Ejector control device

Abstract

The invention relates to a control device for an injector. The control device includes a processor and a memory. Memory stores, as permissible slave injection, a first injection range predetermined in a range of crank angle from a start time of an intake stroke to an end time of the intake stroke and a second injection range predetermined in a range of crank angle from a start time of a compression stroke to an end time of the compression stroke The invention relates to a range of crank angles of fuel injection of an injector. The processor executes a first injection process for causing the injector to perform fuel injection in a first injection range and a second injection process for causing the injector to perform fuel injection in a second injection range (B). The second injection range is not continuous with the first injection range and is shorter than the first injection range.

Description

Technical Field

[0001] The present disclosure relates to a control device for an injector. Background Art

[0002] The internal combustion engine disclosed in Japanese Patent Publication No. 11-241626 has a plurality of cylinders, a plurality of pistons and a plurality of injectors. Each cylinder is a space for sucking in a mixture of air and fuel for combustion. Each piston is located in a corresponding cylinder. Each piston reciprocates in the cylinder as the mixture is burned. Each injector directly injects fuel into the cylinder from a side corresponding to the top dead center relative to the corresponding piston.

[0003] In the technology described in the above-mentioned publication for directly injecting fuel into the cylinder, fuel sometimes adheres to the top surface of the piston and the wall surface of the cylinder. When fuel adheres to the top surface of the piston, particulate matter is easily generated during combustion in the combustion stroke. In contrast, the fuel in a state of being adhered to the wall surface of the cylinder vaporizes in the cylinder during, for example, the exhaust stroke. The fuel vaporized in the exhaust stroke is discharged from the cylinder as unburned hydrocarbons. In order to reduce both these particulate matter and unburned hydrocarbons, a technology is sought to prevent the amount of fuel adhered to the top surface of the piston and the amount of fuel adhered to the wall surface of the cylinder from becoming excessive. Summary of the invention

[0004] The control device of the injector involved in one embodiment of the present disclosure controls an injector that injects fuel into a cylinder of an internal combustion engine from a side corresponding to the top dead center of a piston, and includes a processor and a memory. The memory is configured to store a first injection range predetermined within a range of a crank angle from the start of an intake stroke to the end of the intake stroke and a second injection range predetermined within a range of a crank angle from the start of a compression stroke to the end of the compression stroke as a range of crank angles that allow fuel injection from the injector. The processor is configured to execute a first injection process that causes the injector to inject fuel within the first injection range and a second injection process that causes the injector to inject fuel within the second injection range. The second injection range is not continuous with the first injection range and is shorter than the first injection range. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 This is a schematic diagram of the internal combustion engine.

[0006] Figure 2 It is an explanatory diagram schematically showing the first injection range and the second injection range.

[0007] Figure 3 : is a flowchart showing the processing procedure of the specific injection control.

[0008] Figure 4 : is a flowchart showing the processing procedure of the first preparation process.

[0009] Figure 5 : is a flowchart showing the processing procedure of the second preparation process.

[0010] Figure 6 It is an explanatory diagram schematically showing an example of a change in the injection pattern.

[0011] Figure 7 It is an explanatory diagram schematically showing another modified example of the injection pattern. DETAILED DESCRIPTION

[0012] Hereinafter, one embodiment of the control device for the injector will be described with reference to the drawings.

[0013] <Schematic structure of internal combustion engine>

[0014] like Figure 1 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. Figure 1 In the figure, only one of the plurality of cylinders 11 is shown. As with the cylinder 11, only one of the piston 12 and the connecting rod 13 is shown. The piston 12 and the connecting rod 13 are provided for each cylinder 11. The number of cylinders 11 is four.

[0015] The cylinder 11 is a space divided by the engine body 10A. The cylinder 11 is a space for burning a mixture of fuel and intake air. The cylinder 11 is cylindrical. Hereinafter, the wall surface of the engine body 10A that divides the cylinder 11 is referred to as the wall surface 11A of the cylinder 11. It should be noted that, although not shown in the figure, the engine body 10A is divided around the cylinder 11 with a cooling water passage for cooling water to flow.

[0016] The piston 12 is located in the corresponding cylinder 11. The piston 12 is cylindrical. The outer diameter of the piston 12 is roughly the same as the inner diameter of the corresponding cylinder 11. The central axis of the piston 12 is roughly the same as the central axis of the cylinder 11. The connecting rod 13 is connected to the piston 12. The crankshaft 14 is connected to the connecting rod 13. The piston 12 reciprocates in the corresponding cylinder 11 along the direction of its central axis. The crankshaft 14 rotates corresponding to the reciprocating movement of the piston 12. When the piston 12 reciprocates in the corresponding cylinder 11, it moves away from or approaches the crankshaft 14. That is, the piston 12 moves between the top dead center farthest from the crankshaft 14 and the bottom dead center closest to the crankshaft 14. It should be noted that the direction when the piston 12 moves to the side corresponding to the top dead center is sometimes referred to as the upper direction, and the opposite direction is referred to as the lower direction. In addition, the end surface facing upward of the two end surfaces of the piston 12 along the direction of its central axis is referred to as the top surface 12A.

[0017] The internal combustion engine 10 includes a plurality of injectors 50. Figure 1 In the figure, only one of the multiple injectors 50 is shown. The injector 50 is provided for each cylinder 11. The injector 50 is located on the upper side of the piston 12 relative to the cylinder 11. The outer shape of the injector 50 is roughly cylindrical. In the present embodiment, the central axis of the injector 50 is roughly parallel to the central axis of the cylinder 11. The front end of the injector 50 is located in the cylinder 11. The front end of the injector 50 is located on the upper side than the top dead center of the piston 12. The injection port 54 provided at the front end of the injector 50 faces the top surface 12A of the piston 12. In addition, the injector 50 injects fuel into the cylinder 11 from the side corresponding to the top dead center of the piston 12. In this way, the injector 50 directly injects fuel into the cylinder 11 without passing through the intake passage 20 described later. It should be noted that the injector 50 injects gasoline as fuel.

[0018] The internal combustion engine 10 includes a plurality of spark plugs 19. Figure 1 In the figure, only one of the plurality of spark plugs 19 is shown. The spark plug 19 is provided for each cylinder 11. The front end of the spark plug 19 is located in the corresponding cylinder 11. The spark plug 19 ignites the mixture in the corresponding cylinder 11.

[0019] 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 the opening degree. Therefore, the intake air amount changes according to the opening degree of the throttle valve 22.

[0020] 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 gas 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 gas. 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 captures particulate matter contained in the exhaust gas.

[0021] 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 cycled once by the crankshaft 14 rotating 720 degrees. When observing a certain cylinder 11, the intake stroke is the period during which the piston 12 in the cylinder 11 reaches the bottom dead center from the top dead center. The compression stroke is the period during which the piston 12 reaches the top dead center from the bottom dead center following the intake stroke. The combustion stroke is the period during which the piston 12 reaches the bottom dead center from the top dead center following the compression stroke. The exhaust stroke is the period during which the piston 12 reaches the top dead center from the bottom dead center following the combustion stroke. It should be noted that the exhaust stroke is followed by the intake stroke of the next cycle.

[0022] 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 amount of intake air. The water temperature sensor 63 detects the temperature of the cooling water at the outlet of the cooling water passage. Each sensor 61, 62, 63 repeatedly sends a signal corresponding to the information detected by itself to the control device 100 described later.

