JP5196028B2 - Fuel injection control device for internal combustion engine - Google Patents

Abstract

As information relating to the characteristics of the spray form of an injector (23), "penetration information", "spray angle information", and "injection angle information" are attached to the injector (23) by means of a QR code (registered trademark) (25). When the injector (23) is mounted, the QR code (25) is read, and the injector control amount is corrected according to the characteristics of the spray form. As the injector (23) has a smaller penetration characteristic, the injection timing of pilot injection is shifted further to the advance side. As the injector (23) has a smaller spray angle characteristic, the injection amount of pilot injection is made larger. As the injector (23) has a smaller injection angle characteristic, the injection timing of main injection is shifted further to the advance side.

Description

  The present invention relates to a fuel injection control device for an internal combustion engine (hereinafter sometimes referred to as an engine) mounted on an automobile or the like. In particular, the present invention relates to a measure for eliminating variations in the combustion state between the cylinders due to individual differences in fuel injection valves (hereinafter also referred to as injectors) arranged for each cylinder.

  In an internal combustion engine that burns fuel injected from each injector provided for each cylinder, such as a multi-cylinder diesel engine mounted in an automobile, in the combustion chamber, if there is an individual difference in each injector, As a result, the fuel injection state in the combustion chamber varies. When such variation in the fuel injection state occurs, a difference occurs in the combustion state between the cylinders. In such a situation, even if good combustion is performed in some cylinders, the combustion state in other cylinders is deteriorated, leading to deterioration in exhaust emission. Misfire may occur.

  In view of this point, as disclosed in each of the following patent documents, storage means (QR code, etc.) that stores information about individual differences of injectors (differences in fuel injection amount in the same fuel pressure and in the same injection period) in advance. Bar code: registered trademark) is attached to each injector. Then, when the injector is mounted, the information stored in the respective storage means is read and written in the engine ECU, so that this information is reflected in the fuel injection control. Accordingly, each injector performs fuel injection with an appropriate fuel injection amount in accordance with the fuel injection amount characteristic of the injector and the like.

  In Patent Document 1, the correction amount of the target fuel pressure is calculated based on the maximum value of the fuel injection rate of the injector, and the correction amount of the injection command timing is calculated based on the deviation amount of the fuel injection timing of the injector. These correction amounts are stored in a QR code and attached to each injector.

  Patent Document 2 discloses a configuration in which variations in the injection amount of each injector are stratified, the information is stored in a stay as a barcode, and the stay is assembled to the injector.

  Patent Document 3 discloses that the internal characteristics of the injector are stored and the internal combustion engine is controlled so as to absorb these individual differences.

JP 2006-200378 A JP 2003-161222 A JP 2002-180897 A

  However, in order to eliminate the above-described inter-cylinder combustion variation, it is necessary to control the injector with higher accuracy.

  The inventor of the present invention has a limitation in eliminating the inter-cylinder combustion variation only by the individual difference information of the injector such as the deviation of the fuel injection amount and the deviation of the fuel injection timing as the characteristics of the injector. Focused on.

  Then, the spray form of the fuel injected from the injector, that is, in which region in the combustion chamber the spray of the fuel injected from the injector forms a spray (combustion field) can be used as individual difference information of the injector. As a result, the present invention was found. In any of the above-mentioned patent documents, the technical idea of attaching information related to the spray form of fuel injected from the injector to each injector and correcting the control amount for the injector according to the spray form information is disclosed. Not.

  The present invention has been made in view of such a point, and the object of the present invention is to more effectively demonstrate the effect of eliminating the variation in the combustion state between the cylinders due to individual differences in the fuel injection valves. 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-described object is to provide information on the characteristics of the spray form in the combustion chamber of the fuel injected from the fuel injection valve as information on individual differences of the fuel injection valves, that is, Information on in which region in the combustion chamber the spray of the injected fuel forms a spray (combustion field) is recorded for each fuel injection valve. Then, by correcting the control amount (fuel injection timing, fuel injection amount, etc.) for the fuel injection valve according to the spray form information, the fuel spray form in each combustion chamber is made uniform, and the inter-cylinder combustion variation is reduced. It can be solved.

-Solution-
Specifically, according to the present invention, for each fuel injection valve provided in the multi-cylinder internal combustion engine, information on the characteristics of the spray form in the combustion chamber of each injected fuel is recorded, and according to the recorded information. The present invention is directed to a fuel injection control device for an internal combustion engine that corrects the control amount of each fuel injection valve. For this fuel injection control device, information on the characteristics of the spray form, information on the penetration force of the fuel injected into the combustion chamber, spray angle of the fuel injected into the combustion chamber (fuel from each injection hole of the fuel injection valve) Information on the spray spread angle (circumferential spread angle in the combustion chamber)) and information on the injection angle of the fuel injected into the combustion chamber . Then, as the recorded information has a smaller penetration force, the control amount of the fuel injection valve is corrected so as to increase the spray reach distance of the fuel injected from the fuel injection valve, and the recording The smaller the spray angle is, the more the amount of fuel spray injected from each injection hole of the fuel injection valve is increased, the control amount of the fuel injection valve is corrected, When the fuel injection start timing from the fuel injection valve is on the advance side of the compression top dead center, the fuel injection timing from the fuel injection valve becomes smaller as the recorded information has a smaller injection angle. A fuel injection control means for advancing is provided.

  When individual differences occur between the fuel injection valves, the penetration force of the fuel injected from the fuel injection valve is different even at the same fuel pressure and the same fuel injection period. Therefore, the spray reach distance of the fuel injected from the fuel injection valve in the combustion chamber also varies depending on the individual difference of the fuel injection valve. As described above, in a situation where the spray reach distance differs for each fuel injection valve, there is a variation between cylinders in the combustion state in the combustion chamber when fuel injection is executed.

Therefore, in this solution, the control amount is corrected so as to increase the spray reach distance of the injected fuel for a fuel injection valve having a small penetration force, based on information recorded in advance about the penetration force of the fuel. To do. Note that the control amount may be corrected so as to shorten the spray reach distance of the injected fuel with respect to the fuel injection valve having a large penetrating force. As a result, the position of the spray of fuel injected from the fuel injection valve (the position of spray in the bore diameter direction) can be adjusted approximately equally in each cylinder. As a result, the positions of the combustion fields in the combustion chambers are substantially equal in all the cylinders, and variations in the combustion state between the cylinders are avoided.
Further, when individual differences occur between the fuel injection valves, the spray angles of the fuel injected from the fuel injection valves are different even at the same fuel pressure. Therefore, the overlapping degree of the fuel sprays injected from the adjacent nozzle holes also varies depending on individual differences of the fuel injection valves. Thus, in the situation where the overlapping degree with the adjacent spray differs for each fuel injection valve, the distribution of the spray in the combustion chamber varies between cylinders.
Therefore, in the present solution, on the basis of the spray angle information recorded in advance, for the fuel injection valve having a small spray angle, the overlapping amount of the fuel sprays injected from the respective injection holes of the fuel injection valve is the same. The control amount is corrected so as to increase. In some cases, the control amount may be corrected for a fuel injection valve having a large spray angle so that the overlapping amount of fuel spray injected from each injection hole of the fuel injection valve becomes small. Thereby, the position of the spray of fuel injected from the fuel injection valve (the position of the spray in the bore circumferential direction: the degree of overlap between the sprays adjacent in the bore circumferential direction) can be adjusted approximately equally in each cylinder. . As a result, the positions of the combustion fields in the combustion chambers are made uniform in all the cylinders, and variations in the combustion state between the cylinders are avoided.
Further, when individual differences occur between the fuel injection valves, the injection angles of the fuel injected from the fuel injection valves are different even at the same fuel pressure. Therefore, the fuel injection angle (spray collision angle) with respect to the inner wall surface of the cavity formed on the top surface of the piston will be different, and if this spray collision angle deviates from an appropriate angle, the amount of soot increases. There is a possibility that.
Therefore, according to the present solution, the fuel injection timing from the fuel injection valve is advanced for the fuel injection valve having a small injection angle based on the information relating to the fuel injection angle recorded in advance (the fuel injection valve). When the fuel injection start timing from is on the more advanced side than the compression top dead center). In some cases, the fuel injection timing from a fuel injection valve is retarded for a fuel injection valve having a large injection angle. As a result, fuel injection is executed at an appropriate spray collision angle in all the cylinders, and an increase in the amount of soot is avoided. As a result, variation in the combustion state between the cylinders is avoided, and exhaust emission can be improved.

