DE102021102108A1 - CONTROL UNIT FOR CONTROLLING A SELF-IGNITING COMBUSTION ENGINE - Google Patents

Abstract

Δt represents a time lag between an advanced apex angular position corresponding to pre-combustion among apex positions of a derivative value of pressure within a cylinder (45A, 45B, 45C, 45D) and a main apex angular position corresponding to main combustion. Hp / Hm represents a peak height ratio which are respective crank angle derivative values. A control unit (50) includes an operation state detection unit (51A) and a fuel injection control unit (51B). The fuel injection control unit (51B) determines a target time lag (or an amount associated with the target time lag) and the target peak height ratio in accordance with operating conditions. The fuel injection control unit (51B) controls at least an injection timing and an injection amount immediately before the main injection and an injection timing and an injection amount of the main injection so that the time lag becomes closer to the target timing lag and the peak height ratio becomes closer to the target peak height ratio.

Description

This application claims priority from Japanese patent application serial number 2020-012280 , which was filed on January 29, 2020, the contents of which are incorporated by reference in their entirety for all purposes.

The invention relates to a control unit for controlling a compression ignition internal combustion engine.

In compression auto-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 auto-ignite and burn. 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 burned by sparks generated by a spark plug. Since the noise development during combustion is greater in compression-ignition internal combustion engines than in externally ignited internal combustion engines, a reduction in the combustion noise was desired.

In a combustion cycle of a compression-ignition internal combustion engine, a main injection is carried out after more than one pre-injection, which act as pre-stage injections. Pre-combustion is generated by each pre-injection. The main combustion is generated by the main injection. Various methods of reducing combustion noise by allowing the pressure wave of each combustion to interfere with another have been disclosed.

That Japanese Patent No. 6288066 For example, discloses a method that involves performing a pre-injection prior to a main injection. A post injection is carried out after the main injection. During a combustion process, the rate of heat generation due to the pre-combustion, which is the combustion of the pre-injection, reaches a peak position. The rate of heat generation due to the main combustion as the main injection combustion also reaches the apex position. A time lag may be created between the peak position of the rate of heat generation by the main combustion and the peak position of the rate of heat generation by the post-combustion, which serves as the post-injection combustion. An internal combustion engine is controlled in such a way that this time delay has a desired length, even if a load or speed of the internal combustion engine (operating states of the internal combustion engine or of the internal combustion engine) vary. A structural system of the engine generates noise. This noise includes a high frequency band with a peak near 3500 [Hz] which is the highest frequency among several resonance frequency bands. The structural system of the engine can generate knocking noises with a peak at 1300 [Hz], 1700 [Hz] and 2500 [Hz] on the low-frequency side of the resonance frequency band. With suitable control, the resonance in the high-frequency range can be suppressed and the knocking noise or knocking is also reduced.

A post-pilot injection and a pilot injection performed before the main injection have been described above. In the present invention, however, unless expressly described otherwise, these injections are not distinguished from one another and are referred to collectively as “preinjection (s)”. A first pressure wave can be generated by the pre-combustion due to the pre-injections. A second pressure wave can be generated by the main combustion due to the main injections. It is believed that the first pressure wave and the second pressure wave can be set to form an offset wave that cancels and reduces the combustion noise.

One aspect of the invention relates to a control unit for a compression ignition internal combustion engine. The control unit serves to inject a main injection, which is a main fuel injection, into a cylinder. The control unit also serves to inject a pilot injection (s), which is / are a single fuel injection or a plurality of fuel injections, into a cylinder, which are pilot injections of the main injection in a combustion process. A single or multiple pre-fuel injection (s) causes pre-combustion, which is a single combustion. The main injection causes a main combustion as a single combustion. Δt represents a time delay between the advance peak time position and the main peak time position within a combustion process. A peak height ratio is represented by Hp / Hm. The advance peak time position is the peak position corresponding to the pre-combustion among a plurality of peak positions represented by a derivative value of the pressure within the cylinder in the course of a combustion process. Instead, the advance peak time position is / may be a peak position corresponding to the pre-combustion among a plurality of peak positions represented by a derivative value of the heat within the cylinder over the course of a combustion process. The main vertex time position is the The peak position of the main combustion among a plurality of peak positions represented by a derivative of either the pressure or the heat within the cylinder over the course of a 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 pre-peak time position. Hm represents the dissipation value of the pressure inside the cylinder or the dissipation value of the heat inside the cylinder at the main peak time position. Alternatively, Δt may represent a time delay based on the crank angle difference and the speed of the crankshaft in a combustion process. The peak height ratio is also represented by Hp / Hm in this situation. The crank angle difference is a difference between the leading apex angular position and the major apex angular position. The advance apex angular position is the apex position corresponding to the pre-combustion among a plurality of apex positions represented by the derivative value of the pressure within the cylinder which changes in accordance with the crank angle. The crank angle is an angle of rotation of the crankshaft. Alternatively, the advance apex angular position is the apex position corresponding to the pre-combustion among a plurality of apex positions represented by the dissipation value of the heat within the cylinder which varies in accordance with the crank angle. The main apex angular position is the apex position corresponding to the main combustion among a plurality of apex positions represented by the dissipation of heat or pressure within the cylinder that varies in accordance with the crank angle. Hp represents the derivative value of the pressure inside the cylinder in the precompression angle position, or represents the derivative value of the heat inside the cylinder. Hm represents the derivative value of the pressure inside the cylinder in the main vertex angle position or represents the dissipation value of the heat inside the cylinder. In each of the above cases, an operating state detection unit of the control unit detects the operating states of the compression-ignition internal combustion engine. A fuel injection control unit of the control unit determines a target time lag or a target time lag allocation amount in accordance with the operating conditions of the compression ignition engine. The fuel injection control unit also determines a target peak height ratio. The operating state detection unit is configured to control at least one injection time and an injection volume of the pilot injection immediately before the main injection in the pre-stage injection and an injection time and an injection volume of the main injection in such a way that Δt approaches the target time delay. Alternatively, these can be controlled in such a way that the amount assigned to the time delay assignment amount or the amount assigned to the time delay based on Δt comes closer to the amount assigned to the target time delay. In both cases, these can be controlled in such a way that Hp / Hm approaches the target peak height ratio.

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 so that the time delay Δt approaches the target time delay (or the target time delay amount) in accordance with the operating conditions of the compression ignition engine. As a result, a frequency of an offset sound wave can approach the optimum frequency in accordance with 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 so that the peak height ratio Hp / Hm approaches the target peak height ratio in accordance with the specific operating condition of the compression ignition engine. This allows the amplitude of the displaced sound wave to approach the optimum amplitude in accordance with the specific operating condition. Therefore, it is possible to reduce the overall combustion noise. This reduction is not limited to knocking noises at a specific resonance frequency of the self-igniting internal combustion engine, but instead covers a wide range of different operating states.

According to another aspect of the invention, the fuel injection control unit of the control unit may change the target time lag or the target time lag allocation amount so that Δt increases. The fuel injection control unit of the control unit may also change the target peak height ratio so that Hp / Hm decreases when the speed of the compression ignition engine is substantially constant while the compression ignition engine load is increased from a low load to a high load. As a result, the overall combustion noise can be reduced appropriately.

In accordance with another aspect of the invention, the desired time / desired peak height ratio corresponding to each of various preset speeds is stored in the control unit. 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 of (1) or (2). (1) is a target offset center frequency that is a frequency substantially in the middle of an offset frequency band that serves to cancel and reduce the combustion noise due to the pre-burns and the main combustion, the target offset center frequency representing the target time delay allocation amount based on the target time delay or the target time delay is determined. (2) is the target vertex height ratio. For the target time / target peak height ratio, positions are defined as a function of the loads on the compression-ignition internal combustion engine in relation to the preset speed. The fuel injection control unit of the control unit selects the target time / target peak height ratio in accordance with the rotational speed of the compression ignition engine. The fuel injection control unit determines the target time delay allocation amount or the target time delay and determines the target peak height ratio depending on the selected target time / target peak height ratio and the load of the compression ignition engine. The fuel injection control unit determines the target time lag amount or the target time lag depending on the rotational speed and the load of the compression ignition engine, and determines the target peak height ratio based on these operating conditions. The fuel injection control unit controls at least the injection timing and the injection amount of the pilot injection immediately before the main injection and controls the injection timing and the injection amount of the main injection so that the offset center frequency, which is the time delay allocation amount based on Δt, the target center frequency, which is the target time delay allocation amount , is approaching or that Δt is approaching the target time delay. The fuel injection control unit controls them so that Hp / Hm approaches the target peak height ratio. The control unit for the fuel injection controls at least the injection time and the injection amount of the pilot injection immediately before the main injection of the preliminary stage and the injection time and the injection amount of the main injection such that the offset center frequency approaches the target offset center frequency and that Δt approaches the target time delay and that Hp / Hm approximates the nominal apex height ratio. The offset center frequency is the amount associated with the time delay based on Δt. The target offset center frequency is the amount assigned to the target time delay.

