JP5126421B2 - Combustion control device for internal combustion engine - Google Patents

Description

  The present invention relates to a combustion control device for a compression ignition type internal combustion engine typified by a diesel engine, and more particularly to a combustion control device for an internal combustion engine that controls the combustion mode of premixed combustion in a combustion chamber.

  In a diesel engine used as an automobile engine or the like, the timing of fuel injection from a fuel injection valve (hereinafter also referred to as an injector), depending on the engine speed, accelerator operation amount, cooling water temperature, intake air temperature, etc. Control of the combustion mode in the combustion chamber is performed by adjusting the fuel injection amount.

  The combustion of the diesel engine is mainly composed of premixed combustion and diffusion combustion as disclosed in Patent Document 1 below. When fuel injection from the injector into the combustion chamber is started, a combustible air-fuel mixture is first generated by vaporization and diffusion of fuel (ignition delay period). Next, this combustible air-fuel mixture self-ignites almost simultaneously in several places in the combustion chamber, and the combustion proceeds rapidly (premixed combustion). Further, fuel injection into the combustion chamber is continued, and combustion is continuously performed (diffusion combustion). Thereafter, since unburned fuel exists even after the fuel injection is completed, heat generation is continued for a while (afterburn period).

  By the way, in a diesel engine, it is important to meet various requirements such as improving exhaust emissions by reducing both NOx generation and smoke generation, reducing combustion noise during the combustion stroke, and ensuring sufficient engine torque. It is. An exhaust gas recirculation (EGR) device that recirculates part of exhaust gas to an intake passage is known as a means for suppressing the amount of NOx generated (see, for example, Patent Document 2 below). In addition, as a measure for suppressing the amount of smoke generated, sub-injection is executed during the compression stroke of the engine, and combustion in this sub-injection is premixed combustion to eliminate oxygen shortage in the combustion field. Is known (see, for example, Patent Document 3 below).

JP 2004-156519 A JP 2004-003415 A JP 2001-193526 A

  Until now, it has been proposed to control the combustion mode in the combustion chamber for the purpose of suppressing both the generation amount of NOx and the generation amount of smoke (Patent Document 1, etc.).

  In the conventional control, in order to achieve various requirements such as improving exhaust emissions, reducing combustion noise during the combustion stroke, and ensuring sufficient engine torque, a technique for realizing proper combustion in the combustion chamber is engine rotation. The appropriate fuel injection mode (fuel injection pattern) is adapted for each operating state (number of engine speeds and required torque of the engine, etc.) (for each grid point of the operating state map using the engine speed and the required torque as parameters).

  For example, experimentally determine the appropriate value of the fuel injection pattern for each engine operating state by trial and error, and create a fuel injection map by mapping the appropriate values corresponding to each of these many engine operating states Was. Then, according to this fuel injection map, a fuel injection pattern suitable for the current engine operating state is set and the injector is controlled.

  However, the method of creating fuel injection patterns for many operating states in this way by trial and error has many parameters and complicates dependencies, so it is necessary to solve simultaneous equations with multiple variables and multiple outputs, for example. Because there are multiple solutions (conformity values) and the solution may be indeterminate, eigensolutions were obtained with fixed conditions. For this reason, there is no guarantee that the optimal fuel injection pattern is set over the entire engine operating region. In other words, in a certain operating state (an operating state for which the above-mentioned conformity value is not required), the amount of NOx generation is significantly increased due to the excessive diffusion combustion ratio in the combustion in the combustion chamber. In the state, there is a possibility that the combustion becomes unstable because the ratio of the premixed combustion in the combustion in the combustion chamber becomes too high. Further, there are cases where the continuity of the combustion mode is lacking during an operation transition (for example, when the engine load changes rapidly).

  The present invention has been made in view of such circumstances, and provides a combustion control device for an internal combustion engine capable of continuously controlling an appropriate combustion mode in accordance with the operating state of the internal combustion engine. Objective.

-Principle of solving the problem-
The solution principle of the present invention taken in order to achieve the above object is that the combustion mode in the combustion chamber is divided into a premixed combustion region and a main combustion region (diffusion combustion region), and the premixed combustion region is considered. By controlling the required heat quantity and continuously changing the premixed combustion amount (premixed combustion degree) by adjusting the fuel injection mode (fuel injection pattern) in the premixed combustion region, improving exhaust emissions and engine torque We are trying to secure it.

-Solution-
Specifically, the present invention relates to a compression self-ignition type in which fuel injected from a fuel injection valve is combusted in a combustion chamber by “premixed combustion” and “main combustion” started after this “premixed combustion”. An internal combustion engine combustion control device is premised, and in such a combustion control device for an internal combustion engine, the first injection and the second injection can be performed as fuel injection in the premixed combustion region. An injection mode adjusting means is provided that can increase or decrease the premixed combustion amount in the premixed combustion region by changing the ratio of the fuel injection amount with the two injections . Then, assuming that the required heat amount in the premixed combustion region is the same, the fuel injection amount ratio between the first injection and the second injection is determined according to the operating state of the internal combustion engine, and the fuel injection amount of the first injection A technical feature is that the premixed combustion amount in the premixed combustion region is continuously increased or decreased by adjusting the fuel injection amount of the second injection .

By this specific matter, the fuel injection pattern is adjusted using only the fuel injection mode (fuel injection pattern) in the premixed combustion region as a parameter, that is, the ratio of the fuel injection amount between the first injection and the second injection is determined as the internal combustion engine. It is possible to increase or decrease the premixed combustion amount (premixed combustion degree) in the premixed combustion region by continuously changing the combustion state in the combustion chamber by changing the engine according to the operating state (engine operating state). it is Ru can.

  In such a configuration, for example, when the engine speed (engine speed) is relatively low and the combustion state is focused on emission reduction, the fuel injection amount of the first injection in the premixed combustion region is increased, By reducing the fuel injection amount of the second injection and increasing the premixed combustion amount (premixed combustion degree) in the premixed combustion region, the NOx generation amount and the smoke generation amount are suppressed.

  On the other hand, for example, when the engine speed is relatively high and the engine torque is put into a combustion state, the fuel injection amount of the first injection in the premixed combustion region is reduced and the fuel injection amount of the second injection is reduced. Increase to decrease the amount of premixed combustion in the premixed combustion region (increase the degree of diffusion combustion in the premixed combustion region). As a result, the preheating function and the torque increase can be realized in the premixed combustion region, and the engine torque can be secured.

  As described above, in the present invention, the premixed combustion region is managed by the required heat amount, and only the fuel injection pattern in the premixed combustion region is adjusted, so that the combustion mode (premixed combustion amount) in the premixed combustion region is continuous. Therefore, it is possible to realize an appropriate combustion mode according to the engine operating state, and to improve exhaust emission and secure engine torque.

  In the present invention, by fixing the injection end timing of the first injection and the injection end timing of the second injection, respectively, and adjusting the injection start timing of the first injection and the injection start timing of the second injection, respectively. And each fuel injection amount of the second injection is set.

