Injector control device

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

[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 combustion of a mixture of intake air and fuel. The piston is located inside the cylinder. The piston reciprocates inside the cylinder with the combustion of the mixture. The injector injects fuel directly 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. If 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 attached 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 these particulate matter and unburned hydrocarbons, a technique is required in which neither the amount of fuel adhering to the top surface of the piston nor the amount of fuel adhering to the wall surface of the cylinder becomes excessive.

Means for Solving the Problems

[0005] The control device for an injector for solving the above problems controls an injector that performs fuel injection from the top dead center side of a piston into a cylinder of an internal combustion engine, and includes an execution unit and a storage unit. The storage unit stores a first injection range predetermined within a range of crank angles from the start timing to the end timing of the intake stroke, as a range of crank angles allowing fuel injection from the injector, and a second injection range predetermined within a range of crank angles from the start timing to the end timing of the compression stroke. The execution unit is capable of executing a first injection process for causing the injector to perform fuel injection within the first injection range and a second injection process for causing the injector to perform fuel injection within the second injection range. The second injection range is not continuous with the first injection range and is shorter than the first injection range.

Advantages of the Invention

[0006] In the above technical idea, it is difficult for both 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 to become excessive amounts.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, an embodiment of a control device for an injector will be described with reference to the drawings. <Schematic Configuration of Internal Combustion Engine> As shown in FIG. 1, the vehicle includes an internal combustion engine 10. The internal combustion engine 10 is a driving source of the vehicle. The internal combustion engine 10 includes an engine body 10A, a plurality of cylinders 11, a plurality of pistons 12, a plurality of connecting rods 13, and a crankshaft 14. Note that in FIG. 1, only one of the plurality of cylinders 11 is shown. The same applies to the pistons 12 and the connecting rods 13. The pistons 12 and the connecting rods 13 are provided for each cylinder 11. The number of cylinders 11 is four.

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

[0010] The piston 12 is positioned within the cylinder 11. The piston 12 is cylindrical. The diameter of the piston 12 generally matches the diameter of the cylinder 11. The central axis of the piston 12 substantially coincides with 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 within the cylinder 11 in a direction along its central axis. The crankshaft 14 rotates in response to the reciprocation of the piston 12. When the piston 12 reciprocates within the cylinder 11, it moves away from or approaches the crankshaft 14. That is, the piston 12 operates between the top dead center where it is farthest from the crankshaft 14 and the bottom dead center where it is closest to the crankshaft 14. Hereinafter, the direction when the piston 12 moves toward the top dead center side may be referred to as upward, and the opposite direction may be referred to as downward. Also, of the two end faces of the piston 12 along the direction of its central axis, the end face facing upward is referred to as the top face 12A.

[0011] The internal combustion engine 10 includes a plurality of injectors 50. In FIG. 1, only one of the plurality of injectors 50 is shown. The injector 50 is provided for each cylinder 11. The injector 50 is positioned above the piston 12 with respect to the cylinder 11. The outer shape of the injector 50 is generally cylindrical. In the present embodiment, the central axis of the injector 50 is substantially parallel to the central axis of the cylinder 11. The tip of the injector 50 is positioned within the cylinder 11. The tip of the injector 50 is positioned above the top dead center of the piston 12. The injection port 54 provided at the tip of the injector 50 faces the top face 12A of the piston 12. Then, the injector 50 performs fuel injection into the cylinder 11 from the top dead center side of the piston 12. Thus, the injector 50 directly injects fuel into the cylinder 11 without passing through the intake passage 20 described later. The injector 50 injects gasoline as fuel.

[0012] The internal combustion engine 10 is equipped with a plurality of spark plugs 19. In FIG. 1, only one of the plurality of spark plugs 19 is shown. The spark plugs 19 are provided for each cylinder 11. The tip of the spark plug 19 is located inside the cylinder 11. The spark plug 19 ignites the air-fuel 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 can adjust its opening degree. Therefore, the intake air amount changes according to the opening degree of the throttle valve 22.

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

[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 are completed in one revolution as the crankshaft 14 rotates 720 degrees. When looking at a certain cylinder 11, the intake stroke is the period during which the piston 12 in that cylinder 11 moves from top dead center to bottom dead center. The compression stroke is the period following the intake stroke during which the piston 12 moves from bottom dead center to top dead center. The combustion stroke is the period following the compression stroke during which the piston 12 moves from top dead center to bottom dead center. The exhaust stroke is the period following the combustion stroke during which the piston 12 moves from bottom dead center to top dead center. Note that after the combustion stroke, it is the intake stroke of the next cycle.

[0016] The internal combustion engine 10 includes a crank angle sensor 61, an air flow meter 62, and a water 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 water temperature sensor 63 detects the temperature of the cooling water at the outlet of the cooling water 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: RAM, ROM, and an electrically rewritable non-volatile type. In the present 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. The CPU 102 calculates the following parameters as needed based on the detection signals received from the various sensors. The CPU 102 calculates the engine rotation speed, which is the rotation speed of the crankshaft 14, based on the transition of the crank angle received from the crank angle sensor 61. The CPU 102 calculates the engine load rate based on the engine rotation speed and the intake air amount received from the air flow meter 62. The engine load rate 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. The CPU 102 performs various controls on the internal combustion engine 10 based on the accelerator operation amount, vehicle speed, engine rotation speed, engine load rate, etc. For example, the CPU 102 performs injection control for the injector 50, ignition timing control for the spark plug 19, and opening degree adjustment control for the throttle valve 22. Through these controls, the CPU 102 burns the air-fuel mixture in the plurality of cylinders 11 in order.

[0021] The CPU 102 is capable of executing specific injection control. The specific injection control is injection control for when the internal combustion engine 10 is cold. As shown in FIG. 2, the memory 104 stores in advance injection enable / disable information, which is the range of crank angles that defines the enable / disable of fuel injection, as information used in the specific injection control. Note that FIG. 2 shows the crank angles 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 at 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 permission information. The first injection range A is the range of crank angles that permits fuel injection from injector 50. The first injection range A is predetermined within the range of crank angles from the start timing M1 of the intake stroke to the end timing M2 of the intake stroke. Memory 104 substantially stores the crank angle that becomes the start period A1 of the first injection range A and the crank angle that becomes the end period A2 of the first injection range A. In the following description, when explaining the timing and range of fuel injection of injector 50, etc., unless otherwise specified, it will be described as the timing and range in terms of crank angle. Note that the start timing M1 of the intake stroke is the timing when piston 12 is at top dead center. The end timing M2 of the intake stroke is the timing when piston 12 is at bottom dead center.

[0023] The start period A1 of the first injection range A is on the retard side from the start timing M1 of the intake stroke and on the advance side from the crank angle of the center MV of the intake stroke. Advance means going back the crank angle with respect to a certain specific crank angle, and retard is the opposite. The start period A1 of the first injection range A is, for example, a crank angle of approximately 60 degrees. The start period A1 of the first injection range A is determined in consideration of the amount of fuel adhering to the top surface 12A of piston 12 injected from injector 50. The amount of fuel injected from injector 50 and adhering to the top surface 12A of piston 12 increases as the position of piston 12 when injector 50 injects fuel is closer to injector 50, that is, as piston 12 is closer to top dead center. The start period A1 of the first injection range A is predetermined by, for example, experiment or simulation as the limit crank angle within the range of crank angles of the intake stroke that can suppress the amount of fuel adhering to the top surface 12A of piston 12 below the first allowable value. The first allowable value can be determined as a value that can suppress the generation amount of particulate matter below a certain amount. Note that when determining the start period A1 of the first injection range A, in-cylinder states such as the distance between piston 12 and injector 50 at each crank angle, the moving direction of piston 12, and the in-cylinder pressure which is the pressure in cylinder 11 are considered.