[0023] The vehicle is equipped with an accelerator sensor 68 and a vehicle speed sensor 69. The accelerator sensor 68 detects the amount of depression of the accelerator pedal in the vehicle as the accelerator operation amount. The vehicle speed sensor 69 detects the running speed of the vehicle as the vehicle speed. Each sensor 68, 69 repeatedly sends a signal corresponding to the information detected by itself to the control device 100 described later.

[0024] <Overview of control device>

[0025] The vehicle is provided with a control device 100. The control device 100 is provided with a processing circuit including a CPU 102 and a memory 104. The CPU 102 corresponds to a processor. The memory 104 includes three types of RAM, ROM, and a non-volatile type that can be electrically rewritten. In the present embodiment, these three types are collectively referred to as the memory 104. The memory 104 pre-stores various programs that record the processing that the CPU 102 should execute. In addition, the memory 104 pre-stores various data required by the CPU 102 to execute various programs.

[0026] The CPU 102 repeatedly receives detection signals from various sensors 61, 62, 63, 68, and 69 installed on the vehicle. The CPU 102 calculates the following parameters at any time based on the detection signals received from the various sensors 61, 62, 63, 68, and 69. The CPU 102 calculates the rotation speed of the crankshaft 14, that is, the engine speed, based on the change in the crank angle received from the crank angle sensor 61. The CPU 102 calculates the engine load factor based on the engine speed and the intake air volume received from the air flow meter 62. The engine load factor is a parameter that determines the amount of air filled into 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 volume. The reference air volume changes according to the engine speed.

[0027] The CPU 102 controls the internal combustion engine 10. The CPU 102 performs various controls on the internal combustion engine 10 based on parameters such as the accelerator operation amount, the vehicle speed, the engine speed, and the engine load factor. For example, the CPU 102 performs various controls such as injection control on the injector 50, ignition timing control on the spark plug 19, and opening adjustment control on the throttle valve 22. Through these controls, the CPU 102 sequentially burns the mixed gas in the plurality of cylinders 11.

[0028] The CPU 102 is configured to execute a special injection control. The special injection control is an injection control for the cold state of the internal combustion engine 10. Figure 2 As shown, the memory 104 stores in advance the range of crank angles that specifies whether fuel injection is possible, i.e., injection availability information, as information used in the specific injection control. Figure 2 The crank angle from the start time M1 of the intake stroke to the end time N2 of the compression stroke is represented by the angle of a clockwise circle. In the following description, the crank angle at the start time M1 of the intake stroke in the specific cylinder 11 is set to zero degrees. And, when referring to the range from the start time M1 of the intake stroke to the end time N2 of the compression stroke, the range is a range including the start time M1 and the end time N2. Similarly, with respect to other ranges, the range is also a range including the start time and the end time.

[0029] The memory 104 stores the first injection range A as injection permission information. The first injection range A is a range of crankshaft angles that allow fuel injection from the injector 50. The first injection range A is predetermined within the range of crankshaft angles from the start time M1 of the intake stroke to the end time M2 of the intake stroke. The memory 104 essentially stores a crankshaft angle A1 as the initial stage of the first injection range A and a crankshaft angle A2 as the final stage of the first injection range A. In the following description, when describing the period and range of fuel injection from the injector 50, unless otherwise specified, the description is made as a period and range in units of crankshaft angles. It should be noted that the start time M1 of the intake stroke is the moment when the piston 12 is at the top dead center. The end time M2 of the intake stroke is the moment when the piston 12 is at the bottom dead center.

[0030] The initial A1 of the first injection range A is on the retard angle side than the start time M1 of the intake stroke and on the advance angle side than the crank angle of the center MV of the intake stroke. The advance angle makes the crank angle go back with respect to a certain crank angle, and the retard angle is opposite. The initial A1 of the first injection range A is, for example, a crank angle of approximately 60 degrees. The initial A1 of the first injection range A is determined in consideration of the amount of the fuel injected from the injector 50 adhering to the top surface 12A of the piston 12. The closer the position of the piston 12 is to the injector 50 when the injector 50 injects the fuel, that is, the closer the piston 12 is to the top dead center, the greater the amount of the fuel injected from the injector 50 adhering to the top surface 12A of the piston 12. The initial A1 of the first injection range A is predetermined by, for example, experiments or simulations as a limit crank angle within the range of the crank angle of the intake stroke that can suppress the amount of fuel adhering to the top surface 12A of the piston 12 to be less than the first allowable value. The first allowable value may be determined as a value capable of suppressing the amount of particulate matter generated to a value below a certain amount. It should be noted that when determining the initial stage A1 of the first injection range A, the cylinder state such as the distance between the piston 12 and the injector 50 at each crankshaft angle, the moving direction of the piston 12, and the pressure in the cylinder 11, i.e., the cylinder pressure, is considered.

[0031] The end A2 of the first injection range A is located at a retard angle side relative to the crank angle of the center MV of the intake stroke and at an advance angle side relative to the end time M2 of the intake stroke. The end A2 of the first injection range A is, for example, a crank angle of approximately 120 degrees. The end A2 of the first injection range A is determined in consideration of the amount of the fuel injected from the injector 50 adhering to the wall surface 11A of the cylinder 11. The greater the exposed area of ​​the wall surface 11A when the injector 50 injects the fuel, that is, the closer the piston 12 is to the bottom dead center, the greater the amount of the fuel injected from the injector 50 adhering to the wall surface 11A of the cylinder 11. The end A2 of the first injection range A is determined in advance by, for example, experiment or simulation, in consideration of the above-mentioned 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 less than the second allowable value. The second allowable value can be determined as a value capable of suppressing the amount of unburned hydrocarbons exhausted from the cylinder 11 to be below a certain amount.

[0032] The memory 104 stores a second injection range B as injection permission information. The second injection range B is the range of crankshaft angles that allow fuel injection from the injector 50, similar to the first injection range A. The second injection range B is predetermined within the range of crankshaft angles from the start time N1 of the compression stroke to the end time N2 of the compression stroke. In addition, the second injection range B is discontinuous and separated from the first injection range A. The memory 104 substantially stores the crankshaft angle B1 as the initial stage of the second injection range B and the crankshaft angle B2 as the final stage of the second injection range B. It should be noted that the start time N1 of the compression stroke is the moment when the piston 12 is at the bottom dead center. The end time N2 of the compression stroke is the moment when the piston 12 is at the top dead center.

[0033] The initial B1 of the second injection range B is on the retarded angle side of the crank angle N1 as the start time of the compression stroke and on the advanced angle side of the crank angle of the center NV of the compression stroke. The initial B1 of the second injection range B is, for example, a crank angle of approximately 220 degrees. The initial B1 of the second injection range B is determined in consideration of the amount of fuel injected from the injector 50 adhering to the wall surface 11A of the cylinder 11, as is the case with the final A2 of the first injection range A. Specifically, the initial B1 of the second injection range B is determined in advance by considering the above-mentioned in-cylinder state as the 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 a limit below the second permissible value, for example, by experiment or simulation. It should be noted that, when the end time M2 of the intake stroke is used as a reference, the initial B1 of the second injection range B is set asymmetrically with respect to the final A2 of the first injection range A. Specifically, the initial stage B1 of the second injection range B is closer to the end timing M2 of the intake stroke than the final stage A2 of the first injection range A is.