  Specifically, the injection end timing of the second injection is fixed at a timing (crank angle) close to TDC (piston compression top dead center). Here, assuming that the combustion by the second injection is diffusion combustion, it can be defined as “minimum ignition delay” of the combustion by the second injection, and if the ignition delay is minimum, the second Since the combustion end timing is uniquely determined by the injection end timing of the injection, if the injection end timing of the second injection is fixed and the injection start timing of the second injection is advanced, the end timing of the premixed combustion region is reached. It is possible to supply the required heat amount (≈the fuel injection amount in the premixed combustion region), and the injection end timing of the second injection is fixed in consideration of such points. When the fuel injection amount of the second injection is increased, the injection start timing is advanced. Conversely, when the fuel injection amount of the second injection is decreased, the injection start timing is retarded.

  For the first injection, the injection end timing is fixed at a timing (crank angle) at which the minimum premixed combustion for fixing the ignition timing of the combustion by the second injection can be realized, and the fuel injection amount of the first injection Is increased, the injection start timing is advanced. Conversely, when the fuel injection amount of the first injection is decreased, the injection start timing is delayed.

  In the present invention, the degree of premixed combustion (premixed combustion amount) in the premixed combustion region may be increased by adjusting the in-cylinder gas state before fuel injection.

  Specifically, the exhaust gas recirculation device that recirculates a part of the exhaust gas discharged to the exhaust system of the internal combustion engine to the intake system increases the recirculation amount (EGR amount) of the exhaust gas to the intake system. The oxygen concentration may be reduced to increase the degree of premix combustion in the premix combustion region.

  When the in-cylinder oxygen concentration is reduced in this way, the degree of premixed combustion in the premixed combustion region increases due to the reduction in the in-cylinder oxygen concentration, and the combustion center of gravity (combustion by the first injection) If the combustion center of gravity) approaches TDC (compression top dead center of the piston), it is less necessary to set the ignition timing of the main combustion region to TDC, so the main combustion is retarded (the main injection is retarded). . When the retardation of the main injection is performed, the amount of NOx can be reduced.

  Further, by reducing the intake air amount by the supercharging device, the pre-ignition pressure in the cylinder may be reduced to increase the degree of premix combustion in the premix combustion region.

  Thus, when the pre-ignition pressure in the cylinder is lowered, the premixed combustion degree in the premixed combustion region is increased due to the reduction in the pre-ignition pressure in the cylinder, and the combustion center of gravity in the premixed combustion region is increased. When (the combustion center of gravity of the combustion by the first injection) approaches TDC (compression top dead center of the piston), it is less necessary to set the ignition timing of the main combustion region to TDC. Retard the injection). When the retardation of the main injection is performed, the amount of NOx can be reduced.

  In this case, the intake air amount may be decreased by an intake throttle valve (throttle valve) to reduce the pre-ignition pressure in the cylinder, the intake air amount may be reduced by the supercharging device, and the intake throttle valve The pressure before ignition in the cylinder may be lowered in combination with the reduction of the intake air amount due to the above.

  Further, in the present invention, when the in-cylinder oxygen concentration is reduced by increasing the EGR amount to increase the premixed combustion degree in the premixed combustion region, the reduction in the in-cylinder oxygen concentration results in the premixed combustion region. The degree of premixed combustion increases, the center of combustion of the premixed combustion region (the center of combustion of the combustion by the second injection) approaches TDC (piston compression top dead center), and premixed combustion is completed by TDC. In order to fix the ignition timing of the main combustion (fixed to TDC ignition), both the first injection and the second injection of the premixed combustion injection are advanced (the entire premixed combustion region is Advance) so that combustion in the premixed combustion region can be completed by TDC.

  Further, in the present invention, when the pre-ignition pressure in the cylinder is reduced by decreasing the intake air amount to increase the degree of premix combustion in the premix combustion region, the premixing is performed by reducing the in-cylinder oxygen concentration. The degree of premixed combustion in the combustion region becomes high, the combustion center of gravity in the premixed combustion region (combustion center of gravity in the combustion by the second injection) approaches TDC (piston compression top dead center), and premixed combustion becomes TDC. In order to fix the ignition timing of the main combustion (fixed to TDC ignition), both the first injection and the second injection of the premix combustion injection are advanced (premix combustion region). The combustion of the premixed combustion region can be completed by TDC.

  The combustion center of gravity means that fuel injected into the combustion chamber (for example, fuel injected by fuel injection for premixed combustion, fuel injected by fuel injection for diffusion combustion) burns in the combustion chamber. In addition, when the complete combustion state in which the combustion of all the fuels is completed is set to the combustion degree “100%”, the combustion degree reaches “50%”. In other words, the cumulative heat generation amount in the combustion chamber reaches “50%” with respect to the heat generation amount when the entire injected fuel burns.

  According to the present invention, the combustion mode in the combustion chamber is considered to be separated into the premixed combustion region and the main combustion region, the premixed combustion region is managed by the required heat amount, and the fuel injection mode of the premixed combustion region is By adjusting, it is possible to continuously change the degree of premixing (premixed combustion amount) in the premixed combustion region, so it is possible to realize an appropriate combustion mode according to the engine operating state, and to improve exhaust emission The engine torque can be secured.

1 is a schematic configuration diagram of an engine to which the present invention is applied and a control system thereof. It is sectional drawing which shows the combustion chamber of a diesel engine, and its peripheral part. It is a block diagram which shows the structure of control systems, such as ECU. It is the figure which illustrated the fuel injection pattern. It is a figure which shows each fuel injection amount of the 1st injection of a premix combustion area | region, and a 2nd injection. It is the figure which illustrated the fuel injection pattern, the heat release rate waveform obtained by the fuel injection pattern, and the amount of generated heat. It is the figure which illustrated the fuel injection pattern, the heat release rate waveform obtained by the fuel injection pattern, and the amount of generated heat. It is a figure which shows the map which sets the total fuel injection amount of a premixed combustion area | region according to the request | requirement heat amount of a premixed combustion area | region. It is a figure which shows the map which sets the premix combustion degree of a premix combustion area | region according to an engine speed and an engine torque. It is a figure which shows the map which sets the fuel injection amount ratio of the 1st injection of a premix combustion area | region, and a 2nd injection according to the premix combustion degree of a premix combustion area | region. A map (a) for setting the advance angle correction amount for the injection start timing of the first injection in the premixed combustion region and a map (b) for setting the advance angle correction amount for the injection start timing of the second injection are shown together. FIG. It is a figure which shows the example in the case of retarding the main combustion at the time of cylinder oxygen concentration reduction. It is a figure which shows the example in the case of advancing premixed combustion in the case of cylinder oxygen concentration reduction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a common rail in-cylinder direct injection multi-cylinder (for example, in-line 4-cylinder) diesel engine (compression self-ignition internal combustion engine) mounted on an automobile will be described.