[0024] The end period A2 of the first injection range A is on the retard side of the crank angle of the center MV of the intake stroke and on the advance side of the end period M2 of the intake stroke. The end period A2 of the first injection range A is, for example, a crank angle of approximately 120 degrees. The end period A2 of the first injection range A is determined in consideration of 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 at the time when the injector 50 injects fuel is larger, that is, as the piston 12 is closer to the bottom dead center. The end period A2 of the first injection range A is determined in advance by, for example, experiments or simulations in consideration of the above in-cylinder state as the limit crank angle within the range of the crank angle of the intake stroke that can suppress the amount of fuel adhering to the wall surface 11A of the cylinder 11 to be equal to or less than a second allowable value. The second allowable value can be determined as a value that can suppress the amount of unburned hydrocarbons discharged from the cylinder 11 to be equal to or less than a certain amount.

[0025] The memory 104 stores the second injection range B as injection permission information. The second injection range B is, like the first injection range A, a range of crank angles that permits fuel injection from the injector 50. The second injection range B is predetermined within the range of crank angles from the start period N1 to the end period N2 of the compression stroke. Also, the second injection range B is not continuous with the first injection range A and is separated. The memory 104 substantially stores the crank angle that becomes the start period B1 of the second injection range B and the crank angle that becomes the end period B2 of the second injection range B. Note that the start period N1 of the compression stroke is the timing when the piston 12 is located at the bottom dead center. The end period N2 of the compression stroke is the timing when the piston 12 is located at the top dead center.

[0026] The start period B1 of the second injection range B is on the retard side of the crank angle that becomes the start period N1 of the compression stroke and on the advance side of the crank angle at the center NV of the compression stroke. The start period B1 of the second injection range B is, for example, a crank angle of approximately 220 degrees. The start period B1 of the second injection range B is determined in consideration of the amount of fuel injected from the injector 50 that adheres to the wall surface 11A of the cylinder 11, similar to the end period A2 of the first injection range A. Specifically, the start period B1 of the second injection range B is determined in advance by, for example, experiments or simulations considering the above in-cylinder state, as the limit crank angle within the range of the crank angle of the compression stroke that can suppress the amount of fuel adhering to the wall surface 11A of the cylinder 11 to be equal to or less than the second allowable value. When the end period M2 of the intake stroke is used as a reference, the start period B1 of the second injection range B is set asymmetrically with respect to the end period A2 of the first injection range A. Specifically, the start period B1 of the second injection range B is closer to the end period M2 of the intake stroke than the end period A2 of the first injection range A.

[0027] The end period B2 of the second injection range B is on the advance side of the crank angle at the center NV of the compression stroke. The end period B2 of the second injection range B is, for example, a crank angle of approximately 260 degrees. The end period B2 of the second injection range B is determined in consideration of the amount of fuel injected from the injector 50 that adheres to the top surface 12A of the piston 12, similar to the start period A1 of the first injection range A. Specifically, the end period B2 of the second injection range B is determined in advance by, for example, experiments or simulations considering the above in-cylinder state, as the limit crank angle within the range of the crank angle of the compression stroke that can suppress the amount of fuel adhering to the top surface 12A of the piston 12 to be equal to or less than the first allowable value. As described above, the end period B2 of the second injection range B is on the advance side of the crank angle at the center NV of the compression stroke. When this setting is compared with the start period A1 of the first injection range A, the following can be said. That is, when the end period M2 of the intake stroke is used as a reference, the end period B2 of the second injection range B is set asymmetrically with respect to the start period A1 of the first injection range A. Specifically, the end period B2 of the second injection range B is closer to the end period M2 of the intake stroke than the start period A1 of the first injection range A.

[0028] Here, the range of the crank angle from the start timing M1 of the intake stroke to the start period A1 of the first injection range A is referred to as the first predetermined range P. The range of the crank angle from the end period A2 of the first injection range A to the start period B1 of the next second injection range B is referred to as the second predetermined range Q. The range of the crank angle from the end period B2 of the second injection range B to the end timing N2 of the compression stroke is referred to as the third predetermined range R. These three predetermined ranges are the ranges of the crank angle that prohibit fuel injection by the injector 50. However, the timings themselves of the start period A1 of the first injection range A, the end period A2 of the first injection range A, the start period B1 of the second injection range B, and the end period B2 of the second injection range B are timings that allow fuel injection 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] <Details of Specific Injection Control> The specific injection control will be described in detail. Regarding one cylinder 11, in the specific injection control, the CPU 102 causes the injector 50 to perform fuel injection 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 perform fuel injection one or more times within the first injection range A for one cylinder 11. In the second injection process, the CPU 102 causes the injector 50 to perform fuel injection one or more times within the second injection range B for one cylinder 11. In the first injection process, basically, the CPU 102 reduces the number of times of starting fuel injection on the retard angle side compared to the number of times of starting fuel injection on the advance angle side with respect to the crank angle at the center of the first injection range A. Also, in the second injection process, basically, the CPU 102 reduces the number of times of starting fuel injection on the advance angle side compared to the number of times of starting fuel injection on the retard angle side with respect to the crank angle at the center of the second injection range B.

[0030] The following describes the specific processing procedure of the specific injection control. During the operation of the internal combustion engine 10, the CPU 102 starts the specific injection control at a predetermined control cycle on the condition that predetermined execution conditions are satisfied. The execution condition is that the temperature of the cooling water detected by the water temperature sensor 63 is equal to or lower than a predetermined temperature. The temperature of the cooling water reflects the temperature inside the cylinder 11. The predetermined temperature is determined in advance by experiments or simulations, for example, as the upper limit temperature at which fuel is considered difficult to vaporize inside the cylinder 11.

[0031] As shown in FIG. 3, when starting the specific injection control, the CPU 102 first executes the process of step S10. In step S10, the CPU 102 calculates the total injection amount required in 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 grasped from the accelerator operation amount and the vehicle speed, and further based on the operating state of the internal combustion engine 10 such as the engine rotation speed and the engine load factor. At this time, the CPU 102 calculates the total injection amount based on the latest values of each parameter such as the accelerator operation amount, the vehicle speed, the engine rotation speed, and the engine load factor. After calculating the total injection amount, the CPU 102 advances the process to step S20. The process of step S10 is the total injection amount calculation process.

