JPWO2012029180A1 - Fuel injection control device for internal combustion engine - Google Patents

Abstract

The “pre-after-injection spray occupation volume Vfuel”, which is the volume of fuel injected into the combustion chamber (3) until after-injection is executed, is calculated for each crank angle. Further, the “in-cylinder volume Vcyl (θ)”, which is the volume in the combustion chamber (3) that increases as the piston (13) moves from the compression top dead center toward the bottom dead center. Calculate for each crank angle. The “remaining air volume Vair (θ)” is calculated for each crank angle by subtracting the “pre-after-injection spray occupation volume Vfuel” from the “in-cylinder volume Vcyl (θ)”. When it is assumed that after-injection has been executed, the “after-injection spray volume Vafter” at the end of execution of the after-injection is calculated, and the “remaining air volume Vair (θ)” is equal to or greater than “after-injection spray volume Vafter”. When it reaches, after injection is executed.

Description

  The present invention relates to a fuel injection control device for an internal combustion engine represented by a diesel engine. In particular, the present invention relates to a countermeasure for optimizing the injection mode of after injection (hereinafter also referred to as sub-injection) performed after main injection (hereinafter also referred to as main injection).

  As is well known in the art, in a diesel engine used as an automobile engine or the like, a fuel injection valve (hereinafter referred to as an injector) may be used depending on the engine speed, accelerator operation amount, cooling water temperature, intake air temperature, and the like. The fuel injection control for adjusting the fuel injection amount and the fuel injection timing is performed.

  By the way, in the expansion (combustion) stroke of the diesel engine, when incomplete combustion of the air-fuel mixture occurs in the combustion chamber, soot is generated in the exhaust gas, leading to deterioration of exhaust emission. For example, in a situation where the required torque of the engine increases (the required torque increases due to depression of the accelerator pedal, etc.) and the fuel injection amount from the injector is increased, the target fuel injection amount (the fuel that generates the required torque is generated only by main injection) If fuel injection is performed so that an injection amount) can be obtained, soot exceeding the allowable amount may occur due to insufficient oxygen in the combustion field.

  In view of this point, the fuel injection amount in the main injection is defined as an amount that can be controlled by the soot (for example, a fuel injection amount that can suppress the soot generation amount to an allowable amount or less), and a shortage of torque generated in the main injection In order to compensate for this, after-injection is performed. That is, after the main injection is performed, after injection is performed after a predetermined fuel injection stop period (interval), and the air utilization rate in the combustion chamber is increased to suppress the generation of soot, but the injection is performed by this after injection. Torque is generated by fuel combustion, and the required torque is obtained by compensating for the shortage of torque generated by combustion in the main injection.

  When such after-injection is executed, the after-injection injection mode is appropriately set so that incomplete combustion of the air-fuel mixture generated by the fuel injected by this after-injection does not occur, that is, soot does not occur. It becomes necessary to do.

  In view of this point, for example, in Patent Document 1 below, exhaust emission is improved by setting the injection timing of fuel injection performed after main injection to the time when the in-cylinder temperature reaches the target temperature. I have to. In Patent Document 2, the generation of soot is suppressed by providing a plurality of injectors for one cylinder and increasing the air utilization rate in the combustion chamber.

  In addition, as another technique, a method of providing a plurality of fuel supply systems having different fuel pressures and appropriately changing the fuel injection rate by selecting a fuel supply system to be used, thereby generating a spray capable of suppressing soot. Etc. are also proposed.

JP 2000-45828 A JP 2009-30517 A

  By the way, the fuel injection timing and fuel injection amount (injection timing and injection amount of the above-described after injection) as described above are adapted by trial and error (construction of an injection pattern suitable for each engine type). To obtain).

  For this reason, after-injection is executed by the above-described trial and error, and only the fuel injection timing and the fuel injection amount capable of reducing the soot are acquired as the appropriate values.

  As described above, as a fuel injection mode for reducing the soot amount in the exhaust gas, a systematic fuel injection control method common to various engines has not yet been established.

  In addition, the technique disclosed in Patent Document 2 and the apparatus provided with a plurality of fuel supply systems having different fuel pressures are not practical because the fuel supply system becomes complicated and the manufacturing cost increases. there were.

  In view of the above, the inventor of the present invention has made it possible to quantitatively handle the use of air in the combustion chamber and to construct a systematic after-injection mode setting method common to various engines. It was.

  The present invention has been made in view of this point, and an object of the present invention is to obtain an after-injection injection mode that can suppress the generation of soot by quantitatively handling the use of air in the combustion chamber. An object of the present invention is to provide a fuel injection control device for an internal combustion engine.

-Principle of solving the problem-
The solution principle of the present invention taken in order to achieve the above object is to determine the volume of the space used for the combustion of the fuel injected into the cylinder before the after injection is performed. And at the timing when the residual air volume (volume of unused space for combustion) that expands as the piston moves toward the bottom dead center side becomes equal to or higher than the spray volume when after injection is performed, Assuming that almost the entire amount of spray in the after-injection can use the remaining air in the cylinder (after-spray spray does not reach the space already used for combustion), the after-injection is executed at this timing. ing.

-Solution-
Specifically, according to the present invention, during one cycle of the internal combustion engine, the fuel injection valve performs main injection, which is fuel injection for generating torque, and after injection, which is fuel injection performed after execution of the main injection. A fuel injection control device for a compression self-ignition internal combustion engine capable of performing a plurality of fuel injections is included. The fuel injection control device of the internal combustion engine is provided with a pre-after-injection spray occupied volume calculation means, a remaining air volume calculation means, an after-injection spray volume calculation means, and an after-injection permission means. The pre-after-injection spray occupancy volume calculating means is a volume in which the fuel spray injected from the fuel injection valve during the same cycle as the after-injection occupies the space in the combustion chamber before the after-injection is executed. “Spray occupied volume before after injection” is calculated for each crank angle. The residual air volume calculation means subtracts the “spray occupancy volume before after injection” for each crank angle from the “in-cylinder volume” calculated for each crank angle, thereby obtaining “ “Remaining air volume” is calculated. When it is assumed that the after-injection has been executed, the after-injection spray volume calculating means is the volume that occupies the space in the combustion chamber when the spray of fuel injected by the after-injection is completed. The “spraying spray volume” is calculated. The after-injection permitting means is configured so that when the “residual air volume” calculated by the residual air volume calculating means reaches or exceeds the “after-injection spray volume” calculated by the after-injection spray volume calculating means, the fuel injection valve Allow after-injection.

  Due to this specific matter, after-injection performed after execution of main injection is performed when the “remaining air volume” exceeds the “after-injection spray volume” (the “remaining air volume” reaches the “after-injection spray volume”). Or after the “residual air volume” reaches the “after spray spray volume”. When after-injection is executed at this timing, substantially the entire amount of spray in this after-injection can use the remaining air in the cylinder (the “remaining air volume” air). In other words, the after-injection spray does not reach the space of the “pre-after-injection spray occupied volume”, which is the volume of the combustion field of the fuel injected into the cylinder until after-injection is executed. Oxygen shortage does not occur in the combustion field of the fuel injected at, and as a result, the generation of soot due to this after injection is suppressed.

  Examples of the method for setting the injection amount of the after injection include the following. In other words, the injection amount of the main injection is set to an amount in which the soot amount generated by combustion in the combustion chamber is equal to or less than a preset soot generation allowable amount, while the injection amount of the after injection is set to the main injection amount. This is set as an amount for obtaining a deficient torque, which is the difference between the torque generated by the combustion of the fuel injected in step 1 and the torque required for the internal combustion engine.

  According to this, the torque required for the internal combustion engine is obtained by the torque generated by the fuel injected by the after-injection while suppressing the amount of soot generated due to the fuel injected by the main injection to an allowable amount or less. be able to. Further, as described above, since the generation of soot due to after-injection is suppressed, it is possible to ensure both the performance of the internal combustion engine and the improvement of exhaust emission.