-Engine configuration-
First, an example of a diesel engine (hereinafter simply referred to as an engine) to which the present invention is applied will be described. FIG. 1 is a schematic configuration diagram of the engine 1 and its control system. FIG. 2 is a cross-sectional view showing the combustion chamber 3 of the diesel engine and its periphery.

  As shown in FIG. 1, the engine 1 of this example is configured as a diesel engine system having a fuel supply system 2, a combustion chamber 3, an intake system 6, an exhaust system 7 and the like as main parts.

  The fuel supply system 2 includes a supply pump 21, a common rail 22, an injector (fuel injection valve) 23, a shutoff valve 24, a fuel addition valve 26, an engine fuel passage 27, an addition fuel passage 28, and the like.

  The supply pump 21 pumps fuel from the fuel tank, makes the pumped fuel high pressure, and supplies it to the common rail 22 via the engine fuel passage 27. The common rail 22 has a function as a pressure accumulation chamber that holds (accumulates) the high-pressure fuel supplied from the supply pump 21 at a predetermined pressure, and distributes the accumulated fuel to the injectors 23. The injector 23 includes a piezoelectric element (piezo element) therein, and is configured by a piezo injector that is appropriately opened to supply fuel into the combustion chamber 3. Details of the fuel injection control from the injector 23 will be described later.

  The supply pump 21 supplies a part of the fuel pumped from the fuel tank to the fuel addition valve 26 via the addition fuel passage 28. The added fuel passage 28 is provided with the shutoff valve 24 for shutting off the added fuel passage 28 and stopping fuel addition in an emergency.

  The fuel addition valve 26 is configured so that the fuel addition amount to the exhaust system 7 becomes a target addition amount (addition amount that makes the exhaust A / F become the target A / F) by an addition control operation by the ECU 100 described later. In addition, it is constituted by an electronically controlled on-off valve whose valve opening timing is controlled so that the fuel addition timing becomes a predetermined timing. That is, a desired fuel is injected and supplied from the fuel addition valve 26 to the exhaust system 7 (from the exhaust port 71 to the exhaust manifold 72) at an appropriate timing.

  The intake system 6 includes an intake manifold 63 connected to an intake port 15a formed in the cylinder head 15 (see FIG. 2), and an intake pipe 64 that constitutes an intake passage is connected to the intake manifold 63. In addition, an air cleaner 65, an air flow meter 43, and a throttle valve (intake throttle valve) 62 are arranged in this intake passage sequentially from the upstream side. The air flow meter 43 outputs an electrical signal corresponding to the amount of air flowing into the intake passage via the air cleaner 65.

  The exhaust system 7 includes an exhaust manifold 72 connected to an exhaust port 71 formed in the cylinder head 15, and exhaust pipes 73 and 74 constituting an exhaust passage are connected to the exhaust manifold 72. . Further, a maniverter (exhaust gas purification device) 77 provided with a NOx storage catalyst (NSR catalyst: NOx Storage Reduction catalyst) 75 and a DPNR catalyst (Diesel Particle-NOx Reduction catalyst) 76 is disposed in the exhaust passage. Yes. Hereinafter, the NSR catalyst 75 and the DPNR catalyst 76 will be described.

The NSR catalyst 75 is an NOx storage reduction catalyst. For example, alumina (Al ₂ O ₃ ) is used as a carrier, and potassium (K), sodium (Na), lithium (Li), cesium (Cs) is supported on the carrier, for example. ), Alkaline metals such as barium (Ba) and calcium (Ca), rare earths such as lanthanum (La) and yttrium (Y), and noble metals such as platinum (Pt) are supported. It becomes the composition.

The NSR catalyst 75 occludes NOx in a state where a large amount of oxygen is present in the exhaust gas, has a low oxygen concentration in the exhaust gas, and a large amount of reducing component (for example, an unburned component (HC) of the fuel). In the existing state, NOx is reduced to NO ₂ or NO and released. NO NOx released as NO ₂ or NO, the N ₂ is further reduced due to quickly reacting with HC or CO in the exhaust. Further, HC and CO are oxidized to H ₂ O and CO ₂ by reducing NO ₂ and NO. That is, by appropriately adjusting the oxygen concentration and HC component in the exhaust gas introduced into the NSR catalyst 75, HC, CO, and NOx in the exhaust gas can be purified. In the present embodiment, the oxygen concentration and HC component in the exhaust gas can be adjusted by the fuel addition operation from the fuel addition valve 26.

  On the other hand, the DPNR catalyst 76 is, for example, a NOx occlusion reduction catalyst supported on a porous ceramic structure, and PM in the exhaust gas is collected when passing through the porous wall. Further, when the air-fuel ratio of the exhaust gas is lean, NOx in the exhaust gas is stored in the NOx storage reduction catalyst, and when the air-fuel ratio becomes rich, the stored NOx is reduced and released. Further, the DPNR catalyst 76 carries a catalyst that oxidizes and burns the collected PM (for example, an oxidation catalyst mainly composed of a noble metal such as platinum).

  Here, the structure of the combustion chamber 3 of a diesel engine and its peripheral part is demonstrated using FIG. As shown in FIG. 2, a cylinder block 11 constituting a part of the engine body is formed with a cylindrical cylinder bore 12 for each cylinder (four cylinders), and a piston 13 is formed inside each cylinder bore 12. Is accommodated so as to be slidable in the vertical direction.

  The combustion chamber 3 is formed above the top surface 13 a of the piston 13. That is, the combustion chamber 3 is defined by the lower surface of the cylinder head 15 attached to the upper part of the cylinder block 11 via the gasket 14, the inner wall surface of the cylinder bore 12, and the top surface 13 a of the piston 13. A cavity (concave portion) 13 b is formed in a substantially central portion of the top surface 13 a of the piston 13, and this cavity 13 b also constitutes a part of the combustion chamber 3.

  As for the shape of the cavity 13b, the concave dimension is small in the central portion (on the cylinder center line P), and the concave dimension is increased toward the outer peripheral side. That is, as shown in FIG. 2, when the piston 13 is in the vicinity of the compression top dead center, the combustion chamber 3 formed by the cavity 13b is a narrow space with a relatively small volume in the central portion, and on the outer peripheral side. The structure is such that the space is gradually expanded toward the expansion space.

  The piston 13 has a small end portion 18a of a connecting rod 18 connected by a piston pin 13c, and a large end portion of the connecting rod 18 is connected to a crankshaft which is an engine output shaft. As a result, the reciprocating movement of the piston 13 in the cylinder bore 12 is transmitted to the crankshaft via the connecting rod 18, and the engine output is obtained by rotating the crankshaft. Further, a glow plug 19 is disposed toward the combustion chamber 3. The glow plug 19 functions as a start-up assisting device that is heated red when an electric current is applied immediately before the engine 1 is started and a part of the fuel spray is blown onto the glow plug 19 to promote ignition and combustion.