[0034] The end B2 of the second injection range B is closer to the advanced angle side than the crank angle of the central NV of the compression stroke. The end B2 of the second injection range B is, for example, a crank angle of approximately 260 degrees. The end B2 of the second injection range B is determined by taking into account the amount of fuel injected from the injector 50 adhering to the top surface 12A of the piston 12, as in the initial A1 of the first injection range A. Specifically, the end B2 of the second injection range B is determined in advance by taking into account the above-mentioned cylinder state and by using, for example, experiments or simulations as the 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 a limit below the first allowable value. As described above, the end B2 of the second injection range B is closer to the advanced angle side than the crank angle of the central NV of the compression stroke. When this setting is compared with the initial A1 of the first injection range A, the following can be known. That is, based on the end time M2 of the intake stroke, the end time B2 of the second injection range B is set asymmetrically with respect to the beginning time A1 of the first injection range A. Specifically, the end time B2 of the second injection range B is closer to the end time M2 of the intake stroke than the beginning time A1 of the first injection range A.

[0035] Here, the range of the crank angle from the start time M1 of the intake stroke to the initial time A1 of the first injection range A is referred to as the first prescribed range P. The range of the crank angle from the final time A2 of the first injection range A to the initial time B1 of the subsequent second injection range B is referred to as the second prescribed range Q. The range of the crank angle from the final time B2 of the second injection range B to the end time N2 of the compression stroke is referred to as the third prescribed range R. These three prescribed ranges are ranges of the crank angle in which the fuel injection by the injector 50 is prohibited. However, the times of the initial time A1 of the first injection range A, the final time A2 of the first injection range A, the initial time B1 of the second injection range B, and the final time B2 of the second injection range B are the times at which fuel injection is permitted as described above. When defined as described above, the first injection range A and the second injection range B satisfy both of the following two conditions (L1) and (L2).

[0036] (L1) The second injection range B is shorter than the first injection range A.

[0037] (L2) The total of the first predetermined range P and the third predetermined range R is longer than the second predetermined range Q.

[0038] <Details of specific injection control>

[0039] The specific injection control is described in detail. Regarding a certain cylinder 11, the CPU 102 causes the injector 50 to perform fuel injection in multiple stages in one cycle of the internal combustion engine 10 in the specific injection control. In order to realize such multiple stages of fuel injection, the CPU 102 is configured to perform a first injection process and a second injection process as a part of the specific injection control. In the first injection process, the CPU 102 causes the injector 50 to perform fuel injection more than once within the first injection range A with respect to a certain cylinder 11 as the object. In the second injection process, the CPU 102 causes the injector 50 to perform fuel injection more than once within the second injection range B with respect to a certain cylinder 11 as the object. In the first injection process, the CPU 102 basically causes the fuel injection to be started at the retardation angle side of the crank angle of the center of the first injection range A less frequently than the fuel injection is started at the advance angle side of the crank angle of the center of the first injection range A. Furthermore, in the second injection process, CPU 102 basically reduces the number of times fuel injection is started at the advanced crank angle side of the center of the second injection range B compared to the number of times fuel injection is started at the retarded crank angle side of the center of the second injection range B.

[0040] The specific processing procedure of the specific injection control is described below. The CPU 102 starts the specific injection control according to the specified control cycle under the condition that the specified execution condition is satisfied during the operation of the internal combustion engine 10. The execution condition is that the temperature of the cooling water detected by the water temperature sensor 63 is below the specified temperature. The temperature of the cooling water reflects the temperature in the cylinder 11. The specified temperature is predetermined by, for example, experiments or simulations as an upper limit temperature that can be regarded as a temperature at which the fuel is difficult to vaporize in the cylinder 11.

[0041] like Figure 3 As shown, after starting the specific injection control, the CPU 102 first executes the processing 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 parameters such as the operating state of the internal combustion engine 10 such as the required torque for the internal combustion engine 10 and the engine speed and engine load rate grasped according to the accelerator operation amount and the vehicle speed. 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 speed, and the engine load rate. After calculating the total injection amount, the CPU 102 causes the processing to enter step S20. The processing of step S10 is the total injection amount calculation processing.

[0042] In step S20, the CPU 102 calculates the total number of injections, i.e., the total number of injections, that is, the total number of injections performed by 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 off the decimal point of the value obtained by the division as the total number of injections. The minimum injection amount is the minimum amount of fuel that can be injected by the injector 50 in one fuel injection. After calculating the total number of injections, the CPU 102 advances the process to step S30.

[0043] In step S30, CPU102 allocates the total number of injections to the intake stroke and the compression stroke. Hereinafter, the number of injections allocated to the intake stroke is referred to as the first number of injections. The number of injections allocated to the compression stroke is referred to as the second number of injections. When the total number of injections is an even number, CPU102 evenly allocates the total number of injections to the intake stroke and the compression stroke. That is, CPU102 makes the first number of injections and the second number of injections the same. In contrast, when the total number of injections is an odd number, CPU102 makes the first number of injections one more than the second number of injections, and makes the sum of the first number of injections and the second number of injections the total number of injections. Then, CPU102 causes the process to enter step S40. It should be noted that the first number of injections can also be referred to as the number of injections allocated to the first injection range A. Furthermore, the first number of injections is the basic value of the number of times the injector 50 performs fuel injection in the first injection range A in order to inject the total injection amount in one cycle of the internal combustion engine 10. The second number of injections can also be referred to as the number of injections allocated to the second injection range B. The second injection number is a basic value of the number of times the injector 50 injects fuel in the second injection range B required to inject the total injection amount in one cycle of the internal combustion engine 10. The process of step S30 constitutes a basic value calculation process together with the process of step S110 of the first preparation process described later.

[0044] In step S40, the CPU 102 performs a first preparation process. In the first preparation process, the CPU 102 determines a target start timing and a target injection amount for each injection when the injector 50 performs fuel injection in the intake stroke. The details of the first preparation process will be described later. Then, the CPU 102 advances the process to step S50.

[0045] In step S50, CPU102 performs a second preparation process. In the second preparation process, CPU102 determines the target start timing and target injection amount of each injection when the injector 50 performs fuel injection in the compression stroke. The details of the second preparation process will be described later. After completing the process of step S50, CPU102 performs the processes of step S60 and step S70. It should be noted that these steps S60 and step S70 are applied to all cylinders 11 that have reached the start period M1 of the intake stroke after the completion of step S50 until the completion of step S50 of the specific injection control of the next cycle. Therefore, sometimes steps S60 and step S70 are performed sequentially for multiple cylinders 11, but for the convenience of explanation below, these steps S60 and S70 are described as a series of processes for a certain cylinder 11.

[0046] In step S60, CPU102 performs the first injection process. Specifically, CPU102 causes injector 50 to perform fuel injection within the first injection range A according to the target start timing and target injection amount determined in the first preparation process. That is, CPU102 repeatedly waits until each target start timing determined in the first preparation process and controls injector 50 in a manner that injects the target injection amount of fuel from injector 50 based on the target start timing. It should be noted that, when the first injection number determined in the above step S30 is one, CPU102 causes injector 50 to perform fuel injection only once. After the total amount of injection amount allocated to the intake stroke is injected, CPU102 enters the process into step S70.

[0047] In step S70, CPU102 performs the second injection process. Specifically, CPU102 causes injector 50 to perform fuel injection within the second injection range B according to the target start timing and target injection amount determined in the second preparation process. That is, CPU102 repeatedly waits until the target start timing determined in the second preparation process and controls injector 50 in a manner that injects the target injection amount of fuel from injector 50 based on the target start timing. It should be noted that, as in the first injection process, when the second injection number determined in the above-mentioned step S30 is one, CPU102 causes injector 50 to perform fuel injection only once. After injecting the total amount of injection amount allocated to the compression stroke, CPU102 ends a series of processes of the specific injection control. Then, if the execution condition is met, CPU102 executes the specific injection control again.

