Hm of fs2(0) is 0.58. The combustion noise at fs2() is indicated by a dotted line in FIG 9. The combustion noise of fs1(0) is more significantly reduced than the combustion noise of fs2(0). This is especially prevalent in the sound frequency bands between about 1.2 [KHz] to about

17320977_1 (GHMatters) P115369.AU

2.5 [KHz].

[0075] FIG. 10 shows crank angle/pressure generation rate fs3(0) for the data S3 in FIG. 5. In the data S3, the offset center frequency is 0.83 [KHz], and the peak height ratio Hp(H)/Hm(H) is 0.75. FIG. 10 further shows crank angle/pressure generation rate fs4(0) for the data S4 in FIG. 5. In the data S4, the offset center frequency is 0.83 [KHz] and the peak height ratio Hp(H)/Hm(H) is 0.26. Since the frequency of fs3(0) and fs4(0), which are converted from the time lag At, are both 0.83 [KHz], the crank angle differences AO are identical. The peak height ratio of fs3(0) is Hp(H)/Hm(H)=0.75, while the peak height ratio of fs4(0) is Hp(L)/Hm(L)=0.26. Under the operation conditions of FIG. 10, the main injection volume is greater than that of the operation conditions of FIG .8. Therefore, the time interval from the beginning of the main injection to the peak of the main injection becomes longer. Due to the restrictions on the interval between the pilot injections and the main injection, it will be difficult to adjust the pilot injections to shorten the time lag At (crank angle differences AO) from the peak of the pilot injection. The observation results of the combustion audio frequency/combustion noise level spectrum of this example are shown in FIG. 11.

[0076] As shown in FIG. 11, the time lags At byfs3(0) and fs4(0) are identical (which when converted offset center frequency is 0.83 [KHz]). FIG. 11 shows the combustion noise of fs3(0) at a peak height ratio Hp/Hm of 0.75. Fs3(0) is indicated by a dotted line in FIG. 11. Fs4(0) is a combustion noise at a peak height ratio Hp/Hm=0.26. Fs4(0) is indicated by a solid line in FIG 11. In the audio frequency band of about 0.5 [KHz] to about 1.2 [KHz], fs3(0) is less effective than fs4(0) in reducing noise. On the other hand, in the audio frequency band of about 1.2 [KHz] to about 2.2 [KHz], centered on about 1.7 [KHz], the noise level suppression effect offs3(0) is reduced compared to fs4(0). Compared with fs3(0), fs4(0) has a lower maximum value of the noise spectrum. This is especially true as the overall combustion noise level is integrated over the range of audio frequencies from 0.9 [KHz] to 5.6 [KHz]. This shows that the combustion noise of fs4(0) is more significantly reduced than fs3(0).

17320977_1 (GHMatters) P115369.AU

[Setting of Target Time/Target Peak Height Ratio Characteristics (FIG. 12, FIG. 13)]

[0077] The target time/target peak height ratio characteristics (see FIG. 12) are prepared and saved in the memory device 53 of the controller 50. For the target time/target peak height ratio characteristics, the optimum target time lag and target peak height ratio may be set in accordance with the above described results based on the operation conditions of the internal combustion engine. The operation conditions of the internal combustion engine are, in particular, the rotation speed and the load (injection volume). Instead of the optimum target time lag, the optimum target time lag associated amount (target offset center frequency) may be set. The vertical axis in FIG. 12 represents either one of the target offset center frequency (or target time lag) or the target peak height ratio. The horizontal axis represents the other. The target offset center frequency is the target time lag associated amount, which is determined based on the target time lag. The target time/target peak height ratio, such as a lookup table or formula, corresponding to each of a plurality of preset rotation speeds and/or fuel injection volumes (load) are saved in the memory device 53.

[0078] An example of the target time/target peak height ratio characteristics based on rotation speed and fuel injection volume (load) are represented in a graph-form in FIG. 12. In FIG. 12, the characteristic when rotation speed Ne is 1600[rpm] is represented by h(1600). The characteristic when the rotation speed Ne is 2000[rpm] is represented by h(2000). The characteristic when the rotation speed Ne is 2400[rpm] is represented by h(2400).

