Injector control unit

Abstract

To prevent both excessive amounts of fuel attached at a top face of a piston and fuel attached to a wall face of a cylinder.SOLUTION: A memory stores, as a range of crank angle for allowing a fuel injection from an injector: a first injection range A predefined within a range of a crank angle from a start period M1 of an intake stroke to an end period M2 of the intake stroke; and a second injection range B predefined within a range of crank angle from a start period N1 of a compression stroke to an end period N2 of the compression stroke. A CPU can execute: a first injection process for causing an injector to perform a fuel injection within the first injection range A; and a second injection process for causing the injector to perform the fuel injection within the second injection range B. The second injection range B is not continuous with the first injection range A and is shorter than the first injection range A.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] This invention relates to a control device for an injector.

Background Art

[0002] The internal combustion engine disclosed in Patent Document 1 includes a cylinder, a piston, and an injector. The cylinder is a space for the mixture of intake air and fuel to burn. The piston is located inside the cylinder. The piston reciprocates inside the cylinder with the combustion of the mixture. The injector directly injects fuel into the cylinder from the top dead center side with respect to the piston.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a technique such as that of Patent Document 1 in which fuel is directly injected into the cylinder, fuel may adhere to the top surface of the piston and the wall surface of the cylinder. When fuel adheres to the top surface of the piston, particulate matter is likely to be generated during combustion in the combustion stroke. On the other hand, the fuel remaining adhered to the wall surface of the cylinder vaporizes in the cylinder during the exhaust stroke or the like. The fuel vaporized during the exhaust stroke is discharged from the cylinder as unburned hydrocarbons. In order to reduce both of these particulate matter and unburned hydrocarbons, a technique is required in which the amount of fuel adhering to the top surface of the piston and the amount of fuel adhering to the wall surface of the cylinder do not become excessive amounts.

Means for Solving the Problems

[0005] The injector control device for solving the above problems controls an injector that injects fuel into the cylinder of an internal combustion engine from the top dead center side of the piston, and comprises an execution unit and a storage unit, wherein the storage unit stores a predetermined range of crank angles that allows fuel injection from the injector, namely a first injection range within the range of crank angles from the start of the intake stroke to the end of the intake stroke, and a second injection range within the range of crank angles from the start of the compression stroke to the end of the compression stroke, and the execution unit is capable of performing a first injection process that causes the injector to inject fuel within the first injection range, and a second injection process that causes the injector to inject fuel within the second injection range, wherein the second injection range is not continuous with the first injection range and is shorter than the first injection range. [Effects of the Invention]

[0006] With the above technical concept, it is difficult for both the amount of fuel adhering to the top of the piston and the amount of fuel adhering to the cylinder walls to become excessive. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram of an internal combustion engine. [Figure 2] Figure 2 is an explanatory diagram schematically representing the first and second injection ranges. [Figure 3] Figure 3 is a flowchart illustrating the processing procedure for specific injection control. [Figure 4] Figure 4 is a flowchart illustrating the processing steps for the first preparation process. [Figure 5] Figure 5 is a flowchart illustrating the processing steps for the second preparation process. [Figure 6] Figure 6 is an explanatory diagram illustrating an example of changing the injection pattern. [Figure 7] Figure 7 is an explanatory diagram illustrating an example of changing the injection pattern. [Modes for carrying out the invention]

[0008] An embodiment of the injector control device will be described below with reference to the drawings. <Overall Configuration of an Internal Combustion Engine> As shown in Figure 1, the vehicle is equipped with an internal combustion engine 10. The internal combustion engine 10 is the power source for the vehicle. The internal combustion engine 10 comprises an engine body 10A, multiple cylinders 11, multiple pistons 12, multiple connecting rods 13, and a crankshaft 14. Note that Figure 1 shows only one of the multiple cylinders 11. The same applies to the pistons 12 and connecting rods 13. A piston 12 and a connecting rod 13 are provided for each cylinder 11. There are four cylinders 11.

[0009] Cylinder 11 is a space partitioned by the engine body 10A. Cylinder 11 is a space for burning a mixture of fuel and intake air. Cylinder 11 is cylindrical. Hereafter, the wall surface of the engine body 10A that partitions cylinder 11 will be referred to as the wall surface 11A of cylinder 11. Although not shown in the diagram, the engine body 10A partitions a cooling water passage around cylinder 11 through which cooling water flows.

[0010] The piston 12 is located inside the cylinder 11. The piston 12 is cylindrical. The diameter of the piston 12 is approximately the same as the diameter of the cylinder 11. The central axis of the piston 12 is approximately the same as the central axis of the cylinder 11. The connecting rod 13 is connected to the piston 12. The crankshaft 14 is connected to the connecting rod 13. The piston 12 reciprocates inside the cylinder 11 in a direction along its central axis. The crankshaft 14 rotates in accordance with the reciprocating motion of the piston 12. As the piston 12 reciprocates inside the cylinder 11, it moves away from the crankshaft 14 and closer to the crankshaft 14. That is, the piston 12 operates between its top dead center, which is furthest from the crankshaft 14, and its bottom dead center, which is closest to the crankshaft 14. In the following, the direction in which the piston 12 moves toward the top dead center will be referred to as upward, and the opposite direction will be referred to as downward. Furthermore, of the two end faces of the piston 12 along its central axis, the end face facing upward will be referred to as the top face 12A.

[0011] The internal combustion engine 10 is equipped with multiple injectors 50. Note that Figure 1 shows only one of the multiple injectors 50. An injector 50 is provided for each cylinder 11. The injector 50 is located above the piston 12 relative to the cylinder 11. The outer shape of the injector 50 is generally cylindrical. In this embodiment, the central axis of the injector 50 is generally parallel to the central axis of the cylinder 11. The tip of the injector 50 is located inside the cylinder 11. The tip of the injector 50 is located above the top dead center of the piston 12. The injection port 54 provided at the tip of the injector 50 faces the top surface 12A of the piston 12. The injector 50 injects fuel into the cylinder 11 from the top dead center side of the piston 12. In this way, the injector 50 injects fuel directly into the cylinder 11 without going through the intake passage 20 described later. Injector 50 injects gasoline as fuel.

[0012] The internal combustion engine 10 is equipped with multiple spark plugs 19. Note that only one of the multiple spark plugs 19 is shown in Figure 1. A spark plug 19 is provided for each cylinder 11. The tip of the spark plug 19 is located inside the cylinder 11. The spark plug 19 ignites the fuel-air mixture inside the cylinder 11.

[0013] The internal combustion engine 10 includes an intake passage 20 and a throttle valve 22. The intake passage 20 is a passage for introducing intake air into each cylinder 11. The intake passage 20 is connected to each cylinder 11. The throttle valve 22 is located in the middle of the intake passage 20. The throttle valve 22's opening degree is adjustable. Therefore, the amount of intake air changes depending on the opening degree of the throttle valve 22.

[0014] The internal combustion engine 10 includes an exhaust passage 30, a three-way catalytic converter 32, and a particulate filter 34. The exhaust passage 30 is a passage for discharging exhaust gas from each cylinder 11. The exhaust passage 30 is connected to each cylinder 11. The three-way catalytic converter 32 is located in the middle of the exhaust passage 30. The three-way catalytic converter 32 purifies hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas. The particulate filter 34 is located downstream of the three-way catalytic converter 32 in the exhaust passage 30. The particulate filter 34 collects particulate matter contained in the exhaust gas.

[0015] The internal combustion engine 10 is a four-stroke, one-cycle engine in which the intake stroke, compression stroke, combustion stroke, and exhaust stroke in each cylinder 11 complete one cycle by the rotation of the crankshaft 14 720 degrees. Looking at a particular cylinder 11, the intake stroke is the period when the piston 12 moves from top dead center to bottom dead center in that cylinder 11. The compression stroke is the period following the intake stroke when the piston 12 moves from bottom dead center to top dead center. The combustion stroke is the period following the compression stroke when the piston 12 moves from top dead center to bottom dead center. The exhaust stroke is the period following the combustion stroke when the piston 12 moves from bottom dead center to top dead center. After the combustion stroke, the intake stroke of the next cycle begins.

[0016] The internal combustion engine 10 includes a crank angle sensor 61, an air flow meter 62, and a coolant temperature sensor 63. The crank angle sensor 61 detects the crank angle which is the rotation angle of the crankshaft 14. The air flow meter 62 detects the intake air amount. The coolant temperature sensor 63 detects the temperature of the coolant at the outlet of the coolant passage. Each of these sensors repeatedly transmits a signal corresponding to the information it has detected to a control device 100 described later.