With this configuration, the optimal target offset center frequency (related amount of target time lag) or target time / target peak height ratio can be easily determined in accordance with the operating conditions on the basis of the target time / target peak height ratio and the operating conditions (speed and load (injection amount)) of the self-igniting internal combustion engine become.

According to a further aspect of the invention, the fuel injection control unit controls the control unit Hp / Hm such that the amount of deviation from the target peak height ratio falls within a tolerance height ratio if at least the injection timing and the injection volume of the pilot injection immediately before the main injection of the pilot injection and the injection timing and the injection volume of the main injection can be controlled so that Hp / Hm approaches the target peak height ratio. The tolerance height ratio is set to a tolerance height ratio target value when the load of the compression ignition engine is in the vicinity of the predetermined load. The tolerance height ratio is set larger than the tolerance height ratio target value when the load of the compression ignition engine becomes smaller than the predetermined load. The tolerance height ratio is set to be smaller than the tolerance height ratio target value when the load of the compression ignition engine becomes larger than the predetermined load.

The accuracy with which the actual peak height ratio Hp / Hm must be brought closer to the target peak height ratio in order to achieve a reduction effect of the combustion noise can be clarified by clarifying the tolerable range of deviation of the actual peak height ratio Hp / Hm relative to the target peak height ratio. This is therefore useful when the actual peak height ratio Hp / Hm cannot be easily adapted to the desired peak height ratio due to various factors.

According to a further aspect of the invention, the fuel injection control unit controls the control unit in such a way that the amount of deviation of the offset center frequency from the target offset center frequency lies within the tolerance frequency if at least the injection timing and the injection volume of the pilot injection are immediately prior to the main injection of the pre-stage injection and the injection timing and the injection volume of the main injection are of this type can be controlled so that the offset center frequency approaches the target offset center frequency. If the load of the compression ignition internal combustion engine is in the vicinity of the predetermined load, the tolerance frequency is set to the tolerance frequency setpoint. The tolerance frequency is set to be larger than the tolerance frequency reference value when the load of the compression ignition engine becomes smaller than the predetermined load. The tolerance frequency becomes is set to be smaller than the tolerance frequency target value when the load of the compression ignition engine is increased to become larger than the predetermined load.

The proximity of the target offset center frequency to which the actual offset center frequency must be brought in order to achieve a reduction effect in the combustion noise can be made clear by illustrating the tolerable range of deviation of the actual offset center frequency relative to the target offset center frequency. This is therefore useful when the actual offset center frequency cannot be easily adapted to the target offset center frequency due to various factors.

• 1 eine schematische Ansicht eines Systems einer selbstzündenden Brennkraftmaschine.
• 2 ein Diagramm, das ein Beispiel für eine Beziehung zwischen einer Voreinspritzung und einer Haupteinspritzung, einem Vorverbrennungsdruck, einem Hauptverbrennungsdruck, einer Druckerzeugungsrate aufgrund der Vorverbrennung, einer Druckerzeugungsrate aufgrund der Hauptverbrennung und einem Kurbelwinkel während eines Verbrennungsprozesses veranschaulicht.
• 3 ein Diagramm, das eine Wärmeerzeugungsrate aufgrund der Vorverbrennung und eine Wärmeerzeugungsrate aufgrund der Hauptverbrennung für das Beispiel von 2 veranschaulicht.
• 4 ein Diagramm, das ein Beispiel von Simulationsergebnissen bei einer Drehzahl der selbstzündenden Brennkraftmaschine von Ne=1600 [1/min] und einem Einspritzvolumen von Qv=30 [mm³/st] zeigt.
• 5 ein Diagramm, das ein Beispiel von Simulationsergebnissen bei einer Drehzahl der selbstzündenden Brennkraftmaschine von Ne=1600 [1/min] und einem Einspritzvolumen von Qv=55 [mm³/st] zeigt.
• 6 ein Diagramm, das ein Beispiel von Simulationsergebnissen bei einer Drehzahl der selbstzündenden Brennkraftmaschine von Ne=2400 [1/min] und einem Einspritzvolumen von Qv=30 [mm³/st] zeigt.
• 7 ein Diagramm, das veranschaulicht, wie die Ergebnisse von 4 bis 6 auf die Positionen der selbstzündenden Brennkraftmaschine während des Betriebs angewendet werden, gezeigt in Bezug auf Drehzahl und Einspritzvolumen (Last).
• 8 ein Diagramm, das die Druckerzeugungsrate an jedem von Datenpunkten S1 und S2 von 4 veranschaulicht.
• 9 ein Diagramm, das das Verbrennungsgeräusch an jedem von Datenpunkten S1 und S2 von 4 veranschaulicht.
• 10 ein Diagramm, das die Druckerzeugungsrate an jedem von Datenpunkten S3 und S4 von 5 veranschaulicht.
• 11 ein Diagramm, das das Verbrennungsgeräusch an jedem von Datenpunkten S3 und S4 von 5 veranschaulicht.
• 12 ein Diagramm, das ein Beispiel von Sollzeit/SollscheitelhöhenVerhältnis-Kennlinien veranschaulicht.
• 13 ein Diagramm, das den tolerierbaren Abweichungsbereich der Sollzeit/Sollscheitelhöhen-Verhältnis-Kennlinien veranschaulicht.
• 14 ein Ablaufdiagramm, das ein Beispiel einer Verarbeitungsprozedur einer Steuereinheit veranschaulicht.

Other objects, features and advantages of the invention will become readily understood after reading the following detailed description, along with the claims and the accompanying drawings.

• 1 a schematic view of a system of a compression ignition internal combustion engine.
• 2 Fig. 13 is a diagram illustrating an example of a relationship between a pilot injection and a main injection, a pre-combustion pressure, a main combustion pressure, a pressure generation rate due to the pre-combustion, a pressure generation rate due to the main combustion, and a crank angle during a combustion process.
• 3 FIG. 13 is a graph showing a rate of heat generation due to the pre-combustion and a rate of heat generation due to the main combustion for the example of FIG 2 illustrated.
• 4th a diagram showing an example of simulation results at a rotational speed of the compression ignition engine of Ne = 1600 [1 / min] and an injection volume of Qv = 30 [mm ³ / st].
• 5 a diagram showing an example of simulation results at a rotational speed of the compression ignition engine of Ne = 1600 [1 / min] and an injection volume of Qv = 55 [mm ³ / st].
• 6th a diagram showing an example of simulation results at a rotational speed of the compression ignition engine of Ne = 2400 [1 / min] and an injection volume of Qv = 30 [mm ³ / st].
• 7th a diagram that illustrates how the results of 4th until 6th applied to the positions of the compression ignition engine during operation, shown in terms of speed and injection volume (load).
• 8th a graph showing the rate of pressure generation at each of data points S1 and S2 from 4th illustrated.
• 9 a graph showing the combustion noise at each of data points S1 and S2 from 4th illustrated.
• 10 a graph showing the rate of pressure generation at each of data points S3 and S4 from 5 illustrated.
• 11 a graph showing the combustion noise at each of data points S3 and S4 from 5 illustrated.
• 12th Fig. 3 is a diagram illustrating an example of desired time / desired peak height ratio characteristics.
• 13th a diagram which illustrates the tolerable deviation range of the desired time / desired peak height ratio characteristic curves.
• 14th Fig. 13 is a flowchart illustrating an example of a processing procedure of a control unit.