  The timing at which the after injection is actually executed is after the fuel injection prohibition period set after the end of the main injection and when the “remaining air volume” is equal to or greater than the “after injection spray volume”. Set as That is, in consideration of the fuel injection prohibition period determined by the responsiveness of the fuel injection valve (the speed of the opening / closing operation), after the fuel injection prohibition period has elapsed, the “remaining air volume” becomes “after injection spray volume” After-injection is executed at a certain timing.

  Specific examples of the combustion field of the fuel injected by the after injection include the following. First, the fuel injection valve is disposed so as to inject fuel from the central portion of the combustion chamber toward the outer peripheral portion, and the spray of fuel injected from the fuel injection valve until the after injection is executed, The fuel spray injected from the fuel injection valve as the after-injection has the above-mentioned “after-injection spray volume” at the central portion in the combustion chamber, while having the “pre-after-injection spray occupied volume” in the outer periphery of the combustion chamber. "have.

  In other words, the combustion field of the fuel injected by the after-injection is present in the center of the combustion chamber rather than the combustion field of the fuel injected until after-injection is executed. After-injection is executed when the “remaining air volume” becomes equal to or greater than the “after-injection spray volume”.

  The following can be cited as a configuration that takes into account fluctuations in fuel pressure that occur after the end of main injection. That is, when it is assumed that the after-injection spray volume calculating means has executed the after-injection based on the fluctuation of the fuel pressure accompanying the execution of the main injection, the after-injection is completed. Further, the “after-injection spray volume”, which is the volume in which the fuel spray occupies the space in the combustion chamber, is calculated.

  More specifically, the after-injection spray volume calculating means calculates the “after-injection spray volume” based on the fuel pressure inside the fuel injection valve that fluctuates after the end of the main injection.

  The “after-injection spray volume” for each crank angle also varies due to the variation in fuel pressure generated after the end of main injection. That is, there is a possibility that a state where the “remaining air volume” is greater than or equal to the “after-injection spray volume” and a state where the “remaining air volume” is less than the “after-injection spray volume” may occur alternately. If after-injection is executed in a state where the “remaining air volume” is less than the “after-injection spray volume”, the fuel injected by the after-injection reaches the space of the “pre-after-injection spray occupied volume”. There is a possibility that the amount of generated Soot will increase. For this reason, in such a situation where the “after-injection spray volume” fluctuates, the “after-injection spray volume” is calculated in consideration of the fluctuation of the fuel pressure that occurs after the end of the main injection. After-injection is executed at a time when the state is equal to or greater than the “after-injection spray volume”. As a result, even if the fuel pressure fluctuates, there is no shortage of oxygen in the combustion field of fuel injected by after injection, and as a result, the generation of soot due to this after injection is suppressed. become.

  In the present invention, the volume of the space used for the combustion of the fuel injected into the cylinder is calculated before the after injection is performed, and the volume of the space unused for the combustion is executed after the injection. After spraying is executed at a timing when the volume of the spray becomes equal to or greater than the spray volume. For this reason, generation | occurrence | production of Soot resulting from after injection can be suppressed.

FIG. 1 is a diagram illustrating a schematic configuration of an engine and a control system thereof according to the embodiment. FIG. 2 is a cross-sectional view showing a combustion chamber of a diesel engine and its peripheral part. FIG. 3 is a block diagram showing a configuration of a control system such as an ECU. FIG. 4 is a schematic diagram of an intake / exhaust system and a combustion chamber for explaining the outline of the combustion mode in the combustion chamber. FIG. 5 is a cross-sectional view showing the combustion chamber and its surroundings during fuel injection. FIG. 6 is a plan view of the combustion chamber during fuel injection. FIG. 7 is a flowchart showing a procedure of after injection execution timing control in the first embodiment. FIG. 8A shows the relationship between the total fuel injection amount and the soot generation amount, and FIG. 8B shows the relationship between the required torque and the fuel injection amount in each of the main and after injections. FIG. 9 is a diagram showing the relationship between the fuel injection pressure and the spray volume. FIG. 10 is a diagram illustrating changes in the in-cylinder volume, the pre-after-injection spray occupation volume, the remaining air volume, and the after-injection spray volume in the first embodiment. FIG. 11 is a flowchart showing a procedure of after injection execution timing control in the second embodiment. FIG. 12 is a diagram showing a variation state of the fuel injection pressure accompanying the execution of the main injection. FIG. 13A is a diagram illustrating changes in the in-cylinder volume, the pre-after-injection spray occupation volume, the remaining air volume, and the after-injection spray volume in the second embodiment, and FIG. 13B is a diagram illustrating the execution of after-injection. It is a figure which shows the change of the residual air volume for explaining a timing, and an after injection spray volume.

  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, a schematic configuration of a diesel engine (hereinafter simply referred to as an engine) according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of an engine 1 and its control system according to the present embodiment. Moreover, FIG. 2 is sectional drawing which shows the combustion chamber 3 of a diesel engine, and its peripheral part.

  As shown in FIG. 1, the engine 1 according to the present embodiment 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 of 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.

  Further, 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 at which the exhaust A / F becomes the target A / F) by the addition control operation by the ECU 100. The 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. Further, an air cleaner 65, an air flow meter 43, and a throttle valve (intake throttle valve) 62 are arranged in this intake passage in order 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 intake system 6 is provided with a swirl control valve 66 for making the swirl flow (horizontal swirl flow) in the combustion chamber 3 variable (see FIG. 2). Specifically, as the intake port 15a, two systems, a normal port and a swirl port, are provided for each cylinder. Of these, a normal valve 15a shown in FIG. A swirl control valve 66 is disposed. An actuator (not shown) is connected to the swirl control valve 66, and the flow rate of air passing through the normal port 15a can be changed according to the opening of the swirl control valve 66 adjusted by driving the actuator. Yes. The larger the opening of the swirl control valve 66, the greater the amount of air taken into the cylinder from the normal port 15a. For this reason, the swirl generated by the swirl port (not shown in FIG. 2) is relatively weakened, and the inside of the cylinder becomes low swirl (a state where the swirl flow rate is low). Conversely, the smaller the opening of the swirl control valve 66, the smaller the amount of air drawn into the cylinder from the normal port 15a. For this reason, the swirl generated by the swirl port is relatively strengthened, and the inside of the cylinder becomes a high swirl (a state where the swirl flow rate is high).

  The exhaust system 7 includes an exhaust manifold 72 connected to the 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. In addition, a maniverter (exhaust gas purification device) 77 including 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. 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 support, and potassium (K), sodium (Na), lithium (Li), cesium (Cs), for example, is supported on this support. Alkali metal such as barium (Ba), alkaline earth such as calcium (Ca), rare earth such as lanthanum (La) and yttrium (Y), and noble metal such as platinum (Pt) were supported. It has a configuration.

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 porous ceramic structure carrying a NOx storage reduction catalyst, 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 having a relatively small volume at the center portion, and is directed toward the outer peripheral side. Thus, the space is gradually enlarged (expanded 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 the intake port 15a for introducing air into the combustion chamber 3 and the exhaust port 71 for exhausting exhaust gas from the combustion chamber 3, and intake air for opening and closing the intake port 15a. An exhaust valve 17 that opens and closes the valve 16 and the exhaust port 71 is 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 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.

  Furthermore, 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 wheel 53 that are connected via a turbine shaft 51. The compressor wheel 53 is disposed facing the intake pipe 64, and the turbine wheel 52 is disposed facing the exhaust pipe 73. For this reason, the turbocharger 5 performs a so-called supercharging operation in which the compressor wheel 53 is rotated using the exhaust flow (exhaust pressure) received by the turbine wheel 52 to increase the intake pressure. The turbocharger 5 in the present embodiment is a variable nozzle type turbocharger, and a variable nozzle vane mechanism (not shown) is provided on the turbine wheel 52 side. By adjusting the opening of the variable nozzle vane mechanism, the engine 1 supercharging pressure 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 provided further downstream than the intercooler 61 is an electronically controlled on-off valve whose opening degree can be adjusted steplessly. It has a function of narrowing down the area and adjusting (reducing) the supply amount of the intake air.