  The following is mentioned as a specific configuration in the case of adjusting the fuel spray reach distance according to the information about the penetration force. That is, the fuel injection control means is configured to advance the fuel injection timing from the fuel injection valve as the recorded information has a smaller penetration force.

  In addition, as the fuel injection operation from the fuel injection valve, at least the main injection and the sub-injection that is performed prior to the main injection and contributes to the preheating in the cylinder can be executed. The control means is configured to advance the fuel injection timing of the sub-injection from the fuel injection valve as the recorded information has a smaller penetration force.

  With these configurations, when the fuel injection timing is set to the advance side with respect to the fuel injection valve having a small penetrating force, fuel injection from the fuel injection valve is performed under a situation where both the pressure and temperature in the cylinder are low. Will be done. In other words, since fuel injection is performed in the cylinder where the pressure is relatively low, the fuel injection pressure becomes sufficiently high relative to the in-cylinder pressure, the penetration force is increased, and the spray reach distance is extended. become. Further, since fuel injection is performed in the cylinder having a relatively low temperature, vaporization of the fuel after injection is suppressed, and most of the fuel remains in a droplet state, that is, while maintaining a high inertia force, It will fly in the combustion chamber. This also increases the penetration force and extends the spray reach distance.

  Conversely, if the fuel injection timing is set to the retarded side for a fuel injection valve having a large penetrating force, fuel injection from the fuel injection valve is performed under a situation where both the pressure and temperature in the cylinder are high. Will be done. That is, since fuel injection is performed in a cylinder having a relatively high pressure, the differential pressure between the fuel injection pressure and the in-cylinder pressure is reduced, the penetration force is reduced, and the spray reach distance is shortened. . In addition, since fuel injection is performed in the cylinder having a relatively high temperature, the vaporization of the fuel after the injection is promoted, and the liquid droplet state in which the high inertia force is obtained is eliminated at an early stage. The penetration force is reduced, and the spray reach distance in the combustion chamber is shortened.

  Thus, by correcting the fuel injection timing according to the information on the penetration force, the position of the spray sprayed (spray position in the bore radial direction) can be adjusted approximately equally in each cylinder. As a result, the arrival distances of the fuel sprays injected from the fuel injection valves in all the cylinders are substantially equal, and the positions of the combustion fields in the combustion chamber are substantially equal in all the cylinders. Variations will be avoided.

  In particular, in an internal combustion engine that performs the main injection and the sub-injection, the reach distances of the fuel spray injected by the sub-injection are substantially equal, and the position of the combustion field in the combustion chamber at the start of the main injection is It becomes uniform in all cylinders. For this reason, the occurrence of cylinder variation in the ratio of premixed combustion and diffusion combustion when the fuel injected in the main injection burns is avoided, and the amount of NOx and soot generated in the cylinder in which the ratio of diffusion combustion increases. On the contrary, it is possible to avoid the occurrence of an increase in the amount of HC or the occurrence of misfire in a cylinder in which the premixed combustion ratio increases.

  The following is mentioned as a specific structure in the case of adjusting the overlap amount of sprays according to the information regarding a spray angle. That is, the fuel injection control means is configured to increase the fuel injection amount injected from each injection hole of the fuel injection valve as the recorded information has a smaller spray angle.

  In addition, as the fuel injection operation from the fuel injection valve, at least the main injection and the sub-injection that is performed prior to the main injection and contributes to the preheating in the cylinder can be executed. The control means is configured to increase the fuel injection amount in the sub-injection from the fuel injection valve as the recorded information has a smaller spray angle.

  With these configurations, when the fuel injection amount is increased with respect to the fuel injection valve having a small spray angle characteristic, the combustion field in the combustion chamber is expanded, and the combustion in the combustion chamber is improved. Will be done.

  Conversely, if the fuel injection amount is reduced with respect to the fuel injection valve having the characteristic that the spray angle is large, the overlapping degree of the adjacent sprays in the combustion chamber will not be increased more than necessary. For this reason, it is eliminated that the air-fuel ratio is partially overrich, and an increase in the amount of HC generated and the occurrence of misfire can be avoided.

  In this way, by correcting the fuel injection amount in accordance with the information regarding the spray angle, the degree of overlap between sprays adjacent in the bore circumferential direction can be made uniform in all the cylinders. For this reason, in all the cylinders, it is possible to optimize the combustion field temperature and the air-fuel ratio in the combustion chamber.

  In particular, in the internal combustion engine that performs the main injection and the sub-injection, when the fuel injection amount of the sub-injection is corrected, the combustion field temperature and the air-fuel ratio in the combustion chamber at the start of the main injection are optimized. Can be achieved. As a result, exhaust emission and drivability can be improved.

  Further, when the fuel injection start timing from the fuel injection valve is retarded from the compression top dead center, the fuel injection control means, the more the recorded information the smaller the injection angle, The fuel injection timing from the fuel injection valve is retarded.

  Specific examples of the case where the fuel injection timing from the fuel injection valve is corrected according to the information related to the injection angle include the following. In other words, as the fuel injection operation from the fuel injection valve, at least the main injection and the fuel injection start for the sub-injection that can be performed prior to the main injection and contribute to the preheating in the cylinder are started. When the timing is on the advance side with respect to the compression top dead center, the fuel injection control means causes the main injection from the fuel injection valve to become smaller as the recorded information has a smaller injection angle. The fuel injection timing is advanced. Further, when the fuel injection start timing is retarded from the compression top dead center, the fuel injection control means moves the fuel injection valve from the fuel injection valve as the recorded information has a smaller injection angle. The fuel injection timing of the main injection is delayed.

  With these configurations, the spray collision angle of the spray injected by the main injection can be adjusted appropriately, and an increase in the amount of soot can be avoided. As a result, exhaust emission can be improved by optimizing the injection timing of the main injection.

  In the present invention, information on the characteristics of the spray form in the combustion chamber such as penetration force, spray angle, and injection angle is recorded as individual differences of the fuel injection valves, and the control amount for the fuel injection valve is corrected based on this information. Like to do. For this reason, the spray form of the fuel in each combustion chamber can be made uniform, and the combustion variation between the cylinders can be surely eliminated.