The inventors found the following features through various experiments and simulations: There is an offset wave or offset wave for reducing the combustion noise of a compression-ignition internal combustion engine. The self-igniting internal combustion engine has a specific resonance frequency in certain operating states. The offset wave must not only be limited to a specific resonance frequency, but can also contain an optimal offset frequency depending on these operating states. At the optimal offset frequency, there is an optimal offset amplitude. In other words, there can also be properties other than the specific resonance frequency that have a major influence on the combustion noise of the compression-ignition internal combustion engine. Instead of forming an offset wave focused only on the resonance frequency, the offset wave can be formed in operating ranges with a frequency and amplitude which are adapted as a function of the operating ranges. This enables a general reduction in combustion noise. This was not previously known.

It was previously known that a frequency of an offset wave or offset wave cancels knocking noises with resonance frequencies of 1300 [Hz], 1700 [Hz] and 2500 [Hz]. These frequencies are specific to engine knocking noises. An internal combustion engine or an internal combustion engine is controlled in such a way that the time interval or the time delay between the peak or The peak position of the heat generation rate by the pre-combustion (pilot combustion) and the peak position of the heat generation rate by the main combustion become a target interval. The internal combustion engine is also controlled such that the time interval or 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 post-combustion becomes a target interval. This means that up to now only the knocking noise-specific resonance frequency of the self-igniting internal combustion engine has been taken into focus. There was no focus on an optimal offset shaft based on specific operating conditions. The injection volume during pre-injection (pilot injection) can be increased in accordance with the operating conditions of the compression ignition engine, but this increase served to enable pre-burns (pilot burns) in the operating range in which combustion is difficult. Achieving an optimal offset amplitude has not yet been taken into account.

In view of the foregoing, it has been desired to provide a control unit configured to adequately reduce the overall combustion noise generated for a wide range of operating conditions of a compressing compression ignition engine.

[Schematic structure of the internal combustion engine system 1 (FIG. 1)]

An exemplary embodiment of the invention will now be described with reference to the drawings. First, a schematic structural example of the internal combustion engine system will be described with reference to FIG 1 described. In the present embodiment, an internal combustion engine is used 10 (eg, diesel engine) installed in a vehicle is described as an example of a compression auto-ignition internal combustion engine.

An entire system will be described in the order from a suction side to a discharge side. An air filter (not shown), an intake air flow detection device 21 (e.g., an intake flow sensor) can be attached to an intake side of an intake manifold 11A be provided. The intake air flow detection device 21 gives a detected signal that corresponds to that of the internal combustion engine 10 sucked air flow corresponds to a control unit 50 the end. An intake air temperature detecting device 28A (for example, an intake air temperature sensor) and an atmospheric pressure detection device 23 (e.g., an atmospheric pressure sensor) can be attached to the intake air flow sensing device 21 be provided. The intake air temperature detecting device 28A is configured to output a detected signal corresponding to a temperature of the intake air captured by the intake air flow detection device 21 flows. The detection device 23 for atmospheric air is configured to send a detected signal, which corresponds to the ambient atmospheric pressure, to the control unit 50 to spend.

As in 1 shown is an outlet side of the exhaust pipe 11A with an inlet side of a compressor 35 connected. The discharge side of the compressor 35 is to the inlet side of the intake pipe 11 B connected. The compressor 35 can be part of a turbocharger 30th being. The compressor 35 a turbocharger 30th is operated by a turbine 36 set in rotation. The turbine 36 is driven to rotate by the exhaust gas. The compressor 35 leads through the suction pipe 11A sucked intake air under pressure from the intake pipe 11 B closed to charge the intake air.

As in 1 shown is the intake manifold 11A upstream of the compressor 35 with a device 24A for detecting the pressure upstream of the compressor (e.g. a pressure sensor). The pressure detection device located upstream of the compressor 24A is configured to receive a sensed signal indicative of a pressure within the intake manifold 11A corresponds to the control unit 50 to spend. The intake pipe 11 B downstream of the compressor 35 is with a detection device 24B for the pressure downstream of the compressor (e.g. a pressure sensor). In particular, there is the pressure detection device 24B between the compressor 35 and an intercooler 16 that is in the suction pipe 11B is located. The detection device 24B for the pressure downstream of the compressor or compressor downstream pressure sensing device 24B gives the detected signal that corresponds to the pressure in the suction pipe 11B corresponds to the control unit 50 the end.

As in 1 shown is the intercooler 16 upstream of the suction pipe 11B arranged. A throttle device 47 is downstream of the intercooler 16 arranged. The intercooler 16 is downstream of the sensing device 24B for the pressure downstream of the compressor. Between the intercooler 16 and the throttle device 47 is an intake air temperature detecting device 28B (e.g. an intake air temperature sensor) is provided. The intake air temperature detecting device 28B outputs the detected signal that indicates the temperature of the intake air at a through the intercooler 16 corresponds to the cooled temperature.

As in 1 shown drives the throttle device 47 a throttle valve 47V for adjusting an opening of the suction pipe 11B based on a control signal from the control unit 50 on. The throttle device 47 is also able to adjust the intake air flow rate. The control unit 50 gives a control signal to the throttle device 47 from that on that from the throttle opening detection device 47S (e.g. a throttle opening sensor) detected signal and based on a target throttle opening. The throttle device 47 is able to open the throttle 47V to adjust. The control unit 50 is to determine a target throttle opening based on an accelerator operation amount obtained based on a detected signal from an accelerator operation amount detection device 25th is detected, and based on an operating state of the internal combustion engine 10 etc. to be determined.

As in 1 is shown, the accelerator operation amount detection device 25th for example, an accelerator pedal actuation angle sensor and can be provided on an accelerator pedal. The control unit 50 may determine the accelerator operation amount by a driver based on a detected signal from the accelerator operation amount detection device 25th to capture.

As in 1 As shown, an intake manifold pressure sensing device 24C (e.g. a pressure sensor) on the intake pipe 11B downstream of the throttle device 47 be provided. An outlet side of an exhaust gas recirculation (EGR) line 13th is with the suction pipe 11B connected. An outlet side of the suction pipe 11 B is to an inlet side of the intake manifold 11C connected. An exhaust side of the intake manifold 11C is with an inlet side of the internal combustion engine 10 connected. The intake manifold pressure sensing device 24C gives a detection signal to the control unit 50 that is the pressure of the intake air just before it enters the intake manifold 11C is equivalent to. The EGR line 13th serves to the exhaust pipe 12B with the suction pipe 11 B to connect. The exhaust gas within the EGR line 13th is via a connection between the exhaust sides of the EGR line 13th and the suction pipe 11 B into the suction pipe 11B derived.

As in 1 shown includes the internal combustion engine 10 a variety of cylinders 45A until 45D . There are injectors on the respective cylinders 43A until 43D provided. The injectors 43A until 43D are via a common rail 41 and fuel lines 42A until 42D supplied with fuel. The injectors 43A until 43D are controlled by control signals from the control unit 50 controlled and inject the fuel into the respective cylinder 45A until 45D on.

As in 1 shown is the internal combustion engine 10 with a rotation detection device 22nd , a coolant temperature detecting device 28C etc. provided. The rotation detection device 22nd can be, for example, a rotation sensor and is configured to output detected signals that indicate the rotational speed of the crankshaft of the internal combustion engine 10 (ie the speed of a motor). The coolant temperature sensing device 28C can be, for example, a temperature sensor and is configured to output detected signals that indicate a temperature in the internal combustion engine 10 circulating coolant.

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

As in 1 shown is the inlet side of the EGR line 13th with the exhaust pipe 12B connected. The EGR line 13th connects the exhaust pipe 12B with the inlet pipe 11 B. This allows the EGR line 13th part of the exhaust gas of the exhaust pipe 12B (corresponding to an exhaust path) into the intake pipe 11B Let it recirculate (according to a suction path). The EGR line 13th is with an EGR cooler 15th and an EGR valve 14th Mistake. The EGR valve 14th represents a flow rate of the through the EGR line 13th flowing EGR gas by opening the EGR line 13th based on the control signal from the control unit 50 adjusts.

As in 1 shown is the exhaust pipe 12B with an exhaust gas temperature detection device 29 Mistake. The exhaust temperature sensing device 29 can for example be an exhaust gas temperature sensor and is configured to send a detected signal, which corresponds to an exhaust gas temperature, to the control unit 50 to spend.