  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 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. 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 output interface 106 is connected to the supply pump 21, the injector 23, the fuel addition valve 26, the throttle valve 62, the swirl control valve 66, the EGR valve 81, and the like. In addition, an actuator (not shown) provided in the variable nozzle vane mechanism of the turbocharger 5 is also connected to the output interface 106.

  Then, the ECU 100 executes various controls of the engine 1 based on outputs from the various sensors described above, calculated values obtained by arithmetic expressions using the output values, or various maps stored in the ROM 102. .

  For example, the ECU 100 controls the opening degree of the EGR valve 81 according to the operating state of the engine 1 and adjusts the exhaust gas recirculation amount (EGR amount) toward the intake manifold 63. The EGR amount is set according to an EGR map stored in advance in the ROM 102. Specifically, this EGR map is a map for determining the EGR amount (EGR rate) using the engine speed and the engine load as parameters. This EGR map is created in advance by experiments, simulations, or the like. That is, by applying the engine speed calculated based on the detection value of the crank position sensor 40 and the opening of the throttle valve 62 (corresponding to the engine load) detected by the throttle opening sensor 42 to the EGR map. An EGR amount (opening degree of the EGR valve 81) is obtained.

  Further, the ECU 100 executes the opening degree control of the swirl control valve 66. In order to control the opening degree of the swirl control valve 66, the amount of movement of the fuel spray injected into the combustion chamber 3 per unit time (or per unit crank rotation angle) in the circumferential direction in the cylinder is changed. Is called.

  Further, the ECU 100 executes pilot injection, pre-injection, main injection (main injection), after injection (sub-injection), post injection, and the like as fuel injection control of the injector 23.

-Fuel injection mode-
Hereinafter, an outline of each operation of the pilot injection, pre-injection, main injection, after-injection, and post-injection in the present embodiment will be described.

(Pilot injection)
The pilot injection is an operation for injecting a small amount of fuel in advance prior to the main injection from the injector 23. That is, after the pilot injection is performed, the fuel injection is temporarily interrupted, and the compressed gas temperature (in-cylinder temperature) is sufficiently increased until the main injection is started to reach the fuel self-ignition temperature. This ensures good ignitability of the fuel injected in the main injection. That is, the pilot injection function in this embodiment is specialized for preheating in the cylinder. In other words, the pilot injection in this embodiment is an injection operation (preheating fuel supply operation) for preheating the gas in the combustion chamber 3.

(Pre-injection)
Pre-injection is an injection operation in which a small amount of fuel is injected in advance prior to main injection from the injector 23. The pre-injection is an injection operation for suppressing the ignition delay of the fuel due to the main injection and leading to stable diffusion combustion. Further, the pre-injection in the present embodiment has not only a function of suppressing the initial combustion speed by the main injection described above but also a preheating function of increasing the in-cylinder temperature. Thereby, it is possible to reliably suppress the initial combustion speed by the main injection and lead to stable diffusion combustion.

(Main injection)
The main injection is an injection operation (torque generation fuel supply operation) for generating torque of the engine 1. The injection amount in the main injection is basically determined so as to obtain the required torque according to the operation state such as the engine speed, the accelerator operation amount, the coolant temperature, the intake air temperature, and the like. 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). As the accelerator opening becomes larger, the required torque value of the engine 1 is higher, and accordingly, the fuel injection amount in the main injection is also set higher.

  Further, the fuel injection amount in the main injection is limited so that the amount of soot generated by the combustion of the air-fuel mixture in the combustion chamber 3 is equal to or less than a predetermined allowable limit amount. The limitation on the fuel injection amount in the main injection will be described later.

(After spray)
After-injection is a fuel injection operation characterized in this embodiment. As will be described in detail later, when all of the fuel injection amount for obtaining the torque required for the engine 1 is executed by the main injection, in a situation where the generated amount of soot exceeds the allowable limit amount, the exhaust emission is reduced. It will worsen. For this reason, the fuel injection amount in the main injection is suppressed to an amount that suppresses the soot (a fuel injection amount that can suppress the soot generation amount to an allowable limit amount or less), and the shortage of the torque generated in the main injection is compensated. After-injection is executed as fuel injection for the purpose. In other words, after executing the main injection, after injection is performed at a predetermined timing after a predetermined fuel injection stop period (interval), while increasing the air utilization rate in the combustion chamber 3 and suppressing the generation of soot, Torque is generated by the combustion of the fuel injected by the after injection, and the required torque is obtained by compensating for the shortage of the torque generated by the combustion by the main injection. Details of the injection timing control of the after injection will be described later.

  In addition, this after injection increases the exhaust gas temperature to raise the temperature of each of the catalysts 75 and 76 to the activation temperature, raises the temperature of the DPNR catalyst 76 to the filter regeneration temperature during PM regeneration, The function of supplying unburned fuel components to the catalysts 75 and 76 is exhibited as necessary.

(Post injection)
The post-injection is an injection operation for directly introducing fuel into the exhaust system 7 to increase the temperature of the manipulator 77. For example, when the accumulated amount of PM trapped in the DPNR catalyst 76 exceeds a predetermined amount (for example, detected by detecting a differential pressure before and after the manipulator 77), post injection is performed. .

-Fuel injection pressure-
The fuel injection pressure at the time of executing each fuel injection described above 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 the engine speed (engine speed) increases. It will 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. In the present embodiment, the fuel pressure is adjusted between 30 MPa and 200 MPa according to the engine load and the like.

  Regarding the fuel injection parameters such as the pilot injection and the main injection, the optimum values differ depending on the engine operating state and the temperature conditions such as 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 and the fuel injection form based on the engine operating state. Specifically, the ECU 100 calculates the engine rotation speed based on the detection value of the crank position sensor 40, obtains the amount of depression of the accelerator pedal (accelerator opening) based on the detection value of the accelerator opening sensor 47, Based on the engine speed and the accelerator opening, fuel injection timing and fuel injection amount in pilot injection, main injection, and the like are determined.

-Outline of combustion mode-
Next, the outline of the combustion mode in the combustion chamber 3 in the engine 1 according to the present embodiment will be described.

  In FIG. 4, gas (air) is sucked into one cylinder of the engine 1 through the intake manifold 63 and the intake port 15 a, and combustion is performed by fuel injection from the injector 23 into the combustion chamber 3. FIG. 6 is a diagram schematically showing how the subsequent gas is discharged to the exhaust manifold 72 through the exhaust port 71.

  As shown in FIG. 4, the gas sucked into the cylinder includes fresh air sucked from the intake pipe 64 through the throttle valve 62 and from the EGR passage 8 when the EGR valve 81 is opened. Inhaled EGR gas is included. The ratio of the amount of EGR gas to the sum of the amount of fresh air (mass) to be sucked and the amount of mass of EGR (mass) to be sucked (that is, the EGR rate) is appropriately controlled by the ECU 100 according to the operating state. It changes according to the opening degree of 81.

  The fresh air and EGR gas sucked into the cylinder in this way are sucked into the cylinder as the piston 13 (not shown in FIG. 4) descends via the intake valve 16 which is opened in the intake stroke. It becomes in-cylinder gas. This in-cylinder gas is sealed in the cylinder by closing the intake valve 16 when the valve is determined according to the operating state of the engine 1 (in-cylinder gas confinement state), and in the subsequent compression stroke The piston 13 is compressed as the piston 13 moves up. When the piston 13 reaches the vicinity of the top dead center, the injector 23 is opened for a predetermined time by the injection amount control by the ECU 100 described above, so that the fuel is directly injected into the combustion chamber 3. Specifically, the pilot injection is performed before the piston 13 reaches the top dead center, and after the fuel injection is temporarily stopped, after a predetermined interval, the piston 13 reaches the vicinity of the top dead center. The main injection is executed. Moreover, after this main injection is performed, the said after injection and post injection are performed through a predetermined interval as needed.

  FIG. 5 is a cross-sectional view showing the combustion chamber 3 and its peripheral part at the time of this fuel injection (main injection), and FIG. ). As shown in FIG. 6, the injector 23 of the engine 1 according to the present embodiment is provided with eight injection holes at equal intervals in the circumferential direction, and fuel is injected equally from these injection holes. It has become so. The number of nozzle holes is not limited to eight.