[0017] The vehicle includes an accelerator sensor 68 and a vehicle speed sensor 69. The accelerator sensor 68 detects the depression amount of the accelerator pedal in the vehicle as the accelerator operation amount. The vehicle speed sensor 69 detects the traveling speed of the vehicle as the vehicle speed. Each of these sensors repeatedly transmits a signal corresponding to the information it has detected to a control device 100 described later.

[0018] <Overview of the control device> The vehicle includes a control device 100. The control device 100 includes a processing circuit including a CPU 102 and a memory 104. The CPU 102 is an execution unit. The memory 104 includes three types: a RAM, a ROM, and an electrically rewritable non-volatile type. In this embodiment, these three types are collectively referred to as the memory 104. The memory 104 stores in advance various programs in which the processes to be executed by the CPU 102 are described. Also, the memory 104 stores in advance various data necessary for the CPU 102 to execute various programs. Note that the memory 104 is a storage unit.

[0019] The CPU 102 repeatedly receives detection signals from various sensors attached to the vehicle. Based on the detection signals received from the various sensors, the CPU 102 calculates the following parameters at any time. Based on the change in the crank angle received from the crank angle sensor 61, the CPU 102 calculates the engine rotation speed, which is the rotation speed of the crankshaft 14. Based on the engine rotation speed and the intake air amount received from the air flow meter 62, the CPU 102 calculates the engine load ratio. The engine load ratio is a parameter that determines the amount of air filled in the cylinder 11, and is a value obtained by dividing the amount of air flowing into one cylinder 11 per cycle of the internal combustion engine 10 by the reference air amount. The reference air amount changes according to the engine rotation speed.

[0020] The CPU 102 controls the internal combustion engine 10. Based on the accelerator operation amount, vehicle speed, engine rotation speed, engine load ratio, etc., the CPU 102 performs various controls on the internal combustion engine 10. For example, the CPU 102 performs injection control for the injector 50, ignition timing control for the ignition plug 19, and opening degree adjustment control for the throttle valve 22. Through these controls, the CPU 102 causes the air-fuel mixture to burn in the plurality of cylinders 11 in sequence.

[0021] The CPU 102 is capable of executing specific injection control. The specific injection control is injection control for the cold state of the internal combustion engine 10. As shown in FIG. 2, the memory 104 stores in advance injection enable / disable information, which is the range of the crank angle that defines the enable / disable of fuel injection, as information used in the specific injection control. Note that FIG. 2 shows the crank angle from the start timing M1 of the intake stroke to the end timing N2 of the compression stroke for a certain specific cylinder 11 by the angle of a clockwise circle. In the following description, the crank angle of the start timing M1 of the intake stroke in this specific cylinder 11 is set to 0 degrees. Also, when referring to the range from the start timing M1 of the intake stroke to the end timing N2 of the compression stroke, it includes the timings of the start timing M1 and the end timing N2 themselves. This also applies to other ranges.

[0022] Memory 104 stores the first injection range A as injection feasibility information. The first injection range A is the range of crank angles that allow fuel injection from the injector 50. The first injection range A is predetermined within the range of crank angles from the start time M1 of the intake stroke to the end time M2 of the intake stroke. In effect, memory 104 stores the crank angle that corresponds to the start time A1 of the first injection range A and the crank angle that corresponds to the end time A2 of the first injection range A. In the following description, when explaining the timing and range of fuel injection from the injector 50, unless otherwise specified, the timing and range will be described in terms of crank angle. The start time M1 of the intake stroke is the timing when the piston 12 is at top dead center. The end time M2 of the intake stroke is the timing when the piston 12 is at bottom dead center.

[0023] The start time A1 of the first injection range A is retarded compared to the start time M1 of the intake stroke, and advanced compared to the crank angle MV at the center of the intake stroke. Advancement is the process of turning the crank angle backward relative to a specific crank angle, and retardation is the opposite. The start time A1 of the first injection range A is, for example, a crank angle of approximately 60 degrees. The start time A1 of the first injection range A is determined by considering the amount of fuel injected from the injector 50 that adheres to the top surface 12A of the piston 12. The amount of fuel injected from the injector 50 that adheres to the top surface 12A of the piston 12 increases as the position of the piston 12 when the injector 50 injects fuel is closer to the injector 50, that is, as the piston 12 is closer to top dead center. The starting time A1 of the first injection range A is predetermined, for example through experimentation or simulation, as the limit crank angle within the range of crank angles during the intake stroke that can keep the amount of fuel adhering to the top surface 12A of the piston 12 below a first permissible value. The first permissible value can be set as a value that can keep the amount of particulate matter generated below a certain amount. In determining the starting time A1 of the first injection range A, the distance between the piston 12 and the injector 50 at each crank angle, the direction of movement of the piston 12, and the in-cylinder conditions such as the in-cylinder pressure, which is the pressure inside the cylinder 11, are taken into consideration.

[0024] The final timing A2 of the first injection range A is retarded compared to the crank angle of the midpoint MV of the intake stroke, and advanced compared to the end timing M2 of the intake stroke. The final timing A2 of the first injection range A is, for example, a crank angle of approximately 120 degrees. The final timing A2 of the first injection range A is determined considering the amount of fuel injected from the injector 50 that adheres to the wall surface 11A of the cylinder 11. The amount of fuel injected from the injector 50 that adheres to the wall surface 11A of the cylinder 11 increases as the exposed area of ​​the wall surface 11A when the injector 50 injects fuel increases, that is, as the closer the piston 12 is to bottom dead center. The final timing A2 of the first injection range A is predetermined, for example by experiment or simulation, considering the above in-cylinder conditions, as the limit crank angle within the range of crank angles of the intake stroke that can keep the amount of fuel adhering to the wall surface 11A of the cylinder 11 below a second permissible value. The second permissible value can be set as a value that can keep the amount of unburned hydrocarbons emitted from cylinder 11 below a certain amount.

[0025] Memory 104 stores the second injection range B as injection feasibility information. The second injection range B, like the first injection range A, is the range of crank angles that allow fuel injection from the injector 50. The second injection range B is predetermined within the range of crank angles from the start time N1 of the compression stroke to the end time N2 of the compression stroke. Furthermore, the second injection range B is not continuous with the first injection range A, but is separate. In effect, memory 104 stores the crank angle that corresponds to the start time B1 of the second injection range B and the crank angle that corresponds to the end time B2 of the second injection range B. The start time N1 of the compression stroke is the timing when the piston 12 is at bottom dead center. The end time N2 of the compression stroke is the timing when the piston 12 is at top dead center.

[0026] The start time B1 of the second injection range B is retarded compared to the crank angle at the start time N1 of the compression stroke, and advanced compared to the crank angle at the center NV of the compression stroke. The start time B1 of the second injection range B is, for example, a crank angle of approximately 220 degrees. The start time B1 of the second injection range B is determined, like the end time A2 of the first injection range A, by considering the amount of fuel injected from the injector 50 that adheres to the wall surface 11A of the cylinder 11. Specifically, the start time B1 of the second injection range B is predetermined, for example by experiment or simulation, by considering the above-mentioned in-cylinder conditions, as the limit crank angle within the range of crank angles of the compression stroke that can keep the amount of fuel adhering to the wall surface 11A of the cylinder 11 below the second allowable value. Note that, with respect to the end time M2 of the intake stroke, the start time B1 of the second injection range B is set asymmetrically with respect to the end time A2 of the first injection range A. Specifically, the start time B1 of the second injection range B is closer to the end time M2 of the intake stroke than the end time A2 of the first injection range A.

[0027] The final stage B2 of the second injection range B is advanced beyond the crank angle of the central NV of the compression stroke. The final stage B2 of the second injection range B is, for example, a crank angle of approximately 260 degrees. The final stage B2 of the second injection range B is determined by considering the amount of fuel injected from the injector 50 that adheres to the top surface 12A of the piston 12, similar to the starting stage A1 of the first injection range A. Specifically, the final stage B2 of the second injection range B is predetermined by experiment or simulation, for example, considering the above-mentioned in-cylinder conditions, as the limit crank angle within the range of crank angles of the compression stroke that can keep the amount of fuel adhering to the top surface 12A of the piston 12 below a first allowable value. As described above, the final stage B2 of the second injection range B is advanced beyond the crank angle of the central NV of the compression stroke. When this setting is compared with the starting stage A1 of the first injection range A, the following can be said. In other words, with respect to the end of the intake stroke M2, the end of the second injection range B, B2, is set asymmetrically with respect to the start of the first injection range A, A1. Specifically, the end of the second injection range B, B2, is closer to the end of the intake stroke M2 than to the start of the first injection range A, A1.