[0032] In step S20, the CPU 102 calculates the total injection number, which is the total number of fuel injections to be made to 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 the memory 104, and calculates the value obtained by rounding down the decimal part of the divided value as the total injection number. The minimum injection amount is the minimum amount of fuel that can be injected into the injector 50 in one fuel injection. After calculating the total injection number, the CPU 102 advances the process 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 is referred to as the first injection number. The number of injections distributed to the compression stroke is referred to as the second injection number. When the total number of injections is even, the CPU 102 equally divides the total number of injections between the intake stroke and the compression stroke. That is, the CPU 102 makes the first injection number and the second injection number the same. On the other hand, when the total number of injections is odd, the CPU 102 makes the first injection number one more than the second injection number and ensures that the sum of the first injection number and the second injection number is equal to the total number of injections. After that, the CPU 102 advances the process to step S40. Note that the first injection number can also be said to be the number of injections distributed to the first injection range A. And the first injection number is the basic value of the number of times to cause the injector 50 to perform fuel injection within the first injection range A, which is necessary for injecting the total injection amount in one cycle of the internal combustion engine 10. The second injection number can also be said to be the number of injections distributed to the second injection range B. And the second injection number is the basic value of the number of times to cause the injector 50 to perform fuel injection within the second injection range B, which is necessary for injecting the total injection amount in one cycle of the internal combustion engine 10. The process of step S30, together with the process of step S110 of the first preparation process described later, constitutes the basic value calculation process.

[0034] In step S40, the CPU 102 performs the first preparation process. In this first preparation process, the CPU 102 determines the target start timing and the target injection amount of each injection when causing the injector 50 to perform fuel injection in the intake stroke. The details of the first preparation process will be described later. After that, the CPU 102 advances the process to step S50.

[0035] In step S50, the CPU 102 performs second preparatory processing. In this second preparatory processing, the CPU 102 determines the target start timing and the target injection amount for each injection when fuel is injected into the injector 50 during the compression stroke. The details of this second preparatory processing will be described later. When the CPU 102 finishes the processing of step S50, it executes the processing of steps S60 and S70. Note that steps S60 and S70 are applied to all cylinders 11 that have reached the start timing M1 of the intake stroke after step S50 ends and until step S50 of the specific injection control in the next cycle ends. Therefore, steps S60 and S70 may be executed in order for a plurality of cylinders 11, but hereinafter, for the sake of convenience of explanation, these will be described as one step.

[0036] In step S60, the CPU 102 performs first injection processing. Specifically, the CPU 102 causes the injector 50 to inject fuel within the first injection range A in accordance with the target start timing and the target injection amount determined in the first preparatory processing. That is, the CPU 102 repeats waiting until each target start timing determined in the first preparatory processing is reached and controlling the injector 50 so that the injector 50 injects fuel corresponding to the target injection amount when the target start timing is reached. Note that when the number of first injections determined in step S30 is one, the CPU 102 causes the injector 50 to inject fuel only once. When the CPU 102 finishes injecting the total amount of the injection amount allocated to the intake stroke, the processing 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 in accordance with the target start timing and the target injection amount determined in the second preparation process. That is, the CPU 102 waits until the target start timing determined in the second preparation process is reached, and controls the injector 50 so that the injector 50 injects fuel corresponding to the target injection amount, and repeats this. Similar to the first injection process, when the number of second injections determined in step S30 is one, the CPU 102 causes the injector 50 to perform fuel injection only once. When the CPU 102 finishes injecting the total amount of the injection amount allocated to the compression stroke, the CPU 102 ends the series of processes of the specific injection control. After this, if the execution conditions are satisfied, the CPU 102 executes the specific injection control again.

[0038] <First Preparation Process> The specific processing procedure of the first preparation process will be described. As shown in FIG. 4, when the CPU 102 starts the first preparation process, it first performs the process of step S110. In step S110, the CPU 102 sets the provisional start timing of each injection when causing the injector 50 to perform fuel injection during the intake stroke. First, the CPU 102 divides the total injection amount calculated in step S10 by the total number of injection times calculated in step S20 to calculate the basic injection amount, which is the basic value of the fuel injection amount per injection by the injector 50 required to inject the total injection amount in one cycle of the internal combustion engine 10. Then, the CPU 102 calculates the fuel injection time per injection required for each fuel injection. Further, the CPU 102 converts this fuel injection time into the required crank interval, which is the range of the crank angle corresponding to the current engine rotation speed. Also, the CPU 102 converts the basic injection interval stored in the memory 104 into the basic crank interval, which is the range of the crank angle corresponding to the current engine rotation speed. The basic injection interval is the basic value of the time interval from the end timing of the first fuel injection to the start timing of the second fuel injection in two consecutive fuel injections. The basic injection interval is determined as a time that can realize each fuel injection while minimizing the load on the electrical system that drives the injector 50. When the CPU 102 calculates the basic crank interval, for each fuel injection for the number of first injections determined in step S30, the CPU 102 determines the provisional start timing of the fuel injection. Specifically, the CPU 102 sets the provisional start timing of the first fuel injection to the start period A1 of the first injection range A. Then, the CPU 102 sets the provisional start timing of the fuel injection after the second time as follows. That is, the CPU 102 determines the provisional start timing of each fuel injection in order so that the timing on the retard side by the length obtained by combining the required crank interval and the basic crank interval with respect to the provisional start timing of the previous fuel injection becomes the provisional start timing of the next fuel injection. Note that when the first injection range A determined in step S30 is one time, the CPU 102 sets the start period A1 of the first injection range A as the start timing of this one fuel injection. When the CPU 102 sets the provisional start timing of each fuel injection, the process proceeds to S120.

[0039] In step S120, the CPU 102 determines whether the first completion condition is satisfied when fuel injection is performed at the tentative start timing determined in step S110. This can also be said to be determining whether the first completion condition is satisfied under the first assumption of performing fuel injection for the number of first injection times with the fuel injection amount per injection within the first injection range A as the basic injection amount. The first completion condition is to finish injecting the first total amount, which is the total amount of fuel injection assigned to the intake stroke and thus the first injection range A, within the first injection range A. The first total amount is the product of the basic injection amount, which is the fuel injection amount per injection calculated in step S110, and the number of first injections. That is, the first total amount is a value determined from the basic injection amount and the number of first injections. As the specific process of step S120, first, the CPU 102 calculates the completion timing of the last fuel injection among the fuel injections for the number of first injections. Specifically, the CPU 102 refers to the tentative start timing of the last fuel injection among the tentative start timings for the number of first injections determined in step S110. Then, the CPU 102 calculates the timing on the retarded side by the required crank interval with respect to this tentative start timing as the completion timing. Then, the CPU 102 compares this completion timing with the end period A2 of the first injection range A. And when the completion timing is the same as or more advanced than the end period A2 of the first injection range A, the CPU 102 determines that the first completion condition is satisfied under the first assumption (step S120: YES). In this case, the CPU 102 advances the process to step S130. Note that the process of step S120 is the first determination process.

[0040] Here, as described above, when setting the provisional start timing of fuel injection for the first injection count in step S110, the CPU 102 sets the provisional start timing of the first fuel injection to the start period A1 of the first injection range A. Therefore, the provisional start timing of fuel injection for the first injection count as a whole tends to be closer to the advanced angle side within the first injection range A. In consideration of this, when the determination in step S120 is affirmative, in most cases, the following first count condition is satisfied. The first count condition is that the number of times of starting fuel injection on the retard angle side is less than the number of times of starting fuel injection on the advanced angle side compared to the crank angle at the center of the first injection range A.

[0041] Now, in step S130, the CPU 102 sets the target start timing of each injection when causing the injector 50 to perform fuel injection during the intake stroke. Specifically, the CPU 102 sets each provisional start timing determined in step S110 as the target start timing of each fuel injection. Also, in step S130, the CPU 102 sets the basic injection amount calculated in step S110 as the target injection amount to be injected into the injector 50 with each target start timing as an opportunity. After this, the CPU 102 ends the first preparatory process.