  The fuel sprays A, A,... Injected from the nozzle holes diffuse in a substantially conical shape. Further, since fuel injection from each nozzle hole (particularly main injection) is performed when the piston 13 reaches the vicinity of compression top dead center, as shown in FIG. Will diffuse in the cavity 13b.

  As described above, the fuel sprays A, A,... Injected from the respective injection holes formed in the injector 23 are mixed with the in-cylinder gas with the passage of time and become air-fuel mixtures in the cylinder. It diffuses in a conical shape and burns by self-ignition. That is, each of the fuel sprays A, A,... Forms a substantially conical combustion field together with the in-cylinder gas, and combustion is started in each of the combustion fields (eight combustion fields in this embodiment). It will be.

  And most of the energy generated by this combustion is obtained as kinetic energy (energy that becomes engine output) for pushing down the piston 13 toward the bottom dead center.

  The in-cylinder gas after combustion is discharged to the exhaust port 71 and the exhaust manifold 72 as the piston 13 rises through the exhaust valve 17 that opens in the exhaust stroke, and becomes exhaust gas.

-After injection execution timing control-
Next, a plurality of embodiments of after injection execution timing control, which is an operation characteristic of the present embodiment, will be described. As described above, when all of the fuel injection amount required to obtain the torque required for the engine 1 (requested torque) is executed by the main injection, in a situation where soot exceeding the allowable limit amount occurs, the exhaust emission is deteriorated. I will invite you. For this reason, the fuel injection amount in the main injection is suppressed to an amount that suppresses the soot (a fuel injection amount that can suppress the soot generation amount to an allowable limit amount or less), and the shortage of the torque generated in the main injection is compensated. After-injection is executed as fuel injection for the purpose.

  The after injection execution timing control in the present embodiment allows the required torque to be obtained by combustion of the fuel injected by the after injection (while making up for the shortage of torque generated by the main injection). This is to suppress the generation amount of soot accompanying the combustion of the fuel injected into the combustion chamber 3 by this after injection (suppress to below the allowable limit amount).

(First embodiment)
First, the first embodiment will be described. The outline of the after-injection execution timing control in the first embodiment will be described. First, fuel injected into the combustion chamber 3 until after-injection is executed (mainly fuel injected in the main injection (the above-described fuel injection) When pilot injection or pre-injection is executed, the volume occupied by the fuel in the combustion chamber 3 (hereinafter referred to as “spray occupied volume before after-injection Vfuel”) is crank angle. It is calculated every time (the operation of calculating “spray occupied volume before fuel injection Vfuel” by the pre-after spray spray occupied volume calculating means). The spray having the “spread occupied volume Vfuel before after-injection” is directed toward the outer peripheral side in the combustion chamber 3 (for example, in the cavity 13b) by penetration (penetration force) when fuel is injected from the injector 23. It will expand. That is, the spray having the “spray occupied volume Vfuel before after injection” occupies the space on the relatively outer peripheral side in the combustion chamber 3 instead of the central portion in the combustion chamber 3.

  Further, the volume in the combustion chamber 3 that increases as the piston 13 moves from the compression top dead center toward the bottom dead center (hereinafter referred to as “cylinder volume Vcyl (θ)”). Calculate for each crank angle.

  Then, by subtracting “pre-after-spray occupancy volume Vfuel” from the “in-cylinder volume Vcyl (θ)”, the volume of the space in the combustion chamber 3 where the air that has not yet contributed to the combustion exists (hereinafter referred to as the volume before fuel injection). , Referred to as “residual air volume Vair (θ)”) for each crank angle (calculation operation of “residual air volume Vair (θ)” by the residual air volume calculating means). As described above, the spray having the “spray occupied volume Vfuel before after-injection” occupies a relatively outer space in the combustion chamber 3, whereas the air having the “remaining air volume Vair (θ)” A space in the center of the combustion chamber 3 is occupied.

  Further, when it is assumed that after injection has been executed, the volume in which the spray of fuel injected by this after injection at the end of execution of the after injection (at the end of after injection) occupies the space in the combustion chamber 3 (Hereinafter referred to as “after-injection spray volume Vafter”) (calculation operation of “after-injection spray volume Vafter” by the after-injection spray volume calculating means). Then, the “remaining air volume Vair (θ)” and the “after-injection spray volume Vafter” are compared for each crank angle, and the “remaining air volume Vair (θ)” is equal to or greater than the “after-injection spray volume Vafter”. After injection, after-injection from the injector 23 is executed (after-injection permission by after-injection permission means).

  Hereinafter, after injection execution timing control in the present embodiment will be specifically described. FIG. 7 is a flowchart showing the procedure of the after injection execution timing control. This flowchart is executed every time the combustion stroke of each cylinder is performed. When after injection is performed in the combustion stroke, the after injection execution timing is calculated, and the after injection is executed according to the calculation result. It has become.

  First, in step ST1, it is determined whether there is an after injection execution request. This after-injection execution request is a situation where the amount of generated Soot exceeds the allowable limit amount when it is assumed that all of the fuel injection amount for obtaining the torque required for the engine 1 is executed by the main injection as described above. Occurs when In other words, after the fuel injection amount in the main injection is suppressed so that the soot generation amount is less than or equal to the allowable limit amount, an after injection execution request is generated, and the execution of the after injection causes a shortage of torque generated in the main injection. Will make up for the minute.

  FIG. 8A shows the relationship between the total fuel injection amount and the soot generation amount, and FIG. 8B shows the relationship between the required torque and the fuel injection amounts of the main injection and the after injection. . As shown in these figures, when the soot generation amount that increases as the total fuel injection amount increases reaches the soot generation amount allowable limit, the after injection is executed (after injection ON). . That is, the total fuel injection amount (the total injection amount of the fuel injection amount for in-cylinder preheating and the fuel injection amount for obtaining the required torque) is a predetermined amount (total fuel injection amount indicated by a broken line in the figure). If it exceeds, the injection amount in the main injection is suppressed to a constant amount (so that the soot generation amount can be suppressed below the allowable limit of soot generation amount: refer to the main injection amount indicated by a one-dot chain line in FIG. 8B) ) By executing after injection (refer to the after injection amount indicated by a two-dot chain line in FIG. 8B), the total fuel injection amount is secured to compensate for the shortage of torque.

  More specifically, since the injection timing of the after injection is set to be retarded from the injection timing of the main injection, in this after injection, the torque generation amount (conversion efficiency to torque) with respect to the unit fuel injection amount is the main. It will be lower than the injection. For this reason, in order to obtain the required torque, the fuel injection amount in the after injection is corrected to increase as the injection timing of the after injection is set to the retard side. That is, the total fuel injection amount is increased by an amount corresponding to the increase correction of the after injection.

  Even when there is no after injection execution request, that is, when all of the fuel injection amount for obtaining the torque required for the engine 1 is executed by the main injection, the generation amount of the soot can be suppressed (the soot generation amount is allowed). If it can be suppressed below the limit), a NO determination is made in step ST1, and after-injection is not executed, until the next combustion stroke is performed (the piston 13 of the cylinder that reaches the next combustion stroke is compressed) Wait until it reaches near the dead center.

  If there is an after injection execution request and the determination in step ST1 is YES, the process proceeds to step ST2 to calculate the pre-after injection spray occupation volume Vfuel. The pre-after-injection spray occupation volume Vfuel is the amount of fuel injected into the combustion chamber 3 until after-injection is executed, such as the pilot injection, pre-injection, and main injection (hereinafter referred to as main injection). The volume occupied by the spray (combustion field) in the combustion chamber 3. The pre-after-injection spray occupation volume Vfuel expands in the combustion chamber 3 toward the outer peripheral side as the crank angle advances due to penetration of the fuel injected by main injection or the like. Note that the spray of fuel injected from the injector 23 moves from the central portion in the combustion chamber 3 toward the outer peripheral portion. However, in the state where the spray is in the central portion in the combustion chamber 3, the fuel is still burned. Is not started (the combustible air-fuel ratio is not reached), and the air (oxygen) existing in the center of the combustion chamber 3 is not consumed.