[0079] For example, for the characteristic of h(1600) (Ne=1600 [rpm]) in FIG. 12, the position of the injection volume (load) of Qv=30 [mm 3 /st] is represented by the position at Ml1 (Ne1600, Qv30). The position of the injection volume (load) of Qv=40[mm 3 /st] is represented by the position at M12 (Ne1600, Qv40). The position of the volume (load) at Qv=55 [mm 3 /st] is represented by the position at M13 (Ne1600, Qv55). Similarly, in the characteristic of h(2000) (Ne=2000 [rpm]) in FIG. 12, the position of the injection volume (load) at Qv=40 [mm 3/st] is represented by the position at M22 (Ne2000, Qv4). The position of the injection volume (load) at Qv=55 [mm 3/st] is represented by the position at 17320977_1 (GHMatters) P115369.AU

M23 (Ne2000, Qv55). Similarly, in the characteristic of h(2400) (Ne=2400 [rpm]) in FIG. 12, the position of the injection volume (load) at Qv=30 [mm 3/st] is represented by the position at M31 (Ne2400, Qv30). The position of the injection volume (load) at Qv=40

[mm 3 /st] is represented by the position at M32 (Ne2400, Qv4O). Dot-chain lines shown in FIG 12 indicate equal-load lines passing through the identical load positions. That is, the dot-chain lines pass through equal loads at different rotation speeds. A shown in FIG. 12, when the rotation 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 lag associated amount is changed so that the time lag At is longer, i.e., the target offset frequency becomes lower. Additionally, the target peak height ratio is changed such that the peak height ratio (Hp/Hm) is reduce.

[0080] For example, the controller 50 may use the detected the operation conditions of the internal combustion engine (e.g., rotation speed and load) and the target time/target peak height ratio characteristics (e.g., those shown FIG. 12), which were saved in the memory device 53 based on the determined optimal target time lag related amount (in this case the target offset center frequency) and the target peak height ratio based on the operation conditions (e.g., rotation speed and load) of the internal combustion engine.

[0081] FIG. 13 illustrates an example for the maximum tolerance limit (Max)h(1600) and an example for the minimum tolerance limit (Min)h(1600). In FIG. 13, the example of Ml1 is based on the data S1 of FIG. 4. If the peak height ratio achieves within the target peak height ratio 0.15 (15%), the target noise level can be kept substantially within 1 [dBA] of the target noise level. If the offset center frequency achieves within the target offset center frequency 0.20 [KHz], the noise level can be substantially kept substantially within 1

[dBA] of the target noise level. As represented by the maximum tolerance limit (Max)h(1600) and the maximum tolerance limit (Min)h(1600) in FIG. 13, even if the peak height ratio is set to a slightly greater value than 0.15 (15%) with respect to the target peak height ratio, the noise level can be kept substantially within 1 [dBA] of the target noise level. Even if the offset center frequency is set to a value slightly greater than 0.2 [KHz] with

17320977_1 (GHMatters) P115369.AU respect to the target offset center frequency, the noise level can be kept substantially within 1 of respect to the target [dBA].

[0082] In the example of M12 shown in FIG. 13, the load is increased relative to M11. If the peak height ratio is set to be within the target peak height ratio 0.15 (15%), the noise level can be substantially kept within 1 [dBA] of the target noise level. If the offset center frequency is set to be within the target offset center frequency 0.2 [KHz], the noise level can be substantially kept within 1 [dBA] of the target noise level. In the example of M13 shown in FIG. 13, the load is further increased relative to M12, while the rotational speed is kept the same. The example of M13 is based on the data S4 of FIG. 5. If the peak height ratio is set at a value slightly smaller than 15 (15%) with respect to the target peak height ratio, the noise level can be substantially kept within 1 [dBA] of the target noise level. If the offset center frequency is set to be within the target offset center frequency 0.1 [KHz], the noise level can be substantially kept within 1 [dBA] of the target noise level. These tolerances have been confirmed by the inventors from the results of various simulations and experiments. As represented by the maximum tolerance limit (Max)h(1600) and the minimum tolerance limit (Min)h(1600) in FIG. 13, based on the example of M13, if the peak height ratio is set to a value within the target peak height ratio 0.15, the noise level can be kept substantially within 1 [dBA] of the target noise level. If the offset center frequency is ,0 set to be within the target offset center frequency 0.2 [KHz] or 0.1 [KHz], the noise level can be substantially kept within 1 [dBA] of the target noise level.