[0048] <First preparation>

[0049] The specific processing process of the first preparation process is described below. Figure 4As shown, after starting the first preparation process, CPU102 first performs the process of step S110. In step S110, CPU102 sets the temporary start timing of each injection when the injector 50 performs fuel injection in the intake stroke. First, CPU102 calculates the basic value of the fuel injection amount based on each injection of the injector 50 required to inject the total injection amount in one cycle of the internal combustion engine 10, that is, the basic injection amount, by dividing the total injection amount calculated in step S10 by the total number of injections calculated in step S20. In addition, CPU102 calculates the fuel injection time required for each fuel injection. In addition, CPU102 converts the fuel injection time into a range of crankshaft angles corresponding to the engine speed at the current moment, that is, a required crankshaft interval.

[0050] Then, the CPU 102 converts the basic injection interval stored in the memory 104 into a basic crankshaft interval, which is a range of crankshaft angles corresponding to the current engine speed. The basic injection interval is a 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 to be a time that minimizes the burden on the electrical system driving the injector 50 and enables each fuel injection.

[0051] After calculating the basic crankshaft interval, the CPU 102 determines the provisional start timing of fuel injection for each of the fuel injections of the first number of injections determined in step S30. Specifically, the CPU 102 sets the provisional start timing of the first fuel injection to the initial stage A1 of the first injection range A.

[0052] Furthermore, CPU102 sets the temporary start timing of the fuel injection after the second time as follows. That is, CPU102 sequentially determines the temporary start timing of each fuel injection in such a manner that the timing that is delayed to the retard angle side by the length of the required crankshaft interval and the basic crankshaft interval combined becomes the temporary start timing of the next fuel injection. It should be noted that, when the first number of injections determined by CPU102 in step S30 is one, the initial A1 of the first injection range A is set as the start timing of the one fuel injection. After setting the temporary start timing of each fuel injection, CPU102 causes the process to enter S120.

[0053] In step S120, CPU 102 determines whether the first completion condition is satisfied when assuming that the fuel injection is performed at the temporary start timing determined in step S110. This can also be said to be a determination of whether the first completion condition is satisfied under the first assumption that the amount of fuel injection per time in the first injection range A is set as the basic injection amount and the fuel injection of the first injection number is performed. The first completion condition is that the total amount of fuel injection allocated to the intake stroke, or more specifically, the first injection range A, is injected within the first injection range A. The first total amount is the product of the amount of fuel injection per time calculated in step S110, i.e., the basic injection amount, and the first injection number. That is, the first total amount is a value determined by the basic injection amount and the first injection number.

[0054] As a specific process of step S120, first, CPU102 calculates the completion timing of the last fuel injection in the fuel injection of the first injection number. Specifically, CPU102 refers to the temporary start timing of the last fuel injection in the temporary start timing of the first injection number determined in step S110. Then, CPU102 calculates the timing that is retarded to the retarded angle side by the amount of the required crankshaft interval relative to the temporary start timing as the completion timing. Then, CPU102 compares the completion timing with the end A2 of the first injection range A. And, when the completion timing is the same as the end A2 of the first injection range A or is closer to the advance angle side than the end A2 of the first injection range A, CPU102 determines that the first completion condition is satisfied under the first assumption (step S120: yes). In this case, CPU102 causes the processing to enter step S130. It should be noted that the processing of step S120 is the first determination processing.

[0055] Here, as described above, when the CPU 102 sets the temporary start timing of the fuel injection of the first injection number in step S110, the temporary start timing of the initial fuel injection is set to the initial A1 of the first injection range A. Therefore, the temporary start timing of the fuel injection of the first injection number has a tendency to be biased toward the advance angle side in the first injection range A as a whole. In consideration of this, when a positive determination is made in step S120, the following first number condition is satisfied in most cases. The first number condition is that the number of times the fuel injection is started at the retard angle side of the crank angle of the center of the first injection range A is less than the number of times the fuel injection is started at the advance angle side of the crank angle of the center of the first injection range A.

[0056] Then, in step S130, the CPU 102 sets the target start timing of each injection when the injector 50 performs fuel injection in the intake stroke. Specifically, the CPU 102 sets each temporary start timing determined in step S110 as the target start timing of each fuel injection. And, in step S130, the CPU 102 sets the basic injection amount calculated in step S110 as the target injection amount to be injected by the injector 50 at each target start timing. Then, the CPU 102 ends the first preparation process.

[0057] In contrast, in step S120 , when the completion timing of the last fuel injection is on the retarded side of the end A2 of the first injection range A, CPU 102 determines that the first completion condition is not satisfied under the first assumption (step S120 : NO). In this case, CPU 102 advances the process to step S140 .

[0058] In step S140, the CPU 102 sets the change value of each parameter when the injector 50 performs fuel injection in the intake stroke. Each parameter includes the number of injections, the injection start timing, and the amount of fuel injected each time by the injector 50. That is, the CPU 102 sets the first change number of injections after the number of injections is changed from the first injection number, the first change timing after the injection start timing is changed from the temporary start timing, and the first change injection amount after the amount of fuel injected each time is changed from the basic injection amount. The CPU 102 sets the first change number of injections, the first change injection amount, and the first change timing of the amount of the first change number of injections in a manner that satisfies all of the following three conditions (X1), (X2), and (X3).

[0059] (X1) The product of the first change number of times and the first change injection amount coincides with the product of the first injection number of times and the basic injection amount.

[0060] (X2) The first change number is smaller than the first injection number.

[0061] (X3) The fuel injection amount per injection is set to a first changed injection amount, and the first completion condition is satisfied when fuel injection of the first changed number of times is performed at the first changed timing.

[0062] It should be noted that, regarding the first change timing of each fuel injection, as in the case of the temporary start timing, the CPU 102 determines the first change timing of each injection by setting the initial A1 of the first injection range A as the start timing of the first fuel injection and starting the fuel injection at a certain interval. When the change value of each parameter is determined in a manner that satisfies all such conditions, the first change 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 a manner that increases the fuel injection amount in one fuel injection and reduces the number of injections of the first injection range A compared to the first number of injections. Then, the CPU 102 causes the process to proceed to step S150.

[0063] In step S150, CPU102 sets each first change timing determined in step S140 as the target start timing of each fuel injection. And, CPU102 sets the first change injection amount determined in step S140 as the target injection amount for the injector 50 to inject at each target start timing in step S150. Then, CPU102 ends the first preparation process. In the case where the target start timing and the target injection amount of each fuel injection are determined by the process of this step S150, that is, in the case where the first completion condition is not satisfied under the above-mentioned first assumption, CPU102 performs the following in the first injection process of step S60. CPU102 causes the injector 50 to inject fuel in an amount of the first change number of times by changing the fuel injection amount of each time from the basic injection amount in a manner that the first total amount can be injected within the first injection range A with a first change number of times less than the first injection number.

[0064] <Second preparation>

[0065] The specific processing process of the second preparation process is described below. Figure 5 As shown, after starting the second preparation process, the CPU 102 first performs the process of step S210. In step S210, the CPU 102 sets the temporary start timing of each injection when the injector 50 performs fuel injection in the compression stroke. As a specific process of step S210, the CPU 102 first determines the temporary start timing of the last fuel injection among the fuel injections of the second injection number. Specifically, the CPU 102 determines the timing that is advanced from the end B2 of the second injection range B to the advance angle side by the above-mentioned required crankshaft interval as the temporary start timing of the last fuel injection.