Specifically, for example, the following formulas (1) to (4) (Guang's formula) can be used as a method of calculating the spray occupied volume Vfuel before after-injection. Equations (1) and (2) are equations for calculating the spray length S of fuel injected by main injection or the like. Equation (1) shows that the elapsed time t from the start of fuel injection is the droplet breakup time t. a calculation formula for the spray length S to reach _b, equation (2) is a calculation formula of the spray length S in after the elapsed time t from the start of fuel injection has passed a droplet splitting time t _b . Equation (3) is a formula for calculating the spray angle θ of fuel injected by main injection or the like. Moreover, Formula (4) calculates the spray volume V (equivalent to the said spray occupation volume Vfuel before after injection) using the spray length S and spray angle (theta) obtained by said Formula (1)-Formula (3). It is a formula.

  Further, instead of the above formulas (1) to (4), the spray volume map (map for obtaining the spray volume based on the injection pressure) shown in FIG. It is also possible to determine the pre-injection spray occupation volume Vfuel.

  After calculating the spray occupation volume Vfuel before after injection in this way, the process proceeds to step ST3, where the in-cylinder volume Vcyl (θ) is calculated. This in-cylinder volume Vcyl (θ) gradually increases as the piston 13 moves from the compression top dead center toward the bottom dead center. That is, the inner diameter dimension of the cylinder bore 12 and the moving distance of the piston 13 (the distance moving toward the bottom dead center) for each rotation of the crankshaft by the unit crank angle are obtained from the engine specifications. The in-cylinder volume Vcyl (θ) can be calculated.

  FIG. 10 is a diagram showing changes in the in-cylinder volume Vcyl (θ), the pre-after-injection spray occupation volume Vfuel, the remaining air volume Vair (θ), and the after-injection spray volume Vafter. FIG. 10 shows changes in the cylinder volume Vcyl (θ), the pre-after-injection spray occupation volume Vfuel, the remaining air volume Vair (θ), and the after-injection spray volume Vafter with respect to the crank angle.

  As can be seen from FIG. 10, the in-cylinder volume Vcyl (θ) is the smallest at the compression top dead center (TDC) of the piston 13, and the crank angle advances as the piston 13 moves toward the bottom dead center. It grows gradually as you go).

  After calculating the pre-after-injection spray occupied volume Vfuel and the in-cylinder volume Vcyl (θ) as described above, the process proceeds to step ST4, and the pre-after-injection spray occupied volume Vfuel is subtracted from the in-cylinder volume Vcyl (θ). (Vcyl (θ) −Vfuel) to calculate the remaining air volume Vair (θ). This remaining air volume Vair (θ) is the volume of the space in which air that does not contribute to the combustion of the fuel injected by the main injection or the like remains.

  As can be seen from FIG. 10, the remaining air volume Vair (θ) gradually increases as the piston 13 moves toward the bottom dead center, that is, as the in-cylinder volume Vcyl (θ) increases. It will become. Further, as described above, as the spray having the spray volume Vfuel before after injection occupies the space on the relatively outer peripheral side in the combustion chamber 3, the air having the remaining air volume Vair (θ) becomes the combustion chamber. 3 occupies a central space.

  In step ST5, the after spray volume Vafter is calculated. When it is assumed that after-injection has been executed, this after-injection spray volume Vafter indicates that fuel spray injected by this after-injection at the end of execution of the after-injection (at the end of after-injection) It is the volume that occupies the space. This after-injection spray volume Vafter can also be calculated from the above formulas (1) to (4). Moreover, it is also possible to obtain the after-injection spray volume Vafter from the spray volume map shown in FIG.

  The fuel injected by this after injection has a relatively small penetration (penetration), so the penetration is small because the injection amount is smaller than the injection amount in the main injection). Will exist in the center of the. That is, the fuel in the after injection is supplied so as to substantially overlap the space where the air having the residual air volume Vair (θ) exists.

  In step ST6, the injection timing of after injection is calculated. Specifically, when the remaining air volume Vair (θ) calculated in step ST4 becomes equal to or greater than the after-injection spray volume Vafter calculated in step ST5 (Vair (θ) ≧ Vafter), the injection of after-injection Calculate as time. In FIG. 10, when the remaining air volume Vair (θ) that expands as the crank angle advances from the compression top dead center (TDC) of the piston 13 coincides with the after-injection spray volume Vafter (timing T1 in the figure). ) Is obtained as the injection timing of the after injection.

  More specifically, after-injection is executed after elapse of a predetermined interval (interval determined by the responsiveness of the injector 23 (speed of opening / closing operation) (fuel injection inhibition period)) after execution of main injection. The injection timing of this after injection is calculated as the timing after the elapse of this interval and the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. In other words, the injection timing of the after injection is calculated as the later time of the time when the predetermined interval has passed and the time when the remaining air volume Vair (θ) becomes equal to or greater than the after-injection spray volume Vafter. Become.

  After calculating the injection timing of after injection in this way, in step ST7, it is determined whether or not the current crank rotation angle has become the injection timing of after injection (the injection timing of after injection calculated in step ST6). . If the crank rotation angle has not yet reached the injection timing of the after injection and it is determined NO in step ST7, it waits for the crank rotation angle to reach the injection timing of the after injection. When the crank rotation angle reaches the injection timing of after injection and YES is determined in step ST7, the process proceeds to step ST8, and after injection is executed.

  The operation as described above is executed for each combustion stroke of each cylinder.

  Since the injection timing of the after injection is set in this way, substantially the entire amount of the spray in the after injection can use the remaining air in the cylinder (the air having the “residual air volume Vair (θ)”). In other words, the after-injection spray does not reach the space of the “pre-after-injection spray occupied volume Vfuel”, which is the volume of the combustion field of the fuel injected into the cylinder before the after-injection is executed. Oxygen deficiency in the combustion field of the fuel injected by injection does not occur, and the generation of soot due to this after injection is suppressed. As a result, the required torque can be obtained by the torque generated by the fuel injected by the after injection, and the generation of soot due to the main injection and the after injection is suppressed, and the exhaust emission can be improved. .

  Further, as described above, the injection timing of the after injection is calculated after the elapse of the predetermined interval and when the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. That is, after injection is executed on the most advanced side of the period in which both of these conditions are satisfied. For this reason, it is possible to secure a high torque generation amount (conversion efficiency to torque) with respect to the unit fuel injection amount in the after injection, and it is possible to minimize the deterioration of the fuel consumption rate due to the execution of the after injection. Note that the technical idea of the present invention is not limited to this, and the effect of reducing the generation of soot can be achieved by performing after injection during a period in which the remaining air volume Vair (θ) is equal to or greater than the after injection spray volume Vafter. Therefore, even if after injection is executed at any timing during this period, it is included in the scope of the technical idea of the present invention.

  When the after-injection amount is set relatively large (when the main-injection amount is largely limited, the after-injection amount is set large), one after When the injection amount is injected, the fuel penetration increases, and the after-injection spray may reach the space already used for combustion (the outer space in the combustion chamber 13). There is. That is, the residual air volume Vair (θ) may not be equal to or greater than the after-injection spray volume Vafter (the after-injection spray volume Vafter when one after-injection is executed). Therefore, in this case, the after injection is divided into a plurality of divided injections (hereinafter referred to as “divided after injection”), and the injection timing of these divided after injections is set by the above-described after injection execution timing control. become. For example, when two split after injections are executed, when setting the injection timing of the second split after injection, the volume of the fuel spray injected in the first split after injection is set to the above after injection. The injection timing of the second divided after injection is set by treating it as the pre-spray occupied volume Vfuel.

(Second Embodiment)
Next, a second embodiment will be described. In the after injection execution timing control in the second embodiment, the after injection execution timing is set in consideration of the fluctuation (pulsation) of the fuel injection pressure accompanying the execution of the main injection.