[0083] In other words, it is preferable to control the peak height ratio Hp/Hm such that the deviation amount from the target peak height ratio falls within the tolerance height ratio. "The tolerance height ratio" is set at 0.15 (15%) (tolerance height ratio reference value) when the load (Qv) is in the vicinity of a predetermined load (e.g., in the vicinity of Qv=40[mm 3 /st]). The tolerance height ratio is set to be greater than the tolerance height ratio reference value as the load (Qv) becomes smaller than the predetermined load (e.g., Qv=40[mm 3 /st]). For example, the tolerance height ratio is set at a value slightly greater than 0.15. The tolerance height ratio is set so as to be smaller than the tolerance height ratio

17320977_1 (GHMatters) P115369.AU reference value as the load (Qv) increases to become greater than the predetermined load (e.g., Qv=40[mm 3/st]). For example, the tolerance height ratio is set to a value slightly smaller than 0.15. Therefore, in FIG. 13, a tolerance interval of the target peak height ratio between the maximum tolerance limit (Max)h(1600) and the minimum tolerance limit (Min)h(1600) is set to be narrower as the load (Qv) increases. The tolerance interval of the target peak height ratio is set to be greater as the load (Qv) decreases.

[0084] It is preferable to control the target offset center frequency so that the deviation amount from the actual target offset center frequency falls within the tolerance frequency. "The tolerance frequency" is set at 0.2 [KHz] (tolerance frequency reference value) when the load (Qv) is in the vicinity of the predetermined load (e.g., Qv=40[mm 3/st]). The tolerance frequency is set to be greater than the tolerance frequency reference value as the load (Qv) becomes smaller than the predetermined load (e.g., Qv=40[mm 3/st]). For example, the tolerance frequency may be set at a value slightly greater than 0.2 [KHz]. The tolerance frequency is set to be smaller than the tolerance frequency reference value as the load (Qv) is increased to become greater than the predetermined load (e.g., Qv=40[mm 3/st]). For example, the tolerance frequency may be set at a value slightly smaller than 0.2 [KHz]. Therefore, in FIG. 13, a tolerance interval of the target offset center frequency between the maximum tolerance limit (Max)h(1600) and the minimum tolerance limit (Min)h(1600) is set ,0 to decrease as the load (Qv) increases. The tolerance interval is set to increase as the load (Qv) decreases.

[Processing Steps of Controller 50 (FIG. 14)]

[0085] An embodiment of processing steps performed by the controller 50 will be described with reference to the flow chart shown in FIG. 14. The controller 50 (e.g., a CPU 51) starts the process shown in FIG. 14, for example, at every predetermined crank angle (e.g., every 180 [°CA] in the case of four-cylinder engines), and proceeds to step S010.

[0086] In step SO10, the controller 50 detects various operation conditions of the internal

17320977_1 (GHMatters) P115369.AU combustion engine and proceeds the process to step S015. For example, the controller 50 may detect a rotation speed of the internal combustion engine, an intake volume, a pressure within the intake manifold, a variable nozzle opening amount, an accelerator pedal depressing amount, a fuel injection volume, etc., based on detected signals from various detecting means, for example those shown in FIG. 1, and may detect a control amount of the injector (e.g., the previous fuel injection volume). The controller 50 (e.g., CPU 51) executing the process of the step SOl1 corresponds to an operation condition detecting unit 51A for detecting the operation conditions of the internal combustion engine (e.g., see FIG. 1).

[0087] The controller 50 calculates a demand torque from a driver based on the operation conditions detected in step S015, and then proceeds the process to step S020. For example, the controller 50 may calculate the demand torque based on maps or lookup tables, calculation formulas, etc. saved in the memory device in accordance with certain aspects, such as the rotation speed of the internal combustion engine and the accelerator pedal depressing amount.

[0088] In step S020, the controller 50 calculates the (subsequent) injection volume (Qv) based on the calculated demand torque and the operation conditions of the internal combustion engine, and proceed the process to step S025. Details of calculation procedures of the injection volume (Qv) will not be described.