[0028] Here, the range of crank angles from the start of the intake stroke M1 to the start of the first injection range A A1 is referred to as the first predetermined range P. The range of crank angles from the end of the first injection range A A2 to the start of the next second injection range B B B1 is referred to as the second predetermined range Q. The range of crank angles from the end of the second injection range B B2 to the end of the compression stroke N2 is referred to as the third predetermined range R. These three predetermined ranges are the ranges of crank angles in which fuel injection by the injector 50 is prohibited. However, the timings of the start of the first injection range A A1, the end of the first injection range A A2, the start of the second injection range B B B1, and the end of the second injection range B B2 are timings in which fuel injection is permitted, as described above. When defined as above, the first injection range A and the second injection range B satisfy both of the following two conditions (L1) and (L2). (L1) The second injection range B is shorter than the first injection range A. (L2) The sum of the first predetermined range P and the third predetermined range R is longer than the second predetermined range Q.

[0029] <Specific Injection Control Details> The specific injection control is described in detail below. With respect to a particular cylinder 11, the CPU 102 causes the injector 50 to inject fuel in multiple stages during one cycle of the internal combustion engine 10. To achieve such multi-stage fuel injection, the CPU 102 can execute a first injection process and a second injection process as part of the specific injection control. In the first injection process, the CPU 102 causes the injector 50 to inject fuel once or more within the first injection range A for a particular cylinder 11. In the second injection process, the CPU 102 causes the injector 50 to inject fuel once or more within the second injection range B for a particular cylinder 11. In the first injection process, the CPU 102 basically reduces the number of times fuel injection is initiated at an advanced angle beyond the center crank angle of the first injection range A compared with the number of times fuel injection is initiated at an advanced angle beyond the center crank angle of the first injection range A. Furthermore, in the second injection process, the CPU 102 basically reduces the number of times fuel injection is initiated at an advanced angle beyond the center crank angle of the second injection range B compared to the number of times fuel injection is initiated at a retarded angle beyond the center crank angle of the second injection range B.

[0030] The specific processing procedure for specific injection control is described below. The CPU 102 starts specific injection control at a predetermined control cycle, provided that predetermined execution conditions are met while the internal combustion engine 10 is running. The execution condition is that the temperature of the coolant detected by the water temperature sensor 63 is below a predetermined temperature. The temperature of the coolant reflects the temperature inside the cylinder 11. The predetermined temperature is determined in advance, for example, by experiment or simulation, as the upper limit temperature at which fuel is considered difficult to vaporize inside the cylinder 11.

[0031] As shown in Figure 3, when the CPU 102 starts specific injection control, it first executes the process in step S10. In step S10, the CPU 102 calculates the total injection amount required for one cylinder 11 in one cycle of the internal combustion engine 10. The CPU 102 calculates the total injection amount based on the required torque for the internal combustion engine 10, which is determined from the accelerator operation amount and vehicle speed, as well as the operating conditions of the internal combustion engine 10, such as engine rotation speed and engine load ratio. At this time, the CPU 102 calculates the total injection amount based on the latest values ​​of each parameter, such as accelerator operation amount, vehicle speed, engine rotation speed, and engine load ratio. Once the CPU 102 has calculated the total injection amount, it proceeds to step S20. The process in step S10 is the total injection amount calculation process.

[0032] In step S20, the CPU 102 calculates the total number of injections, which is the total number of times fuel is injected into one injector 50 in one cycle of the internal combustion engine 10. The CPU 102 divides the latest total injection amount calculated in step S10 by the minimum injection amount stored in memory 104, and rounds down the decimal part of the resulting value to obtain the total number of injections. The minimum injection amount is the smallest amount of fuel that can be injected into the injector 50 in a single fuel injection. Once the CPU 102 has calculated the total number of injections, it proceeds to step S30.

[0033] In step S30, the CPU 102 distributes the total number of injections between the intake stroke and the compression stroke. Hereinafter, the number of injections distributed to the intake stroke will be referred to as the first injection count, and the number of injections distributed to the compression stroke will be referred to as the second injection count. If the total number of injections is even, the CPU 102 divides the total number of injections equally between the intake stroke and the compression stroke. That is, the CPU 102 makes the first injection count and the second injection count the same. On the other hand, if the total number of injections is odd, the CPU 102 makes the first injection count one more than the second injection count, and makes the sum of the first injection count and the second injection count equal the total number of injections. After this, the CPU 102 proceeds to step S40. The first injection count can also be said to be the number of injections distributed to the first injection range A. The first injection count is the basic value of the number of times the injector 50 will inject fuel within the first injection range A, which is necessary to inject the total amount of fuel in one cycle of the internal combustion engine 10. The second injection count can also be said to be the number of injections allocated to the second injection range B. The second injection count is the basic value of the number of times the injector 50 will inject fuel within the second injection range B, which is necessary to inject the total amount of fuel in one cycle of the internal combustion engine 10. The process in step S30, together with the process in step S110 of the first preparation process described later, constitutes the basic value calculation process.

[0034] In step S40, the CPU 102 performs a first preparation process. In this first preparation process, the CPU 102 determines the target start timing and target injection amount for each fuel injection when injecting fuel into the injector 50 during the intake stroke. Details of the first preparation process will be described later. After this, the CPU 102 proceeds to step S50.

[0035] In step S50, the CPU 102 performs a second preparation process. In this second preparation process, the CPU 102 determines the target start timing and target injection amount for each fuel injection when injecting fuel into the injector 50 during the compression stroke. Details of this second preparation process will be described later. After completing the process in step S50, the CPU 102 executes the processes in steps S60 and S70. These steps S60 and S70 are applied to all cylinders 11 that have reached the intake stroke start time M1 between the completion of step S50 and the completion of step S50 of the next cycle's specific injection control. Therefore, steps S60 and S70 may be executed sequentially for multiple cylinders 11, but for the sake of explanation, they will be described as a single step below.

[0036] In step S60, the CPU 102 performs the first injection process. Specifically, the CPU 102 causes the injector 50 to inject fuel within the first injection range A according to the target start timing and target injection amount defined in the first preparation process. That is, the CPU 102 repeatedly waits until each target start timing defined in the first preparation process is reached, and then controls the injector 50 to inject the target injection amount of fuel triggered by the target start timing. If the number of first injections defined in step S30 is 1, the CPU 102 causes the injector 50 to inject fuel only once. Once the CPU 102 has finished injecting the total amount of fuel allocated to the intake stroke, it proceeds to step S70.

[0037] In step S70, the CPU 102 performs the second injection process. Specifically, the CPU 102 causes the injector 50 to inject fuel within the second injection range B according to the target start timing and target injection amount defined in the second preparation process. That is, the CPU 102 repeatedly waits until the target start timing defined in the second preparation process is reached, and then controls the injector 50 to inject the target amount of fuel when the target start timing is reached. Similar to the first injection process, if the number of second injections defined in step S30 is 1, the CPU 102 causes the injector 50 to inject fuel only once. Once the CPU 102 has injected the total amount of fuel allocated to the compression stroke, it terminates the series of processes for the specific injection control. After this, if the execution conditions are met, the CPU 102 executes the specific injection control again.