As in 1 shown is the outlet side of the exhaust pipe 12B with the inlet side of the turbine 36 connected. The outlet side of the turbine 36 is to the inlet side of the exhaust pipe 12C connected. The turbine 36 is with a variable nozzle 33 which is able to control the flow rate of the to the turbine 36 to control exhaust gas conducted. The variable nozzle 33 can be the opening of the flow path that the exhaust gas to the turbine 36 leads, adjust. The opening of the variable nozzle 33 is by a nozzle control device 31 set. The control unit 50 outputs a control signal to the nozzle control device 31 off that on one of the nozzle opening detecting device 32 (eg a nozzle opening sensor) is based on the detected signal and a target nozzle opening, so that the opening of the variable nozzle 33 can be adjusted.

As in 1 shown is the exhaust pipe 12B upstream of the turbine 36 . The exhaust pipe 12B is provided with a turbine upstream pressure detecting device 26A (eg, a pressure sensor). The turbine upstream pressure sensing device 26A gives a detected signal that corresponds to the pressure in the exhaust pipe 12B corresponds to the control unit 50 the end. The exhaust pipe 12C is located downstream of the turbine 36 . The exhaust pipe 12C is with a turbine downstream pressure sensing device 26B (e.g. a pressure sensor). The turbine downstream pressure sensing device 26B gives a detected signal that corresponds to the pressure in the exhaust pipe 12C corresponds to the control unit 50 the end.

As in 1 shown is an exhaust gas purifier 61 with the outlet side of the exhaust pipe 12C connected. When the internal combustion engine 10 for example a diesel engine, the exhaust gas cleaner can 62 an oxidation catalyst, a fine particulate collecting filter, a selective reduction catalyst, and so on.

A vehicle speed detecting device 27 may be, for example, a vehicle speed detection sensor, and may be provided on one or more wheels of a vehicle, and so on. The vehicle speed detecting device 27 outputs detected signals corresponding to a speed of the wheel (s) of the vehicle to the control unit 50 the end.

As in 1 shown includes the control unit 50 a CPU 51 , a RAM 52 , a storage device 53 , a timer 54 etc. The detected signals from the various detection devices described above are fed into the control unit 50 (e.g. the CPU 51 ) and the control unit 50 (e.g. the CPU 51 ) outputs control signals to the various actuators, etc. described above. The input / output of the control unit 50 is not limited to the detection devices and / or the actuator or the actuator described above. Temperatures and pressures on each part can be calculated through estimated calculation without the need for mounted sensors. The control unit 50 is configured to operate states of the internal combustion engine 10 based on the detected signals from the various sensing devices (e.g., the sensors) including the sensing devices described above to control various actuators, etc. including the actuator (s) described above. The storage device 53 For example, it can be 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 stored. The control unit 50 (e.g. the CPU 51 ) contains an operating status acquisition unit 51A , a fuel injection control unit 51B and the like, some details of which will be described later.

The control unit 50 injects a main injection and one or more pilot injections into the cylinder, in which the air has been compressed and heated, to achieve a combustion process in accordance with the operating state of the internal combustion engine 10 perform. The main injection is a main fuel injection. The pilot injection (s) is / are one or more fuel injections that are pilot injections of the main injection. In the description according to the present embodiment, all injections which precede the main injection of an internal combustion engine's combustion process are referred to as a “pilot injection” or “pilot injection”. The number and the injection volume of pilot injections, the injection volume of the main injection, etc. can be appropriately calculated based on the total fuel injection volume, the operating state of the internal combustion engine, etc. in a combustion process.

2 illustrates the rate of pressure generation within a cylinder due to the pilot injections and the main injection. 3 illustrates the rate of heat generation due to the pilot injections and the main injection. A cylinder is a cylinder of the internal combustion engine, for example a first cylinder. In 2 and 3 shows the pressure generation rate and the heat generation rate in a combustion process. In the examples of 2 and 3 leads the control unit 50 three pilot injections just before the piston is in the top dead center of compression of the target cylinder. A main injection is performed in a position shortly after the piston has reached compression top dead center. The top compression dead center corresponds to a position at which the crank angle = 0 [deg].

2 Fig. 13 shows the results of experiments or simulations in which the horizontal axis represents the crank angle which is the rotation angle of the crankshaft and the vertical axis represents the rate of pressure generation in the cylinder. In the example of 2 the intake air (air) is compressed and heated by pistons in a combustion chamber. The fuel is off during the three Pre-injections injected into the combustion chamber. During these pre-injections, the fuel is self-ignited. With the main injection, too, the fuel is injected and self-ignited. It is assumed that the three pilot injections together bring about a single pilot or preliminary combustion, which essentially brings about a single combustion. The pressure within the cylinder due to the pre-combustion varies as shown by the pre-combustion pressure Pp shown in FIG 2 indicated by a dashed line. A single main combustion is generated by a main injection. The pressure inside the cylinder due to the main combustion overlaps with the pressure generated by the pre-combustion pressure Pp. Therefore, the pressure within the cylinder varies as represented by the main combustion pressure Pm shown in FIG 2 is indicated by a dotted and dashed line.

The pressure generation rate f (θ) is in 2 indicated by a solid line. The pressure generation rate f (θ) 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 depending on 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 pre-combustion pressure Pp and the main combustion pressure Pm. As in 2 As shown, the pressure generation rate f (θ) in a combustion process has a plurality of peak positions. For example, the peaks of the pressure generation rate f (θ) may be at positions where the derivative of the pressure generation rate f (θ), or the second derivative of the pressure, is zero. One apex position is the apex position corresponding to a pre-combustion and another apex position is an apex angular position Pap. One of the other apex positions is a main apex angular position Pam corresponding to the main combustion. As in 2 As shown in FIG. 1, the crank angle of the prelude angular position Pap is represented by θp, and the derivative value of the pressure within the cylinder at the prelude angular position Pap is represented by Hp. Similarly, the crank angle of the main apex angular position Pam is represented by θm, and the derivative value of the pressure inside the cylinder at the main apex angular position Pam is represented by Hm. A crank angle difference Δθ (Δθ = θm-θp) exists between the main vertex angle position Pam and the leading vertex angle position Pap. A delay (a delay corresponding to Δθ) converted into time based on the crank angle difference and the rotational speed of the crankshaft is represented by Δt. The derivative value of the pressure within the cylinder at the control apex angular position Pap (ie, the value of the pressure generation rate) is represented by Hp. The derivative value of the pressure inside the cylinder at the main vertex angular position Pam (ie, the value of the pressure generation rate) is represented by Hm. The peak height ratio is represented by Hp / Hm.

Although not shown in the drawings, the 2 shown horizontal axis can be changed from crank angle [deg] to a time [s]. The vertical axis can be changed from the pressure generation rate based on the crank angle [Mpa / deg] to a pressure generation rate based on the time [Mpa / s]. In this case, the pressure generation rate (particularly, the derivative value of the pressure inside the cylinder) is substantially the same as that in FIG 2 shown pressure generation rate f (θ). For example, the pressure generation rate has a plurality of vertex positions. The peak position due to the pre-burns represents the pre-peak time position Ptp. The peak position due to the main combustion represents the main peak time position Ptm. When the main apex time position represents Ptm (tm, Hm) and the apex time position represents Ptp (tp, Hp), the time lag can be represented by Δt = tm-tp and the apex height ratio can be represented by Hp / Hm.

2 focuses on the pressure inside the cylinder. 3 however, it focuses on the heat inside the cylinder. The horizontal axis in 3 represents crank angle, similar to the horizontal axis in 2 . The vertical axis in 3 represents the rate of heat generation, more precisely a dissipation of the heat within the cylinder based on the crank angle. In 3 results of experiments or simulations are shown.