  The cylinder head 15 is formed with an intake port 15a for introducing air into the combustion chamber 3 and an exhaust port 71 for discharging exhaust gas from the combustion chamber 3, and an intake valve for opening and closing the intake port 15a. 16 and an exhaust valve 17 for opening and closing the exhaust port 71 are provided. The intake valve 16 and the exhaust valve 17 are disposed to face each other with the cylinder center line P interposed therebetween. That is, the engine 1 of this example is configured as a cross flow type. The cylinder head 15 is provided with the injector 23 that directly injects fuel into the combustion chamber 3. The injector 23 is disposed at a substantially upper center of the combustion chamber 3 in a standing posture along the cylinder center line P, and injects fuel introduced from the common rail 22 toward the combustion chamber 3 at a predetermined timing. It has become.

  Further, as shown in FIG. 1, the engine 1 is provided with a supercharger (turbocharger) 5. The turbocharger 5 includes a turbine wheel 52 and a compressor impeller 53 that are connected via a turbine shaft 51. The compressor impeller 53 is arranged facing the inside of the intake pipe 64, and the turbine wheel 52 is arranged facing the inside of the exhaust pipe 73. Therefore, the turbocharger 5 performs a so-called supercharging operation in which the compressor impeller 53 is rotated using the exhaust flow (exhaust pressure) received by the turbine wheel 52 to increase the intake pressure. The turbocharger 5 in this example is a variable nozzle type turbocharger (VNT), and a variable nozzle vane mechanism 54 is provided on the turbine wheel 52 side, and an opening degree (VN opening degree) of the variable nozzle vane mechanism 54 is adjusted. By doing so, the supercharging pressure of the engine 1 can be adjusted.

  An intake pipe 64 of the intake system 6 is provided with an intercooler 61 for forcibly cooling the intake air whose temperature has been raised by supercharging in the turbocharger 5. The throttle valve 62 is provided further downstream than the intercooler 61. The throttle valve 62 is an electronically controlled on-off valve whose opening degree can be adjusted in a stepless manner. The throttle air flow area of the intake air is reduced under a predetermined condition, and the supply amount of the intake air is adjusted (reduced). ) Function.

  Further, the engine 1 is provided with an exhaust gas recirculation passage (EGR passage) 8 that connects the intake system 6 and the exhaust system 7. The EGR passage 8 is configured to reduce the combustion temperature by recirculating a part of the exhaust gas to the intake system 6 and supplying it again to the combustion chamber 3, thereby reducing the amount of NOx generated. In addition, the EGR passage 8 is opened and closed steplessly by electronic control, and the exhaust gas passing through the EGR passage 8 (recirculating) is cooled by an EGR valve 81 that can freely adjust the exhaust flow rate flowing through the passage. An EGR cooler 82 is provided. The EGR passage 8, the EGR valve 81, the EGR cooler 82, and the like constitute an EGR device (exhaust gas recirculation device).

-Sensors-
Various sensors are attached to each part of the engine 1, and signals related to the environmental conditions of each part and the operating state of the engine 1 are output.

  For example, the air flow meter 43 outputs a detection signal corresponding to the flow rate of intake air (intake air amount) upstream of the throttle valve 62 in the intake system 6. The intake air temperature sensor 49 is disposed in the intake manifold 63 and outputs a detection signal corresponding to the temperature of the intake air. The intake pressure sensor 48 is disposed in the intake manifold 63 and outputs a detection signal corresponding to the intake air pressure. The A / F (air-fuel ratio) sensor 44 outputs a detection signal that continuously changes in accordance with the oxygen concentration in the exhaust gas downstream of the manipulator 77 of the exhaust system 7. Similarly, the exhaust temperature sensor 45 outputs a detection signal corresponding to the temperature of the exhaust gas (exhaust temperature) downstream of the manipulator 77 of the exhaust system 7. The rail pressure sensor 41 outputs a detection signal corresponding to the fuel pressure stored in the common rail 22 (hereinafter also referred to as fuel pressure). The throttle opening sensor 42 detects the opening of the throttle valve 62.

-ECU-
As shown in FIG. 3, the ECU 100 includes a CPU 101, a ROM 102, a RAM 103, a backup RAM 104, and the like. The ROM 102 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 101 executes various arithmetic processes based on various control programs and maps stored in the ROM 102. The RAM 103 is a memory that temporarily stores calculation results in the CPU 101, data input from each sensor, and the like. The backup RAM 104 is a non-volatile memory that stores data to be saved when the engine 1 is stopped, for example.

  The CPU 101, the ROM 102, the RAM 103, and the backup RAM 104 are connected to each other via the bus 107, and are connected to the input interface 105 and the output interface 106.

  The input interface 105 is connected with the rail pressure sensor 41, the throttle opening sensor 42, the air flow meter 43, the A / F sensor 44, the exhaust temperature sensor 45, the intake pressure sensor 48, and the intake temperature sensor 49. Further, the input interface 105 includes a water temperature sensor 46 that outputs a detection signal corresponding to the cooling water temperature of the engine 1, an accelerator opening sensor 47 that outputs a detection signal corresponding to the depression amount of the accelerator pedal, and the engine 1. A crank position sensor 40 that outputs a detection signal (pulse) each time the output shaft (crankshaft) rotates by a certain angle is connected.

  On the other hand, the injector 23, the fuel addition valve 26, the throttle valve 62, the variable nozzle vane mechanism 54, the EGR valve 81, and the like are connected to the output interface 106.

  The ECU 100 executes various controls of the engine 1 based on the outputs of the various sensors described above. For example, the ECU 100 performs fuel injection control of the injector 23. As fuel injection control of the injector 23, in this embodiment, fuel injection in a premixed combustion region (premixed injection) and fuel injection in the main combustion region (main injection), which will be described later, are executed.

  The total fuel injection amount of the fuel injection in the premixed combustion region and the fuel injection in the main combustion region is determined according to operating conditions such as engine speed, accelerator operation amount, cooling water temperature, intake air temperature, and environmental conditions. It is set as the fuel injection amount necessary to obtain the required torque. For example, the higher the engine speed (the engine speed calculated based on the detection value of the crank position sensor 40), the larger the accelerator operation amount (the accelerator pedal depression amount detected by the accelerator opening sensor 47). The higher the required accelerator torque of the engine 1, the higher the accelerator opening.

  And the combustion control apparatus (for example, injection form adjustment means and combustion control means) of the internal combustion engine of this invention is implement | achieved by the program run by ECU100.

-Fuel injection pressure-
The fuel injection pressure when executing the fuel injection control is determined by the internal pressure of the common rail 22. As the common rail internal pressure, generally, the target value of the fuel pressure supplied from the common rail 22 to the injector 23, that is, the target rail pressure, increases as the engine load (engine load) increases and as the engine speed (engine speed) increases. It is supposed to be expensive. That is, when the engine load is high, the amount of air sucked into the combustion chamber 3 is large. Therefore, a large amount of fuel must be injected from the injector 23 into the combustion chamber 3, and therefore the injection from the injector 23 is performed. The pressure needs to be high. Further, when the engine speed is high, the injection period is short, so the amount of fuel injected per unit time must be increased, and therefore the injection pressure from the injector 23 needs to be increased. . Thus, the target rail pressure is generally set based on the engine load and the engine speed.