[0089] In step S025, the controller 50 determines the target time lag associated amount and the target peak height ratio based on the operation conditions of the internal combustion engine and the target time/target peak height ratio characteristics (see FIG. 12) saved in the memory device. The controller 50 then proceeds the process to step S030. The operation conditions may be, for example, the rotation speed of an engine and the load (fuel injection volume). The target time lag associated amount may be, for example, the target offset center frequency. For example, the controller 50 may select h(1600) from the target time/target peak height ratio characteristics shown in FIG. 12 when the rotation speed is at 1600 [rpm] and the load (injection volume) is at 30 [mm 3/st]. The controller 50 determines the target 17320977_1 (GHMatters) P115369.AU time lag associated amount (target offset center frequency) and the target peak height ratio referring to the position of Ml1, which corresponds to the position of 30 [mm 3/st] at the selected h(1600).

[0090] In step S030, the controller 50 determines the number of pilot injections, the injection timing and injection volume of each pilot injection, and the injection timing and the injection volume of the main injection for the subsequent fuel injection operation based on the (subsequent) injection volume (Qv), the target time lag associated amount (target offset center frequency), the target peak height ratio, and the operation conditions of the internal combustion engine. The controller 50 then directs the system to complete this process. In one combustion process, the number of pilot injections is one or more and the number of main injections is one.

[0091] At this moment, the injection timing of the main injection and the injection timing of the pilot injection immediately before the main injection are set based on the target time lag associated amount (target offset center frequency). For example, the target time intervals in accordance with the target time lag associated amount (target offset center frequency) may be saved, for example, in the format of maps or a lookup table or the like. The controller 50 determines the injection timing of the main injection and the injection timing of the pilot injection(s) immediately before the main injection such that the target time interval is achieved using the target time lag associated amount and the map or lookup table. The maps or lookup tables are prepared using the simulations, experiments, etc. and are saved in the memory device 53.

[0092] The total pilot injection volume and the injection volume of the main injection are determined using the predetermined calculation formulas, maps or lookup tables, etc. based on the target peak height ratio. The total pilot injection volume is a sum of the injection volumes of multiple pilot injections. For example, the controller 50 divides the (subsequent) injection volume (Qv) into the total pilot injection volume and the main injection volume in accordance with the target peak height ratio. In this way, the controller 50 determines the 17320977_1 (GHMatters) P115369.AU total pilot injection volume and the main injection volume. The above-mentioned predetermined formulas, maps and lookup tables are prepared using the simulations and the experiments, and are saved in the memory device 53.

[0093] As described above, the number of pilot injections, the injection timing and the injection volume of each pilot injection, and the injection timing and the injection volume of the main injection are determined. Accordingly, although not shown in the drawings, the controller 50 executes each injection process by a scheduling process of the existing pilot injections and a scheduling process of the existing main injection, at a targeted timing.

[0094] The above-described target time lag associated amount (target offset center frequency) may be changed to the target time lag. The target time lag is half the time of one cycle at the target offset center frequency (a half wavelength). For example, the target time/target peak height ratio characteristics may be saved in a memory device. The target time/target peak height ratio characteristics may be the target offset center frequency (target time lag associated amount) representing the horizontal axis of the target time/target peak time ratio characteristics shown in FIG. 12, which may be changed to represent the target time lag. In step S025, the controller 50 determines the target time lag and the target peak height ratio based on the operation conditions of the internal combustion engine (e.g., rotation speed and load (injection volume)) and the target time/target peak height ratio characteristics saved in the memory device 53. In step S030, the controller 50 sets the injection timing of the main injection and the injection timing of the pilot injection(s) immediately before the main injection based on the target time lag.

[0095] The controller 50 (e.g., CPU 51) executing the processes of the above-described steps S025 and S030 corresponds to a fuel injection controlling unit 51B (e.g., see FIG. 1). The fuel injection controlling unit 51B determines the target time lag, or the target time lag associated amount, and the target peak height ratio in accordance with the operation conditions of the internal combustion engine. The fuel injection controlling unit 51B controls the internal combustion engine so that the time lag (At) comes closer to the target 17320977_1 (GHMatters) P115369.AU time lag and the peak height ratio (Hp/Hm) comes closer to the target peak height ratio. More specifically, the fuel injection controlling unit 51B is configured to control at least the injection timing and the injection volume of one or more pilot injection immediately before the main injection of the pre-stage injection and the injection timing and the injection volume of the main injection.