The heat generation rate g (θ) is in 3 represented by a solid line. The heat generation rate g (θ) indicates the dissipation value of the heat inside the cylinder based on the crank angle. The dissipation value of the heat within the cylinder varies depending on the crank angle during a combustion process. The derivative value is a slope of changes in the total heat inside the cylinder due to the pre-combustion heat Ep and the main combustion heat Em. As in FIG 3 As shown, the rate of heat generation g (θ) in a combustion process has multiple peak positions. For example, the peaks of the rate of heat generation g (θ) may be at positions where the derivative of the rate of heat generation g (θ), or the second derivative of heat, is zero. the The apex position corresponding to the pre-combustion is represented by the pre-apex angular position Eap. Similarly, the apex position corresponding to the main combustion is represented by the main apex angular position Eam. As in 3 As shown in FIG. 1, the crank angle of the advance apex angle position Eap is represented by θp, and the dissipation value of the heat inside the cylinder at the advance apex angle position Eap is represented by Hp. Similarly, the crank angle of the main apex angular position Eam is represented by θm, and the dissipation value of the heat inside the cylinder at the main apex angular position Eam is represented by Hm. The difference between the main vertex angle position Eam and the advance vertex angle position Eap is represented by the crank angle difference Δθ (Δθ = θm-θp). The time delay (a delay corresponding to Δθ) converted into time based on the crank angle difference and the rotational speed of the crankshaft is represented by Δt. The dissipation value of the heat inside the cylinder at the advance apex angular position Eap, that is, the value of the rate of heat generation is represented by Hp. The dissipation value of the heat inside the cylinder at the main vertex angular position Eam, that is, the value of the rate of heat generation, is represented by Hm. The peak height ratio is represented by Hp / Hm.

Although not shown in the drawings, the 3 The horizontal axis shown can be changed from crank angle [deg] to time [s]. The vertical axis can be changed from the rate of heat generation based on the crank angle [J / deg] to the rate of heat generation based on time [J / s]. In this case, the heat generation rate (the dissipation value of the heat inside the cylinder) is substantially the same as the heat generation rate g (θ) in FIG 3 . For example, the peak positions among the plurality of peak positions of the heat generation rate corresponding to the pre-combustion and the main combustion are represented by an advanced 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 pre-peak time position is represented by Etp (tp, Hp), the time lag is represented by Δt = tm-tp and the peak height ratio is represented by Hp / Hm.

The inventors conducted various experiments and simulations. As a result, it has been found that there is an optimal time lag Δt and an optimal peak height ratio Hp / Hm that reduce the combustion noise of the internal combustion engine. In the 2 The crank angle / pressure generation rate shown can be used for both the time delay Δt and the peak height ratio Hp / Hm. Alternatively, the in 3 The crank angle / heat generation rate and time delay shown can be used for both the time delay Δt and the peak height ratio Hp / Hm. Alternatively, a time / pressure generation rate (not shown) or a time / heat generation rate (not shown) can also be used for the delay time Δt and the peak height ratio Hp / Hm. In the following description of the present embodiment, the time lag Δt and the peak height ratio Hp / Hm based on the crank angle / pressure generation rate will be described, an example of which in FIG 2 is shown.

[Results of simulations and / or experiments (FIG. 4 to FIG. 7)]

The results of simulations or experiments are shown when the time delay Δt and the peak height ratio Hp / Hm are changed to different values for different operating states of the internal combustion engine. Some of the results are referring to 4th until 7th discussed. In the 4th until 6th The offset center frequency shown represents an amount assigned to the time delay Δt or a time delay assignment amount. The offset center frequency can correspond, for example, to the offset (for example the phase difference) of the frequencies of the pressure waves that are generated by the pre-combustion and the main combustion. The offset center frequency is calculated based on the time delay Δt. The offset center frequency can, for example, be a frequency at which the time delay Δt [s] is a time which the frequency needs to complete half a cycle, feq = 1 / (2 * Δt). In other words, twice the time delay Δt [s] is the time it takes to complete an entire cycle of the offset center frequency. For example, if the time delay is represented by Δt = 0.26 [ms], the frequency is represented by 1 / (0.00026 [s] * 2) = 1.923 [KHz]. The offset center frequency is a frequency essentially in the middle of the offset frequency band (e.g. f = 0.3 / Δt to f = 0.7 / Δt), which is used to cancel or reduce the combustion noise due to the pre-combustion and the main combustion.

In some embodiments, the main combustion can generate a certain pressure wave, which can then generate noise. The frequency and amplitude of these pressure waves can vary based on the engine speed and the amount of fuel injected corresponding to the main combustion. Pre-combustion can be used to reduce the noise generated by the main combustion. The pre-combustion can, for example, be configured to have a different one Generate pressure wave, which can also generate a noise. The pre-pressure wave can also have a frequency and an amplitude that is based on the speed of the internal combustion engine and the fuel injection quantity that corresponds to the pre-combustion. In order to reduce the noise, it can be advantageous to set the time between the pre-combustion and the main combustion in such a way that the frequencies are out of phase with one another due to the corresponding pressure waves. That is, it may be beneficial to set the frequencies so that they interfere with each other to cause destructive interference.

4th shows results when the engine speed is represented by Ne = 1600 [rpm] and the injection volume (load) injected in a combustion process is represented by Qv = 30 [mm ³ / st]. 4th shows the results of simulations or experiments when the time lag Δt and the peak height ratio Hp / Hm are set to different values. The results of the simulations and experiments are in 4th marked by solid circles. The offset center frequency is a frequency converted from the time delay Δt, as described above. That is, one cycle of the offset center frequency is completed in twice the time of the time delay Δt. When this internal combustion engine is idling, the number of revolutions Ne is about 700 [rpm] and the injection volume (load) Qv is about 5 [mm ³ / st].

In 4th are the curves of combustion noise levels D1 until D5 resulting from the simulations or experiments are represented by chain-dotted lines. D1 to D5 indicate the total combustion noise levels (such as measured in decibels) integrated in the audio frequency range 0.9 to 5.6 [KHz] of the observed combustion noise. There is a relationship between the combustion noise levels that is D5>D4>D3>D2> D1. This means, D5 has a louder sound than D4 , D4 is louder than D3 , etc. A range in which the peak height ratio Hp / Hm exceeds 1.0 is unrealistic because it is a range in which the peak position of the pre-combustion Pp is higher than the peak position of the main combustion Pm. The peak height ratio Hp / Hm of less than 0.2 is not taken into account in these experiments or simulations because it would result in the pre-combustion being too small to be realistic. Therefore, the peak height ratio Hp / Hm is considered to be less than or equal to 1.0 and greater than or equal to 0.2. A range in which the offset center frequency exceeds 2.2 [KHz] is unrealistic because it is an area near the injection frequency limit of the injector and requires control in which the time delay Δt is less than about 0.227 [ms]. A range in which the offset center frequency is less than 0.6 [KHz] is the range in which the time delay Δt is longer than about 0.833 [m]. Therefore, 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 less than or equal to 2.2 [KHz] and more than or equal to 0.6 [KHz] is contemplated (and similarly in FIG 5 and 6th ).

4th shows an operating state at a speed of 1600 [1 / min] and a fuel injection quantity (load) of 30 [mm ³ / st]. The horizontal axis in 7th represents the speed while the vertical axis represents the fuel injection amount (load). The operating status in 4th is in 7th indicated by U1. In the operating state U1 For example, the offset center frequency can be set between about 1.9 [KHz] and about 2.2 [KHz] in order to keep the combustion noise level below D1, as in FIG 4th is shown. In other words, the time delay Δt for these operating states can be set between approximately 0.227 [ms] and approximately 0.263 [ms]. At the combustion noise level D1 the peak height ratio Hp / Hm is between about 0.85 and about 1.0.

For the operating status of 5 is the speed of the internal combustion engine Ne 1600 [1 / min] and the injection quantity (load) injected in a combustion process is Qv 55 [mm ³ / st]. 5 shows the results of the simulations (or experiments) of the time lag Δt and the peak height ratio Hp / Hm at various values (positions indicated by filled circles in 5 are shown), based on this operating state. The offset center frequency is a frequency converted from the time delay Δt, as described above.

In 5 are curves of the combustion noise level D1 until D5 represented by dotted chain lines and represent the observed total combustion noise levels, similar to FIG 4th . The combustion noise levels are arranged in the order D5>D4>D3>D2> D1. This means, D5 has a louder sound than D4 , D4 is louder than D3 , etc. For these experiments or simulations, only the realistic operating conditions have to be taken into account. This means that only a peak height ratio Hp / Hm of less than or equal to 1.0 and greater than or equal to 0.2 is taken into account. An offset center frequency of less than or equal to 2.2 [KHz] and greater than or equal to 0.6 [KHz] is also taken into account. The fuel injection volume Qv is compared with that of the operating states of 4th elevated. An offset frequency less than or equal to approximately 0.9 [KHz] is also taken into account.