[0042] On the other hand, in step S120, when the completion timing of the last fuel injection is on the retard angle side of the end period A2 of the first injection range A, the CPU 102 determines that the first completion condition is not satisfied under the first assumption (step S120: NO). In this case, the CPU 102 advances the process to step S140.

[0043] In step S140, the CPU 102 sets change values of each parameter when causing the injector 50 to perform fuel injection during the intake stroke. Each parameter includes the number of injections, the injection start timing, and the fuel injection amount per injection by the injector 50. That is, the CPU 102 sets a first changed number of injections obtained by changing the number of injections from the first number of injections, a first changed timing obtained by changing the injection start timing from the temporary start timing, and a first changed injection amount obtained by changing the fuel injection amount per injection from the basic injection amount. The CPU 102 sets the first changed number of injections, the first changed injection amount, and the first changed timings for the first changed number of injections so as to satisfy all of the following three conditions (X1), (X2), and (X3).

[0044] (X1) The product of the first changed number of injections and the first changed injection amount matches the product of the first number of injections and the basic injection amount. (X2) The first changed number of injections is less than the first number of injections.

[0045] (X3) When fuel injection for the first changed number of injections is performed at the first changed timings with the fuel injection amount per injection being the first changed injection amount, the first completion condition is satisfied. Regarding the first changed timing of each fuel injection, the CPU 102 determines the first changed timing of each injection so that fuel injection starts at regular intervals with the start period A1 of the first injection range A as the start timing of the first fuel injection, similar to the case of the temporary start timing. When the change values of each parameter are determined so as to satisfy all such conditions, the first changed injection amount becomes larger than the basic injection amount. That is, the CPU 102 reallocates the start timing of each injection from the temporary start timing in such a way that the fuel injection amount in one fuel injection is increased while the number of injections in the first injection range A is reduced from the first number of injections. After this, the CPU 102 advances the process to step S150.

[0046] In step S150, the CPU 102 sets each of the first change timings determined in step S140 as the target start timing of each fuel injection. Also, in step S150, the CPU 102 sets the first change injection amount determined in step S140 as the target injection amount to be injected into the injector 50 starting from each target start timing. After that, the CPU 102 ends the first preparation process. When the target start timing and the target injection amount of each fuel injection are determined by the process of this step S150, that is, when the first completion condition is not satisfied under the above first assumption, the CPU 102 performs the following in the first injection process of step S60. The CPU 102 changes the fuel injection amount per injection from the basic injection amount to the first change injection amount such that the first total amount can be injected within the first injection range A in the first change number that is less than the first injection number, and causes the injector 50 to perform fuel injection for the first change number of times.

[0047] <Second Preparation Process> The specific processing procedure of the second preparation process will be described. As shown in FIG. 5, when the CPU 102 starts the second preparation process, it first performs the process of step S210. In step S210, the CPU 102 sets the temporary start timing of each injection when causing the injector 50 to perform fuel injection during the compression stroke. As the specific process of step S210, first, the CPU 102 determines the temporary start timing of the last fuel injection among the fuel injections for the second injection count. Specifically, the CPU 102 determines the timing on the advance angle side by the necessary crank interval from the end period B2 of the second injection range B as the temporary start timing of the last fuel injection. After that, the CPU 102 determines the temporary start timing of other fuel injections as follows. That is, the CPU 102 determines the start timing of each fuel injection in order such that the timing on the advance angle side by the combined length of the basic crank interval and the necessary crank interval with respect to the temporary start timing of the fuel injection one time later becomes the temporary start timing of the fuel injection one time earlier. In this way, the CPU 102 determines the temporary start timing of each fuel injection at regular intervals so that the end timing of the last fuel injection coincides with the end period B2 of the second injection range B. Note that when the second injection range B determined in step S30 is one time, the CPU 102 determines the start timing of this one-time fuel injection as the timing on the advance angle side by the necessary crank interval from the end period B2 of the second injection range B. When the CPU 102 sets the start timing of each fuel injection, the process proceeds to S220.

[0048] In step S220, the CPU 102 determines whether the second completion condition is satisfied when fuel injection is performed at the tentative start timing determined in step S210. This can also be said to determine whether the second completion condition is satisfied under the second assumption that fuel injection is performed the number of times of the second injection within the second injection range B with the fuel injection amount per injection as the basic injection amount. The second completion condition is to finish injecting within the second injection range B the second total amount, which is the total amount of fuel injection assigned to the compression stroke and thus to the second injection range B. The second total amount is the product of the basic injection amount calculated in step S110 of the first preparatory process and the number of times of the second injection. That is, the second total amount is a value determined from the basic injection amount and the number of times of the second injection. As a specific process of step S220, the CPU 102 compares the start timing of the first fuel injection among the tentative start timings for the number of times of the second injection determined in step S210 with the start period B1 of the second injection range B. Then, when this start timing is the same as or on the retarded side of the start period B1 of the second injection range B, the CPU 102 determines that the second completion condition is satisfied under the second assumption (step S220: YES). In this case, the CPU 102 advances the process to step S230. Note that the process of step S220 is the second determination process.

[0049] Here, as described above, when setting the tentative start timing of fuel injection for the number of times of the second injection in step S210, the CPU 102 makes the end timing of the last fuel injection coincide with the end period B2 of the second injection range B. Therefore, the tentative start timing of fuel injection for the number of times of the second injection as a whole tends to be on the retarded side within the second injection range B. In consideration of this, when step S220 is positively determined, in most cases, the following second number condition is satisfied. The second number condition is that the number of times of starting fuel injection on the advanced angle side of the crank angle at the center of the second injection range B is smaller than the number of times of starting fuel injection on the retarded angle side of the crank angle at the center of the second injection range B.

[0050] Now, in step S230, the CPU 102 sets the target start timing for each injection when causing the injector 50 to perform fuel injection during the compression stroke. Specifically, the CPU 102 sets each provisional start timing determined in step S210 as the target start timing for each fuel injection. Also, in step S230, the CPU 102 sets the basic injection amount calculated in the first preparation process as the target injection amount to be injected into the injector 50 with each target start timing as an opportunity. After this, the CPU 102 ends the second preparation process.

[0051] On the other hand, in step S220, when the start timing of the first fuel injection is on the advanced angle side from the start period B1 of the second injection range B, the CPU 102 determines that the second completion condition is not satisfied under the second assumption (step S220: NO). In this case, the CPU 102 advances the process to step S240.

[0052] In step S240, the CPU 102 sets the change value of each parameter when causing the injector 50 to perform fuel injection during the compression stroke. The types of parameters are the same as those in step S140 of the first preparation process. That is, each parameter includes the number of injections, the injection start timing, and the fuel injection amount per injection by the injector 50. Then, the CPU 102 sets the second change number of injections with the number of injections changed from the second number of injections, the second change timing with the injection start timing changed from the provisional start timing, and the second change injection amount with the fuel injection amount per injection changed from the basic injection amount. At that time, the CPU 102 makes all of the following three conditions (Y1), (Y2), and (Y3) satisfied.