[0038] <First Preparation Process> The specific processing procedure for the first preparation process will now be explained. As shown in Figure 4, when the CPU 102 starts the first preparation process, it first performs the process in step S110. In step S110, the CPU 102 sets the provisional start timing for each fuel injection when the injector 50 injects fuel during the intake stroke. First, the CPU 102 calculates the basic injection amount, which is the basic value of the amount of fuel injected per injection by the injector 50 that is required to inject the total injection amount in one cycle of the internal combustion engine 10, by dividing the total injection amount calculated in step S10 by the total number of injections calculated in step S20. Then, the CPU 102 calculates the fuel injection time required for each fuel injection. Furthermore, the CPU 102 converts this fuel injection time into the required crank interval, which is the range of crank angles corresponding to the current engine rotation speed. The CPU 102 also converts the basic injection interval stored in memory 104 into the basic crank interval, which is the range of crank angles corresponding to the current engine rotation speed. The basic injection interval is the basic time interval between the end of the first fuel injection and the start of the second fuel injection in two consecutive fuel injections. The basic injection interval is set to a time that minimizes the load on the electrical system driving the injector 50 while enabling each fuel injection. After calculating the basic crank interval, the CPU 102 determines the provisional start timing of the fuel injection for each of the first number of fuel injections determined in step S30. Specifically, the CPU 102 sets the provisional start timing of the first fuel injection to the start time A1 of the first injection range A. Then, the CPU 102 sets the provisional start timing of the second and subsequent fuel injections as follows: That is, the CPU 102 sequentially determines the provisional start timing of each fuel injection by retarding the timing of the next fuel injection by the sum of the required crank interval and the basic crank interval relative to the provisional start timing of the previous fuel injection. Furthermore, if the first injection range A determined in step S30 is one injection, the CPU 102 sets the start time A1 of the first injection range A as the start timing for this one fuel injection. Once the CPU 102 has set the provisional start timing for each fuel injection, it proceeds to S120.

[0039] In step S120, the CPU 102 determines whether the first completion condition is met if fuel injection is performed at the provisional start timing determined in step S110. This can also be described as determining whether the first completion condition is met under the first assumption that fuel injection is performed for the first number of injections, with the amount of fuel injected per injection being the basic injection amount within the first injection range A. The first completion condition is that the first total amount, which is the total amount of fuel injection allocated to the intake stroke and thus to the first injection range A, is injected within the first injection range A. The first total amount is the product of the basic injection amount, which is the amount of fuel injected per injection calculated in step S110, and the first number of injections. In other words, the first total amount is a value determined from the basic injection amount and the first number of injections. As for the specific processing in step S120, the CPU 102 first calculates the completion timing of the last fuel injection among the fuel injections for the first number of injections. Specifically, the CPU 102 refers to the provisional start timing of the last fuel injection among the provisional start timings for the first number of injections determined in step S110. The CPU 102 then calculates the completion timing as a timing retarded by the required crank interval relative to this provisional start timing. The CPU 102 then compares this completion timing with the end time A2 of the first injection range A. If the completion timing is the same as or more advanced than the end time A2 of the first injection range A, the CPU 102 determines that the first completion condition is met under the first assumption (step S120: YES). In this case, the CPU 102 proceeds to step S130. The process in step S120 is the first determination process.

[0040] As described above, in step S110, when the CPU 102 sets the provisional start timing for the first fuel injection for the first number of injections, it sets the provisional start timing for the first fuel injection to the start time A1 of the first injection range A. Therefore, the provisional start timing for the first number of fuel injections as a whole tends to be towards the advanced side of the first injection range A. In conjunction with this, when step S120 is judged to be positive, the following first number condition is usually met. The first number condition is that the number of times fuel injection is started at an advanced angle side of the central crank angle of the first injection range A is less than the number of times fuel injection is started at an advanced angle side of the central crank angle of the first injection range A.

[0041] In step S130, the CPU 102 sets the target start timing for each fuel injection when the injector 50 injects fuel during the intake stroke. Specifically, the CPU 102 sets the provisional start timings determined in step S110 as the target start timing for each fuel injection. In step S130, the CPU 102 also sets the basic injection amount calculated in step S110 as the target injection amount to be injected into the injector 50 at each target start timing. After this, the CPU 102 finishes the first preparation process.

[0042] On the other hand, in step S120, the CPU 102 determines that if the completion timing of the last fuel injection is retarded to the end time A2 of the first injection range A, the first completion condition is not met under the first assumption (step S120: NO). In this case, the CPU 102 proceeds to step S140.

[0043] In step S140, the CPU 102 sets the values ​​of the parameters to be changed when the injector 50 injects fuel during the intake stroke. Each parameter includes the number of injections, the injection start timing, and the amount of fuel injected per injection by the injector 50. Specifically, the CPU 102 sets the first number of injections, which is the number of injections changed from the first number of injections; the first timing, which is the injection start timing changed from the provisional start timing; and the first injection amount, which is the amount of fuel injected per injection changed from the basic injection amount. The CPU 102 sets the first number of injections, the first injection amount, and the first timing for the first number of injections so as to satisfy all three of the following conditions (X1), (X2), and (X3).

[0044] (X1) The product of the first change count and the first change injection amount is equal to the product of the first injection count and the base injection amount. (X2) The number of first changes is less than the number of first injections.

[0045] (X3) The first completion condition is met when the fuel injection amount per injection is set as the first modified injection amount, and fuel injections for the first number of modification cycles are performed at the first modification timing. Regarding the first modification timing for each fuel injection, the CPU 102 determines the first modification timing for each injection so that, similar to the case of the provisional start timing, the start time A1 of the first injection range A is set as the start timing for the first fuel injection, and fuel injections are started at regular intervals. When the modification values ​​for each parameter are set to satisfy all these conditions, the first modified injection amount becomes greater than the basic injection amount. In other words, the CPU 102 reassigns the start timing for each injection from the provisional start timing, increasing the fuel injection amount in a single fuel injection while reducing the number of injections in the first injection range A to the number of first injections. After this, the CPU 102 proceeds to step S150.

[0046] In step S150, the CPU 102 sets the first modification timings defined in step S140 as the target start timings for each fuel injection. Also in step S150, the CPU 102 sets the first modified injection amount defined in step S140 as the target injection amount to be injected into the injector 50 triggered by each target start timing. After this, the CPU 102 finishes the first preparation process. If the target start timing and target injection amount for each fuel injection are determined by the process in step S150, that is, if the first completion condition is not met under the above first assumption, the CPU 102 does the following in the first injection process of step S60. The CPU 102 causes the injector 50 to perform fuel injections for the first number of modification times, using a first modified injection amount which is the amount of fuel injected per injection changed from the basic injection amount, so that the first total amount can be injected within the first injection range A in a first number of modification times which is fewer than the first number of injections.

[0047] <Second Preparation Process> The specific processing procedure for the second preparation process will now be explained. As shown in Figure 5, when the CPU 102 starts the second preparation process, it first performs the process in step S210. In step S210, the CPU 102 sets the provisional start timing for each fuel injection when the injector 50 injects fuel during the compression stroke. Specifically, in step S210, the CPU 102 first determines the provisional start timing for the last fuel injection out of the fuel injections for the second number of injections. Specifically, the CPU 102 sets the provisional start timing for the last fuel injection to be advanced by the required crank interval from the end of the second injection range B2. After this, the CPU 102 determines the provisional start timing for the other fuel injections as follows. That is, the CPU 102 sequentially determines the start timing for each fuel injection by advancing the timing by the sum of the basic crank interval and the required crank interval for the provisional start timing of the next fuel injection, so that this advance is equal to the provisional start timing of the previous fuel injection. In this way, the CPU 102 determines the provisional start timing for each fuel injection at regular intervals so that the end timing of the last fuel injection coincides with the end time B2 of the second injection range B. If the second injection range B determined in step S30 is one injection, the CPU 102 sets the start timing of this one fuel injection as an advance timing by the required crank interval from the end time B2 of the second injection range B. Once the CPU 102 has set the start timing for each fuel injection, it proceeds to S220.

[0048] In step S220, the CPU 102 determines whether the second completion condition is met if fuel injection is performed at the provisional start timing determined in step S210. This can also be described as determining whether the second completion condition is met under the second assumption that fuel injection is performed for the second number of injections, with the amount of fuel injected per injection being the basic injection amount within the second injection range B. The second completion condition is that the second total amount, which is the total amount of fuel injection allocated to the compression stroke and thus to the second injection range B, is injected within the second injection range B. The second total amount is the product of the basic injection amount calculated in step S110 of the first preparation process and the second number of injections. In other words, the second total amount is a value determined from the basic injection amount and the second number of injections. As a specific process in step S220, the CPU 102 compares the start timing of the first fuel injection among the provisional start timings for the second number of injections determined in step S210 with the start time B1 of the second injection range B. The CPU 102 then determines that the second completion condition is met under the second assumption if this start timing is the same as or later than the start timing B1 of the second injection range B (step S220: YES). In this case, the CPU 102 proceeds to step S230. The process in step S220 is the second determination process.