[0096] The controller for the compression self-ignition internal combustion engine according to the present disclosure should not be limited to the configuration, structure, processing procedure, or the like as described in the present embodiments, and various modifications, additions, and/or deletions are possible without departing from the gist of the present disclosure.

[0097] For instance, in the present embodiments of FIG. 2, FIG. 3, FIG. 8, and FIG. 10, examples are described to determine the crank angle difference AO with the horizontal axis representing the crank angle. However, it is also possible to determine the time lag At with the horizontal axis representing time. Further, in FIG. 4, FIG. 5, FIG. 6, FIG. 12, and FIG. 13, examples are described with the horizontal axis representing the offset center frequency (time lag associated amount). However, it is also possible to set the horizontal axis to represent the time lag At (f=1/(At*2).

[0098] The controller for the compression self-ignition internal combustion engine according to the present disclosure shall not be limited to a diesel engine. The controller may also be applied to a compression self-ignition gasoline engine.

[0099] Greater than or equal to (>), less than or equal to (<), greater than (>), less than (smaller than) (<), etc., may or may not contain the equal sign. Further, the numerical values used in the description of the present embodiments are merely used as one example. The overall disclosure shall not be limited to these numerical values.

17320977_1 (GHMatters) P115369.AU

[0100] The various examples described in detail above, with reference to the attached drawings, are intended to be representative of the present disclosure, and are thus non-limiting embodiments. The detailed description is intended to teach a person of skill in the art to make, use, and/or practice various aspects of the present teachings, and thus does not limit the scope of the disclosure in any manner. Furthermore, each of the additional features and teachings disclosed above may be applied and/or used separately or with other features and teachings in any combination thereof, so as to provide an improved compression self-ignition internal combustion engine, and/or methods of making and using the same.

[0101] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

[0102] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

17320977_1 (GHMatters) P115369.AU

Claims (5)

Claims

1. A controller for controlling a compression self-ignition internal combustion engine, comprising:

a compression self-ignition internal combustion engine configured to:

inject a main injection as a main fuel injection and inject a pilot injection, as one or more pilot fuel injections, as a pre-stage injection to the main fuel injection into a cylinder, both injections occurring in one combustion process;

generate a pilot combustion from the pilot injection, and

generate a main combustion from the main injection, wherein:

when At is set as a time lag between a pilot peak time position and a main peak time position in one combustion process, and when Hp/Hm is set as a peak height ratio:

the pilot peak time position is a peak position corresponding to the pilot combustion among a plurality of peak positions, the plurality of peak positions being peaks of a derivative value of a pressure within the cylinder that varies over time or of a derivative value of heat within the cylinder that varies over time,

the main peak time position is a peak position corresponding to the main combustion among the plurality of peak positions,

the Hp represents a value of the derivative value of the pressure within the cylinder at a pilot peak position or value of the derivative value of heat within the cylinder at the pilot peak time position,

the Hm represents a value of the derivative value of the pressure within the cylinder at a main peak position or a value of the derivative value of the heat within the cylinder at the main peak time position, or

when At is set as a lag converted to time based on a crank angle difference and a rotation speed of the crankshaft in the one combustion process, and Hp/Hm is set as the peak height ratio:

the crank angle difference is a difference between a pilot peak angle position and 19150159_1 (GHMatters) P115329.AU a main peak angle position, the pilot peak angle position is a peak position corresponding to the pilot combustion among a plurality of peak positions, the plurality of peak positions being peaks of a derivative value of the pressure within the cylinder that varies in accordance with a crank angle, the crank angle being a rotation angle of the crankshaft, or of a derivative value of the heat within the cylinder that varies in accordance with the crank angle, the main peak angle position is a peak position corresponding to the main combustion among the plurality of peak positions, the Hp represents the value of the derivative of the pressure within the cylinder at the pilot peak angle position or the value of the derivative of the heat within the cylinder at the pilot peak angle position, and the Hm represents the value of the derivative of the pressure within the cylinder at the main peak angle position or the value of the derivative of the heat within the cylinder at the main peak angle position, and the controller comprises: an operation condition detecting unit configured to detect operation conditions of the compression self-ignition internal combustion engine, and a fuel injection controlling unit, wherein the fuel injection controlling unit is configured to: determine a target time lag or a target time lag associated amount in accordance with the detected operation conditions of the compression self-ignition internal combustion engine, determine a target peak height ratio in accordance with the detected operation conditions of the compression self-ignition internal combustion engine, and control at least an injection timing and an injection volume of the pilot injection and at least an injection timing and an injection volume of the main

19150159_1 (GHMatters) P115329.AU injection such that the At comes closer to the target time lag or such that the time lag associated amount based on the At comes closer to the target time lag associated amount, and such that the Hp/Hm comes closer to the target peak height ratio.