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

[0054] (Y3) When fuel injection for the second change number of times is performed at the second change timing with the fuel injection amount per injection as the second change injection amount, the second completion condition is satisfied. Regarding the second change timing of each fuel injection, the CPU 102 determines the second change timing of each injection so that the end period B2 of the second injection range B becomes the end timing of the last fuel injection and the fuel injections are started at regular intervals, in the same manner as when the tentative start timing was determined in step S210. Regarding the process of this step S240, the CPU 102 will reassign the start timing of each injection from the tentative start timing, while increasing the fuel injection amount in one fuel injection and reducing the number of injections in the second injection range B to be less than the second number of injections. When the CPU 102 performs the process of step S240, the process proceeds to step S250.

[0055] In step S250, the CPU 102 sets each second change timing determined in step S240 as the target start timing of each fuel injection. Also, in step S250, the CPU 102 sets the second change injection amount determined in step S240 as the target injection amount to be injected into the injector 50 starting from each target start timing. After that, the CPU 102 ends the second preparation process. When the target start timing and target injection amount of each fuel injection are determined by the process of this step S250, that is, when the second completion condition is not satisfied under the second assumption, the CPU 102 performs the following in the second injection process of step S70. The CPU 102 causes the injector 50 to perform fuel injection for the second number of changes with the second change injection amount obtained by changing the fuel injection amount per time from the basic injection amount so that the second total amount can be injected within the second injection range B with the second number of changes less than the second number of injections.

[0056] <Operation 1 of the Embodiment> Now, assume that the CPU 102 is executing specific injection control. And assume that the total number of injection times calculated by the CPU 102 in step S20 is 5 times. In this case, as shown in FIG. 2, in step S30, the CPU 102 sets the number of injection times during the intake stroke to 3 times and the number of injection times during the compression stroke to 2 times. And in the first preparation process of step S40, the CPU 102 sets the start timings of the 3 fuel injections such that the number of times of starting fuel injection on the advanced angle side from the crank angle at the center of the first injection range A in the first injection range A increases. Then, in step S60, the CPU 102 performs fuel injection triggered by these respective start timings. Also, in the second preparation process of step S50, the CPU 102 sets the start timings of the 2 fuel injections such that the number of times of starting fuel injection on the retarded angle side from the crank angle at the center of the second injection range B in the second injection range B increases. Then, in step S70, the CPU 102 performs fuel injection triggered by these respective start timings. In FIG. 2, the range of the crank angle at which fuel injection is performed is indicated by hatching. This also applies to FIGS. 6 and 7 described later. FIGS. 2, 6, and 7 are explanatory diagrams for easily explaining the characteristics of each injection pattern and do not necessarily reflect the actual injection amount, injection interval, etc.

[0057] <Operation 2 of the Embodiment> When the temperature in the cylinder 11 is low, the fuel injected by the injector 50 is difficult to vaporize. Therefore, if fuel injection is performed from the injector 50 without any countermeasures, the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 may increase. Thus, when the temperature in the cylinder 11 is low, the CPU 102 performs specific injection control. In the specific injection control, the CPU 102 causes the injector 50 to inject fuel in multiple stages during one cycle of the internal combustion engine 10 for one cylinder 11. By this, the CPU 102 reduces the fuel injection amount per fuel injection. And thereby, the CPU 102 makes it difficult for the fuel to reach the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11.

[0058] In performing such multi-stage fuel injection, in the present embodiment, 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, a first injection range A and a second injection range B in which fuel injection by the injector 50 is permitted are defined. 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 performs fuel injection approaches the top dead center. Taking this basic characteristic into account and further considering the moving direction of the piston 12, the start period A1 of the first injection range A and the end period B2 of the second injection range B are defined. Specifically, in the intake stroke, the piston 12 moves from the top dead center toward the bottom dead center. That is, 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 the bottom dead center toward the top dead center. That is, in the compression stroke, the piston 12 approaches the injector 50. Therefore, assuming that fuel injection is performed by the injector 50 in a situation where the piston 12 is at the same position in the intake stroke and the compression stroke, the length of time from when the injector 50 injects fuel until the fuel reaches the piston 12 is shorter in the compression stroke. This is because in the compression stroke, the piston 12 approaches the fuel while the fuel is moving in the cylinder 11. Considering such a background, in order to reduce the amount of fuel adhering to the top surface 12A of the piston 12, in the compression stroke, it is necessary to end the fuel injection by the injector 50 in a situation where the piston 12 is located more on the bottom dead center side than in the intake stroke. Taking this into consideration, the end period B2 of the second injection range B is closer to the end timing M2 of the intake stroke, that is, the timing when the piston 12 is at the bottom dead center, than the start period A1 of the first injection range A.

[0059] Also, as described above, the amount of fuel adhering to the wall surface 11A of the cylinder 11 increases as the position of the piston 12 approaches the bottom dead center when the injector 50 performs fuel injection. Considering this basic characteristic and further taking into account the in-cylinder pressure, the end period A2 of the first injection range A and the start period B1 of the second injection range B are defined. Specifically, in the compression stroke, as the in-cylinder pressure gradually increases, the temperature of the gas in the cylinder 11 increases. Therefore, in the compression stroke, the vaporization of the fuel injected by the injector 50 is promoted. Thus, in the compression stroke, even when fuel injection is performed by the injector 50 under the condition that the piston 12 is located closer to the bottom dead center side than in the intake stroke, it is possible to suppress the fuel from reaching the wall surface 11A of the cylinder 11. This is because the fuel can vaporize before reaching the wall surface 11A of the cylinder 11 in the compression stroke. Considering such a background, in order to reduce the amount of fuel adhering to the wall surface 11A of the cylinder 11, in the compression stroke, it is allowed to start fuel injection by the injector 50 under the condition that the piston 12 is located closer to the bottom dead center side than in the intake stroke. In consideration of this, the start period B1 of the second injection range B is closer to the end period M2 of the intake stroke than the end period A2 of the first injection range A.

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

[0061] On one hand, within the period from the start timing N1 of the compression stroke to the end timing N2 of the compression stroke, the piston 12 gradually moves toward the top dead center. Therefore, as described in the operation 2 of the embodiment, during the compression stroke, compared with the intake stroke, the fuel injected by the injector 50 is more likely to reach the top surface 12A of the piston 12. In this regard, according to the configuration of the present embodiment, since the second injection range B is set 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 from 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 at the time of fuel injection gets closer to the bottom dead center. Specifically, the amount of unburned hydrocarbons increases linearly according to the position of the piston 12. On the other hand, the amount of particulate matter increases as the position of the piston 12 at the time of fuel injection gets closer to the top dead center. Specifically, the amount of particulate matter increases exponentially according to the position of the piston 12. Considering the exponentially rapid increase characteristic of the amount of particulate matter, it is necessary to ensure as much as possible the range of crank angle that prohibits fuel injection when the piston 12 is located on the top dead center side.

[0063] In this regard, in the present embodiment, the sum of the first predetermined range P and the third predetermined range R that prohibit 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 described in the operation 2 of the embodiment, when considering the moving direction of the piston 12, in the compression stroke, compared with the intake stroke, it is necessary to end fuel injection at a timing when the piston 12 is farther from the top dead center. Conversely, in the intake stroke, fuel injection is permitted even at a timing when the piston 12 is not so far from the top dead center. Therefore, if the end period B2 of the second injection range B is closer to the end timing M2 of the intake stroke than the start period A1 of the first injection range A as in the present embodiment, it is possible to reduce the amount of fuel adhering to the top surface 12A of the piston 12 while maximizing the range of crank angle that permits fuel injection.