Among the in 5 the operating states shown is the speed 1600 [1 / min] and is the fuel injection amount (load) 55 [mm ³ / st]. The horizontal axis in 7th represents the rotational speed and the vertical axis represents the fuel injection amount (load). The operating status of 5 is in 7th indicated by U2. To keep the combustion noise level below D2 when below the operating condition U2 is operated, the offset center frequency can be set to about equal to or more than 0.9 [KHz], that is, the time delay Δt can be set to less than or equal to about 0.556 [ms], while the peak height ratio Hp / Hm between about 0.2 can be set to about 0.5. The conditions under the combustion noise level of D2 are the conditions of 5 where the realistic offset frequency is less than or equal to 0.9 [KHz].

Under the operating condition of 6th is the speed of the internal combustion engine Ne 2400 [1 / min] and the injection quantity (load) Qv injected in a combustion process is 30 [mm ³ / st]. 6th shows the results of the simulations (or experiments) of the time lag Δt and the peak height ratio Hp / Hm at various values (positions, indicated by solid circles in 6th specified) under this condition. The offset center frequency is a frequency converted from the time delay Δt, as described above.

In 6th are curves of the combustion noise level D2 until D5 represented by dot-chain lines. Similar to in 4th indicates 6th 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 greater than or equal to 0.2 are taken into account. Offset center frequencies of less than or equal to 2.2 [KHz] and greater than or equal to 0.6 [KHz] are taken into account. The rotational speed Ne is in comparison with the operating conditions of 4th elevated. Under the operating states of 6th it was not possible to reduce the combustion noise level to D1.

Among the in 6th operating states shown, the speed is 2400 [1 / min] and the fuel injection quantity (load) is 30 [mm ³ / st]. The horizontal axis of 7th represents the rotational speed and the vertical axis represents the fuel injection amount (load). The operating states of 6th are in 7th represented by U3. To keep the combustion noise level below the in 6th operating condition shown U3 below D2, the offset center frequency can be set in the range from about 1.22 [KHz] to about 2.2 [KHz], ie the time delay Δt can be set between about 0.227 [ms] and about 0.410 [ms] while the peak height ratio Hp / Hm can be set between about 0.75 and about 1.0.

As described above, when the rotational speed is substantially constant and the load (fuel injection amount) is increased from a low load to a high load, the favorable time delay range Δt is lengthened and set later while maintaining the entire preferred peak height ratio Hp / Hm range is reduced. This effectively reduces the combustion noise. When the load (fuel injection amount) is substantially constant and the speed is increased from low speed to high speed, both an advantageous range of the time lag Δt and an advantageous range of the peak height ratio Hp / Hm are expanded low.

As described above, the time delay Δt (or the offset center frequency converted from the time delay Δt (time delay-related amount)) and the peak height ratio Hp / Hm significantly influence a reduction in the combustion noise. An optimal time delay Δt and an optimal peak height ratio Hp / Hm are also present.

[Optimal time delay Δt and optimal peak height ratio Hp / Hm under each operating condition (FIG. 8 to FIG. 11)]

8th Fig. 13 shows a crank angle / pressure generation rate fs1 (θ) for the data S1 in 4th . In the data S1 the offset center frequency is 1.9 [KHz] and the peak height ratio Hp (H) / Hm (H) is 0.88. 8th also shows a crank angle / pressure generation rate fs2 (θ) for the data S2 in 4th . 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 that are converted from the time delay Δt are both 1.9 [KHz], the crank angle differences Δθ are identical. The peak height ratio of fs1 (θ) is Hp (H) / Hm (H) = 0.88, while the peak height ratio of fs2 (θ) 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 shown.

9 shows the results of the combustion sound frequency and the combustion noise level of fs1 (θ) and fs2 (θ). The time delays Δt of fs1 (θ) and fs2 (θ) are identical (converted frequency is 1.9 [KHz]). The peak height ratio Hp / Hm of fs1 (Θ) is 0.88. The combustion noise at fs1 (Θ) is indicated by a solid line in 9 shown. The peak height ratio Hp / Hm of fs2 (θ) is 0.58. The combustion noise at fs2 (θ) is in 9 by a shown dotted line. The combustion noise of fs1 (Θ) is significantly reduced than the combustion noise of fs2 (θ). This is particularly prevalent in the sound frequency bands between approx. 1.2 [KHz] to approx. 2.5 [KHz].

10 shows the crank angle / pressure generation rate fs3 (θ) for the data S3 in 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. 10 also shows the crank angle / pressure generation rate fs4 (θ) for the data S4 in 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 (θ) and fs4 (θ), which are converted from the time offset Δt, are both 0.83 [KHz], the crank angle differences Δθ are identical. The apex height ratio of fs3 (θ) is Hp (H) / Hm (H) = 0.75, while the apex height ratio of fs4 (θ) is Hp (L) / Hm (L) = 0.26. Under the operating states of 10 the main injection volume is greater than under the operating conditions of FIG. 8. Therefore, the time interval from the start of the main injection to the peak of the main injection becomes longer. Because of the restrictions on the interval between the pilot injections and the main injection, it will be difficult to set the pilot injections so that the time lag Δt (crank angle differences Δθ) from the peak of the pilot injection is shortened. The observation results of the combustion sound frequency / combustion noise level spectrum of this example are shown in FIG 11 shown.

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

[Adjustment of the characteristic curves for the ratio of target time and target peak height (FIG. 12, FIG. 13)]

The characteristic curves for the target time / target peak height ratio (see 12th ) are prepared and in the storage device 53 the control unit 50 saved. For the characteristics of the target time / target peak height ratio, the optimal target time lag and the optimal target peak height ratio can be set in accordance with the above-described results based on the operating conditions of the internal combustion engine. The operating states of the internal combustion engine are in particular the speed and the load (injection volume). Instead of the optimal target time delay, the optimal target time delay allocation amount (target offset center frequency) can be set. The vertical axis in 12th represents either the desired offset center frequency (or desired time delay) or the desired peak height ratio. The horizontal axis represents the other. The target offset center frequency is the target time delay allocation amount which is determined based on the target time delay. The desired time / desired peak height ratio, such as a look-up table or formula, corresponding to each of a plurality of preset speeds and / or fuel injection volume (load) are in the storage device 53 saved.

An example of the characteristics of the desired time / desired peak altitude ratio based on speed and fuel injection volume (load) is shown in FIG 12th graphically represented. In 12th If the speed Ne is 1600 [1 / min], the characteristic is represented by h (1600). The characteristic curve at a speed Ne of 2000 [1 / min] is represented by h (2000). The characteristic curve at a speed Ne of 2400 [1 / min] is represented by h (2400).

For example, for the characteristic of h (1600) (Ne = 1600 [1 / min]) in 12th the position of the injection volume (load) of Qv = 30 [mm ³ / st] represented by the position at M11 (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 [1 / min]) in 12th the position of the injection volume (load) at Qv = 40 [mm ³ / st] represented by the position at M22 (Ne2000, Qv40). The position of the injection amount (load) at Qv = 55 [mm ³ / st] is represented by the position at M23 (Ne2000, Qv55). Similarly, in the characteristic of h (2400) (Ne = 2400 [1 / min]) in 12th the position of the injection volume (load) at Qv = 30 [mm ³ / st] 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, Qv40). In 12th The dotted chain lines shown show uniform load lines that run through the identical load positions. That is, the dotted chain lines run through the same loads at different speeds. As in 12th is shown, when the engine speed is substantially constant and the engine load increases from a low load to a high load, the target time delay allocation amount is changed so that the time delay Δt is longer, that is, the target offset frequency becomes lower. In addition, the target peak height ratio is changed so that the peak height ratio (Hp / Hm) is reduced.

For example, the control unit 50 the recorded operating states of the internal combustion engine (e.g. speed and load) and the target time / target peak height ratio characteristics (e.g. the in 12th shown) that are in the storage device 53 based on the determined optimal target time delay allocation amount (in this case the target offset center frequency) and the target peak height ratio based on the operating states (eg speed and load) of the internal combustion engine.