[0049] As described above, in step S210, when the CPU 102 sets the provisional start timing for the second number of fuel injections, it ensures that the end timing of the last fuel injection coincides with the end time B2 of the second injection range B. Therefore, the provisional start timing for the second number of fuel injections tends to be on the retarded side of the second injection range B overall. In conjunction with this, when step S220 is judged positively, the following second number condition is usually met. The second number condition is that the number of times fuel injection is started on the advanced side of the center crank angle of the second injection range B is less than the number of times fuel injection is started on the retarded side of the center crank angle of the second injection range B.

[0050] In step S230, the CPU 102 sets the target start timing for each fuel injection when the injector 50 injects fuel during the compression stroke. Specifically, the CPU 102 sets the provisional start timings determined in step S210 as the target start timing for each fuel injection. In step S230, the CPU 102 also sets the basic injection amount calculated in the first preparation process as the target injection amount to be injected into the injector 50 at each target start timing. After this, the CPU 102 finishes the second preparation process.

[0051] On the other hand, in step S220, the CPU 102 determines that if the start timing of the first fuel injection is advanced beyond the start time B1 of the second injection range B, the second completion condition is not met under the second assumption (step S220: NO). In this case, the CPU 102 proceeds to step S240.

[0052] In step S240, the CPU 102 sets the change values ​​for each parameter when the injector 50 injects fuel during the compression stroke. The types of parameters are the same as in step S140 of the first preparation process. That is, each parameter includes the number of injections, the injection start timing, and the amount of fuel injected per injection by the injector 50. The CPU 102 then sets the second modified number of injections, which is the number of injections changed from the second number of injections; the second modified timing, which is the injection start timing changed from the provisional start timing; and the second modified injection amount, which is the amount of fuel injected per injection changed from the basic injection amount. At this time, the CPU 102 ensures that all three of the following conditions (Y1), (Y2), and (Y3) are met.

[0053] (Y1) The product of the second change count and the second change injection amount is equal to the product of the second injection count and the basic injection amount. (Y2) The number of second changes is less than the number of second injections.

[0054] (Y3) The second completion condition is met when the fuel injection amount per injection is set as the second modified injection amount, and fuel injections equal to the second modification number of times are performed at the second modification timing. Regarding the second modification timing for each fuel injection, the CPU 102 determines the second modification timing for each injection in the same way as when the provisional start timing was determined in step S210, such that the end time B2 of the second injection range B becomes the end timing of the last fuel injection, and that fuel injections start at a certain interval. In this process of step S240, the CPU 102 reassigns the start timing of each injection from the provisional start timing by increasing the amount of fuel injected in a single fuel injection while decreasing the number of injections in the second injection range B to the number of second injections. After performing the process in step S240, the CPU 102 proceeds to step S250.

[0055] In step S250, the CPU 102 sets the second modification timings defined in step S240 as the target start timings for each fuel injection. Also in step S250, the CPU 102 sets the second modification injection amount defined in step S240 as the target injection amount to be injected into the injector 50 triggered by each target start timing. After this, the CPU 102 finishes the second preparation process. If the target start timing and target injection amount for each fuel injection are determined by the process in step S250, that is, if the second completion condition is not met under the second assumption, the CPU 102 does the following in the second injection process in step S70. The CPU 102 causes the injector 50 to perform fuel injections for the second modification number of times, using a second modification injection amount which is the fuel injection amount per injection changed from the basic injection amount, so that the second total amount can be injected within the second injection range B in fewer second modification number of injections than the second number of injections.

[0056] <Effect of Embodiment 1> Let's assume that CPU 102 is currently performing specific injection control. And let's assume that the total number of injections calculated by CPU 102 in step S20 is 5. In this case, as shown in Figure 2, in step S30, CPU 102 sets the number of injections in the intake stroke to 3 and the number of injections in the compression stroke to 2. Then, in the first preparation process in step S40, CPU 102 sets the start timings for 3 fuel injections so that the number of times fuel injections are started advanced beyond the center crank angle of the first injection range A is greater than the number of times fuel injections are started within the first injection range A. Then, in step S60, CPU 102 performs fuel injections triggered by each of these start timings. Furthermore, in the second preparation process in step S50, CPU 102 sets the start timings for 2 fuel injections so that the number of times fuel injections are started retarded beyond the center crank angle of the second injection range B is greater than the number of times fuel injections are started within the second injection range B. Then, in step S70, CPU 102 performs fuel injections triggered by each of these start timings. In Figure 2, the range of crank angles in which fuel injection occurs is indicated by hatching. The same applies to Figures 6 and 7, which will be discussed later. Figures 2, 6, and 7 are explanatory diagrams intended to clearly illustrate the characteristics of each injection pattern and do not necessarily reflect the actual injection amount or injection interval.

[0057] <Effect of the Embodiment 2> When the temperature inside cylinder 11 is low, the fuel injected by injector 50 is less likely to vaporize. Therefore, if fuel is injected from injector 50 without any countermeasures, a large amount of fuel may adhere to the top surface 12A of piston 12 and the wall surface 11A of cylinder 11. To address this, CPU 102 performs specific injection control when the temperature inside cylinder 11 is low. In specific injection control, CPU 102 injects fuel into injector 50 in multiple stages during one cycle of the internal combustion engine 10 for each cylinder 11. This reduces the amount of fuel injected per fuel injection. As a result, CPU 102 makes it less likely for fuel to reach the top surface 12A of piston 12 and the wall surface 11A of cylinder 11.

[0058] In performing this multi-stage fuel injection, in this embodiment, the first injection range A and the second injection range B that allow fuel injection by the injector 50 are determined by considering the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 according to the position of the piston 12. As described above, the amount of fuel adhering to the top surface 12A of the piston 12 increases as the position of the piston 12 when the injector 50 injects fuel approaches top dead center. Taking this basic characteristic into account, the start time A1 of the first injection range A and the end time B2 of the second injection range B are determined by further considering the direction of movement of the piston 12. Specifically, in the intake stroke, the piston 12 moves from top dead center to bottom dead center. In other words, in the intake stroke, the piston 12 moves away from the injector 50. On the other hand, in the compression stroke, the piston 12 moves from bottom dead center to top dead center. In other words, in the compression stroke, the piston 12 moves towards the injector 50. Therefore, assuming that the piston 12 is in the same position during both the intake and compression strokes, and fuel injection is performed by the injector 50, the time it takes for the fuel to reach the piston 12 after the injector 50 injects it is shorter during the compression stroke. This is because during the compression stroke, the piston 12 approaches the fuel while the fuel is moving through the cylinder 11. Considering this background, in order to reduce the amount of fuel adhering to the top surface 12A of the piston 12, it is necessary for the fuel injection by the injector 50 to end during the compression stroke when the piston 12 is closer to the bottom dead center position compared to the intake stroke. In consideration of this, the end time B2 of the second injection range B is closer to the end time M2 of the intake stroke, i.e., the timing when the piston 12 is at bottom dead center, than the start time A1 of the first injection range A.

[0059] Furthermore, as mentioned above, the amount of fuel adhering to the cylinder wall 11A increases as the position of the piston 12 when the injector 50 injects fuel approaches bottom dead center. Taking this basic characteristic into account, and further considering the in-cylinder pressure, the end time A2 of the first injection range A and the start time B1 of the second injection range B are determined. Specifically, during the compression stroke, as the in-cylinder pressure gradually increases, the temperature of the gas inside the cylinder 11 also increases. Therefore, during the compression stroke, the vaporization of the fuel injected by the injector 50 is promoted. Consequently, during the compression stroke, even when fuel is injected by the injector 50 when the piston 12 is positioned closer to bottom dead center than during the intake stroke, it is possible to suppress the fuel from reaching the cylinder wall 11A. This is because during the compression stroke, the fuel can vaporize before reaching the cylinder wall 11A. Considering this background, in order to reduce the amount of fuel adhering to the wall surface 11A of the cylinder 11, it is permissible for the injector 50 to start fuel injection during the compression stroke when the piston 12 is located closer to the bottom dead center compared to the intake stroke. In conjunction with this, the start time B1 of the second injection range B is closer to the end time M2 of the intake stroke than the end time A2 of the first injection range A.

[0060] <Effects of the Embodiment> (1) In the configuration of this embodiment, the first injection range A and the second injection range B are not continuous. As a result, a certain range including at least the bottom dead center of the piston 12 is a range in which fuel injection by the injector 50 does not occur. That is, when the exposed area of ​​the cylinder wall surface 11A is at its largest, fuel injection by the injector 50 does not occur. Therefore, compared to the case in which fuel injection is performed when the piston 12 is at the bottom dead center, the adhesion of fuel to the cylinder wall surface 11A can be suppressed.