[0065] (4) As described in the operation 2 of the embodiment, when considering the moving direction of the piston 12, in the compression stroke, it is allowed to perform fuel injection at a timing when the piston 12 is closer to the bottom dead center than in the intake stroke. Therefore, if the start period B1 of the second injection range B is closer to the end period M2 of the intake stroke than the end period A2 of the first injection range A as in this embodiment, it is possible to maximize the range of the crank angle that allows fuel injection while reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11.

[0066] (5) In the first injection process, the CPU 102 of this embodiment basically reduces the number of times of starting fuel injection on the retarded angle side rather than on the advanced angle side with respect to the crank angle at the center of the first injection range A, compared to the number of times of starting fuel injection on the advanced angle side with respect to the crank angle at the center of the first injection range A. Also, in the second injection process, the CPU 102 basically reduces the number of times of starting fuel injection on the advanced angle side rather than on the retarded angle side with respect to the center of the second injection range B, compared to the number of times of starting fuel injection on the retarded angle side with respect to the center of the second injection range B. Therefore, in this embodiment, the number of times of fuel injection when the piston 12 is close to the bottom dead center is reduced. Therefore, 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 the crank angle for prohibiting fuel injection by the injector 50 is ensured on the top dead center side. By this, the generation amount of particulate matter, that is, the amount of fuel adhering to the top surface 12A of the piston 12 can be strictly limited. Moreover, as described above, by reducing the number of times of fuel injection when the piston 12 is close to the 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 factor increases, the total fuel injection amount required in one cycle of the internal combustion engine 10 increases. Along with this, if fuel injection is performed on the injector 50 with the fuel injection amount per injection as the basic injection amount, it may not be possible to inject the entire first total amount, which is the total amount of fuel injection assigned to the intake stroke and thus the first injection range A, within the first injection range A. In this regard, in the configuration of the present embodiment, when the first completion condition is not satisfied under the first assumption, the fuel injection amount per injection is reassigned so that the first total amount can be injected within the first injection range A. Therefore, 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, the required amount of fuel in the intake stroke can be reliably injected within the first injection range A. Similarly, in the configuration of the present embodiment, 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, the required amount of fuel in the compression stroke can be reliably injected within the second injection range B.

[0069] <Modified Example> The above embodiment can be implemented with the following modifications. The above embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0070] ·Regarding the first preparation process, the content of step S140 is not limited to the example of the above embodiment. In step S140, it is only necessary to be able to adjust the number of injections, the injection start timing, and the fuel injection amount per injection so that the total fuel injection amount assigned to the intake stroke and thus the first injection range A can be completely injected within the first injection range A. At that time, for example, these parameters may be adjusted so that the first number condition is satisfied. Also, for example, the fuel injection amount per injection may be different for each fuel injection. From the same perspective, the content of step S240 of the second preparation process can also be changed. In step S240, it is only necessary to be able to adjust the parameters so that the total fuel injection amount assigned to the compression stroke and thus the second injection range B can be completely 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 described later, the first determination process can also be abolished in the first preparation process. In the first preparation process, it is only necessary to be able to determine the target start timing of each injection when causing the injector 50 to perform fuel injection in the first injection process, and the target injection amount to be injected into the injector 50 triggered by each target start timing. For example, instead of setting the target start timing after temporarily setting the temporary start timing as in the above embodiment, the target start timing may be set together with the target injection amount by adjusting from the beginning so as to satisfy the first completion condition. That is, the target injection amount and the target start timing of each fuel injection are set so that the total amount can be completely injected within the first injection range A by calculating backward from the total amount of the fuel injection amount assigned to the intake stroke and the number of injections. At that time, the target injection amounts of each fuel injection may all be different, or only a part of the plurality of fuel injections may have a different target injection amount from the others. Also, the interval from the end timing of the first fuel injection to the start timing of the second fuel injection in two consecutive fuel injections may all be different in the plurality of fuel injections, or only a part of the plurality of fuel injections may have a different interval from the others. The first number condition may or may not be satisfied.

[0072] For example, when adopting a mode in which the target injection amounts of each fuel injection are all different, as shown in FIG. 6, among the plurality of fuel injections performed in the first injection range A, the fuel injection performed on the retard side may have a smaller target injection amount. And at that time, for example, the target start timing of the first fuel injection may be set as the start period A1 of the first injection range A, and the target start timing of each fuel injection may be set. At the same time, while making the intervals from the end timing to the start timing of the fuel injection different from each other for each fuel injection, the target start timing of the second and subsequent fuel injections may be appropriately set. When performing the first injection process according to the target injection amount and the target start timing set in this way, since the amount of fuel injected per injection by the injector 50 decreases as the piston 12 approaches the bottom dead center, the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be reduced.

[0073] In the example of FIG. 6, the mode in which the target injection amounts of the respective fuel injections in the first injection range A are all different has been described. However, even if the relationship in which the target injection amount is smaller for the fuel injection performed on the retard side in the first injection range A is not satisfied, if the following first fuel amount condition is satisfied, the effect of reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be enjoyed. The first fuel amount condition is that when causing the injector 50 to perform a plurality of 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 content of the first preparation process can be appropriately changed from the example of the above embodiment. In the first preparation process, the number of injections, the injection start timing, and the fuel injection amount per injection may be set so that the total amount of the fuel injection amount assigned to the intake stroke and thus the first injection range A can be completely injected within the first injection range A. Regardless of whether the temporary 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 set content of the first preparation process. Therefore, the content of the first injection process changes depending on the set content of the first preparation process. That is, the fuel injection amount and the injection start timing at each injection when causing the injector 50 to perform fuel injection in the first injection process can be appropriately changed. It is not essential that the start timing of the first fuel injection in the first injection process is the start period A1 of the first injection range A.

[0076] · Similar to the first preparation process, the entire content of the second preparation process is not limited to the examples of the above embodiments. In the second preparation process, it is only necessary to be able to determine the target start timing of each injection when causing the injector 50 to perform fuel injection in the second injection process, and the target injection amount to be injected into the injector 50 with each target start timing as an opportunity. For example, similar to the first preparation process, in the second preparation process, the setting of the provisional start timing and thus the second determination process may be abolished, and from the beginning, the target start timing may be set together with the target injection amount by adjusting so as to satisfy the second completion condition. That is, the target injection amount and the target start timing of each fuel injection are set so that the total amount can be injected within the second injection range B by back-calculating from the total amount of the fuel injection amount and the number of injections assigned to the compression stroke. When adopting such an aspect, for example, as shown in FIG. 6, among the multiple fuel injections performed in the second injection range B, the fuel injection amount may be made smaller for the fuel injection performed on the advanced angle side. And at that time, for example, the target start timing of each fuel injection may be set so that the end timing of the last fuel injection coincides with the end period B2 of the second injection range B. When the second injection process is performed according to the target injection amount and the target start timing set in this way, since the fuel injected per injection by the injector 50 decreases as the piston 12 approaches the bottom dead center, the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be reduced.