FIG. 1 is a schematic configuration diagram of a diesel 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 waveform diagram showing changes in the heat generation rate (heat generation amount per unit rotation angle of the crankshaft) and changes in the fuel injection rate (fuel injection amount per unit rotation angle of the crankshaft) during the expansion stroke. It is. FIG. 5A is a plan view of the injector, and FIG. 5B is a side view of the injector. FIG. 6 is a schematic configuration diagram of a system for writing QR code information to the ECU. FIG. 7 is a plan view of a part of the combustion chamber showing the state of spray in pilot injection when the fuel injection timing is corrected according to the penetration information. FIG. 8 is a plan view of a part of the combustion chamber showing the state of spray in pilot injection when the fuel injection amount is corrected according to the spray angle information. FIG. 9 is a side view of a part of the combustion chamber showing the relationship between the injection direction of the main injection and the piston position when the fuel injection timing is corrected according to the injection angle information. FIG. 10 is a flowchart showing the procedure of the injector control amount correction operation based on the characteristic information of the spray form.

  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. As the injector 23, an electromagnetic drive type or a piezoelectric type including a piezoelectric element (piezo element) is adopted. Details of the fuel injection control from the injector 23 will be described later.

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

  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 exhaust system 7 includes an exhaust manifold 72 connected to an exhaust port 71 formed in the cylinder head 15, and exhaust pipes 73 and 74 constituting an exhaust passage are connected to the exhaust manifold 72. 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 an intake port 15a for introducing air into the combustion chamber 3 and an exhaust port 71 for discharging exhaust gas from the combustion chamber 3, and an intake valve for opening and closing the intake port 15a. 16 and an exhaust valve 17 for opening and closing the exhaust port 71 are provided. The intake valve 16 and the exhaust valve 17 are disposed to face each other with the cylinder center line P interposed therebetween. That is, the engine 1 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 inside of the intake pipe 64, and the turbine wheel 52 is disposed facing the inside of 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 the environmental conditions of each part and the operating state of the engine 1 are output.

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

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

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

  The input interface 105 is connected with the rail pressure sensor 41, the throttle opening sensor 42, the air flow meter 43, the A / F sensor 44, the exhaust temperature sensor 45, the intake pressure sensor 48, and the intake temperature sensor 49. Further, the input interface 105 includes a water temperature sensor 46 that outputs a detection signal corresponding to the cooling water temperature of the engine 1, an accelerator opening sensor 47 that outputs a detection signal corresponding to the depression amount of the accelerator pedal, and the engine 1. A crank position sensor 40 that outputs a detection signal (pulse) each time the output shaft (crankshaft) rotates by a certain angle is connected. On the other hand, the injector 23, the fuel addition valve 26, the throttle valve 62, the EGR valve 81, and the like are connected to the output interface 106.

  The ECU 100 executes various controls of the engine 1 based on the outputs of the various sensors described above. For example, the ECU 100 executes pilot injection (sub-injection) and main injection (main injection) as fuel injection control of the injector 23.

  The pilot injection is an injection operation in which a small amount of fuel is injected in advance prior to the main injection from the injector 23. The pilot injection is an injection operation for suppressing the ignition delay of fuel due to the main injection and leading to stable diffusion combustion, and is also referred to as sub-injection. Further, the pilot 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. 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.

  The main injection is an injection operation (torque generation fuel supply operation) for generating torque of the engine 1. In the present embodiment, the main injection is performed by the injection amount for obtaining the required torque that is determined according to the operating state such as the engine speed, the accelerator operation amount, the coolant temperature, the intake air temperature, and the like.

  In addition to the pilot injection and main injection described above, after injection and post injection are performed as necessary. This after-injection is an injection operation for increasing the exhaust gas temperature. Specifically, in this embodiment, after-injection is performed at a timing at which most of the combustion energy of the fuel supplied by this after-injection is obtained as exhaust heat energy without being converted into engine torque. I have to. 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 for executing the main fuel injection 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. A specific method for setting the target value of the fuel pressure will be described later.

  Regarding the fuel injection parameters such as the pilot injection and the main injection, the optimum values differ depending on the temperature conditions of the engine 1 and the intake air.

  For example, the ECU 100 adjusts the fuel discharge amount of the supply pump 21 so that the common rail pressure becomes equal to the target rail pressure set based on the engine operating state, that is, the fuel injection pressure matches the target injection pressure. To measure. Further, the ECU 100 determines the fuel injection amount 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, A fuel injection amount in main injection is determined based on the engine speed and the accelerator opening.

-Setting of target fuel pressure-
Next, a method for setting the target fuel pressure will be described. In the diesel engine 1, it is important to meet various requirements such as improvement of exhaust emission by reducing NOx generation amount and smoke generation amount, reduction of combustion noise during combustion stroke, and sufficient securing of engine torque. As a method for simultaneously satisfying these requirements, it is effective to appropriately control the change state of the heat generation rate in the cylinder during the combustion stroke (change state represented by the heat generation rate waveform).

  The solid line of the waveforms shown in the upper part of FIG. 4 shows an ideal heat generation rate waveform related to the combustion of fuel injected in pilot injection and main injection, with the horizontal axis representing the crank angle and the vertical axis representing the heat generation rate. ing. TDC in the figure indicates the crank angle position corresponding to the compression top dead center of the piston 13. The waveform shown in the lower part of FIG. 4 shows the waveform of the injection rate of fuel injected from the injector 23 (fuel injection amount per unit rotation angle of the crankshaft).

  As the heat generation rate waveform, for example, combustion of fuel injected by main injection from the compression top dead center (TDC) of the piston 13 is started, and a predetermined piston position after the compression top dead center of the piston 13 (for example, compression) The heat generation rate reaches a maximum value (peak value) at 10 degrees after top dead center (ATDC 10 °), and further, a predetermined piston position after compression top dead center (for example, 25 degrees after compression top dead center (ATDC 25) The combustion of the fuel injected in the main injection is completed at the time of ()). If combustion of the air-fuel mixture is performed in such a state where the heat generation rate changes, for example, 50% of the air-fuel mixture in the cylinder burns at 10 degrees after compression top dead center (ATDC 10 °). Completed status. That is, the combustion center of gravity is 10 degrees after compression top dead center (ATDC 10 °), and about 50% of the total heat generation amount in the expansion stroke is generated by ATDC 10 °, and the engine 1 is operated with high thermal efficiency. Is possible.

  The relationship between the crank angle and the fuel injection rate waveform when the combustion center of gravity is reached is the period from when the fuel injection stop signal is transmitted to the injector 23 until the fuel injection is completely stopped (see FIG. 4 is located in the period T1).

  Note that the combustion of the fuel injected by the pilot injection has a heat generation rate of 10 [J / ° CA] at the compression top dead center (TDC) of the piston 13, and thus the fuel injected by the main injection. Thus, stable combustion (premixed combustion and diffusion combustion) is realized. This value is not limited to this. For example, it is appropriately set according to the fuel injection amount in the main injection.

  In such a situation in which combustion with an ideal heat generation rate waveform is performed, the cylinder is sufficiently preheated by pilot injection, and the fuel injected in the main injection is immediately self-ignited by this preheating. The thermal decomposition proceeds due to exposure to a temperature environment higher than the temperature, and combustion starts immediately after injection. In addition, as a combustion mode of the fuel injected by the main injection, a ratio between the premixed combustion and the diffusion combustion is appropriately ensured.