  The outline of the after injection execution timing control in the second embodiment will be described. As in the case of the first embodiment described above, the “spray occupied volume Vfuel before after injection”, “in-cylinder volume Vcyl (θ)”, The “remaining air volume Vair (θ)” is calculated for each crank angle. In addition, “fuel injection pressure Pcyl (θ)” is calculated for each crank angle in consideration of fluctuations in fuel injection pressure accompanying the execution of main injection. When it is assumed that after-injection has been executed based on this “fuel injection pressure Pcyl (θ)”, the fuel injected by this after-injection at the end of execution of the after-injection (at the end of after-injection) The “after injection spray volume Vafter”, which is the volume that occupies the space in the combustion chamber 3, was calculated, and the “residual air volume Vair (θ)” reached the “after injection spray volume Vafter” or more. At the time, after injection from the injector 23 is executed.

  Hereinafter, after injection execution timing control in the present embodiment will be specifically described. FIG. 11 is a flowchart showing the procedure of the after injection execution timing control. This flowchart is also executed every time the combustion stroke of each cylinder is performed. When after injection is performed in the combustion stroke, the after injection execution timing is calculated, and the after injection is executed according to the calculation result. It has become.

  Determination operation of step ST1 (determination operation of whether there is an after injection execution request), calculation operation of step ST2 to step ST4 (calculation operation of spray occupied volume Vfuel before after injection, calculation operation of in-cylinder volume Vcyl (θ) The calculation operation of the residual air volume Vair (θ) is the same as that of the first embodiment described above, and the description thereof is omitted here.

  In step ST10, “fuel injection pressure Pcyl (θ)” is calculated for each crank angle in consideration of fluctuations in the fuel injection pressure accompanying the execution of main injection.

  FIG. 12 shows an example of a fluctuation (pulsation) state of the fuel injection pressure accompanying the execution of the main injection. As shown in FIG. 12, the injection hole is closed (injector valve closed) by the forward movement of the needle from the state in which the injection hole is opened by the backward movement of the needle in the injector 23 and the main injection is performed, and the fuel injection is performed. When is stopped, pressure fluctuation occurs in the fuel in the injector 23. This pressure fluctuation repeatedly rises and falls with the target rail pressure (command injection pressure) as the central pressure, and converges to the target rail pressure with the passage of time. For this reason, if after-injection is performed at the timing when the fuel pressure is higher than the target rail pressure, the after-injection spray volume Vafter becomes larger than the specified amount (spray volume when injected at the target rail pressure). Conversely, when the after injection is performed at the timing when the fuel pressure is lower than the target rail pressure, the after injection spray volume Vafter becomes smaller than the specified amount.

  FIG. 13A is a diagram illustrating changes in the in-cylinder volume Vcyl (θ), the pre-after-injection spray occupation volume Vfuel, the remaining air volume Vair (θ), and the after-injection spray volume Vafter in the present embodiment. FIG. 13B is an enlarged view showing changes in the remaining air volume Vair (θ) and the after-injection spray volume Vafter in a predetermined period immediately after the end of the main injection. As shown in FIG. 13, in the predetermined period immediately after the end of the main injection, the after-injection spray volume Vafter becomes larger and smaller than the remaining air volume Vair (θ) due to fluctuations in fuel pressure. Will be repeated.

  In step ST5, the after-injection spray volume Vafter is calculated in consideration of such a change in fuel pressure. That is, when it is assumed that after-injection has been executed, the volume of fuel injected by this after-injection at the end of execution of the after-injection (at the end of after-injection injection) occupies the space in the combustion chamber 3 The spray spray volume Vafter is calculated. More specifically, a pressure sensor is installed inside the injector 23, and the inside of the injector 23, that is, the fuel pressure is monitored by the pressure sensor. Then, based on the fuel pressure acquired for each crank angle, the after injection spray volume Vafter is obtained from the above formulas (1) to (4) or the spray volume map.

  In step ST6, the injection timing of after injection is calculated. Specifically, the time (Vair (θ) ≧ Vafter) when the remaining air volume Vair (θ) becomes equal to or greater than the after-injection spray volume Vafter is calculated as the after-injection injection timing. In FIG. 13B, when the remaining air volume Vair (θ) that expands as the crank angle advances from the compression top dead center (TDC) of the piston 13 coincides with the after-injection spray volume Vafter (in the figure). This timing T2) is obtained as the after injection timing.

  More specifically, as described above, after injection, after execution of the main injection, a predetermined interval (an interval determined by the response of the injector 23 (speed of opening / closing operation) (fuel injection prohibition period)) has elapsed. Since it is executed, the injection timing of the after injection is calculated as the timing after the elapse of this interval and the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. In other words, the injection timing of the after injection is calculated as the later time of the time when the predetermined interval has passed and the time when the remaining air volume Vair (θ) becomes equal to or greater than the after-injection spray volume Vafter. Become. For example, in FIG. 13B, when the end point of the fuel injection prohibition period is on the advance side (TDC side) from the timing T2 in the figure, the timing T2 in the figure is obtained as the injection timing of the after injection. On the other hand, when the end point of the fuel injection prohibition period is the timing T3 in the drawing, the timing T4 in the drawing is obtained as the injection timing of the after injection.

  After calculating the injection timing of after injection in this way, in step ST7, it is determined whether or not the current crank rotation angle has become the injection timing of after injection (the injection timing of after injection calculated in step ST6). . If the crank rotation angle has not yet reached the injection timing of the after injection and it is determined NO in step ST7, it waits for the crank rotation angle to reach the injection timing of the after injection. When the crank rotation angle reaches the injection timing of after injection and YES is determined in step ST7, the process proceeds to step ST8, and after injection is executed.

  The operation as described above is executed for each combustion stroke of each cylinder.

  Since the injection timing of the after injection is set in this way, even in the present embodiment, substantially the entire amount of the spray in the after injection is the remaining air in the cylinder (the air of the “residual air volume Vair (θ)”). ) Will be available. In other words, the after-injection spray does not reach the space of the “pre-after-injection spray occupied volume Vfuel”, which is the volume of the combustion field of the fuel injected into the cylinder before the after-injection is executed. Oxygen deficiency in the combustion field of the fuel injected by injection does not occur, and the generation of soot due to this after injection is suppressed. As a result, the required torque can be obtained by the torque generated by the fuel injected by the after injection, and the generation of soot due to the main injection and the after injection is suppressed, and the exhaust emission can be improved. .

  Further, in the present embodiment, since the fluctuation (pulsation) of the fuel injection pressure accompanying the execution of the main injection is taken into account, it becomes possible to calculate the after injection spray volume Vafter with higher accuracy, and the generation of soot. In addition to the suppression of the above, it is possible to reliably prevent fuel from adhering to the wall surface (adhering to the cylinder bore wall surface).

  Also in the present embodiment, the injection timing of the after injection is calculated as the time point after the elapse of the predetermined interval and the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. For this reason, it is possible to secure a high torque generation amount (conversion efficiency to torque) with respect to the unit fuel injection amount in the after injection, and it is possible to minimize the deterioration of the fuel consumption rate due to the execution of the after injection.

  Even in the present embodiment, when the after injection is divided into a plurality of times, the injection timing of each divided after injection is set by the above-described after injection execution timing control. Also in this case, when two split after injections are executed, in setting the injection timing of the second split after injection, the volume of the fuel spray injected in the first split after injection is the above The injection timing of the second divided after injection is set by treating it as the spray occupation volume Vfuel before after injection.

-Other embodiments-
In each embodiment described above, the case where the present invention is applied to an in-line four-cylinder diesel engine mounted on an automobile has been described. The present invention is applicable not only to automobiles but also to engines used for other purposes. Further, the number of cylinders and the engine type (separate type engine, V-type engine, etc.) are not particularly limited.

  In each of the above embodiments, the NSR catalyst 75 and the DPNR catalyst 76 are provided as the manipulator 77, but the NSR catalyst 75 and a DPF (Diesel Particle Filter) may be provided.