[0077] In addition, in the example of FIG. 6, the aspect in which the target injection amounts of each fuel injection in the second injection range B are all different has been described. However, even if the relationship that the fuel injection amount is smaller for the fuel injection performed on the advanced angle side in the second injection range B is not satisfied, as long as the following second fuel amount condition is satisfied, the effect of reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be obtained. The second fuel amount condition is that when causing the injector 50 to perform 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 content of the second preparatory process can be appropriately changed from the examples of the above embodiments. In the second preparatory process, it is only necessary to be able to set the number of injections, the injection start timing, and the fuel injection amount per injection so that the total amount of fuel injection assigned to the compression stroke and thus the second injection range B can be completely injected within the second injection range B. Regardless of whether the 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 reflects the set content of the second preparatory process. Therefore, the content of the second injection process changes according to the set content of the second preparatory process. That is, the fuel injection amount and the injection start timing at each injection when causing the injector 50 to perform fuel injection in the second injection process can be appropriately changed. It is not essential to match the end timing of the last fuel injection in the second injection process with the end period B2 of the second injection range B.

[0080] · The method of distributing the total number of injections to the intake stroke and the compression stroke is not limited to the examples of the above embodiments. Based on the fuel injection amount injected into the injector 50 in one fuel injection, etc., the number of injections may be determined so that the required amount of fuel can be injected in each of the first injection range A and the second injection range B. Also, as in the above embodiments, the number of injections once distributed to the intake stroke and the compression stroke may be further adjusted.

[0081] · The method of determining the total number of injections is not limited to the examples of the above embodiments. Any method can be used as long as an appropriate number of injections can be determined. · The mode of determining the total number of injections may be abolished, and from the beginning, the number of injections may be individually determined according to the operating state of the internal combustion engine 10, etc. in each of the intake stroke and the compression stroke.

[0082] ·The method of distributing the total injection amount to the intake stroke and the compression stroke is not limited to the examples of the above embodiments. It is only necessary to distribute the amounts that can be injected in each of the first injection range A and the second injection range B.

[0083] Regarding the method of distributing the total injection amount to the intake stroke and the compression stroke, for example, as shown in FIG. 7, the total amount of the injection amount distributed to the compression stroke may be larger than the total amount of the injection amount distributed to the intake stroke. Then, the injection amounts distributed in this way may be injected in multiple times in each of the first injection range A and the second injection range B. At this time, for example, in the first injection range A, the fuel injection amount per injection may be made smaller for the fuel injection performed on the retarded angle side. Also, the start timing of the first fuel injection in the first injection range A may be set to the start period A1 of the first injection range A. Further, for example, in the second injection range B, the fuel injection amount per injection may be made smaller for the fuel injection performed on the advanced angle side. At the same time, each fuel injection may be performed so that the end timing of the last fuel injection in the second injection range B coincides with the end period 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 period B1 of the second injection range B. As described above, in the compression stroke, since the vaporization of the fuel is promoted in relation to the in-cylinder pressure, it is difficult for the fuel to reach the wall surface 11A of the cylinder 11. Therefore, increasing the total amount of the injection amount distributed to the compression stroke as in the modified example of FIG. 7 is suitable for reducing the amount of fuel adhering to the wall surface 11A of the cylinder 11. In addition, if fuel injection is performed in the first injection range A and the second injection range B, it is ensured that the amount of fuel adhering to the top surface 12A of the piston 12 is reduced. From this, there is no concern that the amount of fuel adhering to the top surface 12A of the piston 12 will increase even if the total amount of fuel distributed to the compression stroke is increased as described above.

[0084] ·How to determine the number of injections and the injection amount in each of the intake stroke and the compression stroke can be changed as appropriate. The main point is that it is only necessary to be able to inject the amount of fuel required in one cycle of the internal combustion engine 10 according to the required torque for the internal combustion engine 10, etc., with the first injection range A and the second injection range B.

[0085] · The parameters for grasping the temperature in the cylinder 11 are not limited to the examples of the above embodiment. As an index of the temperature in the cylinder 11, instead of the temperature of the cooling water, the integrated value of the intake air amount since the internal combustion engine 10 starts may be used. As long as the temperature in the cylinder 11 can be grasped, any parameter may be used. The content of the execution conditions of the specific injection control may be changed according to the parameter adopted.

[0086] · The execution conditions of the specific injection control are not limited to those that determine that the temperature in the cylinder 11 is low. Not limited to the case where the temperature in the cylinder 11 is low, the content of the execution conditions may be appropriately set so that the specific injection control can be executed as necessary.

[0087] · The setting method of the first injection range A and the second injection range B is not limited to the examples of the above embodiment. It is only necessary that the first injection range A and the second injection range B are not continuous and the second injection range B is shorter than the first injection range A.

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

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

[0090] · It is not essential that the sum of the first predetermined range P and the third predetermined range R is 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 in advance a plurality of pairs of the first injection range A and the second injection range B. For example, a plurality of pairs of the first injection range A and the second injection range B corresponding to, for example, the operating state of the internal combustion engine 10 may be prepared in advance, and the first injection range A and the second injection range B may be changed according to differences such as the operating state of the internal combustion engine 10.

[0092] · The overall configuration of the internal combustion engine 10 is not limited to the example of the above embodiment. For example, the number of cylinders 11 may be changed. Even when 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 an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke once each. Further, the cylinder 11 is not limited to being partitioned within the engine body 10A itself. For example, a cylindrical member may be accommodated inside the engine body 10A, and the cylinder 11 may be partitioned by the inner peripheral surface of such a cylindrical member. In this case, the inner peripheral 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 attached so as to perform fuel injection from above the top dead center of the piston 12 within the cylinder 11. That is, it is sufficient that the injection port 54 of the injector 50 is 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 and the like can be appropriately changed.

[0093] · A control device for controlling the injector 50 and a control device for controlling operation target components other than the injector 50 in the internal combustion engine 10 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 execute various processes according to a computer program. The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores program codes or instructions configured to cause the CPU to execute processes. The memory, that is, the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0095] (b) The processing circuit has one or more dedicated hardware circuits that execute various processes. Examples of the dedicated hardware circuits include, for example, application-specific integrated circuits, that is, ASICs or FPGAs.

[0096] (c) The processing circuit has a processor that executes part of the various processes according to a computer program and a dedicated hardware circuit that executes the remaining processes of the various processes. <Appendix> Describe the technical idea that can be grasped from the above embodiments and modification examples.

[0097] [Appendix 1] An injector that performs fuel injection from the top dead center side of a piston into a cylinder of an internal combustion engine is a control target, and includes an execution unit and a storage unit. The storage unit stores, as a range of crank angles that allows fuel injection from the injector, a first injection range predetermined within a range of crank angles from the start timing to the end timing of the intake stroke, and a second injection range predetermined within a range of crank angles from the start timing to the end timing of the compression stroke. The execution unit is capable of executing a first injection process that causes the injector to perform fuel injection within the first injection range and a second injection process that causes the injector to perform fuel injection within the second injection range. The second injection range is not continuous with the first injection range and is shorter than the first injection range. A control device for an injector.

[0098] [Appendix 2] When the range of crank angles from the start timing of the intake stroke to the start timing of the first injection range is defined as a first predetermined range, the range of crank angles from the end timing of the first injection range to the start timing of the next second injection range is defined as a second predetermined range, and the range of crank angles from the end timing of the second injection range to the end timing 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. The control device for an injector according to [Appendix 1].