  The “correction operation of the control amount of the injector 23 according to the spray form of the fuel injected from the injector 23”, which will be described later, is performed in order to realize combustion with this ideal heat generation rate waveform.

  The waveform indicated by the two-dot chain line α in FIG. 4 is a heat generation rate waveform when the fuel injection pressure is set higher than the appropriate value, and both the combustion rate and the peak value of the heat generation rate are too high. Therefore, there is a concern about an increase in combustion noise and an increase in the amount of NOx generated. On the other hand, a waveform indicated by a two-dot chain line β in FIG. 4 is a heat generation rate waveform when the fuel injection pressure is set lower than an appropriate value, and the timing at which the combustion rate is low and the peak of the heat generation rate appears. There is a concern that sufficient engine torque cannot be secured due to the large shift to the retard side.

-Configuration of the injector 23-
Next, the configuration of the injector 23 will be described. FIG. 5A is a plan view of the injector 23, and FIG. 5B is a side view of the injector 23. As shown in these drawings, the injector 23 has a substantially cylindrical shape, and is provided with a valve portion 23a capable of switching between injection and stop of fuel into the combustion chamber 3, and the valve portion 23a. And a drive unit 23b having a drive coil (both not shown) for driving the nozzle needle.

  The valve portion 23a includes the nozzle needle and a valve body with which the nozzle needle abuts and separates. When the nozzle needle abuts and separates from the valve body, the valve is closed (stops fuel injection) and opens. (Fuel injection) is performed. Moreover, the drive part 23b contains the drive coil by which the coil which generate | occur | produces electromagnetic force by electricity supply was wound, the pipe as a cylindrical member which forms a magnetic circuit with this drive coil, and the armature as a movable body. The nozzle needle is driven through the armature by using an electromagnetic force, that is, an attractive force generated in the drive coil.

  Further, the injector 23 is provided with a connector portion 23c for supplying power to the drive coil or the like at the upper end portion thereof, and a cable (not shown) via a connection port 23d provided on the side surface of the connector portion 23c. Connected to the ECU 100.

  As a feature of the injector 23, the top surface of the connector portion 23c is a flat surface, and a spray form of fuel injected from the injector 23 (a combustion field in the combustion chamber 3 is formed on the top surface). Information on the characteristics of the form of spray to be formed is written by a QR (Quick Response) code 25 (“QR code” is a registered trademark of DENSO WAVE INCORPORATED).

  Information regarding the characteristics of the spray form written by the QR code 25 includes “penetration (penetration force) information”, “spray angle information”, and “injection angle information”. Note that information other than these three pieces of information (for example, information relating to a conventionally known injection amount) may be written. Then, by reading these pieces of information with a code reader 92 (see FIG. 6) to be described later, characteristic data of the spray form of the fuel injected from each injector 23 can be acquired.

  The QR code 25 is a kind of two-dimensional code, and in the manufacturing stage or testing stage of the injector 23, the characteristics of the spray form are individually measured by experiments or simulations, and the connector section 23c is measured according to the result. Molded. For example, the injector 23 is assembled to a test engine, fuel is injected from the injector 23 into the combustion chamber, the shape of the spray is imaged, and the characteristics of the spray form are measured by the image processing. It is done.

  The QR code 25 is formed by laser marking or the like. The forming position of the QR code 25 is set, for example, on the side surface of the connector portion 23c when the connection port 23d with the signal cable extending to the ECU 100 exists on the top surface of the connector portion 23c.

(Information written in QR code 25)
Here, each information regarding the characteristics of the spray form written by the QR code 25 will be described.
(1) Penetration Information “Penetration information” is information regarding the spray reach distance of the fuel injected from the injector 23. That is, it is information regarding the difference in the length of the fuel spray reach distance of each injector 23 when fuel is injected at the same injection pressure and the same injection period.

  Specifically, for example, two types of fuel injection periods (opening period of the injector 23) are set for each of two types of fuel injection pressures, and information on the length of the spray reach distance for a total of four fuel injection modes Is written in the QR code 25. Alternatively, one type of fuel injection period is set for one type of fuel injection pressure, and information regarding the length of the spray reach distance at this time is written in the QR code 25. That is, as the information, the longer the spray reach distance, the more the individual difference information is written in the QR code 25 that the injector 23 has the characteristic that the penetration (penetration force) increases. .

An example of a factor that causes an individual difference in the penetration is that when the inner diameter of the injection hole formed in the injector 23 is smaller than the design dimension, the penetration is increased. When the inner diameter is larger than the design dimension, the penetration is reduced.
(2) Spray angle information “Spray angle information” refers to the spread angle of the spray when the fuel is injected from the injection holes of the injectors 23 formed at a plurality of locations (for example, 8 locations). It is the information regarding the angle over the left-right direction of spray (circumferential direction in the combustion chamber 3) when viewed from above. That is, it is information relating to the difference in fuel spray angle between the injectors 23 when fuel is injected at the same injection pressure.

  Specifically, for example, information regarding the spray angle for two types or one type of fuel injection pressure is written in the QR code 25. As the information indicates that the spray angle is larger, the individual difference information that the injector 23 has a characteristic of increasing the spray angle is written in the QR code 25. That is, information that the injector 23 has a greater degree of overlap with the adjacent spray (fuel spray injected from the adjacent injection hole) after fuel injection is written in the QR code 25.

As an example of the factor that causes the individual difference in the spray angle, there is a processing error of the nozzle hole formed in the injector 23.
(3) Injection angle information The above “injection angle information” refers to the spray flight direction (spray axial direction) with respect to the vertical downward direction when fuel is injected from the injection holes of the injectors 23 formed at a plurality of locations. Information about the angle. That is, it is information relating to the difference in fuel injection angle of each injector 23 when fuel injection is performed at the same injection pressure.

  Specifically, for example, information regarding the injection angle for two types or one type of fuel injection pressure is written in the QR code 25. That is, as the information has a larger injection angle, the individual difference information that the injector 23 has a characteristic that the injection angle becomes larger (fuel is injected in a direction close to the horizontal direction) is QR code. 25 is written.

  An example of a factor that causes an individual difference in the injection angle is a processing error of the injection hole formed in the injector 23.

-QR code reading operation-
Next, the reading operation of the QR code 25 attached to the injector 23 as described above will be described. The operation of reading the QR code 25 is performed when the injector 23 is assembled to the cylinder head 15 of the engine 1, and information on the QR code 25 is written in the ECU 100. That is, when the injectors 23 are assembled to the respective cylinders, information (penetration information, spray angle information, injection angle information) regarding the characteristics of the spray form of each injector 23 is read for each cylinder and written to the ECU 100. Will be.

  FIG. 6 is a schematic configuration diagram of a system for writing the QR code information into the ECU 100. The writing system 9 includes a controller 91, a code reader 92, and a writing device 93.

  The code reader 92 is a general handy type code reader configured to include an optical detection unit, a calculation unit that performs image processing, and the like, and has a code reading unit 92a at the tip thereof. The code reading unit 92a is brought close to the QR code 25 attached to the injector 23 so as to read information on the QR code 25 and output code data.