[0061] On the other hand, during the period from the start time N1 of the compression stroke to the end time N2 of the compression stroke, the piston 12 gradually moves toward the top dead center. Therefore, as explained in the operation 2 of the embodiment, during the compression stroke, the fuel injected by the injector 50 is more likely to reach the top surface 12A of the piston 12 compared to the intake stroke. In this respect, according to the configuration of this embodiment, since the second injection range B is set to be short, it is difficult for a large amount of fuel to be injected during the compression stroke. Therefore, it is possible to avoid a large amount of fuel adhering to the top surface 12A of the piston 12.

[0062] (2) The amount of unburned hydrocarbons increases as the position of the piston 12 during fuel injection approaches bottom dead center. More specifically, the amount of unburned hydrocarbons increases linearly with respect to the position of the piston 12. On the other hand, the amount of particulate matter increases as the position of the piston 12 during fuel injection approaches top dead center. More specifically, the amount of particulate matter increases exponentially with respect to the position of the piston 12. When considering the exponential increase in the amount of particulate matter, it is necessary to ensure as wide a range of crank angles as possible in which fuel injection is prohibited when the piston 12 is located towards top dead center.

[0063] In this respect, in this embodiment, the sum of the first predetermined range P and the third predetermined range R for prohibiting fuel injection is longer than the second predetermined range Q. Therefore, the above configuration is very effective in reducing the amount of particulate matter.

[0064] (3) As explained in the second part of the embodiment, when considering the direction of movement of the piston 12, in the compression stroke, fuel injection must be terminated at a timing when the piston 12 is further away from top dead center than in the intake stroke. Conversely, in the intake stroke, fuel injection is permitted even when the piston 12 is not far from top dead center. Therefore, as in this embodiment, if the end time B2 of the second injection range B is closer to the end time M2 of the intake stroke than the start time A1 of the first injection range A, the range of crank angles in which fuel injection is permitted can be maximized while reducing the amount of fuel adhering to the top surface 12A of the piston 12.

[0065] (4) As explained in the second operation of the embodiment, when considering the direction of movement of the piston 12, in the compression stroke, fuel injection is permitted at a timing closer to the bottom dead center of the piston 12 compared to the intake stroke. Therefore, as in this embodiment, if the start time B1 of the second injection range B is closer to the end time M2 of the intake stroke than the end time A2 of the first injection range A, the range of crank angles in which fuel injection is permitted can be maximized while reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11.

[0066] (5) In this embodiment, the CPU 102 basically reduces the number of times fuel injection is initiated at a crank angle retarded to the center of the first injection range A compared with the number of times fuel injection is initiated at a crank angle retarded to the center of the first injection range A compared with the number of times fuel injection is initiated at a crank angle retarded to the center of the second injection range B compared with the number of times fuel injection is initiated at a crank angle retarded to the center of the second injection range B. In the second injection process, the CPU 102 basically reduces the number of times fuel injection is initiated at a crank angle advanced to the center of the second injection range B compared with the number of times fuel injection is initiated at a crank angle retarded to the center of the second injection range B. Therefore, in this embodiment, the number of fuel injections when the piston 12 is close to bottom dead center is reduced. As a result, in this embodiment, the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be reduced.

[0067] As described in (2) above, in this embodiment, a large range of crank angles is secured on the top dead center side for prohibiting fuel injection by the injector 50. This makes it possible to strictly limit the amount of particulate matter generated, i.e., the amount of fuel adhering to the top surface 12A of the piston 12. Furthermore, as described above, by reducing the number of fuel injections when the piston 12 is close to bottom dead center, the amount of fuel adhering to the wall surface 11A of the cylinder 11 can also be strictly limited.

[0068] (6) For example, when the engine load rate increases, the total amount of fuel required for one cycle of the internal combustion engine 10 increases. Consequently, if the fuel injection amount per injection is used as the basic injection amount and the injector 50 is allowed to inject fuel, it may not be possible to inject the first total amount, which is the total amount of fuel injection allocated to the intake stroke and thus to the first injection range A, within the first injection range A. In this regard, in the configuration of this embodiment, if the first completion condition is not met under the first assumption, the fuel injection amount per injection is reassigned so that the first total amount can be injected in the first injection range A. Therefore, the amount of fuel required for the intake stroke can be reliably injected within the first injection range A while reducing the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11. Similarly, in the configuration of this embodiment, the amount of fuel required for the compression stroke can be reliably injected within the second injection range B while reducing the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11.

[0069] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0070] Regarding the first preparation process, the processing content of step S140 is not limited to the example of the above embodiment. In step S140, it is sufficient to adjust the number of injections, the injection start timing, and the amount of fuel injected per injection so that the total amount of fuel injection allocated to the intake stroke and thus to the first injection range A can be injected within the first injection range A. In this case, for example, these parameters may be adjusted so that the condition for the first number of injections is met. Also, for example, the amount of fuel injected per injection may not be the same for each fuel injection. In a similar view, the content of step S240 of the second preparation process can also be changed. In step S240, it is sufficient to adjust the parameters so that the total amount of fuel injection allocated to the compression stroke and thus to the second injection range B can be injected within the second injection range B.

[0071] The overall content of the first preparation process is not limited to the example of the above embodiment. As will be explained later, the first determination process can also be abolished in the first preparation process. In the first preparation process, it is sufficient to determine the target start timing for each injection when the injector 50 performs fuel injection in the first injection process, and the target injection amount to be injected by the injector 50 triggered by each target start timing. For example, instead of setting a provisional start timing first and then determining the target start timing as in the above embodiment, the target start timing may be set from the beginning by adjusting to satisfy the first completion condition, along with the target injection amount. That is, the target injection amount and target start timing for each fuel injection are set by working backward from the total amount of fuel injection allocated to the intake stroke and the number of injections, so that the total amount can be injected within the first injection range A. In this case, the target injection amount for each fuel injection may all be different, or the target injection amount may be different for only some of the multiple fuel injections. Furthermore, the interval between the end of the first fuel injection and the start of the second fuel injection in two consecutive fuel injections may be different for all of the multiple fuel injections, or it may be different for only some of the multiple fuel injections. The first number condition may or may not be met.

[0072] For example, if a configuration is adopted in which the target injection amount for each fuel injection is different, as shown in Figure 6, the target injection amount may be smaller for fuel injections performed on the retarded side among the multiple fuel injections performed in the first injection range A. In this case, for example, the target start timing for the first fuel injection may be set as the start time A1 of the first injection range A, and the target start timing for each fuel injection may be set accordingly. At the same time, the interval from the end timing to the start timing of each fuel injection may be made different for each fuel injection, and the target start timing for the second and subsequent fuel injections may be set as appropriate. When the first injection process is performed according to the target injection amount and target start timing set in this way, the amount of fuel injected by the injector 50 per injection decreases as the piston 12 approaches bottom dead center, thereby reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11.

[0073] In the example shown in Figure 6, a configuration was described in which the target injection amount for each fuel injection in the first injection range A is all different. However, even if the relationship that the target injection amount is smaller for fuel injections performed at a retarded angle in the first injection range A is not satisfied, the effect of reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be enjoyed if the following first fuel quantity condition is satisfied. The first fuel quantity condition is that, when the injector 50 performs multiple fuel injections in the same first injection range A, the fuel injection amount in the last fuel injection in the first injection range A is smaller than the fuel injection amount in the first fuel injection in the first injection range A.

[0074] As described above, the contents of the first preparation process can be appropriately modified from the example of the above embodiment. In the first preparation process, it is sufficient to set the number of injections, the injection start timing, and the amount of fuel injected per injection so that the total amount of fuel injection allocated to the intake stroke and thus to the first injection range A can be injected within the first injection range A. Whether or not a provisional start timing is set, both the first number condition and the first fuel amount condition may be satisfied, or only one of these two conditions may be satisfied, or neither of these two conditions may be satisfied.

[0075] The content of the first injection process reflects the settings of the first preparation process. Therefore, the content of the first injection process changes depending on the settings of the first preparation process. In other words, the amount of fuel injected and the injection start timing for each injection when the injector 50 is used to inject fuel in the first injection process can be changed as appropriate. It is not necessary for the start timing of the first fuel injection in the first injection process to be the start time A1 of the first injection range A.