[0066] Then, CPU102 determines the temporary start timing of other fuel injections as follows. That is, CPU102 determines the start timing of each fuel injection in sequence in such a manner that the timing of the temporary start timing of the subsequent fuel injection is advanced to the advance angle side by the length of the basic crankshaft interval and the required crankshaft interval combined, becoming the temporary start timing of the previous fuel injection. In this way, CPU102 determines the temporary start timing of each fuel injection at regular intervals in such a manner that the end timing of the last fuel injection is consistent with the end B2 of the second injection range B. It should be noted that, when the second injection number determined by CPU102 in step S30 is one, the start timing of the one fuel injection is determined as the timing of the required crankshaft interval advanced to the advance angle side from the end B2 of the second injection range B. After setting the start timing of each fuel injection, CPU102 causes the process to enter S220.

[0067] In step S220, CPU102 determines whether the second completion condition is satisfied when assuming that the fuel injection is performed at the temporary start timing determined in step S210. This can also be said to be determining whether the second completion condition is satisfied under the second assumption that the amount of fuel injection per time in the second injection range B is set as the basic injection amount and the fuel injection of the second injection number is performed. The second completion condition is that the total amount of fuel injection allocated to the compression stroke, or more specifically, the second total amount, is injected in the second injection range B. The second total amount is the product of the basic injection amount and the second injection number calculated in step S110 of the first preparation process. That is, the second total amount is a value determined by the basic injection amount and the second injection number. As a specific process of step S220, CPU102 compares the start timing of the first fuel injection in the temporary start timing of the second injection number determined in step S210 with the initial B1 of the second injection range B. Furthermore, when the start timing is the same as the initial B1 of the second injection range B or is closer to the retardation angle side than the initial 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 proceeds to step S230. It should be noted that the process of step S220 is the second determination process.

[0068] Here, as described above, when the CPU 102 sets the temporary start timing of the fuel injection of the second injection number in step S210, the end timing of the last fuel injection is consistent with the end B2 of the second injection range B. Therefore, the temporary start timing of the fuel injection of the second injection number has a tendency to be biased toward the retard angle side in the second injection range B as a whole. In consideration of this, when a positive determination is made in step S220, the following second number condition is satisfied in most cases. The second number condition is that the number of times the fuel injection is started at the advanced angle side of the crank angle of the center of the second injection range B is less than the number of times the fuel injection is started at the retarded angle side of the crank angle of the center of the second injection range B.

[0069] Then, in step S230, the CPU 102 sets the target start timing of each injection when the injector 50 performs fuel injection in the compression stroke. Specifically, the CPU 102 sets each temporary start timing determined in step S210 as the target start timing of each fuel injection. In addition, 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 by the injector 50 at each target start timing. Then, the CPU 102 ends the second preparation process.

[0070] In contrast, in step S220 , when the start timing of the first fuel injection is advanced relative to the initial stage B1 of the second injection range B, CPU 102 determines that the second completion condition is not satisfied under the second assumption (step S220 : NO). In this case, CPU 102 advances the process to step S240 .

[0071] In step S240, CPU 102 sets the change value of each parameter when injector 50 performs fuel injection in 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 amount of fuel injected each time based on injector 50. In addition, CPU 102 sets the second changed number of injections after the number of injections is changed from the second number of injections, the second changed timing after the injection start timing is changed from the temporary start timing, and the second changed injection amount after the amount of fuel injected each time is changed from the basic injection amount. At this time, CPU 102 satisfies all of the following three conditions (Y1), (Y2), and (Y3).

[0072] (Y1) The product of the second changed number of injections and the second changed injection amount matches the product of the second number of injections and the basic injection amount.

[0073] (Y2) The second change number is smaller than the second injection number.

[0074] (Y3) The fuel injection amount per injection is set to a second changed injection amount, and the second completion condition is satisfied when fuel injection of the second changed number of times is performed at the second changed timing.

[0075] It should be noted that, regarding the second change timing of each fuel injection, as in the case of determining the temporary start timing in step S210, the CPU 102 determines the second change timing of each injection in such a manner that the end B2 of the second injection range B becomes the end timing of the last fuel injection and the fuel injection is started at a certain interval. Regarding the processing of this step S240, the CPU 102 reallocates the start timing of each injection from the temporary start timing in such a manner that the fuel injection amount in one fuel injection is increased on the one hand, and the number of injections of the second injection range B is reduced compared to the second number of injections on the other hand. After performing the processing of step S240, the CPU 102 advances the processing to step S250.

[0076] In step S250, CPU102 sets each second change timing determined in step S240 as the target start timing of each fuel injection. And, CPU102 sets the second change injection amount determined in step S240 as the target injection amount for the injector 50 to inject at each target start timing in step S250. Then, CPU102 ends the second preparation process. In the case where the target start timing and the target injection amount of each fuel injection are determined by the process of this step S250, that is, in the case where the second completion condition is not satisfied under the second assumption, CPU102 performs the following in the second injection process of step S70. CPU102 causes the injector 50 to inject fuel in the second change number of times in an amount after the fuel injection amount is changed from the basic injection amount in a manner that the second total amount can be injected within the second injection range B with a second change number less than the second injection number.

[0077] <First Function of Implementation Method>

[0078] Now, it is assumed that the CPU 102 performs a specific injection control. Also, it is assumed that the total number of injections calculated by the CPU 102 in step S20 is 5. In this case, Figure 2 As shown, the CPU 102 sets the number of injections in the intake stroke to 3 and the number of injections in the compression stroke to 2 in step S30. Furthermore, the CPU 102 sets the start timing of the three fuel injections in a manner that the number of times the fuel injection is started at the advance angle side of the crank angle of the center of the first injection range A becomes greater in the first preparation process of step S40.

[0079] In step S60, CPU 102 performs fuel injection at each start timing. In step S50, CPU 102 sets the start timing of the two fuel injections so that the number of times fuel injection is started at the crank angle retarded from the center of the second injection range B increases.

[0080] Then, CPU 102 performs fuel injection in step S70 using each of these start timings as an opportunity. Figure 2 In FIG. 1 , the range of the crank angle in which fuel injection is performed is indicated by hatching. Figure 6 as well as Figure 7 Same here. Figure 2 , Figure 6 as well as Figure 7 These are explanatory diagrams for easily understanding the characteristics of each injection mode, and do not necessarily reflect actual injection amounts, injection intervals, and the like.

[0081] <Second Effect of Embodiment>

[0082] When the temperature in the cylinder 11 is low, the fuel injected by the injector 50 is difficult to vaporize. Therefore, if it is assumed that no countermeasures are taken and the fuel is injected from the injector 50, the amount of fuel attached to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 may increase. Therefore, the CPU 102 performs a specific injection control when the temperature in the cylinder 11 is low. In the specific injection control, the CPU 102 causes the injector 50 to inject fuel in multiple stages in one cycle of the internal combustion engine 10 for one cylinder 11. As a result, the CPU 102 reduces the fuel injection amount of each fuel injection. As a result, 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.

[0083] When performing such multiple-stage fuel injection, in the present embodiment, the first injection range A and the second injection range B that are allowed to inject fuel from the injector 50 are determined in consideration of the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 according to the position of the piston 12. As described above, the closer the position of the piston 12 is to the top dead center when the injector 50 performs fuel injection, the greater the amount of fuel adhering to the top surface 12A of the piston 12. While considering this basic feature, the initial stage A1 of the first injection range A and the final stage B2 of the second injection range B are determined in consideration of the moving direction of the piston 12. Specifically, in the intake stroke, the piston 12 moves from the top dead center to the bottom dead center. That is, in the intake stroke, the piston 12 moves away from the injector 50.