  The controller 91 is connected to the code reader 92, receives code data as a result of reading the QR code 25 from the code reader 92, and outputs the code data to the writing device 93 as data relating to the characteristics of the spray form of the injector 23. . Specifically, the code data (penetration information, spray angle information, injection angle information) of the QR code 25 attached to the injectors 23, 23,... For each cylinder is read and the code data is read into the writing device 93. Output.

  These pieces of information are transferred from the writing device 93 to the ECU 100 and written into the ROM 102 or the RAM 103 provided in the ECU 100. Thereby, ECU100 memorize | stores the penetration information, spray angle information, and injection angle information about each injector 23,23, ... attached to each cylinder individually for each cylinder.

Incidentally, various kinds of information read by the code reader 92, once after taken into the personal computer, the personal computer, the QR code 25 is converted into processable data (correction data) in the ECU 100, and outputs the ECU 100 The system configuration may be as follows.

-Spray form correction operation-
Next, the spray form correction operation, which is an operation characteristic of the present embodiment, will be described. This spray form correction operation controls the fuel injection form from the injector 23 (corrects the control amount of the injector 23) using at least one of the read penetration information, spray angle information, and injection angle information. It is. Here, the case where the fuel injection form from the injector 23 is controlled using all the above information will be described.

  In the present embodiment, a case will be described in which the pilot injection timing is corrected using the penetration information, the pilot injection amount is corrected using the spray angle information, and the main injection timing is corrected using the injection angle information. Hereinafter, each correction operation will be specifically described.

(Pilot injection timing correction operation using penetration information)
First, the operation | movement which correct | amends the injection timing of pilot injection according to the said penetration information is demonstrated.

  In this correction operation, on the basis of the penetration information obtained by reading the QR code 25, the injector 23 having a characteristic with a small penetration (characteristic with a short spray reach distance) advances the injection timing of the pilot injection. The injection timing of pilot injection is corrected so as to shift to the corner side. In other words, the injection timing of the pilot injection is corrected so that the injection timing of the pilot injection is shifted to the retard side as the injector 23 has a characteristic of greater penetration. The reason will be described below.

  Due to the individual difference of the injectors 23, the penetration (penetration force) of the fuel injected from the injectors 23 may be different even at the same fuel pressure and the same fuel injection period. As a result, the spray reach distance of the fuel injected by pilot injection in the combustion chamber 3 also varies depending on the individual difference of the injectors 23. Thus, in the situation where the spray reach distance differs for each injector 23, the ratio between the premixed combustion and the diffusion combustion in the combustion chamber 3 when the main injection is executed varies.

  For example, in the case of the injector 23 having a characteristic of low penetration, the spray reach distance of the fuel injected by the pilot injection is shorter than the appropriate distance, and the distance between the combustion field and the injection hole of the injector 23 is short. When the main injection is executed, the fuel injected by the main injection starts burning in the combustion field immediately after the injection, and most of the fuel becomes diffusion combustion. Conversely, in the case of the injector 23 having a large penetration characteristic, the spray reach distance of the fuel injected by the pilot injection is longer than the appropriate distance, and the distance between the combustion field and the injection hole of the injector 23 is long. Therefore, when the main injection is executed, the fuel injected in the main injection does not start diffusion combustion for a relatively long time until it reaches the combustion field, and most of it is premixed combustion.

  As described above, the amount of NOx and soot generated may increase in the cylinder in which the diffusion combustion ratio increases (the cylinder to which the injector 23 having the low penetration characteristic is attached). . On the other hand, in a cylinder in which the ratio of premixed combustion increases (a cylinder to which an injector 23 having a large penetration characteristic is attached), the amount of HC generated increases, and in some cases, misfire occurs. There is a possibility of being invited.

  Therefore, based on the penetration information read from the QR code 25, for the injector 23 having the characteristic of low penetration, the injection timing of the pilot injection is corrected to the advance side, and the characteristic of high penetration is obtained. For the injector 23, the injection timing of pilot injection is corrected to the retard side.

  More specifically, based on the penetration information read from the QR code 25, the difference in the spray reach distance of the target injector 23 (to which the QR code 25 is attached) with respect to the proper spray reach distance. The CPU 101 calculates (deviation from the proper spray reach distance). Then, the injection timing of the pilot injection is corrected according to the deviation between the appropriate spray arrival distance and the spray arrival distance based on the penetration information obtained from the QR code 25. For example, a map for obtaining the correction amount of the injection timing of the pilot injection from the deviation of the spray arrival distance is stored in advance in the ROM 102, and the operation of reading the correction amount of the injection timing of the pilot injection from this map is performed.

  In addition, the actual spray reach distance is shorter than the proper spray reach distance, and a plurality of steps (for example, correction levels of “−1” to “−”) are set on the minus side according to the difference from the proper spray reach distance. 3), the correction amount of the injection timing corresponding to the difference in the spray reach distance in three stages) is stored in the ROM 102 in advance. In addition, the actual spray reach distance is longer than the proper spray reach distance, and there are a plurality of levels (for example, correction levels “+1” to “+3”) on the plus side according to the difference from the proper spray reach distance. The correction amount of the injection timing corresponding to the difference in the spray reach distance in the three stages) is stored in the ROM 102 in advance. Then, the correction amount of the pilot injection timing may be set in a plurality of stages according to the deviation. For example, the fuel injection timing is corrected by 1 ° CA in the crank angle for each stage. Specifically, when the spray reach distance before correction is relatively long and the correction level due to the deviation is “+3”, the pilot injection timing of the injector 23 is delayed by 3 ° CA in terms of crank angle. Correct the angle. Further, for example, when the spray arrival distance before correction is relatively short and the correction level due to the deviation is “−1”, the injection timing of the pilot injection of the injector 23 is advanced by 1 ° CA in crank angle. Correct the angle.

  When the injection timing of the pilot injection is set to the advance side for the injector 23 having such a small penetration characteristic, fuel injection from the injector 23 is performed under a situation where both the pressure and temperature in the cylinder are low. It will be. In other words, since fuel injection is performed in the cylinder where the pressure is relatively low, the fuel injection pressure becomes sufficiently high relative to the cylinder pressure, the penetration becomes large, and the spray reach distance is extended. Become. Further, since fuel injection is performed in the cylinder having a relatively low temperature, vaporization of the fuel after injection is suppressed, and most of the fuel remains in a droplet state, that is, while maintaining a high inertia force, It will fly in the combustion chamber. This also increases the penetration and extends the spray reach distance. FIG. 7 is a plan view of a part of the combustion chamber 3 showing the state of spraying in the pilot injection. A two-dot chain line in the figure indicates a spray form before the injection timing is corrected in the injector 23 having a characteristic of low penetration. Moreover, the solid line in the figure shows the spray form in which the spray reach distance is extended by correcting the injection timing in the injector 23 having the characteristic of low penetration.