  The target rail pressure is set according to a fuel pressure setting map stored in the ROM 102, for example. That is, by determining the fuel pressure according to this fuel pressure setting map, the valve opening period (injection rate waveform) of the injector 23 is controlled, and the fuel injection amount during the valve opening period can be defined.

  Regarding the fuel injection parameter in the fuel injection control, the optimum value varies depending on the temperature conditions of the engine 1 and the intake air.

  For example, the ECU 100 adjusts the fuel discharge amount of the supply pump 21 so that the common rail pressure becomes equal to the target rail pressure set based on the engine operating state, that is, the fuel injection pressure matches the target injection pressure. To measure. Further, the ECU 100 determines the fuel injection amount based on the engine operating state. Specifically, the ECU 100 calculates the engine speed (engine speed) based on the detected value of the crank position sensor 40, and also depresses the accelerator pedal (accelerator opening amount) based on the detected value of the accelerator opening sensor 47. The total injection amount (total injection amount in premixed injection and main injection described later) is determined based on the engine speed, the accelerator opening, and the like.

-Fuel injection control-
In the diesel engine 1, it is important to meet various requirements such as improvement of exhaust emission by reducing the NOx generation amount and smoke generation amount, reduction of combustion noise during the combustion stroke, and sufficient securing of engine torque. The fuel injection control (fuel injection pattern adjustment) as described below has been found as a method for simultaneously satisfying these requirements. The fuel injection control will be specifically described.

  First, in this embodiment, as shown in FIG. 4, the combustion in the combustion chamber 3 is classified into a premixed combustion region and a main combustion region (diffusion combustion region) in time series.

  The premixed combustion region is defined as a combustion region in which all combustion is completed in the own process. Note that the premixed combustion region is pure self-ignition combustion, so that an ignition delay occurs and the initial combustion is always premixed combustion. The main combustion is basically defined as diffusion combustion whose ignition timing is TDC. As will be described later, the ignition timing of main combustion may be retarded with respect to TDC.

  The fuel injection in the premixed combustion region is referred to as “premixed injection”, and the fuel injection in the main combustion region is referred to as “main injection”. In addition, the premix injection can be divided into two, and the first premix injection (previous injection) is referred to as “first injection”, and the second premix injection (the first injection). The injection after injection) will be referred to as “second injection”. The first injection is premixed component injection, and the second injection is preheated component injection and fuel injection close to TDC.

  The feature of this embodiment is that the premixed combustion region is managed by the required heat amount, the fuel injection pattern in the premixed combustion region (see FIG. 4) is adjusted, and the premixed combustion amount in the premixed combustion region is continuously increased. By changing to, an appropriate combustion mode corresponding to the engine operating state is realized, and exhaust emission is improved and engine torque is secured. Hereinafter, this technical idea will be described.

  First, as shown in FIG. 4, the required heat amount (≈fuel injection amount) in the premixed combustion region is the same (same), and the fuel injection amount ratio between the first injection and the second injection of the premixed injection is continuously set. By changing (including the second injection = 0%), the premixed combustion degree (premixed combustion amount) in the premixed combustion region can be increased or decreased. The “degree of premix combustion” is the ratio of the heat generation amount of premix combustion to the total heat generation amount in the premix combustion region.

  Specifically, as shown in FIG. 4, the fuel injection amount of the second injection in the premixed combustion region is decreased (the advance amount of the injection start timing of the second injection is decreased), and the first If the injection end timing of one injection is the same and the fuel injection amount is increased by advancing the injection start timing of the first injection, the temperature in the combustion chamber can be kept low due to an increase in the interference cooling effect. Is promoted, and the degree of premixing in the premixed combustion region increases. When the premixing degree in the premixed combustion region is increased in this way, the NOx generation amount and the smoke generation amount can be suppressed. Note that the spray interference cooling is a phenomenon in which the spray of the fuel injected earlier is cooled by the endothermic reaction of the fuel injected subsequently, and as the fuel injection amount increases, the spray interference is increased as described later. The cooling effect is increased.

  On the contrary, as shown in FIG. 4, the fuel injection amount of the first injection of the premixed injection is reduced (the advance amount of the injection start timing of the first injection is reduced), and the second injection If the injection end timing is the same and the injection start timing of the second injection is advanced to increase the injection amount, the combustion mode by the second injection shifts to diffusion combustion, so in the premixed combustion region A preheating function and a torque increase can be realized.

  As described above, by continuously changing the fuel injection amount ratio between the first injection and the second injection of the premixed injection (including the second injection = 0%), the premixed combustion degree in the premixed combustion region The (premixed combustion amount) can be continuously changed. As a result, an appropriate combustion mode corresponding to the engine operating state (for example, engine speed / load) can be realized, and exhaust emission can be improved and engine torque can be secured.

  The fuel injection control described above is executed by the ECU 100.

-About penetration-
Here, the relationship between the fuel injection amount and the penetration force will be described. In the injector 23, when fuel injection is started in response to the injection command signal, the opening area of the injection hole is gradually increased as the needle closing the injection hole is retracted from the injection hole.

  The opening area of the injection hole of the injector 23 is correlated with the flight distance of fuel (spray) injected from the injection hole. That is, when fuel is injected with a small opening area of the injection hole, the size of the droplet of fuel injected from the injection hole is also small, so that the kinetic energy is also small (penetration force is small). ing. For this reason, the flight distance of this fuel droplet is also short. On the other hand, when fuel is injected in a state where the opening area of the injection hole is large, the size of the droplet of fuel injected from the injection hole is also large, so that the kinetic energy is also large (the penetration force is large). Yes. For this reason, the flight distance of this fuel droplet becomes long.

  Thus, there is a correlation between the opening area of the injection hole of the injector 23 and the flight distance of the fuel (spray) injected from the injection hole, and the opening area of the injection hole becomes large in the valve opening process of the injector 23. As the fuel flows, the kinetic energy of the fuel (droplet) injected from the injection hole increases, and the flight distance of the subsequently injected fuel becomes longer than the fuel injected previously. In other words, the longer the valve opening period of the injector 23 is set (in other words, the more the injection amount per injection is set), the more the fuel injected subsequently in the preceding injected spray becomes. The amount passing through increases. Therefore, the degree to which the spray of fuel injected earlier is cooled by the endothermic reaction of the subsequently injected fuel as the injection amount in the first injection of the premixed combustion injection is set larger. Becomes higher and the above-described spray interference cooling effect is increased.

-Fuel injection pattern in premixed combustion region-
In the present embodiment, as described above, the fuel injection amount ratio of the first injection and the second injection of the premixed injection is continuously changed (including the second injection = 0%), thereby the premixed combustion degree (premixed combustion). It is characterized in that the amount of combustion) is continuously changed. The fuel injection pattern for realizing such control will be specifically described below.