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

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

[0101] [Supplementary Note 5] In the first injection process, the number of times of starting fuel injection on the retard angle side of the center of the first injection range is less than the number of times of starting fuel injection on the advance angle side of the center of the first injection range. The injector control device according to any one of [Supplementary Note 1] to [Supplementary Note 4].

[0102] [Supplementary Note 6] In the second injection process, the number of times of starting fuel injection on the advance angle side of the center of the second injection range is less than the number of times of starting fuel injection on the retard angle side of the center of the second injection range. The injector control device according to any one of [Supplementary Note 1] to [Supplementary Note 5].

[0103] [Supplementary Note 7] In the first injection process, the injector is made to perform a plurality of fuel injections in the same first injection range, and the last fuel injection amount in the first injection range is less than the first fuel injection amount in the first injection range. The injector control device according to any one of [Supplementary Note 1] to [Supplementary Note 6].

[0104] [Supplementary Note 8] In the second injection process, the injector is made to perform a plurality of fuel injections in the same second injection range, and the first fuel injection amount in the second injection range is less than the last fuel injection amount in the second injection range. The injector control device according to any one of [Supplementary Note 1] to [Supplementary Note 7].

[0105] [Appendix 9] The execution unit includes a total injection amount calculation process for calculating the total injection amount of fuel required in one of the cylinders in one cycle of the internal combustion engine based on the operating state of the internal combustion engine, and a basic injection amount that is the basic value of the fuel injection amount per injection by the injector, a first injection count that is the basic value of the number of times of fuel injection by the injector within the first injection range, and a second injection count that is the basic value of the number of times of fuel injection by the injector within the second injection range, which are required for injecting the total injection amount in one cycle of the internal combustion engine. The execution unit also includes a basic value calculation process for calculating these values, a first determination process for determining whether the first completion condition is satisfied under the first assumption that fuel injection is performed the number of times of the first injection count with the basic injection amount as the fuel injection amount per injection within the first injection range prior to the first injection process when the first total amount, which is the total amount of the fuel injection amount allocated to the first injection range determined from the basic injection amount and the first injection count, is used as the first completion condition for finishing injection within the first injection range, and a second determination process for determining whether the second completion condition is satisfied under the second assumption that fuel injection is performed the number of times of the second injection count with the basic injection amount as the fuel injection amount per injection within the second injection range prior to the second injection process when the second total amount, which is the total amount of the fuel injection amount allocated to the second injection range determined from the basic injection amount and the second injection count, is used as the second completion condition for finishing injection within the second injection range. The execution unit is capable of executing these processes. When the first completion condition is not satisfied under the first assumption, in the first injection process, the injector is caused to perform fuel injection the number of times of the first change count, which is less than the first injection count, with a value obtained by changing the fuel injection amount per injection from the basic injection amount so that the first total amount can be injected and finished within the first injection range. When the second completion condition is not satisfied under the second assumption, in the second injection process, the injector is caused to perform fuel injection the number of times of the second change count, which is less than the second injection count, with a value obtained by changing the fuel injection amount per injection from the basic injection amount so that the second total amount can be injected and finished within the second injection range. A control device for an injector according to any one of [Appendix 1] to [Appendix 8].

Description of Reference Numerals

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

Claims

1. An injector that performs fuel injection from the top dead center side of a piston into a cylinder of an internal combustion engine is a control target, and includes an execution unit and a storage unit, The storage unit stores, as a range of crank angles that allows fuel injection from the injector, a first injection range predetermined within a range of crank angles from the start timing to the end timing of the intake stroke, and a second injection range predetermined within a range of crank angles from the start timing to the end timing of the compression stroke, and the execution unit can execute a first injection process for causing the injector to perform fuel injection within the first injection range, and a second injection process for causing the injector to perform fuel injection within the second injection range, and the second injection range is not continuous with the first injection range and is shorter than the first injection range A control device for an injector.

2. When a range of crank angles from the start timing of the intake stroke to the start timing of the first injection range is defined as a first predetermined range, a range of crank angles from the end timing of the first injection range to the start timing of the next second injection range is defined as a second predetermined range, and a range of crank angles from the end timing of the second injection range to the end timing 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 The control device for an injector according to Claim 1.

3. The end timing of the second injection range is closer to the end timing of the intake stroke than the start timing of the first injection range The control device for an injector according to Claim 1.

4. The start timing of the second injection range is closer to the end timing of the intake stroke than the end timing of the first injection range The control device for an injector according to claim 1.

5. In the first injection process, the number of times of starting fuel injection on the retard side of the center of the first injection range is smaller than the number of times of starting fuel injection on the advance side of the center of the first injection range. The control device for an injector according to claim 1.

6. In the second injection process, the number of times of starting fuel injection on the advance side of the center of the second injection range is smaller than the number of times of starting fuel injection on the retard side of the center of the second injection range. The control device for an injector according to claim 1.

7. In the first injection process, the injector is caused to perform fuel injection a plurality of times within the same first injection range, and the last fuel injection amount within the first injection range is smaller than the first fuel injection amount within the first injection range. The control device for an injector according to claim 1.

8. In the second injection process, the injector is caused to perform fuel injection a plurality of times within the same second injection range, and the first fuel injection amount within the second injection range is smaller than the last fuel injection amount within the second injection range. The control device for an injector according to claim 1.

9. The execution unit A total injection amount calculation process for calculating the total injection amount of fuel required in one cylinder of the internal combustion engine in one cycle of the internal combustion engine based on the operating state of the internal combustion engine, A basic value calculation process for calculating a basic injection amount that is a basic value of the fuel injection amount per injection by the injector, a first injection number that is a basic value of the number of times of causing the injector to perform fuel injection within the first injection range, and a second injection number that is a basic value of the number of times of causing the injector to perform fuel injection within the second injection range, which are required for injecting the total injection amount in one cycle of the internal combustion engine. When a first completion condition is that the total amount of fuel injection amounts assigned to the first injection range, which is determined from the basic injection amount and the first injection number, is injected within the first injection range until completion, Prior to the first injection process, a first determination process for determining whether the first completion condition is satisfied is performed on the basis of a first assumption that fuel injection is performed the number of times of the first injection number with the fuel injection amount per time within the first injection range being the basic injection amount, When a second completion condition is that the total amount of fuel injection amounts assigned to the second injection range, which is determined from the basic injection amount and the second injection number, is injected within the second injection range until completion, Prior to the second injection process, a second determination process for determining whether the second completion condition is satisfied is executable on the basis of a second assumption that fuel injection is performed the number of times of the second injection number with the fuel injection amount per time within the second injection range being the basic injection amount, When the first completion condition is not satisfied under the first assumption, in the first injection process, the fuel injector is caused to perform fuel injection the number of times of the first change number with the fuel injection amount per time being a value changed from the basic injection amount so that the first total amount can be injected within the first injection range until completion with the first change number being less than the first injection number, When the second completion condition is not satisfied under the second assumption, in the second injection process, the fuel injector is caused to perform fuel injection the number of times of the second change number with the fuel injection amount per time being a value changed from the basic injection amount so that the second total amount can be injected within the second injection range until completion with the second change number being less than the second injection number, The control device for an injector according to claim 1.

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