  Conversely, if the injection timing of pilot injection is set to the retard side for the injector 23 having a large penetration characteristic, fuel injection from the injector 23 is performed under a situation where both the pressure and temperature in the cylinder are high. Will be. That is, since fuel injection is performed in a cylinder having a relatively high pressure, the differential pressure between the fuel injection pressure and the in-cylinder pressure is reduced, the penetration is reduced, and the spray reach distance is shortened. In addition, since fuel injection is performed in the cylinder having a relatively high temperature, the vaporization of the fuel after the injection is promoted, and the liquid droplet state in which the high inertia force is obtained is eliminated at an early stage. The penetration is reduced and the spray reach distance in the combustion chamber 3 is shortened. A one-dot chain line in FIG. 7 shows a spray form before the injection timing is corrected in the injector 23 having a large penetration characteristic. Moreover, the solid line in the figure shows the spray form in which the spray reach distance is shortened by correcting the injection timing in the injector 23 having the characteristic of large penetration.

  Thus, by correcting the injection timing of the pilot injection according to the penetration information obtained from the QR code 25, the position of the spray injected by the pilot injection (the position of the spray in the bore radial direction) is set in each cylinder. It can be adjusted substantially evenly. In other words, for the injector 23 having a characteristic that the penetration is small, the injection timing of the pilot injection is corrected to the advance side to increase the spray reach distance, and for the injector 23 having the characteristic that the penetration is large In this case, the injection timing of the pilot injection is corrected to the retard side to shorten the spray arrival distance. As a result, the reach of the fuel sprays injected by pilot injection is substantially equal in all cylinders, and the position of the combustion field in the combustion chamber 3 at the start of main injection is made uniform in all cylinders. Thus, variation in the ratio of premixed combustion and diffusion combustion when the fuel injected by main injection is burned is avoided. For this reason, the amount of NOx and soot generated increases in the cylinder where the ratio of diffusion combustion increases, and conversely, the amount of HC generated increases in the cylinder where the ratio of premixed combustion increases. A misfire will be avoided. As a result, it is possible to improve exhaust emission and drivability by optimizing the injection timing of pilot injection.

  In the above description, the injection timing of the pilot injection is corrected to the advance side for the injector 23 having the characteristic that the actual penetration is small with respect to the penetration that can obtain an appropriate spray reach distance, and the penetration is For the injector 23 having a large characteristic, the injection timing of the pilot injection is corrected to the retard side. However, the present invention is not limited to this, but only for the injector 23 having a small penetration characteristic, the injection timing of the pilot injection is corrected to the advance side so as to match the penetration of the other injectors 23 as described above. By correcting the set fuel injection pressure, the penetration of the injectors 23 having a large penetration characteristic may be reduced to set the penetrations of all the injectors 23 to appropriate values. Further, only for the injector 23 having a large penetration characteristic, the injection timing of the pilot injection is corrected to the retard side so that it matches the penetration of the other injectors 23 and is set as described above. You may make it set the penetration of all the injectors 23 to an appropriate value by enlarging the penetration of the injector 23 which has a characteristic with a small penetration by correct | amending a fuel injection pressure.

(Pilot injection correction using spray angle information)
Next, control for correcting the injection amount of pilot injection in accordance with the spray angle information will be described.

  Specifically, based on the spray angle information acquired by reading the QR code 25, the injection amount correction is performed so that the injector 23 having a smaller spray angle has a higher pilot injection amount. . In other words, the injection amount correction is performed so as to reduce the injection amount of the pilot injection for the injector 23 having the characteristic that the spray angle is large. The reason will be described below.

  Due to individual differences of the injectors 23, the spray angle of the fuel injected from the injectors 23 may be different even at the same fuel pressure. As a result, the overlapping degree of the fuel sprays injected from the adjacent nozzle holes (the overlapping degree in the circumferential direction in the combustion chamber 3) also varies depending on the individual difference of the injectors 23. Thus, in the situation where the overlapping degree with the adjacent spray differs for each injector 23, the spray distribution in the combustion chamber 3 in each cylinder varies. For example, in a cylinder provided with an injector 23 having a small spray angle characteristic, the degree of overlap with the adjacent spray is small or does not overlap. On the contrary, in the cylinder provided with the injector 23 having the characteristic that the spray angle is large, the overlapping degree with the adjacent spray becomes large.

  In particular, in a situation where the cooling water temperature is low, such as when cold, the positional relationship between the fuel spray injected by the pilot injection and the fuel spray injected by the main injection is not properly obtained. As a result, the amount of HC generated may increase, or in some cases, misfire may occur.

  Therefore, on the basis of the spray angle information read from the QR code 25, for the injector 23 having the characteristic of a small spray angle, the fuel injection amount in the pilot injection is increased and corrected so that the characteristic of the spray angle is large. For the injector 23 that it has, the fuel injection amount in pilot injection is corrected to decrease. Specifically, the fuel injection amount is corrected by correcting the valve opening period of the injector 23 when the pilot injection is performed.

  More specifically, based on the spray angle information read from the QR code 25, the difference in the spray angle of the target injector 23 (to which the QR code 25 is attached) with respect to the appropriate spray angle ( The deviation from the appropriate spray angle is calculated by the CPU 101. Then, the injection amount of the pilot injection is corrected according to the deviation between the appropriate spray angle and the spray angle based on the spray angle information obtained from the QR code 25. For example, a map for obtaining an injection correction amount for pilot injection from the deviation of the spray angle is stored in the ROM 102 in advance, and an operation for reading the injection correction amount for pilot injection from this map is performed.

  Further, for an actual spray angle smaller than an appropriate spray angle, a plurality of steps (for example, correction levels “−1” to “−3” on the minus side) according to the difference from the appropriate spray angle. 3), the injection correction amount corresponding to the difference in the spray angle is stored in the ROM 102 in advance. In addition, for an actual spray angle larger than the appropriate spray angle, a plurality of steps (for example, correction levels “+1” to “+3”) are set on the plus side according to the difference from the appropriate spray angle. An injection correction amount corresponding to the difference in the spray angle in the three steps) is stored in the ROM 102 in advance. Then, the injection correction amount of pilot injection may be set in a plurality of stages according to the deviation. For example, the injection amount is corrected by 10% for each stage. Specifically, when the spray angle is relatively large and the correction level due to the deviation is “+3”, the pilot injection amount of the injector 23 is corrected to be reduced by 30%. Further, for example, when the spray angle is relatively small and the correction level due to the deviation is “−1”, the injection amount of the pilot injection of the injector 23 is corrected to be increased by 10%.

  When the fuel injection amount is increased and corrected for the injector 23 having such a small spray angle characteristic, the preheating place (combustion field) in the combustion chamber 3 is expanded, and the inside of the combustion chamber 3 is expanded. By being sufficiently preheated, combustion in the main injection is performed satisfactorily. FIG. 8 is a plan view of a part of the combustion chamber 3 showing the state of spraying in the pilot injection. The solid line in the figure shows the spray form in the case where the injection amount increase correction is performed in the injector 23 having the characteristic that the spray angle is small.

  On the contrary, if the fuel injection amount is corrected to be reduced for the injector 23 having the characteristic that the spray angle is large, the overlapping degree between the adjacent sprays in the combustion chamber 3 is not increased more than necessary. For this reason, it is eliminated that the air-fuel ratio is partially overrich, and an increase in the amount of HC generated and the occurrence of misfire can be avoided. A one-dot chain line in FIG. 8 shows a spray form when the above-described injection amount reduction correction is performed in the injector 23 having a characteristic of a large spray angle.