[0076] Similar to the first preparation process, the overall content of the second preparation process is not limited to the examples of the above embodiment. In the second preparation process, it is sufficient to determine the target start timing for each injection when the injector 50 performs fuel injection in the second injection process, and the target injection amount to be injected by the injector 50 triggered by each target start timing. For example, similar to the first preparation process, in the second preparation process, the setting of a provisional start timing and, consequently the second determination process, may be abolished, and the target start timing and target injection amount may be set from the beginning by adjusting to satisfy the second completion condition. That is, the target injection amount and target start timing for each fuel injection are set by calculating backward from the total amount of fuel injection and the number of injections allocated to the compression stroke so that the total amount can be injected within the second injection range B. When such an embodiment is adopted, for example, as shown in Figure 6, the target injection amount may be smaller for the fuel injections performed on the advance side among the multiple fuel injections performed in the second injection range B. In this case, for example, the target start timing for each fuel injection may be set so that the end timing of the last fuel injection coincides with the end time B2 of the second injection range B. When the second injection process is performed according to the target injection amount and target start timing set in this way, the amount of fuel injected by the injector 50 per injection decreases as the piston 12 approaches bottom dead center, thereby reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11.

[0077] In the example shown in Figure 6, a configuration was described in which the target injection amount for each fuel injection in the second injection range B is all different. However, even if the relationship that the target injection amount is smaller for fuel injections performed on the advanced side in the second injection range B is not satisfied, the effect of reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be enjoyed if the following second fuel quantity condition is satisfied. The second fuel quantity condition is that, when the injector 50 performs multiple fuel injections in the same second injection range B, the fuel injection amount in the first fuel injection in the second injection range B is smaller than the fuel injection amount in the last fuel injection in the second injection range B.

[0078] As described above, the contents of the second preparation process can be appropriately modified from the example of the above embodiment. In the second preparation process, it is sufficient to set the number of injections, the injection start timing, and the amount of fuel injected per injection so that the total amount of fuel injection allocated to the compression stroke and thus to the second injection range B can be injected within the second injection range B. Whether or not a provisional start timing is set, both the second number condition and the second fuel amount condition may be satisfied, or only one of these two conditions may be satisfied, or neither of these two conditions may be satisfied.

[0079] The content of the second injection process will reflect the settings of the second preparation process. Therefore, the content of the second injection process will change depending on the settings of the second preparation process. In other words, the amount of fuel injected and the injection start timing for each injection when the injector 50 is injected during the second injection process can be changed as appropriate. It is not necessary to match the end timing of the last fuel injection in the second injection process with the end time B2 of the second injection range B.

[0080] The method of allocating the total number of injections to the intake stroke and compression stroke is not limited to the example of the above embodiment. The number of injections may be determined so that the required amount of fuel is injected in the first injection range A and the second injection range B, respectively, taking into account the amount of fuel injected into the injector 50 in one fuel injection. Furthermore, as in the above embodiment, the number of injections that have been initially allocated to the intake stroke and compression stroke may be further adjusted.

[0081] The method for determining the total number of injections is not limited to the examples of the embodiments described above. Any method that can determine an appropriate number of injections is acceptable. The method of determining the total number of injections can be abolished, and the number of injections may be determined individually from the beginning for each of the intake stroke and compression stroke, according to the operating conditions of the internal combustion engine 10.

[0082] The method of distributing the total injection amount to the intake stroke and compression stroke is not limited to the example of the above embodiment. It is sufficient to distribute the amount so that it can be injected in both the first injection range A and the second injection range B.

[0083] Regarding the distribution of the total injection amount to the intake stroke and compression stroke, for example, as shown in Figure 7, the total amount of injection amount distributed to the compression stroke may be greater than the total amount of injection amount distributed to the intake stroke. The injection amount thus distributed may be injected in multiple steps within each of the first injection range A and the second injection range B. In this case, for example, in the first injection range A, the amount of fuel injected per step may be smaller for fuel injections performed on the retarded ignition timing side. The start timing of the first fuel injection in the first injection range A may be set to the start time A1 of the first injection range A. Also, for example, in the second injection range B, the amount of fuel injected per step may be smaller for fuel injections performed on the advanced ignition timing side. In addition, each fuel injection may be performed such that the end timing of the last fuel injection in the second injection range B coincides with the end time B2 of the second injection range B, and the start timing of the first fuel injection in the second injection range B coincides with the start time B1 of the second injection range B. As described above, during the compression stroke, fuel vaporization is promoted in relation to the cylinder pressure, making it difficult for fuel to reach the cylinder wall 11A. Therefore, increasing the total amount of fuel injected into the compression stroke, as shown in the modified example in Figure 7, is suitable for reducing the amount of fuel adhering to the cylinder wall 11A. Furthermore, if fuel injection is performed in the first injection range A and the second injection range B, it is guaranteed that the amount of fuel adhering to the top surface 12A of the piston 12 will be reduced. Thus, as described above, there is no concern that increasing the total amount of fuel injected into the compression stroke will result in an increase in the amount of fuel adhering to the top surface 12A of the piston 12.

[0084] The determination of the number of injections and injection amounts in the intake stroke and compression stroke can be changed as appropriate. In short, it is sufficient to be able to inject the required amount of fuel for one cycle of the internal combustion engine 10, according to the required torque for the internal combustion engine 10, in the first injection range A and the second injection range B.

[0085] The parameters for determining the temperature inside cylinder 11 are not limited to the examples of the above embodiment. Instead of the coolant temperature, the cumulative amount of intake air since the internal combustion engine 10 started may be used as an indicator of the temperature inside cylinder 11. Any parameters can be used as long as the temperature inside cylinder 11 can be determined. The content of the execution conditions for specific injection control may be changed to match the parameters adopted.

[0086] The execution conditions for specific injection control are not limited to specifying that the temperature inside cylinder 11 is low. The content of the execution conditions may be set appropriately so that specific injection control can be executed as needed, not just when the temperature inside cylinder 11 is low.

[0087] The method for setting the first injection range A and the second injection range B is not limited to the example of the above embodiment. It is sufficient that the first injection range A and the second injection range B are not continuous, and that the second injection range B is shorter than the first injection range A.

[0088] It is not essential that the start time B1 of the second injection range B is closer to the end time M2 of the intake stroke than the end time A2 of the first injection range A. For example, the start time B1 of the second injection range B and the end time A2 of the first injection range A may be separated by the same amount from the end time M2 of the intake stroke.

[0089] It is not essential that the end time B2 of the second injection range B is closer to the end time M2 of the intake stroke than the start time A1 of the first injection range A. For example, the end time B2 of the second injection range B and the start time A1 of the first injection range A may be separated by the same amount from the end time M2 of the intake stroke.

[0090] It is not mandatory that the sum of the first predetermined range P and the third predetermined range R be longer than the second predetermined range Q. For example, the sum of the first predetermined range P and the third predetermined range R may be the same length as the second predetermined range Q.

[0091] The memory 104 may store multiple pairs of first injection range A and second injection range B in advance. For example, multiple pairs of first injection range A and second injection range B corresponding to the operating state of the internal combustion engine 10 may be prepared in advance, and the first injection range A and second injection range B may be changed according to the differences in the operating state of the internal combustion engine 10.

[0092] The overall configuration of the internal combustion engine 10 is not limited to the examples of the above embodiments. For example, the number of cylinders 11 may be changed. Even if the number of cylinders 11 is changed, one cycle of the internal combustion engine 10 can be treated as a series of periods in which one cylinder 11 undergoes the intake stroke, compression stroke, combustion stroke, and exhaust stroke once each. Furthermore, the cylinders 11 are not limited to those partitioned within the engine body 10A itself. For example, a cylindrical member may be housed inside the engine body 10A, and the cylinders 11 may be partitioned by the inner circumferential surface of such a cylindrical member. In this case, the inner circumferential surface of this cylindrical member constitutes the wall surface 11A of the cylinder 11. The internal combustion engine 10 only needs to have an injector 50 installed in the cylinder 11 so as to inject fuel from the top dead center side of the piston 12. That is, the injection port 54 of the injector 50 should be located above the top dead center of the piston 12. The inclination between the central axis of the injector 50 and the central axis of the cylinder 11 can be adjusted as needed.

[0093] A control device for controlling the injector 50 and a control device for controlling other controllable components in the internal combustion engine 10 besides the injector 50 may be provided separately. The processing circuit of the control device 100 may have any of the following configurations: (a), (b), and (c).