[0084] In contrast, in the compression stroke, the piston 12 moves from the bottom dead center to the top dead center. That is, in the compression stroke, the piston 12 approaches the injector 50. Therefore, assuming that the injector 50 performs fuel injection under the condition that the piston 12 is at the same position in the intake stroke and the compression stroke, the length of time from the injection of the fuel by the injector 50 to the arrival of the fuel at the piston 12 is shorter in the case of the compression stroke. This is because the piston 12 approaches the fuel while the fuel moves in the cylinder 11 in the compression stroke. Considering such a background, in order to reduce the amount of fuel attached to the top surface 12A of the piston 12, in the compression stroke, the fuel injection by the injector 50 needs to be completed under the condition that the piston 12 is located further to the bottom dead center side than in the intake stroke. In consideration of this, the end B2 of the second injection range B is closer to the end period M2 of the intake stroke, that is, the timing when the piston 12 is at the bottom dead center, than the beginning A1 of the first injection range A.

[0085] As described above, the closer the position of the piston 12 is to the bottom dead center when the injector 50 performs fuel injection, the greater the amount of fuel adhered to the wall surface 11A of the cylinder 11. The final stage A2 of the first injection range A and the initial stage B1 of the second injection range B are determined in consideration of this basic feature and the cylinder pressure.

[0086] Specifically, in the compression stroke, as the 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. Therefore, in the compression stroke, even if the fuel is injected by the injector 50 in a state where the piston 12 is located on the bottom dead center side compared to 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 be vaporized before reaching the wall surface 11A of the cylinder 11 in the compression stroke.

[0087] In consideration of such background, when the amount of fuel adhering to the wall surface 11A of the cylinder 11 is reduced, it is allowed to start fuel injection by the injector 50 when the piston 12 is located at the bottom dead center side in the compression stroke compared with the intake stroke. In consideration of this, the initial stage B1 of the second injection range B is closer to the end time M2 of the intake stroke than the final stage A2 of the first injection range A.

[0088] <Effects of implementation>

[0089] (1) In the structure of the present embodiment, the first injection range A and the second injection range B are not continuous. Therefore, a certain range including at least the bottom dead center of the piston 12 is a range in which fuel injection by the injector 50 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 at the bottom dead center, it is possible to suppress the adhesion of fuel to the wall surface 11A of the cylinder 11.

[0090] In contrast, during the period from the start time N1 of the compression stroke to the end time N2 of the compression stroke, the piston 12 gradually moves to the side corresponding to the top dead center. Therefore, as described in the second effect of the embodiment, the fuel injected by the injector 50 in the compression stroke is more likely to reach the top surface 12A of the piston 12 than in the intake stroke. In this regard, according to the structure of the present embodiment, the second injection range B is set short, so it is difficult to inject a lot of fuel in the compression stroke. Therefore, a large amount of fuel is prevented from adhering to the top surface 12A of the piston 12.

[0091] (2) The closer the position of the piston 12 is to the bottom dead center when the fuel injection is performed, the greater the amount of unburned hydrocarbons. Specifically, the amount of unburned hydrocarbons increases linearly according to the position of the piston 12. In contrast, the closer the position of the piston 12 is to the top dead center when the fuel injection is performed, the greater the amount of particulate matter. Specifically, the amount of particulate matter increases exponentially according to the position of the piston 12. Considering the characteristic that the amount of particulate matter increases sharply in the form of an exponential function, it is necessary to ensure as much as possible the range of crankshaft angles in which fuel injection is prohibited when the piston 12 is located on the side corresponding to the top dead center.

[0092] In this regard, in the present embodiment, the total of the first predetermined range P and the third predetermined range R where fuel injection is prohibited is longer than the second predetermined range Q. Therefore, the above-described configuration is very effective in reducing the amount of particulate matter.

[0093] (3) As described in the second effect of the embodiment, when the moving direction of the piston 12 is considered, in the compression stroke, the fuel injection needs to be completed at a timing when the piston 12 is further away from the top dead center than in the intake stroke. On the contrary, in the intake stroke, the fuel injection is allowed even at a timing when the piston 12 is not so far away from the top dead center. Therefore, if the end B2 of the second injection range B is closer to the end period M2 of the intake stroke than the beginning A1 of the first injection range A as in the present embodiment, the amount of fuel attached to the top surface 12A of the piston 12 can be reduced and the range of the crank angle allowing the fuel injection can be ensured to the maximum extent.

[0094] (4) As described in the second effect of the embodiment, when the moving direction of the piston 12 is taken into consideration, fuel injection is permitted at a timing when the piston 12 is closer to the bottom dead center than in the intake stroke in the compression stroke. Therefore, if the initial stage B1 of the second injection range B is closer to the end time M2 of the intake stroke than the final stage A2 of the first injection range A as in the present embodiment, the amount of fuel adhering to the wall surface 11A of the cylinder 11 can be reduced and the range of the crank angle allowing fuel injection can be ensured to the maximum extent.

[0095] (5) The CPU 102 of the present embodiment basically reduces the number of times fuel injection is started at the crank angle of the center of the first injection range A on the retard angle side compared to the number of times fuel injection is started at the crank angle of the center of the first injection range A on the advance angle side in the first injection process. Furthermore, the CPU 102 basically reduces the number of times fuel injection is started at the advance angle side compared to the number of times fuel injection is started at the center of the second injection range B on the retard angle side in the second injection process. Therefore, in the present embodiment, the number of times fuel injection is performed when the piston 12 approaches the bottom dead center is reduced. Therefore, in the present embodiment, the amount of fuel attached to the wall surface 11A of the cylinder 11 can be reduced.

[0096] It should be noted that, as described in (2) above, in the present embodiment, a crank angle range in which fuel injection by the injector 50 is prohibited is ensured to be relatively large on the side corresponding to the top dead center. As a result, the amount of particulate matter generated, that is, the amount of fuel attached to the top surface 12A of the piston 12 can be strictly limited. On this basis, as described above, by reducing the number of fuel injections when the piston 12 approaches the bottom dead center, the amount of fuel attached to the wall surface 11A of the cylinder 11 can also be strictly limited.

[0097] (6) For example, when the engine load rate increases, the total amount of fuel injection required in one cycle of the internal combustion engine 10 increases. Accordingly, if the amount of fuel injection per time is set as the basic injection amount and the injector 50 performs fuel injection, there is a possibility that the total amount of fuel injection allocated to the intake stroke, more specifically, the first total amount, cannot be injected in the first injection range A. In this regard, in the structure of the present embodiment, when the first completion condition is not satisfied under the first assumption, the amount of fuel injection per time is redistributed so that the first total amount can be injected in the first injection range A. Therefore, the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 can be reduced, and the amount of fuel required in the intake stroke can be reliably injected in the first injection range A. Similarly, in the structure of the present embodiment, the amount of fuel adhering to the top surface 12A of the piston 12 and the wall surface 11A of the cylinder 11 can be reduced, and the amount of fuel required in the compression stroke can be reliably injected in the second injection range B.

[0098] <Change Example>

[0099] The above-mentioned embodiment can be modified and implemented as follows. The above-mentioned embodiment and the following modified examples can be combined and implemented within the scope of no technical contradiction.