  Thus, by correcting the injection amount of the pilot injection according to the spray angle information obtained from the QR code 25, the overlapping degree of the adjacent sprays in the bore circumferential direction is made uniform in all the cylinders. Can do. For this reason, in all the cylinders, it is possible to optimize the combustion field temperature and the air-fuel ratio in the combustion chamber 3 at the start of the main injection. As a result, an increase in the amount of HC generated in some cylinders or a misfiring can be avoided, and exhaust emission and drivability can be improved by optimizing the amount of pilot injection. be able to.

  In addition, when correcting the injection amount of the pilot injection according to the spray angle information as described above, when correcting the increase of the pilot injection amount (injection amount correction for the injector 23 having a small spray angle characteristic). In this case, a part of the fuel injected by the pilot injection may contribute to the torque generation of the engine 1. In this case, the fuel amount corresponding to the torque due to the pilot injection is subtracted from the fuel injection amount of the main injection so that the torque required by the driver can be obtained appropriately.

  In the above description, for the injector 23 having the characteristic that the actual spray angle is small relative to the proper spray angle, the pilot injection amount is corrected to the increase side, and the spray angle is large. For the injector 23, the pilot injection amount is corrected to the decreasing side. Not only this but only the injector 23 which has the characteristic that a spray angle is small, correct | amends the pilot injection quantity to the increase side, and the overlap degree of sprays overlaps the sprays in other injectors 23 The degree of overlap between the sprays in all the cylinders may be set appropriately by adjusting the fuel injection pressure set as described above so as to match the degree. Further, by correcting the pilot injection amount to the reduction side only for the injector 23 having a characteristic that the spray angle is large, the overlapping degree of the sprays is matched with the overlapping degree of the sprays in the other injectors 23. In this way, the degree of overlap between the sprays in all the cylinders may be set appropriately by correcting the fuel injection pressure set as described above.

(Correction of main injection timing using injection angle information)
Next, control for correcting the injection timing of the main injection in accordance with the injection angle information will be described. Moreover, in the following description, the case where the injection start timing of the main injection is set to the advance side (BTDC) with respect to the compression top dead center (TDC) of the piston 13 will be described.

  Specifically, on the basis of the injection angle information acquired by reading the QR code 25, the injector 23 having a smaller injection angle has a main injection timing that shifts the injection timing of the main injection to the advance side. Correct the injection timing of the injection. In other words, the injection timing of the main injection is corrected so that the injector 23 having the characteristic of a large injection angle shifts the injection timing of the main injection to the retard side. The reason will be described below.

  Due to individual differences of the injectors 23, the injection angle of the fuel injected from the injectors 23 may be different even at the same fuel pressure. As a result, the injection angle of the fuel injected by the main injection with respect to the inner wall surface of the cavity 13b formed on the top surface of the piston 13 (hereinafter referred to as the spray collision angle) is different. If the angle deviates from an appropriate angle, the generation amount of soot may increase.

  Therefore, based on the injection angle information read from the QR code 25, for the injector 23 having a small injection angle characteristic, the injection timing is set to the advance side, and the injection angle has a large characteristic. For the injector 23, the injection timing is set to the retard side.

  More specifically, based on the injection angle information read from the QR code 25, the difference in the injection angle of the target injector 23 (to which the QR code 25 is attached) with respect to the appropriate injection angle ( Deviation from an appropriate injection angle) is calculated by the CPU 101. Then, the injection timing of the main injection is corrected according to the deviation between the appropriate injection angle and the injection angle based on the injection angle information obtained from the QR code 25. For example, a map for obtaining the correction amount of the injection timing of the main injection from the deviation of the injection angle is stored in the ROM 102 in advance, and the operation of reading the correction amount of the injection timing of the main injection from this map is performed.

  Further, for an actual injection angle smaller than an appropriate injection angle, a plurality of steps (for example, correction levels of “−1” to “−3”) on the minus side according to the difference from the appropriate injection angle. 3), the correction amount of the injection timing corresponding to the difference in the injection angle is stored in the ROM 102 in advance. In addition, for an actual injection angle larger than the appropriate injection angle, a plurality of steps (for example, correction levels “+1” to “+3”) are set on the plus side according to the difference from the appropriate injection angle. A correction amount of the injection timing corresponding to the difference in the injection angle in the three steps) is stored in the ROM 102 in advance. Then, the correction amount of the injection timing of the main injection may be set in a plurality of stages according to the deviation. For example, the fuel injection timing is corrected by 1 ° CA in the crank angle for each stage. Specifically, when the injection angle before correction is relatively large and the correction level due to the above deviation is “+3”, the injection timing of the main injection of the injector 23 is retarded by 3 ° CA in terms of crank angle. to correct. Further, for example, when the injection angle before correction is relatively small and the correction level due to the deviation is “−1”, the injection timing of the main injection of the injector 23 is advanced by 1 ° CA as a crank angle. to correct.

  Thus, by correcting the injection timing of the main injection according to the injection angle, the main injection is executed at an appropriate spray collision angle in all the cylinders. The one-dot chain line in FIG. 9 indicates the piston position (at the top dead center) when the injection timing is corrected to the advance side with respect to the injector 23 (see the injection angle θ1 in the figure) having the characteristic that the injection angle is small. The relationship between the piston 13) moving toward the main injection direction is shown. The spray collision angle in this case (the angle formed by the injection direction of the main injection and the tangent at the point where the fuel in the main injection collides among the inner wall surfaces of the cavity 13b) is A in the figure. Further, the solid line in FIG. 9 indicates the piston position and the main injection when the injection timing is corrected to the retard side with respect to the injector 23 (see the injection angle θ2 in the figure) having a large injection angle. The relationship with the injection direction is shown. The spray collision angle in this case is B in the figure. These spray collision angles are set as approximate angles by correcting the injection timing as described above.

  Thus, by correcting the injection timing of the main injection according to the injection angle information obtained from the QR code 25, the spray collision angle of the spray injected by the main injection can be made uniform in all the cylinders. It is possible to avoid an increase in the amount of soot generated by optimizing the spray collision angle. As a result, it is possible to improve exhaust emission by optimizing the injection timing of the main injection.

  In addition, the said description was a case where the injection start timing of main injection was set to the advance side (BTDC) rather than the compression top dead center (TDC) of the piston 13. If the injection start timing of the main injection is set to the retard side (ATDC) with respect to the compression top dead center (TDC) of the piston 13, based on the injection angle information acquired by reading the QR code 25. The injector 23 having a smaller injection angle corrects the injection timing of the main injection so that the injection timing of the main injection is shifted to the retard side. In other words, the injection timing of the main injection is corrected so that the injector 23 having the characteristic of a large injection angle shifts the injection timing of the main injection to the advance side. In this case, the piston 13 indicated by the alternate long and short dash line in FIG. 9 is moving toward the bottom dead center.

-Fuel injection control amount correction operation-
Next, a specific operation procedure for correcting the control amount of the injector 23 in accordance with each piece of information regarding the characteristics of the spray form as described above will be specifically described with reference to the flowchart of FIG. As described above, the control amount correction operation shown in FIG. 10 includes a pilot injection timing correction operation using penetration information, a pilot injection amount correction operation using spray angle information, and a main injection timing using injection angle information. A correction operation is performed.

  First, in step ST1, the penetration information, the spray angle information, and the injection angle information written in the ECU 100 are acquired (read) for each cylinder. For example, each information written in the ROM 102 is read out to the CPU 101.