13th illustrates an example of the maximum tolerance limit (Max) h (1600) and an example of the minimum tolerance limit (Min) h (1600). In 13th the example for M11 is based on the data S1 the end 4th . If the peak height ratio reaches 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 reaches ± 0.20 [KHz] within the target offset center frequency, the noise level can be kept substantially within ± 1 [dBA] of the target noise level. As by the maximum tolerance limit (Max) h (1600) and the maximum tolerance limit (Min) h (1600) in 13th as shown, the noise level can be kept substantially within ± 1 [dBA] of the target noise level even if the peak height ratio is set to a value slightly greater than ± 0.15 (15%) with respect to the target peak height ratio. Even if the offset center frequency is set to a value slightly larger than ± 0.2 [KHz] with respect to the target offset center frequency, the noise level can be kept substantially within ± 1 with respect to the target value [dBA].

In the in 13th shown example of M12, 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 kept substantially 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 kept substantially within ± 1 [dBA] of the target noise level. In the in 13th shown example of M13, the load is further increased relative to M12 while the speed is kept the same. M13's example is based on the data S4 from 5 . If the peak height ratio is set to a value slightly less than ± 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. If the offset center frequency is set to be within the target offset center frequency ± 0.1 [KHz], the noise level can be kept substantially within ± 1 [dBA] of the target noise level. These tolerances were confirmed by the inventors based on the results of various simulations and experiments. As by the maximum tolerance limit (Max) h (1600) and the minimum tolerance limit (Min) h (1600) in 13th As shown, based on the example of M13, the noise level can be maintained substantially within ± 1 [dBA] of the target noise level if the peak height ratio is set to a value within the target peak height ratio ± 0.15. If the offset center frequency is set to a value within the target offset center frequency ± 0.2 [KHz] or ± 0.1 [KHz], the noise level can be kept substantially within ± 1 [dBA] of the target noise level.

In other words, it is preferable to control the peak height ratio Hp / Hm so that the amount of deviation from the target peak height ratio falls within the tolerance height ratio. "The tolerance height ratio" is set to 0.15 (15%) (reference value for the tolerance height ratio) if the load (Qv) is close to a predetermined load (e.g. close to Qv = 40 [mm ³ / st]) . The tolerance height ratio is set to be larger than the reference value of the tolerance height ratio when the load (Qv) becomes smaller than the predetermined load (for example, Qv = 40 [mm ³ / st]). For example, the tolerance height ratio is set to a value slightly larger than 0.15. The tolerance height ratio is set to be smaller than the reference value of the tolerance height ratio when the load (Qv) becomes larger than the predetermined load (for example, Qv = 40 [mm ³ / st]). The tolerance height ratio is, for example, set to a value that is slightly smaller than 0.15. Hence, in 13th a tolerance interval of the nominal peak height ratio between the maximum tolerance limit (Max) h (1600) and the minimum tolerance limit (Min) h (1600) is set so that it becomes narrower with increasing load (Qv). The tolerance interval of the The nominal vertex height ratio is set in such a way that it increases with decreasing load (Qv).

It is preferable to control the target offset center frequency so that the amount of deviation from the actual target offset center frequency is within the tolerance frequency. “The tolerance frequency” is set to 0.2 [KHz] (tolerance frequency setpoint) if the load (Qv) is close to the predetermined load (eg Qv = 40 [mm ³ / st]). The tolerance frequency is set to be larger than the tolerance frequency reference value when the load (Qv) becomes smaller than the predetermined load (for example, Qv = 40 [mm ³ / st]). The tolerance frequency can, for example, be set to a value that is slightly greater than 0.2 [KHz]. The tolerance frequency is set to be smaller than the tolerance frequency reference value when the load (Qv) is increased to become larger than the predetermined load (for example, Qv = 40 [mm ³ / st]). For example, the tolerance frequency can be set to a value that is slightly less than 0.2 [KHz]. Hence, in 13th 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 in such a way that it decreases with increasing load (Qv). The tolerance interval is set so that it increases as the load (Qv) decreases.

[Processing steps of the control unit 50 (FIG. 14)]

One embodiment of processing steps performed by the control unit 50 will be performed below with reference to the in 14th The flow chart shown is described. The control unit 50 (e.g. a CPU 51 ) begins the in 14th illustrated process, for example, at every predetermined crank angle (for example, every 180 [° CA] for four-cylinder engines) and proceeds to step S010 away.

In step S010 detects the control unit 50 different operating states of the internal combustion engine and leads the process to step S015 away. For example, the control unit 50 an engine speed, an intake volume, a pressure within the intake manifold, a variable nozzle opening amount, an accelerator operation amount, a fuel injection volume, etc. based on detected signals from various detection means such as those in FIG 1 and can detect a control variable of the injector (for example the previous fuel injection volume). The control unit 50 (e.g. the CPU 51 ) showing the process of the step S010 executes, corresponds to an operating state detection unit 51A for detecting the operating states of the internal combustion engine (see for example 1 ).

The control unit 50 calculates a driver requested torque based on the in step S015 recorded operating states and then leads the process to step S020 away. For example, the control unit 50 calculate the request torque based on maps or look-up tables, calculation formulas, etc. stored in the storage device in accordance with certain aspects such as the engine speed and the accelerator operation amount.

In step S020 calculates the control unit 50 the (subsequent) injection volume (Qv) based on the calculated request torque and the operating states of the internal combustion engine and leads the process to step S025 away. Details of calculation methods of the injection volume (Qv) will not be described.

In step S025 determines the control unit 50 the target time delay allocation amount and the target peak height ratio based on the operating conditions of the internal combustion engine and the target time / target peak height ratio characteristics stored in the storage device (see FIG 12th ). The control unit 50 then leads the process to step S030 away. The operating states can be, for example, the speed of an engine and the load (fuel injection volume). The target time delay allocation amount can be, for example, the target offset center frequency. For example, the control unit 50 h (1600) from the in 12th Select the characteristic curves shown for the ratio of target time and target peak height if the speed is 1600 [1 / min] and the load (injection quantity) is 30 [mm ³ / st]. The control unit 50 determines the target time delay allocation amount (target offset center frequency) and the target vertex height ratio with reference to the position of M11 ^{corresponding to the position of 30 [mm 3} / st] at the selected h (1600).

In step S030 determines the control unit 50 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 for the subsequent fuel injection based on the (subsequent) injection volume (Qv), the target time delay allocation amount (the target offset center frequency), the target peak altitude ratio, and the operational peak conditions the internal combustion engine. The control unit 50 then instructs the system to complete this process. In a combustion process, the number of pilot injections is one or more and the number of main injections is one.

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 delay allocation amount (the target offset center frequency). For example, the target time intervals may be stored in accordance with the target time delay allocation amount (target offset center frequency) in the format of maps or a look-up table or the like. The control unit 50 determines the injection timing of the main injection and the injection timing of the pilot injection (s) immediately before the main injection so that the target time interval is achieved using the target time delay allocation amount and the map or the look-up table. The maps or look-up tables are prepared using the simulations, experiments, etc., and are stored in the storage device 53 saved.

The total pilot injection volume and the injection volume of the main injection are determined using the predetermined calculation formulas, maps or look-up tables, etc. based on the target peak height ratio. The total pre-injection volume is a sum of the injection volumes of several pre-injections. The control unit 50 divides, for example, the (subsequent) injection volume (Qv) into the total pre-injection volume and the main injection volume according to the nominal peak height ratio. In this way, the control unit determines 50 the total pilot injection volume and the main injection volume. The above-mentioned predetermined formulas, maps and look-up tables are created using the simulations and experiments and are stored in the storage device 53 saved.

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 control unit 50 each injection process through a planning process of the existing pre-injections and a planning process of the existing main injection at a specific point in time.