[0100] ·Regarding the first preparation process, the processing content of step S140 is not limited to the example of the above-mentioned embodiment. In step S140, it is sufficient to adjust the number of injections, the injection start timing, and the amount of fuel injected each time in such a manner that the total amount of fuel injection allocated to the intake stroke, more specifically the first injection range A, can be injected within the first injection range A. At this time, for example, each parameter can be adjusted in such a manner that the first number condition is satisfied. And, for example, the amount of fuel injected each time can also be different in each fuel injection, rather than being the same. From the same point of view, the content of step S240 of the second preparation process can also be changed. In step S240, it is sufficient to adjust each parameter in such a manner that the total amount of fuel injection allocated to the compression stroke, more specifically the second injection range B, can be injected within the second injection range B.

[0101] The entire content of the first preparation process is not limited to the example of the above-mentioned embodiment. As described later, the first determination process can be omitted in the first preparation process. In the first preparation process, it is sufficient to determine the target start timing of each injection when the injector 50 performs fuel injection in the first injection process and the target injection amount to be injected by the injector 50 at each target start timing. For example, instead of determining the target start timing after temporarily setting the temporary start timing as in the above-mentioned embodiment, the target start timing may be adjusted from the beginning so as to satisfy the first completion condition and set together with the target injection amount. That is, the CPU 102 reversely calculates the total amount of fuel injection allocated to the intake stroke and the number of injections, and sets the target injection amount and the target start timing of each fuel injection so that the total amount can be injected within the first injection range A. At this time, the target injection amount of each fuel injection may be different from all others, or only a part of the multiple fuel injections may be different from the others. In addition, 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 be different from all others in the multiple fuel injections, or only a part of the multiple fuel injections may be different from the others. The first number condition may or may not be satisfied.

[0102] For example, in the case of adopting a scheme in which the target injection amounts of the respective fuel injections are all different, as shown in FIG. Figure 6 As shown, in the multiple fuel injections performed in the first injection range A, the target injection amount of the fuel injection performed on the lag angle side can be smaller. At this time, the CPU 102 can, for example, set the target start timing of the initial fuel injection to the initial A1 of the first injection range A and set the target start timing of each fuel injection. At the same time, the CPU 102 can also make the interval from the end timing to the start timing of the fuel injection different from each other in each fuel injection, and appropriately set the target start timing of the fuel injection after the second time. When the first injection process is performed according to the target injection amount and target start timing set in this way, the closer the piston 12 is to the bottom dead center, the less fuel is injected each time by the injector 50, so the amount of fuel attached to the wall 11A of the cylinder 11 can be reduced.

[0103] It should be noted that in Figure 6In the example of , a scheme is described in which the target injection amount of each fuel injection in the first injection range A is made different. However, even if the relationship that the target injection amount of the fuel injection performed on the retard angle 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 achieved. The first fuel amount condition is that when the injector 50 performs multiple fuel injections in the same first injection range A, the fuel injection amount in the last fuel injection in the first injection range A is smaller than the fuel injection amount in the first fuel injection in the first injection range A.

[0104] As described above, the content of the first preparation process can be appropriately changed from the example of the above-mentioned embodiment. In the first preparation process, the number of injections, the injection start timing, and the amount of fuel injected per injection can be set in such a manner that the total amount of fuel injection allocated to the intake stroke, more specifically, the first injection range A, can be 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, only one of the two conditions may be satisfied, or neither of the two conditions may be satisfied.

[0105] The content of the first injection process reflects the setting content of the first preparation process. Therefore, the content of the first injection process changes according to the setting content of the first preparation process. That is, the fuel injection amount in each injection when the injector 50 performs fuel injection in the first injection process and the injection start timing can be appropriately changed. It is not necessary that the start timing of the first fuel injection in the first injection process is the initial stage A1 of the first injection range A.

[0106] ·As with the first preparation process, the overall content of the second preparation process is not limited to the example of the above-mentioned embodiment. In the second preparation process, it is sufficient to determine the target start timing of each injection when the injector 50 is caused to perform fuel injection in the second injection process and the target injection amount to be injected by the injector 50 based on each target start timing. For example, as with the first preparation process, in the second preparation process, the setting of the temporary start timing and even the second determination process may be omitted, and adjustments may be made from the beginning in a manner that satisfies the second completion condition and the target start timing may be set together with the target injection amount. That is, the CPU 102 reversely calculates the total amount of fuel injection allocated to the compression stroke and the number of injections, and sets the target injection amount and the target start timing of each fuel injection in a manner that the total amount can be injected within the second injection range B. In the case of adopting such a scheme, the CPU 102 may also, for example Figure 6As shown in FIG. 1 , the target injection amount of the fuel injection performed on the advance angle side in the multiple fuel injections performed in the second injection range B is smaller. At this time, the CPU 102 can set the target start timing of each fuel injection in such a way that the end timing of the last fuel injection coincides with the end B2 of the second injection range B. When the second injection process is performed according to the target injection amount and target start timing set in this way, the closer the piston 12 is to the bottom dead center, the less fuel is injected each time by the injector 50, so the amount of fuel attached to the wall surface 11A of the cylinder 11 can be reduced.

[0107] It should be noted that in Figure 6 In the example of , a scheme is described in which the target injection amount of each fuel injection in the second injection range B is made different. However, even if the relationship that the target injection amount of the fuel injection performed on the advanced angle side in the second injection range B is not satisfied, if 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 achieved. The second fuel amount condition is that when the injector 50 performs multiple fuel injections in the same second injection range B, the fuel injection amount in the first fuel injection in the second injection range B is smaller than the fuel injection amount in the last fuel injection in the second injection range B.

[0108] As described above, the content of the second preparation process can be appropriately changed from the example of the above-mentioned embodiment. In the second preparation process, the number of injections, the injection start timing, and the amount of fuel injection per injection can be set so that the total amount of fuel injection allocated to the compression stroke and the second injection range B can be injected in the second injection range B. Regardless of whether the temporary start timing is set, both the second number condition and the second fuel amount condition may be satisfied, only one of the two conditions may be satisfied, or neither of the two conditions may be satisfied.

[0109] The content of the second injection process reflects the setting content of the second preparation process. Therefore, the content of the second injection process changes according to the setting content of the second preparation process. That is, the fuel injection amount and injection start timing of each injection when the injector 50 performs fuel injection in the second injection process can be appropriately changed. It is not necessary to make the end timing of the last fuel injection in the second injection process coincide with the end B2 of the second injection range B.

[0110] The method of allocating the total number of injections to the intake stroke and the compression stroke is not limited to the example of the above embodiment. The number of injections may be determined based on the amount of fuel injected by the injector 50 in one fuel injection so that the required amount of fuel can be injected in each of the first injection range A and the second injection range B. Furthermore, the number of injections temporarily allocated to the intake stroke and the compression stroke may be further adjusted as in the above embodiment.

[0111] The method for determining the total number of injections is not limited to the example of the above-mentioned embodiment. The method for determining the total number of injections is not limited as long as an appropriate number of injections can be determined.

[0112] The method of determining the total number of injections may be abandoned, and the number of injections may be determined individually in the intake stroke and the compression stroke from the beginning according to the operating state of the internal combustion engine 10 and the like.

[0113] The method of distributing the total injection amount to the intake stroke and the compression stroke is not limited to the example of the above-mentioned embodiment. It is sufficient as long as the amount that can be injected completely in the first injection range A and the second injection range B is distributed.