  In step ST2, first, a correction amount for the pilot injection timing is obtained in accordance with the penetration information described above. That is, the injector 23 corrects the injection timing of the pilot injection so that the injector 23 having the characteristic of less penetration shifts the injection timing of the pilot injection to the advance side.

  Next, in step ST3, the degree of overlap with the adjacent spray is calculated from the above-described spray angle information when pilot injection is executed. In this calculation, in addition to the spray angle information described above, the swirl amount in the cylinder is obtained from the engine speed, the intake air amount, and the swirl value, and the degree of overlap is calculated from the spray angle information and the swirl amount. It will be. Thereafter, in step ST4, a correction amount of the injection amount of pilot injection is obtained from the degree of overlap. That is, the injection amount correction is performed so that the injection amount of the pilot injection is increased for the injector 23 of the cylinder having a smaller overlapping degree.

  Next, in step ST5, a correction amount for the main injection timing is obtained according to the above-described injection angle information. That is, the injector 23 having a smaller injection angle corrects the injection timing of the main injection so that the injection timing of the main injection is shifted to the advance side (the injection start timing of the main injection is the compression of the piston 13). If it is set on the advance side from the top dead center).

  In this way, the injection timing of pilot injection, the injection amount of pilot injection, and the injection timing of main injection are respectively obtained, and each control amount of the injector 23 provided in each cylinder is controlled.

  With the above operation, the position of the spray in the bore radial direction and the degree of overlap in the bore circumferential direction of the fuel injected by pilot injection can be made substantially the same in all the cylinders, and the fuel injected by the main injection can be The spray collision angle can be made substantially the same for all cylinders. For this reason, it becomes possible to make the spray form in the combustion chamber 3 substantially the same in all the cylinders, and the combustion variation between the cylinders is eliminated. As a result, in the state where the spray forms of all the cylinders are substantially matched, as described above, the injection forms of the pilot injection and the main injection (in accordance with the operating state such as the engine speed, the accelerator operation amount, the coolant temperature, the intake air temperature, etc.) By controlling the fuel injection amount, fuel injection timing, fuel injection period, etc., it is possible to realize combustion with an ideal heat generation rate waveform (the heat generation rate waveform described with reference to FIG. 4) in all cylinders. . Thereby, it is possible to improve exhaust emission and drivability.

(Modification)
In the above-described embodiment, when the pilot injection timing is corrected using the penetration information, the pilot injection amount is corrected using the spray angle information, and the main injection timing is corrected using the injection angle information. Explained. In addition to these, the injector 23 may be controlled by a combination as described below (a combination of information on the characteristics of the spray form and a control amount).
-Correction of the injection timing of the main injection using the penetration information.
-Correction of the injection amount of pilot injection using penetration information.
-Correction of the injection amount of the main injection using the penetration information.
-Correction of the injection amount of the main injection using the spray angle information.
・ Correction of injection timing of pilot injection using spray angle information.
-Correction of injection timing of main injection using spray angle information.
-Correction of the injection amount of the main injection using the injection angle information.

  Even in these combinations, the same effects as those of the above-described embodiment can be obtained. For example, when correcting the injection timing of the main injection using the spray angle information, specifically, the injector 23 having the characteristic of a large spray angle shifts the injection timing of the main injection to the retard side. I will let you. According to this, by delaying the injection timing of the main injection, the premixed combustion ratio of the fuel injected by the main injection is prevented from becoming excessive, and the ratio of premixed combustion and diffusion combustion is optimized. Can be achieved.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to a common rail in-cylinder direct injection multi-cylinder diesel engine mounted on an automobile has been described. The present invention is not limited to this, and can also be applied to a diesel engine mounted other than an automobile. Further, the present invention is applicable not only to a diesel engine but also to a fuel direct injection gasoline engine.

  Further, in the above embodiment, the information regarding the characteristics of the spray form of the injector 23 is recorded by the QR code 25. The present invention is not limited to this, and information relating to the characteristics of the spray form may be recorded by other means such as a barcode.

  INDUSTRIAL APPLICABILITY The present invention can be applied to control for eliminating variations in combustion states among cylinders due to individual differences among injectors in a common rail in-cylinder direct injection multi-cylinder diesel engine mounted on an automobile.

1 engine (internal combustion engine)
3 Combustion chamber 23 Injector (fuel injection valve)
25 QR code

Claims (8)

For each fuel injection valve provided in the multi-cylinder internal combustion engine, information on the characteristics of the spray form in the combustion chamber of each injected fuel is recorded, and the control amount of each fuel injection valve is determined according to this recorded information. A fuel injection control device for an internal combustion engine to correct,
Information about the characteristics of the spray form, information about the penetration of fuel injected into the combustion chamber, the information about the spray angle of the fuel injected into the combustion chamber, and, with information about the injection angle of the injected fuel into the combustion chamber There,
As the recorded information has a smaller penetration force, the control amount of the fuel injection valve is corrected so as to increase the spray reach distance of the fuel injected from the fuel injection valve ,
The control amount of the fuel injection valve is corrected so that the amount of overlap between the fuel sprays injected from the injection holes of the fuel injection valve increases as the sprayed information has a smaller spray angle. And
When the fuel injection start timing from the fuel injection valve is on the advance side of the compression top dead center, the fuel injection timing from the fuel injection valve becomes smaller as the recorded information has a smaller injection angle. A fuel injection control device for an internal combustion engine, comprising fuel injection control means for advancing . The fuel injection control device for an internal combustion engine according to claim 1,
The fuel injection control means is configured to advance the fuel injection timing from the fuel injection valve as the recorded information has a smaller penetration force. Injection control device. The fuel injection control device for an internal combustion engine according to claim 2,
As the fuel injection operation from the fuel injection valve, at least main injection and sub-injection that is performed prior to the main injection and contributes to preheating in the cylinder can be performed.
The fuel injection control means is configured to advance the fuel injection timing of the sub injection from the fuel injection valve as the recorded information has a smaller penetration force. 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 control means is configured to increase the amount of fuel injected from each nozzle hole of the fuel injection valve as the recorded information has a smaller spray angle. A fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 4,
As the fuel injection operation from the fuel injection valve, at least main injection and sub-injection that is performed prior to the main injection and contributes to preheating in the cylinder can be performed.
The fuel injection control means is configured to increase the fuel injection amount in the sub-injection from the fuel injection valve as the recorded information has a smaller spray angle. A fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1,
As the fuel injection operation from the fuel injection valve, at least main injection and sub-injection that is performed prior to the main injection and contributes to preheating in the cylinder can be performed.
The fuel injection control means is configured to advance the fuel injection timing of the main injection from the fuel injection valve as the recorded information has a smaller injection angle. A fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1,
When the fuel injection start timing from the fuel injection valve is retarded from the compression top dead center, the fuel injection control means is configured such that the smaller the injection angle is, the smaller the fuel injection is. A fuel injection control device for an internal combustion engine, wherein the fuel injection timing from the valve is retarded. The fuel injection control device for an internal combustion engine according to claim 7,
As the fuel injection operation from the fuel injection valve, at least main injection and sub-injection that is performed prior to the main injection and contributes to preheating in the cylinder can be performed.
The fuel injection control means is configured to delay the fuel injection timing of the main injection from the fuel injection valve as the recorded information has a smaller injection angle. A fuel injection control device for an internal combustion engine.

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