<Injection start timing and injection end timing of the first injection and the second injection>
First, the injection start timing and the injection end timing of the first injection and the second injection of the premixed injection will be described.

  As shown in FIG. 4, the injection end timing of the second injection is fixed at a timing (crank angle) close to TDC (compression top dead center of the piston 13). Here, assuming that the combustion by the second injection is diffusion combustion, it can be defined as “minimum ignition delay” of the combustion by the second injection, and if the ignition delay is minimum, the second Since the combustion end timing is uniquely determined by the injection end timing of injection, if the injection end timing of the second injection is fixed and the injection start timing is advanced, the required heat amount (≈ In consideration of such points, the injection end timing of the second injection is fixed. When the fuel injection amount of the second injection is increased, the injection start timing is advanced. Conversely, when the fuel injection amount of the second injection is decreased, the injection start timing is retarded.

  For the first injection, the injection end timing is fixed at a timing (crank angle) at which the minimum premixed combustion for fixing the ignition timing of the combustion by the second injection can be realized, and the fuel injection amount of the first injection is increased. If so, the injection start timing is advanced. Conversely, if the fuel injection amount of the first injection is decreased, the injection start timing is retarded.

<Fuel injection amount ratio between first injection and second injection>
In this embodiment, since the premixed combustion region is managed by the required heat amount (required heat energy), the required heat amount, that is, the fuel injection amount in the premixed combustion region is made the same (without changing the fuel injection amount), and the premixing is performed. By adjusting only the fuel injection amount ratio between the first injection and the second injection, the fuel injection pattern in the premixed combustion region is set and fuel injection is performed.

Specifically, for example, as shown in FIG. 5, when the total fuel injection amount of the first injection and the second injection is 6 mm ³ and the target combustion mode in the premixed combustion region is the minimum premixed combustion, The fuel injection amount ratio [first injection: second injection] is set to [2 mm ³ : 4 mm ³ ]. Also, when the target combustion mode is small / medium premixed combustion, the fuel injection amount ratio [first injection: second injection] is [3 mm ³ : 3 mm ³ ], and when the target combustion mode is small / medium premixed combustion The fuel injection amount ratio [first injection: second injection] is set to [4 mm ³ : 2 mm ³ ]. When the target combustion mode is the maximum premixed combustion, the fuel injection amount ratio [first injection: second injection] is set to [6 mm ³ : 0 mm ³ ].

<Fuel injection pattern>
(1) FIG. 6A shows a fuel injection pattern in which the combustion mode in the premixed combustion region is the minimum premixed combustion and the fuel injection pattern of the main injection. FIG. 6A shows the heat generation rate waveform and the amount of generated heat (required heat amount) obtained by these fuel injection patterns.

  In the combustion mode shown in FIG. 6A, most of the combustion by the fuel injection of the second injection is diffusion combustion, and the premixed combustion degree in the premixed combustion region can be set low. For example, the premixed combustion degree (ratio) can be set to 20 to 60%. In FIG. 6A, the delay of the combustion center of gravity with respect to the injection start timing of the first injection is referred to as “reference ignition delay”.

  (2) FIG. 6B shows a fuel injection pattern in which the combustion mode in the premixed combustion region is the above-described small / medium premixed combustion and a fuel injection pattern of the main injection. FIG. 6B shows the heat generation rate waveform and the amount of generated heat (required heat amount) obtained by these fuel injection patterns.

  In the fuel injection pattern of the premixed injection shown in FIG. 6B, the combustion injection amount of the first injection is increased with respect to the fuel injection pattern of the premixed injection shown in FIG. The injection amount is reduced. Thereby, in FIG. 6B, the ignition delay of the first injection is increased and the degree of premixed combustion in the premixed combustion region is higher than in the combustion mode of FIG. 6A. In the fuel injection pattern of FIG. 6B, the premixed combustion degree (ratio) can be set to 30 to 70%, for example.

  (3) FIG. 7A shows a fuel injection pattern in which the combustion mode in the premixed combustion region is the above-described medium and small premixed combustion and a fuel injection pattern of the main injection. FIG. 7A shows the heat generation rate waveform and the amount of generated heat (required heat amount) obtained by these fuel injection patterns.

  In the fuel injection pattern of the premixed injection shown in FIG. 7A, the combustion injection amount of the first injection is increased with respect to the fuel injection pattern of the premixed injection shown in FIG. The combustion injection amount is reduced. Accordingly, in FIG. 7A, the ignition delay of the first injection is increased and the degree of premixed combustion in the premixed combustion region is higher than that in the combustion mode of FIG. 6B. In the fuel injection pattern of FIG. 7A, the premixed combustion degree (ratio) can be set to 40 to 80%, for example.

  (4) FIG. 7B shows a fuel injection pattern in which the combustion mode in the premixed combustion region is the maximum premixed combustion and the fuel injection pattern of the main injection. FIG. 7B shows the heat generation rate waveform and the amount of generated heat (required heat amount) obtained by these fuel injection patterns.

In the fuel injection pattern shown in FIG. 7B, the fuel injection amount of the first injection is the total injection amount (6 mm ³ ) in the premixed combustion region, and the second injection is “0”. The ignition delay is maximized and the premixed combustion degree is maximized. In the fuel injection pattern of FIG. 7B, the premixed combustion degree (ratio) can be set to 50 to 100%, for example.

  As described above, the total injection amount of the first injection and the second injection is the same, the fuel injection amount of the first injection is increased, and the fuel injection amount of the second injection is decreased, so that the premixing is performed. The premixed combustion degree (premixed combustion amount) in the combustion region can be continuously increased. Conversely, by decreasing the fuel injection amount of the first injection and increasing the fuel injection amount of the second injection, the degree of premix combustion in the premix combustion region is continuously reduced (premix combustion region). The degree of diffusive combustion can be continuously increased).

-Specific control procedure-
Next, a specific example in which the fuel injection from the injector 23 is executed by adjusting the fuel injection pattern in the premixed combustion region (the fuel injection amount ratio between the first injection and the second injection in the premixed combustion region) as described above. A typical control procedure will be described. In addition, the process demonstrated below is performed in ECU100.

  First, the total required heat amount (total fuel injection amount) is determined with reference to a known map or the like according to the operating state such as engine speed, accelerator operation amount, cooling water temperature, intake air temperature, and environmental conditions. Of the total required heat amount, the required heat amount in the premixed combustion region is determined. The required amount of heat in this premixed combustion region is variably set depending on whether the engine operating state is focused on preheating or engine torque. However, if the required heat quantity in the premixed combustion region is too large, the premixed combustion cannot be completed by TDC (compression top dead center of the piston 13), and the advance amount of the first injection in the premixed combustion region In view of the limitation, it is necessary to limit the required heat amount in the premixed combustion region with an upper limit guard.

  (S1) Based on the required amount of heat in the premixed combustion region, the total injection amount (first injection + second injection) in the premixed combustion region is obtained with reference to the map shown in FIG.