[0094] (a) The processing circuit has one or more processors that perform various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform the processes. Memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0095] (b) The processing circuit has one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs.

[0096] (c) The processing circuit comprises a processor that executes a portion of the various processes according to a computer program, and a dedicated hardware circuit that executes the remaining processes among the various processes. <Note> The technical concepts that can be understood from the above embodiments and modified examples are described below.

[0097] [Note 1] A control device for an injector that controls an injector that injects fuel into the cylinder of an internal combustion engine from the top dead center side of the piston, comprising an execution unit and a storage unit, wherein the storage unit stores a predetermined range of crank angles that allows fuel injection from the injector, namely a first injection range within the range of crank angles from the start of the intake stroke to the end of the intake stroke, and a predetermined second injection range within the range of crank angles from the start of the compression stroke to the end of the compression stroke, and the execution unit is capable of performing a first injection process that causes the injector to inject fuel within the first injection range, and a second injection process that causes the injector to inject fuel within the second injection range, wherein the second injection range is not continuous with the first injection range and is shorter than the first injection range.

[0098] [Note 2] The injector control device according to [Note 1], wherein the range of crank angles from the start of the intake stroke to the start of the first injection range is defined as a first predetermined range, the range of crank angles from the end of the first injection range to the start of the next second injection range is defined as a second predetermined range, and the range of crank angles from the end of the second injection range to the end of the compression stroke is defined as a third predetermined range, the sum of the first predetermined range and the third predetermined range is longer than the second predetermined range.

[0099] [Note 3] The injector control device according to [Note 1] or [Note 2], wherein the end of the second injection range is closer to the end of the intake stroke than the start of the first injection range.

[0100] [Note 4] The start time of the second injection range is closer to the end time of the intake stroke than the end time of the first injection range. This is the injector control device described in any one of [Note 1] to [Note 3].

[0101] [Note 5] The injector control device described in any one of [Note 1] to [Note 4], wherein in the first injection process, the number of times fuel injection is initiated at an advanced angle beyond the center of the first injection range is less than the number of times fuel injection is initiated at an advanced angle beyond the center of the first injection range.

[0102] [Note 6] The injector control device described in any one of [Note 1] to [Note 5], wherein in the second injection process, the number of times fuel injection is initiated at an advanced angle beyond the center of the second injection range is less than the number of times fuel injection is initiated at an advanced angle beyond the center of the second injection range.

[0103] [Note 7] The injector control device according to any one of [Note 1] to [Note 6], wherein in the first injection process, the injector is made to inject fuel multiple times within the same first injection range, and the amount of fuel injected in the last injection within the first injection range is less than the amount of fuel injected in the first injection range.

[0104] [Note 8] The injector control device according to any one of [Note 1] to [Note 7], wherein in the second injection process, the injector is made to inject fuel multiple times within the same second injection range, and the amount of fuel injected in the first injection within the second injection range is less than the amount of fuel injected in the last injection within the second injection range.

[0105] [Note 9] The execution unit performs a total injection amount calculation process based on the operating state of the internal combustion engine to calculate the total amount of fuel required for one cylinder in one cycle of the internal combustion engine, and calculates the basic injection amount, which is the basic value of the amount of fuel injected per injection by the injector required to inject the total injection amount in one cycle of the internal combustion engine, the first injection count, which is the basic value of the number of times the injector will inject fuel within the first injection range, and the second injection count, which is the basic value of the number of times the injector will inject fuel within the second injection range. When the first completion condition is defined as the completion of injecting a first total amount, which is the total amount of fuel injection allocated to the first injection range determined from the basic injection amount and the first injection count, prior to the first injection process, a first determination process is performed to determine whether the first completion condition is met, based on the first assumption that fuel injection is performed within the first injection range for the first number of injections, with the amount of fuel injection per injection being the basic injection amount, and the second injection count, the first determination process determines whether the first completion condition is met, and the fuel injection allocated to the second injection range is determined from the basic injection amount and the second injection count. When the second completion condition is defined as the total amount of injection, which is the sum of the injection amounts, being injected within the second injection range, it is possible to perform a second determination process prior to the second injection process, which determines whether the second completion condition is met, under the second assumption that fuel injection is performed within the second injection range for the number of second injections, with the amount of fuel injected per injection being the basic injection amount, and if the first completion condition is not met under the first assumption, the first injection process will complete the injection of the first total amount within the first injection range in a first number of changes that is fewer than the number of first injections. A control device for an injector as described in any one of [Note 1] to [Note 8], wherein the amount of fuel injected per injection is changed from the basic injection amount to enable the injector to perform fuel injection for the first number of changes, and if the second completion condition is not met under the second assumption, in the second injection process, the injector is instructed to perform fuel injection for the second number of changes, with the amount of fuel injected per injection being changed from the basic injection amount to enable the injector to complete the injection of the second total amount within the second injection range in a second number of changes that is fewer than the second number of injections. [Explanation of symbols]

[0106] 10... Internal combustion engine 11 cylinders 12... Piston 50... Injector 100...Control device 102…CPU 104...Memory

Claims

1. The target of control is the injector that injects fuel into the cylinder of an internal combustion engine from the top dead center side of the piston. It comprises an execution unit and a storage unit, The aforementioned storage unit is The range of crank angles in which fuel injection from the injector is permitted includes a first injection range predetermined within the range of crank angles from the start of the intake stroke to the end of the intake stroke, and a second injection range predetermined within the range of crank angles from the start of the compression stroke to the end of the compression stroke. I remember, The execution unit is, A first injection process in which the injector injects fuel within the first injection range, A second injection process in which the injector injects fuel within the second injection range, It is possible to do this, The second injection range is not continuous with the first injection range and is shorter than the first injection range. In the first injection process, the number of times fuel injection is initiated at an advanced angle beyond the center of the first injection range is less than the number of times fuel injection is initiated at an advanced angle beyond the center of the first injection range. Injector control device.

2. The target of control is the injector that injects fuel into the cylinder of an internal combustion engine from the top dead center side of the piston. It comprises an execution unit and a storage unit, The aforementioned storage unit is The range of crank angles in which fuel injection from the injector is permitted includes a first injection range predetermined within the range of crank angles from the start of the intake stroke to the end of the intake stroke, and a second injection range predetermined within the range of crank angles from the start of the compression stroke to the end of the compression stroke. I remember, The execution unit is, A first injection process in which the injector injects fuel within the first injection range, A second injection process in which the injector injects fuel within the second injection range, It is possible to do this, The second injection range is not continuous with the first injection range and is shorter than the first injection range. The execution unit is, A total injection amount calculation process that calculates the total amount of fuel required for one cylinder in one cycle of the internal combustion engine based on the operating state of the internal combustion engine, A basic value calculation process that calculates the basic injection amount, which is the basic value of the amount of fuel injected per injection by the injector, which is necessary to inject the total injection amount in one cycle of the internal combustion engine; the first injection count, which is the basic value of the number of times the injector injects fuel within the first injection range; and the second injection count, which is the basic value of the number of times the injector injects fuel within the second injection range, which are necessary to inject the total injection amount in one cycle of the internal combustion engine. When the first completion condition is defined as the completion of injecting a first total amount, which is the total amount of fuel injection allocated to the first injection range determined from the basic injection amount and the first number of injections, within the first injection range, Prior to the first injection process, a first determination process is performed to determine whether the first completion condition is met, based on the first assumption that fuel injection is performed for the first number of injections within the first injection range, with the amount of fuel injected per injection being the basic injection amount. When the second completion condition is defined as the completion of injecting the second total amount, which is the total amount of fuel injection allocated to the second injection range determined from the basic injection amount and the second number of injections, within the second injection range, Prior to the second injection process, a second determination process can be performed to determine whether the second completion condition is met, based on the second assumption that fuel injection is performed within the second injection range for the number of times the second injection is performed with the amount of fuel injected per injection being the basic injection amount. If the first completion condition is not met under the first assumption, the first injection process causes the injector to perform fuel injections for the first number of modification rounds, with the amount of fuel injected per injection being changed from the basic injection amount, so that the first total amount can be injected within the first injection range in fewer modification rounds than the first number of injection rounds. If the second completion condition is not met under the second assumption, the second injection process causes the injector to perform fuel injections for the second number of changes, with the amount of fuel injected per injection being changed from the basic injection amount, so that the second total amount can be injected within the second injection range in fewer changes than the second number of injections. Injector control device.

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