  In each of the above embodiments, the routine of each flowchart (FIG. 7 in the first embodiment and FIG. 11 in the second embodiment) is executed in the combustion stroke of the engine 1. The present invention is not limited to this, and the after-injection injection timing may be set according to the map value of the control map stored in advance in the ROM 102. For example, various maps for obtaining the pre-after-injection spray occupation volume Vfuel, the cylinder volume Vcyl (θ), the remaining air volume Vair (θ), and the after-injection spray volume Vafter according to parameters such as the specifications of the engine 1 and the engine speed The map is stored in the ROM 102, and each map value is read from the operating state of the engine 1 and the after injection timing is set.

  In the second embodiment, the internal pressure of the injector 23 is detected by the pressure sensor. However, the internal pressure of the injector 23 is estimated by the rail internal pressure detected by the rail pressure sensor 41, and the after injection spray volume. Vafter may be calculated. Alternatively, a fuel injection pressure map (a map in which the value of the fluctuating fuel injection pressure can be acquired for each crank angle) using the fuel injection pressure at the time of main injection execution and the valve opening period in the main injection as parameters is the ROM 102. The fuel injection pressure for each crank angle may be acquired from this fuel injection pressure map.

  Further, in each of the above embodiments, the spray occupation volume Vfuel before after injection is set to a volume that occupies the outer peripheral portion in the combustion chamber 3, and the remaining air volume Vair (θ) and the after injection spray volume Vafter are set in the combustion chamber 3. It was described as a volume occupying the central part. The present invention is not limited to this, and when the fuel spray injected by the main injection or the like flows in the circumferential direction by the swirl flow in the combustion chamber 3, the space between the sprays (8 in the above embodiment) The space between the sprays generated at the location) may be handled as occupied by the remaining air volume Vair (θ) and the after spray spray volume Vafter.

  The present invention relates to after-injection injection timing control that enables a required torque to be achieved and a soot generation amount to be kept below an allowable amount in a common rail in-cylinder direct injection multi-cylinder diesel engine mounted on an automobile. It is possible to apply.

1 engine (internal combustion engine)
13b Cavity 23 Injector (fuel injection valve)
3 Combustion chamber 100 ECU
Vfuel Vapor spray volume before injection Vcyl (θ) Cylinder volume Vair (θ) Residual air volume Vafter After spray volume

-Solution-
Specifically, according to the present invention, during one cycle of the internal combustion engine, the fuel injection valve performs main injection, which is fuel injection for generating torque, and after injection, which is fuel injection performed after execution of the main injection. A fuel injection control device for a compression self-ignition internal combustion engine capable of performing a plurality of fuel injections is included. For the fuel injection control device of the internal combustion engine, the injection amount of the main injection is set to an amount in which the soot amount generated by combustion in the combustion chamber is equal to or less than a preset soot generation allowable amount. The injection amount of the injection is set as an amount for obtaining a shortage torque that is a difference between the torque generated by the combustion of the fuel injected by the main injection and the torque required for the internal combustion engine. Further, a spray occupied volume calculating means, a remaining air volume calculating means, an after injection spray volume calculating means, and an after injection permitting means are provided. The pre-after-injection spray occupancy volume calculating means is a volume in which the fuel spray injected from the fuel injection valve during the same cycle as the after-injection occupies the space in the combustion chamber before the after-injection is executed. “Spray occupied volume before after injection” is calculated for each crank angle. The residual air volume calculation means subtracts the “spray occupancy volume before after injection” for each crank angle from the “in-cylinder volume” calculated for each crank angle, thereby obtaining “ “Remaining air volume” is calculated. The after-injection spray volume calculating means calculates the fuel spray in the space in the combustion chamber at the end of each after- injection execution assuming that the above-mentioned after-injection is executed at each crank angle. is the volume occupied "after injection spray volume" a calculated, respectively. The after-injection permission means includes a "remaining air volume" of the crank angle calculated by the remaining air volume calculating means and an "after-injection spray volume" for each of the assumed after-injections calculated by the after-injection spray volume calculating means. And after injection at the execution timing of the assumed after injection in which the “remaining air volume” is equal to or greater than the “after injection spray volume”.

By this specific matter, after injection performed after execution of main injection is permitted such that the “remaining air volume” is equal to or greater than the “after injection spray volume”. When after-injection is executed at this timing, substantially the entire amount of spray in this after-injection can use the remaining air in the cylinder (the “remaining air volume” air). In other words, the after-injection spray does not reach the space of the “pre-after-injection spray occupied volume”, which is the volume of the combustion field of the fuel injected into the cylinder until after-injection is executed. Oxygen shortage does not occur in the combustion field of the fuel injected at, and as a result, the generation of soot due to this after injection is suppressed.

In addition , the torque required for the internal combustion engine can be obtained by the torque generated by the fuel injected by the after injection while suppressing the amount of soot generated due to the fuel injected by the main injection below the allowable amount. . Further, as described above, since the generation of soot due to after-injection is suppressed, it is possible to ensure both the performance of the internal combustion engine and the improvement of exhaust emission.

The timing is actually after-injection is executed, even after elapse of the fuel injection prohibition period set after completion of the main injection, the "residual air volume" is the "after-injection spray volume" or the It is executed at the assumed execution timing of after injection . That is, in consideration of the fuel injection prohibition period determined by the responsiveness of the fuel injection valve (the speed of the opening / closing operation), after the fuel injection prohibition period has elapsed, the “remaining air volume” becomes “after injection spray volume” so that the after-injection is executed at the timing when the "or more.

The following can be cited as a configuration that takes into account fluctuations in fuel pressure that occur after the end of main injection. That is, the after-injection spray volume calculating means calculates the “after-injection spray volume” for each assumed after-injection based on the fluctuation of the fuel pressure accompanying the execution of the main injection.

More specifically, the after-injection spray volume calculation means calculates the “after-injection spray volume” for each assumed after-injection based on the fuel pressure inside the fuel injection valve that fluctuates after the end of the main injection. ] Is calculated.

The “after-injection spray volume” for each crank angle also varies due to the variation in fuel pressure generated after the end of main injection. That is, there is a possibility that the state where "residual air volume" is "after-injection spray volume" or more, the state of the inverted "residual air volume" is less than "after-injection spray volume" occurs alternately. When the "residual air volume" will running after injection in a state where less than "after-injection spray volume",及fuel this injected in the after-injection is the space of the "spray volume occupied before the after-injection" There is a possibility that the amount of generated Soot will increase. For this reason, in such a situation where the “after-injection spray volume” fluctuates, the “after-injection spray volume” is calculated in consideration of the fluctuation of the fuel pressure that occurs after the end of the main injection. After-injection is executed so as to be equal to or greater than the “after-injection spray volume”. As a result, even if the fuel pressure fluctuates, there is no shortage of oxygen in the combustion field of fuel injected by after injection, and as a result, the generation of soot due to this after injection is suppressed. become.

In the present invention, the volume of the space used for the combustion of the fuel injected into the cylinder is calculated before the after injection is performed, and the volume of the space unused for the combustion is executed after the injection. and so as to perform the after injection with the spray volume over time. For this reason, generation | occurrence | production of Soot resulting from after injection can be suppressed.

Further, when it is assumed that after injection has been executed, the volume in which the spray of fuel injected by this after injection at the end of execution of the after injection (at the end of after injection) occupies the space in the combustion chamber 3 (Hereinafter referred to as “after-injection spray volume Vafter”) (calculation operation of “after-injection spray volume Vafter” by the after-injection spray volume calculating means). Then, the “remaining air volume Vair (θ)” and the “after-injection spray volume Vafter” are compared for each crank angle, and the “remaining air volume Vair (θ)” is equal to or greater than the “after-injection spray volume Vafter”. After-injection from the injector 23 is executed at the timing (the after-injection permission means permits after-injection).

In step ST5, the after spray volume Vafter is calculated. When it is assumed that after-injection has been executed, this after-injection spray volume Vafter indicates that fuel spray injected by this after-injection at the end of execution of the after-injection (at the end of after-injection) volume der occupying the space is, for each crank angle, spray of fuel in each of the after-injection performed at the end when it is assumed that perform the after-injection at the crank angle occupies a space in the combustion chamber Volume. This after-injection spray volume Vafter can also be calculated from the above formulas (1) to (4) .