  The map in FIG. 8 is a map obtained by mapping the total injection amount in the premixed combustion region by experiment / simulation using the required heat amount as a parameter, and is stored in the ROM 102 of the ECU 100, for example. In the map of FIG. 8, the total fuel injection amount in the premixed combustion region is set to increase as the required heat amount increases.

  (S2) The premixed combustion degree in the premixed combustion region is obtained based on the engine speed and the required torque with reference to the map shown in FIG.

  The map in FIG. 9 is a map of values obtained by empirically matching the degree of premixed combustion in the premixed combustion region in advance through experiments and simulations using the engine speed and engine torque as parameters. Stored in the ROM 102. In the map of FIG. 9, the premixing degree in the premixed combustion region is set to be larger as the engine speed is lower and the required torque is lower.

  (S3) The fuel injection amount ratio between the first injection and the second injection is obtained with reference to the map of FIG. 10 using the premixing degree of the premixed combustion region obtained in the processing of (S2) described above. The fuel injection amount of the first injection is obtained by multiplying the total fuel injection amount by the fuel injection amount ratio by using the fuel injection amount ratio and the total fuel injection amount in the premixed combustion region obtained in the process of (S1). And the fuel injection amount of the second injection are obtained.

  Note that the fuel injection amount ratio map shown in FIG. 10 is a map in which the fuel injection amount ratio between the first injection and the second injection is preliminarily adapted by experiments and simulations, etc., with the degree of premixing as a parameter. And stored in the ROM 102 of the ECU 100. In the map of FIG. 10, the ratio of the fuel injection amount of the first injection increases as the premixed combustion degree increases (the premixing degree is closer to 100%). 0 ”is also included). In the map of FIG. 10, the ratio between the fuel injection amount of the first injection and the fuel injection amount of the second injection is set with the total injection amount in the premixed combustion region being “1”.

  (S4) Referring to the maps shown in FIGS. 11 (a) and 11 (b) using the fuel injection amount of the first injection and the fuel injection amount of the second injection obtained in the process of (S3) described above. Then, the advance angle correction amount of the injection start timing of the first injection and the advance angle correction amount of the injection start timing of the second injection are respectively obtained. Then, the fuel injection pattern in the premixed combustion region as shown in FIG. 4 is determined based on the advance correction amount of the injection start timing of the first injection and the advance correction amount of the injection start timing of the second injection. Then, fuel injection from the injector 23 is executed.

  It should be noted that the advance angle correction amount map for the first injection shown in FIG. 11A and the advance angle correction amount map for the second injection shown in FIG. 11B are respectively prepared in advance by experiments, simulations, or the like. It is stored in the ROM 102 of the ECU 100.

  For example, when the engine speed is relatively high and the engine torque is put into a combustion state by the above control procedure, the fuel injection amount of the first injection of the premixed injection is reduced and the fuel of the second injection is used. By setting a fuel injection pattern in which the injection amount is increased, for example, the fuel injection pattern shown in FIG. 6A, the degree of premixed combustion in the premixed combustion region is reduced (the degree of diffusion combustion in the premixed combustion region is increased). be able to. As a result, a preheating function and a torque increase can be realized in the premixed combustion region, and a sufficient engine torque can be secured.

  On the other hand, for example, when the engine speed is relatively low and the combustion state is focused on reducing emissions, the fuel injection amount of the first injection of the premixed injection is increased and the fuel injection amount of the second injection is increased. Is set (for example, the fuel injection amount of the second injection is “0”), for example, the fuel injection pattern shown in FIG. Can be maximized. Thereby, the NOx generation amount and the smoke generation amount can be suppressed.

  As described above, in the present embodiment, the fuel injection amount ratio between the first injection and the second injection in the premixed combustion region is adjusted according to the engine operating state, so that the combustion mode (premixed combustion in the premixed combustion region) is adjusted. Degree) can be continuously changed, which makes it possible to realize an appropriate combustion mode according to the engine operating condition, and to meet various demands such as improvement of exhaust emission and sufficient securing of engine torque. Can do.

  Here, in the present embodiment, the required heat amount in the premixed combustion region can be set variably, and when the engine operating state is regarded as important in preheating, the required heat amount (fuel injection amount) in the premixed combustion region is set to While increasing the amount, the required heat amount (fuel injection amount) of the main combustion amount is reduced. On the other hand, when the engine operation state is focused on torque, the required heat amount (fuel injection amount) in the premixed combustion region is reduced and the required heat amount (fuel injection amount) of the main combustion amount is increased.

  The fuel injection pattern of the main injection may be the same, the fuel injection pattern of the main injection can be adjusted, and the fuel injection amount (fuel injection period) of the main injection can be increased or decreased according to the engine operating state. You may comprise.

-Other control parameters-
In the present embodiment, the degree of premixed combustion in the premixed combustion region is increased by adjusting the in-cylinder gas state before fuel injection with the fuel injection pattern of the fuel injected from the injector 23 fixed. May be.

  Specifically, by increasing the opening degree of the EGR valve 81 and increasing the EGR amount, the in-cylinder oxygen concentration is reduced and the degree of premix combustion in the premix combustion region is increased. When the in-cylinder oxygen concentration is reduced in this way, the premixed combustion region in the premixed combustion region becomes higher due to the reduction in the in-cylinder oxygen concentration, and as shown in FIG. When the center of gravity (combustion center of gravity (heat generation rate peak) of combustion by the first injection) approaches TDC (compression top dead center of piston 13), the necessity of setting the ignition timing of the main combustion region to TDC is reduced. The main combustion is retarded (the main injection is retarded). When retarding such main combustion (diffusion combustion), the amount of NOx can be reduced.

  Also, when the EGR amount is increased to reduce the in-cylinder oxygen concentration and increase the degree of premixed combustion in the premixed combustion region, the premixed combustion in the premixed combustion region is reduced by reducing the in-cylinder oxygen concentration. As the degree increases, as shown in FIG. 13, the combustion center of gravity of the premixed combustion region (combustion center of gravity of combustion by the second injection (heat generation rate peak)) approaches TDC (compression top dead center of the piston 13). Therefore, when the premixed combustion is not completed by TDC, the first injection and the second injection of the premixed combustion injection are performed in order to fix the ignition timing of the main combustion (fixed to TDC ignition). By advancing both together (advancing the entire premixed combustion region), combustion in the premixed combustion region can be completed by TDC. However, since the unburned HC (hydrocarbon) increases when the first injection is advanced too much, it is necessary to limit the advance amount of the first injection with a guard value in order to suppress this.

  When the premixed injection is advanced, if only the first injection is advanced, the combustion by the second injection becomes diffusion combustion and smoke may be generated. As described above, the first injection and the first injection are performed. It is necessary to advance the two injections together.