2. The controller for controlling the compression self-ignition internal combustion engine as defined in claim 1, wherein the fuel injection controlling unit of the controller is configured to:

change the target time lag or the target time lag associated amount such that the At increases, and change the target peak height ratio, such that the Hp/Hm decreases

when the rotation speed of the compression self-ignition internal combustion engine is substantially constant and a load of the compression self-ignition internal combustion engine is increased from a low load to a high load.

3. The controller for controlling the compression self-ignition internal combustion engine as defined in claim 1 or 2, wherein:

characteristics of a target time and the target peak height ratio corresponding to each of various preset rotation speeds are saved in the controller,

a vertical axis representing the target time/target peak height ratio characteristics represents one of the following (1) or (2), and a horizontal axis represents the other (1) or (2):

(1) the target time lag or a target offset center frequency, which is a frequency at substantially the center of an offset frequency band that serves to cancel and reduce combustion noise due to the pilot combustions and the main combustion, and which is the target time lag associated amount determined based on the target time lag, and

(2) the target peak height ratio,

for the target time/target peak height ratio characteristics, positions are set corresponding to loads of the compression self-ignition internal combustion engine with

19150159_1 (GHMatters) P115329.AU respect to the preset rotation speed, and the fuel injection controlling unit of the controller is configured to: select the target time/target peak height ratio characteristic in accordance with the rotation speed of the compression self-ignition internal combustion engine, determine the target peak height ratio and one of the target time lag associated amount or the target time lag based on the selected target time/target peak height ratio characteristics and the load of the compression self-ignition internal combustion engine so as to determine the target time lag associated amount or the target time lag in accordance with the rotation speed and the load of the compression self-ignition internal combustion engine, and determine the target peak height ratio, and control at least the injection timing and the injection volume of the pilot injection immediately before the main injection and the injection timing and the injection volume of the main injection such that: the offset center frequency, which is the time lag associated amount based on the At, comes closer to the target center frequency, which is the target time lag associated amount, or the At comes closer to the target time lag, and the Hp/Hm comes closer to the target peak height ratio.

4. The controller for controlling the compression self-ignition internal combustion engine as defined in claim 3, wherein:

the fuel injection controlling unit of the controller is configured to control the Hp/Hm such that a deviation amount from the target peak height ratio falls within a tolerance height ratio when at least the injection timing and the injection volume of the pilot injection immediately before the main injection and the injection timing and the injection volume of the main injection are controlled,

the tolerance height ratio is set to a tolerance height ratio reference value when the load of the compression self-ignition internal combustion engine is in a vicinity of a predetermined load,

19150159_1 (GHMatters) P115329.AU the tolerance height ratio is set to become larger than the tolerance height ratio reference value as the load of the compression self-ignition internal combustion engine becomes smaller than the predetermined load, and the tolerance height ratio is set to become smaller than the tolerance height ratio reference value as the load of the compression self-ignition internal combustion engine increases to become greater than the predetermined load.

5. The controller for controlling the compression self-ignition internal combustion engine as defined in claim 3 or 4, wherein:

the fuel injection controlling unit of the controller is configured to control such that a deviation amount of the offset center frequency from the target offset center frequency falls within a tolerance frequency when at least the injection timing and the injection volume of the pilot injection immediately before the main injection and the injection timing and the injection volume of the main injection are controlled,

the tolerance frequency is set at a tolerance frequency reference value when the load of the compression self-ignition internal combustion engine is in the vicinity of the predetermined load,

the tolerance frequency is set to become larger than the tolerance frequency reference value as the load of the compression self-ignition internal combustion engine becomes smaller than the predetermined load, and

the tolerance frequency is set to become smaller than the tolerance frequency reference value as the load of the compression self-ignition internal combustion engine is increased to become greater than the predetermined load.

19150159_1 (GHMatters) P115329.AU