The target time lag allocation amount (the target offset center frequency) described above can be changed to the target time lag. The target time delay is half the time of a cycle at the target offset center frequency (half a wavelength). For example, the characteristic curves for the ratio of the desired time to the desired peak height can be stored in a storage device. The target time-to-peak height ratio characteristics may be the target offset center frequency (target time delay allocation amount) which is the horizontal axis of the in 12th represents the characteristic curves shown for the ratio of target time to target peak height, which can be changed to represent the target time delay. In step S025 determines the control unit 50 the target time lag and the target peak height ratio based on the operating conditions of the internal combustion engine (eg, speed and load (injection amount)) and those in the storage device 53 stored characteristic curves for the ratio of target time to target peak height. In step S030 attaches the control unit 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.

The control unit 50 (e.g. CPU 51 ) following the processes of the steps described above S025 and S030 executes corresponds to a fuel injection control unit 51B (see e.g. 1 ). The fuel injection control unit 51B determines the target time delay or the amount associated with the target time delay and the target peak height ratio in accordance with the operating conditions of the internal combustion engine. The fuel injection control unit 51B controls the engine so that the time delay (Δt) approaches the target time delay and the peak height ratio (Hp / Hm) approaches the target peak height ratio. More specifically, is the fuel injection control unit 51B configured to control at least the injection time and the injection volume of one or more pilot injections immediately before the main injection of the pre-stage injection and the injection time and the injection volume of the main injection.

The control unit for the compression ignition engine according to the invention is not limited to the configuration, construction, processing procedure or the like described in the present embodiments, and various modifications, additions and / or omissions are possible without departing from the gist of the invention.

In the present embodiments of 2 , 3 , 8th and 10 For example, examples for determining the crank angle difference Δθ are described, with the horizontal axis representing the crank angle. However, it is also possible to determine the time delay Δt, the horizontal axis representing time. Furthermore, in 4th , 5 , 6th , 12th and 13th Examples are described in which the horizontal axis represents the offset center frequency (the amount of time delay). However, it is also possible set the horizontal axis so that it represents the time delay Δt (f = 1 / (Δt * 2)).

The control unit for the compression ignition engine according to the invention is not limited to a diesel engine. The control unit can also be applied to a compression ignition gasoline engine.

Greater than or equal to (≥), less than or equal to (≤), greater than (>), less than (<), etc. may or may not contain the equal sign. Furthermore, the numerical values used in the description of the present embodiments are used only as an example. The entire disclosure is not limited to these numerical values.

The various examples which have been described in detail above with reference to the accompanying drawings are intended to be representative of the invention and are therefore non-limiting embodiments. The detailed description is intended to enable any person skilled in the art to make, use, and / or practice various aspects of the present teachings, and consequently in no way limits the scope of the invention. Furthermore, each of the additional features and teachings disclosed above can be applied and / or used separately or with other features and teachings in any combination thereof to provide an improved compression compression ignition internal combustion engine and / or method of making and using the same .

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 2020012280 [0001]
• JP 6288066 [0005]

Claims (5)

Control unit (50) for controlling a compression-ignition internal combustion engine, comprising: a compression ignition engine configured to: Injection of a main injection as a main fuel injection and injection of a pilot injection, as one or more pre-fuel injections, as a pre-stage injection for the main fuel injection into a cylinder, both injections taking place in a combustion process; Generating a pre-combustion from the pre-injection, and Generating a main combustion from the main injection, where: when Δt is set as a time lag between an advance peak time position and a main peak time position in a combustion process and when Hp / Hm is set as a peak height ratio: the pre-peak time position among a plurality of peak positions is a peak position corresponding to the pre-combustion, the plurality of peak positions peaks of a derivative value of a pressure within the cylinder that changes over time, or a derivative value of the heat within the cylinder that changes changes over the course of time, the main peak time position among the plurality of peak positions is a peak position corresponding to the main combustion, Hp represents a value of the derivative value of the pressure inside the cylinder at the forward peak position or a value of the derivative value of the heat within the cylinder at the forward peak time position, Hm represents a value of the dissipation value of the pressure inside the cylinder at the main peak position or a value of the dissipation value of the heat inside the cylinder at the main peak time position, or when Δt is set as a time-converted delay based on a crank angle difference and a rotational speed of the crankshaft in the one combustion process and Hp / Hm as the peak height ratio: the crank angle difference is a difference between a leading vertex angle position and a main vertex angle position, the advance vertex angle position among a plurality of vertex positions is a vertex position corresponding to the pre-combustion, the plurality of vertex positions 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 a derivative value the heat inside the cylinder, which varies in accordance with the crank angle, the main vertex angular position among the plurality of vertex positions is a vertex position corresponding to the main combustion, Hp represents the value of the derivative of the pressure within the cylinder at the prelude angular position or the value of the derivative of the heat within the cylinder at the prelude angular position, and Hm represents the value of the derivative of the pressure within the cylinder at the main vertex angular position or the value of the derivative of the heat within the cylinder at the main vertex angular position, and the control unit (50) comprises: an operating condition acquisition unit (51A) configured to acquire operating conditions of the compression-ignition internal combustion engine, and a fuel injection control unit (51B), the fuel injection control unit (51B) configured to: Determining a target time delay or an amount assigned to the target time delay in accordance with the detected operating states of the compression-ignition internal combustion engine, Determining a nominal peak height ratio in accordance with the detected operating states of the compression-ignition internal combustion engine, and Controlling at least one injection time and an injection volume of the pre-injection and at least one injection time and an injection volume of the main injection such that Δt approaches the target time delay or that the amount assigned to the time delay based on Δt approaches the amount assigned to the target time delay, and such that Hp / Hm approximates the target height ratio. Control unit (50) for controlling a compression ignition internal combustion engine Claim 1 wherein the fuel injection control unit (51B) of the control unit (50) is configured to: change the target time delay or the amount associated with the target time delay so that Δt increases, and changing the target peak height ratio so that Hp / Hm decreases as the rotational speed of the auto-ignition Internal combustion engine is essentially constant and the load of the compression ignition engine is increased from a low load to a high load. Control unit (50) for controlling a compression ignition internal combustion engine Claim 1 or 2 wherein: characteristics of the target time and the target peak height ratio corresponding to each of different preset speeds are stored in the control unit (50), a vertical axis representing the characteristics of the target time / peak height ratio, representing one of the following (1) or (2), and a horizontal axis representing the other of (1) or (2): (1) the target time lag or a target offset center frequency , which is a frequency substantially in the middle of an offset frequency band which serves to cancel and reduce the combustion noise due to the pre-burns and the main combustion, and which is an amount associated with the target time lag determined based on the target time lag, and (2 ) the target peak height ratio, for the target time / target peak height ratio characteristics, positions corresponding to loads of the compression ignition engine with respect to the preset speed are set, and the fuel injection control unit (51B) of the control unit (50) is configured to: select the target time / target peak height ratio Characteristic curve in over matching with the speed of the compression ignition engine, determining the target peak height ratio and one of the amount assigned to the target time delay or the target time delay based on the selected target time / target peak height ratio characteristic curve and the load of the compression ignition engine, by the amount assigned to the target time delay or the target time delay in accordance to determine with the speed and the load of the compression ignition engine and to 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, that of the time delay assigned amount based on Δt is approaching the target center frequency, which is the amount assigned to the target time delay, or Δt is approaching the target time delay deceleration approaches, and Hp / Hm approaches the desired peak height ratio. Control unit (50) for controlling a compression ignition internal combustion engine Claim 3 wherein: the fuel injection control unit (51B) of the control unit (50) is configured to control Hp / Hm such that an amount of deviation 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-ignition engine is in the vicinity of a predetermined load, the tolerance height ratio is set so that it becomes greater than the reference value of the tolerance height ratio when the The load of the compression ignition engine becomes smaller than the predetermined load, and the tolerance level ratio is set to be smaller than the reference value of the tolerance level ratio when the load of the compression ignition is applied nnkraftmaschine increases to become larger than the predetermined load. Control unit (50) for controlling a compression ignition internal combustion engine Claim 3 or 4th wherein: the fuel injection control unit (51B) of the control unit (50) 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 if 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 to a tolerance frequency reference value when the load of the compression ignition engine is in the vicinity of the predetermined load, the tolerance frequency is set so that it is greater than the tolerance frequency reference value when the The load of the compression ignition engine becomes smaller than the predetermined load, and the tolerance frequency is set to become smaller than the tolerance frequency reference value when the load of the compression ignition engine is increased to be greater than al s to become the predetermined load.

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