  Moreover, the premixed combustion degree in the premixed combustion region may be increased by reducing the pre-ignition pressure in the cylinder, which is a parameter for setting the in-cylinder gas state before fuel injection. Specifically, the pre-ignition pressure in the cylinder is reduced by operating the nozzle vane opening (VN opening) provided in the variable nozzle vane mechanism 54 of the turbocharger 5 to reduce the intake air amount. Thus, the degree of premixed combustion in the premixed combustion region may be increased. Further, the degree of premixed combustion in the premixed combustion region may be increased by reducing the intake air amount by reducing the throttle valve (intake throttle valve) 62 and reducing the pre-ignition pressure in the cylinder. . Furthermore, the pressure before ignition in the cylinder may be lowered by combining the reduction of the intake air amount by the turbocharger 5 and the reduction of the intake air amount by the throttle valve 62.

  Even when the premixed combustion region in the premixed combustion region is increased by reducing the pre-ignition pressure in the cylinder in this way, as described above, the combustion center of gravity (by the first injection) When the combustion gravity center of combustion) approaches TDC, the main combustion is retarded (main injection is retarded) to reduce the NOx amount of diffusion combustion.

  In addition, when the combustion center of gravity in the premixed combustion region (combustion center of gravity of combustion by the second injection) approaches TDC and premixed combustion is not completed by TDC, the ignition timing of main combustion is fixed. In order to (fix to TDC ignition), both the first injection and the second injection of the premixed combustion injection are advanced (the entire premixed combustion region is advanced).

-Other embodiments-
In the above example, the case where the present invention is applied to a common rail in-cylinder direct injection multi-cylinder (four-cylinder) diesel engine has been described. The present invention is not limited to this, and can be applied to a diesel engine having any number of cylinders such as a six-cylinder diesel engine. The engine to which the present invention is applicable is not limited to an automobile engine.

  In the above example, the engine 1 to which the piezo injector 23 that changes the fuel injection rate by changing to the fully opened valve state only during the energization period has been described, but the present invention is applied to an engine to which the variable injection rate injector is applied. Is also possible.

  INDUSTRIAL APPLICABILITY The present invention can be used for combustion control of a compression self-ignition internal combustion engine represented by a diesel engine. More specifically, the present invention is effectively used when appropriately controlling the combustion mode of premixed combustion in a combustion chamber. be able to.

1 engine (internal combustion engine)
3 Combustion chamber (cylinder)
23 Injector (fuel injection valve)
23a Injector injection pressure sensor 5 Turbocharger 6 Intake system 54 Variable nozzle vane mechanism 62 Throttle valve 7 Exhaust system 8 EGR passage 81 EGR valve 100 ECU

Claims (12)

In a combustion control device for a compression self-ignition internal combustion engine in which fuel injected from a fuel injection valve burns in a combustion chamber by "premixed combustion" and "main combustion" started after this "premixed combustion"
As the fuel injection in the premixed combustion region , the first injection and the second injection can be executed, and the premixed combustion region in the premixed combustion region is changed by changing the fuel injection amount ratio between the first injection and the second injection. An injection mode adjusting means capable of increasing or decreasing the mixed combustion amount ;
The required heat amount in the premixed combustion region is the same, and the fuel injection amount ratio between the first injection and the second injection is obtained according to the operating state of the internal combustion engine, and the fuel injection amount of the first injection and the second A combustion control device for an internal combustion engine, wherein the premixed combustion amount in the premixed combustion region is continuously increased or decreased by adjusting a fuel injection amount of injection . The combustion control apparatus for an internal combustion engine according to claim 1,
The fuel injection amount of the first injection is increased and the fuel injection amount of the second injection is decreased to increase the premix combustion amount in the premix combustion region . A combustion control apparatus for an internal combustion engine. The combustion control apparatus for an internal combustion engine according to claim 1 ,
It intends to reduce the fuel injection quantity of the first injection, by going to increase the fuel injection amount of the second injection, that is configured to reduce the premixed combustion amount of the premixed combustion region A combustion control apparatus for an internal combustion engine. The combustion control apparatus for an internal combustion engine according to any one of claims 1 to 3 ,
By fixing the injection end timing of the first injection and the injection end timing of the second injection, respectively, and adjusting the injection start timing of the first injection and the injection start timing of the second injection, respectively. combustion control device for an internal combustion engine, characterized that you set the respective fuel injection quantity of 2 injection. The combustion control apparatus for an internal combustion engine according to any one of claims 1 to 4 ,
An oxygen concentration adjusting means capable of adjusting an in-cylinder oxygen concentration, and when the in-cylinder oxygen concentration is reduced and the combustion center of gravity of the premixed combustion region is close to the compression top dead center of the piston, combustion control device for an internal combustion engine, characterized in retard to Rukoto fuel injection combustion zone. The internal combustion engine combustion control device according to any one of claims 1 to 4 ,
A pressure adjusting means capable of adjusting the pre-ignition pressure in the cylinder, and when the pre-ignition pressure in the cylinder is reduced, the combustion center of gravity of the premixed combustion region is close to the compression top dead center of the piston; A combustion control device for an internal combustion engine, which retards fuel injection in the main combustion region . The combustion control device for an internal combustion engine according to any one of claims 1 to 4 ,
An adjustable oxygen concentration adjusting means the oxygen concentration in the cylinder, upon reducing said cylinder oxygen concentration, if those premixing combustion in the premixed combustion territory within no completed, the first injection and second 2. A combustion control apparatus for an internal combustion engine, wherein two injections are advanced . The combustion control device for an internal combustion engine according to any one of claims 1 to 4 ,
An adjustable pressure regulator means pre-ignition pressure in the cylinder, when the pressure was decreased before ignition in the cylinder, if the person premixing combustion in the premixed combustion territory within no completed, the first A combustion control device for an internal combustion engine, wherein the injection and the second injection are advanced . The combustion control apparatus for an internal combustion engine according to claim 5 or 7 ,
The oxygen concentration adjusting means is an exhaust gas recirculation device that recirculates a part of the exhaust gas discharged into the exhaust system of the internal combustion engine to the intake system, and the exhaust gas recirculation device controls a recirculation amount of the exhaust gas to the intake system. by increasing the combustion control apparatus for an internal combustion engine, it characterized that you have been configured to reduce the cylinder oxygen concentration. The combustion control device for an internal combustion engine according to claim 6 or 8 ,
The pressure adjusting means is a supercharging device that supercharges intake air in the intake system, and is configured to reduce the pre-ignition pressure in the cylinder by reducing the amount of intake air by the supercharging device. A combustion control apparatus for an internal combustion engine. The combustion control device for an internal combustion engine according to claim 6 or 8 ,
The pressure adjusting means is an intake throttle valve that adjusts the intake air amount in the intake system, and is configured to reduce the pre-ignition pressure in the cylinder by reducing the intake air amount by the intake throttle valve. A combustion control device for an internal combustion engine. The combustion control device for an internal combustion engine according to claim 10 or 11 ,
The supercharging device and the intake throttle valve are provided, and the pressure before ignition in the cylinder is reduced by combining the reduction of the intake air amount by the supercharging device and the reduction of the intake air amount by the intake throttle valve. A combustion control device for an internal combustion engine, characterized in that

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