In step ST6, the injection timing of after injection is calculated. Specifically, as the residual air volume Vair calculated in step ST4 (theta) is the after-injection spray volume Vafter than calculated in step ST5 (Vair (θ) ≧ Vafter ), injection after injection to calculate the time. In FIG. 10, the remaining air volume Vair (θ) that expands as the crank angle advances from the compression top dead center (TDC) of the piston 13 coincides with the after-injection spray volume Vafter (timing in the figure). T1), so that the injection timing of the after-injection is required.

More specifically, after-injection is executed after elapse of a predetermined interval (interval determined by the responsiveness of the injector 23 (speed of opening / closing operation) (fuel injection inhibition period)) after execution of main injection. The injection timing of the after injection is calculated as a timing after the elapse of this interval and the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. In other words, the injection timing of the after injection is calculated as the time when the predetermined interval has passed and the later time of the injection timing at which the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. Become.

Further, as described above, the injection timing of the after injection is calculated so that the remaining air volume Vair (θ) is not less than the after injection spray volume Vafter after the elapse of the predetermined interval. That is, after injection is executed on the most advanced side of the period in which both of these conditions are satisfied. For this reason, it is possible to secure a high torque generation amount (conversion efficiency to torque) with respect to the unit fuel injection amount in the after injection, and it is possible to minimize the deterioration of the fuel consumption rate due to the execution of the after injection. Note that the technical idea of the present invention is not limited to this, and the effect of reducing the generation of soot can be achieved by performing after injection during a period in which the remaining air volume Vair (θ) is equal to or greater than the after injection spray volume Vafter. Therefore, even if after injection is executed at any timing during this period, it is included in the scope of the technical idea of the present invention.

The outline of the after injection execution timing control in the second embodiment will be described. As in the case of the first embodiment described above, the “spray occupied volume Vfuel before after injection”, “in-cylinder volume Vcyl (θ)”, The “remaining air volume Vair (θ)” is calculated for each crank angle. In addition, “fuel injection pressure Pcyl (θ)” is calculated for each crank angle in consideration of fluctuations in fuel injection pressure accompanying the execution of main injection. When it is assumed that after-injection has been executed based on this “fuel injection pressure Pcyl (θ)”, the fuel injected by this after-injection at the end of execution of the after-injection (at the end of after-injection) spraying of the volume occupying the space in the combustion chamber 3 calculates the "after-injection spray volume Vafter", so that the "residual air volume Vair (theta)" becomes the above-mentioned "after-injection spray volume Vafter" more In addition, after- injection from the injector 23 is executed.

In step ST5, the after-injection spray volume Vafter is calculated in consideration of such a change in fuel pressure. That is, when it is assumed that after-injection has been executed, the volume of fuel injected by this after-injection at the end of execution of the after-injection (at the end of after-injection injection) occupies the space in the combustion chamber 3 The spray spray volume Vafter is calculated. More specifically, a pressure sensor is installed inside the injector 23, and the inside of the injector 23, that is, the fuel pressure is monitored by the pressure sensor. Then, based on the fuel pressure that is acquired for each crank angle, obtaining the equations (1) to (4) or we after injection spray volume Vafter.

In step ST6, the injection timing of after injection is calculated. Specifically, as described above remaining air volume Vair (theta) is the after-injection spray volume Vafter more (Vair (θ) ≧ Vafter) , and calculates the injection timing of the after-injection. In FIG. 13B, the residual air volume Vair (θ) that expands as the crank angle advances from the compression top dead center (TDC) of the piston 13 matches the after-injection spray volume Vafter (FIG. 13B). Middle timing T2) , the injection timing of after-injection is determined.

More specifically, as described above, after injection, after execution of the main injection, a predetermined interval (an interval determined by the response of the injector 23 (speed of opening / closing operation) (fuel injection prohibition period)) has elapsed. Therefore, the injection timing of the after injection is calculated as a timing after the elapse of this interval and the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. In other words, the injection timing of the after injection is calculated as the time when the predetermined interval has passed and the later time of the injection timing at which the remaining air volume Vair (θ) becomes equal to or greater than the after injection spray volume Vafter. Become. For example, in FIG. 13B, when the end point of the fuel injection prohibition period is on the advance side (TDC side) from the timing T2 in the figure, the timing T2 in the figure is obtained as the injection timing of the after injection. On the other hand, when the end point of the fuel injection prohibition period is the timing T3 in the drawing, the timing T4 in the drawing is obtained as the injection timing of the after injection.

Also in this embodiment, the injection timing of the after injection is calculated so that the remaining air volume Vair (θ) is equal to or greater than the after injection spray volume Vafter after the elapse of the predetermined interval. For this reason, it is possible to secure a high torque generation amount (conversion efficiency to torque) with respect to the unit fuel injection amount in the after injection, and it is possible to minimize the deterioration of the fuel consumption rate due to the execution of the after injection.

Claims (6)

During one cycle of the internal combustion engine, a plurality of fuel injections including a main injection that is a fuel injection for generating torque and an after injection that is a fuel injection performed after execution of the main injection are executed from the fuel injection valve. In a possible fuel injection control device for a compression ignition type internal combustion engine,
Before the above-described after injection is performed, the crank angle is defined as the “spray occupied volume before after injection”, which is the volume in which the fuel spray injected from the fuel injection valve occupies the space in the combustion chamber during the same cycle as the after injection. Spray occupancy volume calculation means before after-injection to be calculated every time;
The “remaining air volume” for each crank angle is calculated by subtracting the “spray occupied volume before after injection” for each crank angle corresponding to the “in-cylinder volume” calculated for each crank angle. A residual air volume calculating means;
Assuming that the above-described after injection has been executed, an after-calculation for calculating the “after-injection spray volume”, which is the volume in which the fuel spray injected by the after-injection at the end of the after-injection execution occupies the space in the combustion chamber Injection spray volume calculating means;
When the "remaining air volume" calculated by the remaining air volume calculating means reaches or exceeds the "after-injection spray volume" calculated by the after-injection spray volume calculating means, after-injection from the fuel injection valve is permitted. A fuel injection control device for an internal combustion engine, comprising after-injection permission means. The fuel injection control device for an internal combustion engine according to claim 1,
The injection amount of the main injection is set to an amount in which the soot amount generated by the combustion in the combustion chamber is equal to or less than a preset soot generation allowable amount, while the injection amount of the after injection is the main injection amount The fuel injection of the internal combustion engine, which is set as an amount for obtaining a deficient torque that is a difference between the torque generated by the combustion of the fuel injected in step 1 and the torque required for the internal combustion engine Control device. The fuel injection control device for an internal combustion engine according to claim 1,
The after injection is configured to be executed after a lapse of a fuel injection prohibition period set after the end of the main injection and when the “remaining air volume” is equal to or greater than the “after injection spray volume”. A fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1,
The fuel injection valve is configured to inject fuel from the central portion of the combustion chamber toward the outer peripheral portion,
The fuel spray injected from the fuel injection valve until the after injection is performed has the “spray occupied volume before after injection” in the outer peripheral portion of the combustion chamber, while the fuel injection valve is used as the after injection. The fuel injection control device for an internal combustion engine, characterized in that the fuel spray injected from the fuel has the above-mentioned “after-injection spray volume” in the center of the combustion chamber. The fuel injection control device for an internal combustion engine according to claim 1,
When the after-injection volume calculation means assumes that the after-injection has been executed based on the fluctuation of the fuel pressure accompanying the execution of the main injection, the fuel injected by the after-injection at the end of the after-injection execution A fuel injection control device for an internal combustion engine, characterized in that an "after-injection spray volume", which is a volume that occupies the space in the combustion chamber, is calculated. The fuel injection control device for an internal combustion engine according to claim 5,
The after-injection spray volume calculating means is configured to calculate an “after-injection spray volume” based on the fuel pressure inside the fuel injection valve that fluctuates after completion of the main injection. Fuel injection control device.

Images