[0114] Regarding the method of allocating the total injection amount to the intake stroke and the compression stroke, for example, Figure 7 As shown in the figure, the total amount of injection allocated to the compression stroke is greater than the total amount of injection allocated to the intake stroke. In addition, the injection amount allocated in this way may be divided into multiple times for injection in the first injection range A and the second injection range B, respectively. In this case, for example, in the first injection range A, the more the fuel injection is performed on the retard angle side, the smaller the amount of fuel injection per time. In addition, the start timing of the first fuel injection in the first injection range A may be set to the initial A1 of the first injection range A.

[0115] Furthermore, the CPU 102 may, for example, make the amount of fuel injection each time smaller as the fuel injection is performed on the advance angle side in the second injection range B. At the same time, the CPU 102 may perform each fuel injection in a manner such 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 beginning period B1 of the second injection range B.

[0116] As described above, in the compression stroke, the fuel vaporization is promoted due to the relationship with the cylinder internal pressure, so it is difficult for the fuel to reach the wall surface 11A of the cylinder 11. Therefore, in order to reduce the amount of fuel adhering to the wall surface 11A of the cylinder 11, it is preferable to Figure 7It should be noted that as long as the fuel injection is performed in the first injection range A and the second injection range B, it is guaranteed that the amount of fuel adhering to the top surface 12A of the piston 12 is reduced. Therefore, even if the total amount of fuel distributed to the compression stroke is increased as described above, there is no worry that the amount of fuel adhering to the top surface 12A of the piston 12 will increase.

[0117] How to determine the number of injections and the injection amount in each of the intake stroke and the compression stroke can be changed appropriately. In short, as long as the first injection range A and the second injection range B can inject the required amount of fuel in one cycle of the internal combustion engine 10 according to the required torque of the internal combustion engine 10, etc.

[0118] The parameter used to grasp the temperature in the cylinder 11 is not limited to the example of the above embodiment. As an indicator of the temperature in the cylinder 11, the cumulative value of the intake air amount after the internal combustion engine 10 is started may be used instead of the temperature of the cooling water. Any parameter can be used as long as the temperature in the cylinder 11 can be grasped. The content of the execution condition of the specific injection control may also be changed according to the adopted parameter.

[0119] The execution condition of the specific injection control is not limited to the case where the temperature in the cylinder 11 is determined to be low. The execution condition is not limited to the case where the temperature in the cylinder 11 is low, and the content of the execution condition may be appropriately set so that the specific injection control can be executed as needed.

[0120] The method of setting the first injection range A and the second injection range B is not limited to the example of the above embodiment. As long as 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, it is sufficient.

[0121] It is not necessary that the initial stage B1 of the second injection range B is closer to the end time M2 of the intake stroke than the final stage A2 of the first injection range A. For example, the initial stage B1 of the second injection range B and the final stage A2 of the first injection range A may be separated from the end time M2 of the intake stroke by the same amount.

[0122] The end B2 of the second injection range B is not necessarily closer to the end M2 of the intake stroke than the beginning A1 of the first injection range A. For example, the end B2 of the second injection range B and the beginning A1 of the first injection range A may be separated from the end M2 of the intake stroke by the same amount.

[0123] The total of the first predetermined range P and the third predetermined range R is not necessarily longer than the second predetermined range Q. For example, the total of the first predetermined range P and the third predetermined range R may be the same length as the second predetermined range Q.

[0124] The memory 104 may also pre-store 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 may be prepared in advance according to the operating state of the internal combustion engine 10, and the first injection range A and the second injection range B may be changed according to the operating state of the internal combustion engine 10.

[0125] The overall structure of the internal combustion engine 10 is not limited to the example of the above-mentioned 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 handled as a series of periods in which one cylinder 11 undergoes one intake stroke, one compression stroke, one combustion stroke, and one exhaust stroke. Furthermore, the cylinder 11 is not limited to being divided by the engine body 10A itself. For example, a cylindrical member may be accommodated inside the engine body 10A, and the cylinder 11 may be divided by the inner peripheral surface of such a cylindrical member. In this case, the inner peripheral surface of the cylindrical member constitutes the wall surface 11A of the cylinder 11. The internal combustion engine 10 only needs to install the injector 50 in such a manner that the fuel is injected into the cylinder 11 from the side corresponding to the top dead center of the piston 12. 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 of the central axis of the injector 50 and the central axis of the cylinder 11 can be appropriately changed.

[0126] A control device for controlling the injector 50 and a control device for controlling operation target parts other than the injector 50 in the internal combustion engine 10 may be provided separately.

[0127] The processing circuit of the control device 100 may have any one of the following configurations (a), (b), and (c).

[0128] (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 RAM and ROM. The memory stores program codes or instructions configured to cause the CPU to execute the process. The memory, i.e., the computer-readable medium, includes all available media that can be accessed by a general-purpose or special-purpose computer.

[0129] (b) The processing circuit has one or more dedicated hardware circuits that execute various types of processing. Examples of dedicated hardware circuits include ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) that are integrated circuits for specific applications.

[0130] (c) The processing circuit includes a processor that executes a part of various processes according to a computer program and a dedicated hardware circuit that executes the rest of the various processes.

Claims

1. A control device for an injector, the control device being configured to control an injector for injecting fuel into a cylinder of an internal combustion engine from a side corresponding to a top dead center of a piston, wherein: The control device includes a processor and a memory. The memory is configured to store, as the range of crank angles permitted for fuel injection from the injector, a first injection range predetermined within a range of crank angles from a start time of an intake stroke to an end time of the intake stroke and a second injection range predetermined within a range of crank angles from a start time of a compression stroke to an end time of the compression stroke, The processor is configured to execute a first injection process for causing the injector to inject fuel within the first injection range and a second injection process for causing the injector to inject fuel 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.

2. The control device for the injector according to claim 1, wherein: When the range of the crank angle from the start of the intake stroke to the initial stage of the first injection range is referred to as the first predetermined range, the range of the crank angle from the end of the first injection range to the initial stage of the second injection range is referred to as the second predetermined range, and the range of the crank angle from the end of the second injection range to the end of the compression stroke is referred to as the third predetermined range, The total of the first predetermined range and the third predetermined range is longer than the second predetermined range.

3. The control device for the injector according to claim 1, wherein: The end of the second injection range is closer to the end of the intake stroke than the beginning of the first injection range.

4. The control device for the injector according to claim 1, wherein: The beginning of the second injection range is closer to the end of the intake stroke than the end of the first injection range.

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

6. The control device for the injector according to claim 1, wherein: In the second injection process, the number of times the fuel injection is started at the advanced angle side from the center of the second injection range is smaller than the number of times the fuel injection is started at the retarded angle side from the center of the second injection range.

7. The control device for an injector according to claim 1, wherein: The first injection process includes causing the injector to perform a plurality of fuel injections in the same first injection range, and a final fuel injection amount in the first injection range is smaller than an initial fuel injection amount in the first injection range.

8. The control device for the injector according to claim 1, wherein: The second injection process includes causing the injector to perform a plurality of fuel injections in the same second injection range, wherein an initial fuel injection amount in the second injection range is smaller than a final fuel injection amount in the second injection range.

9. The control device for an injector according to any one of claims 1 to 8, wherein: The processor is configured to execute: a total injection amount calculation process of calculating a total injection amount of fuel required in one of the cylinders in one cycle of the internal combustion engine based on an operating state of the internal combustion engine; a basic value calculation process of calculating a basic injection amount required to inject the total injection amount in one cycle of the internal combustion engine, a first injection number, and a second injection number, the basic injection amount being a basic value based on the fuel injection amount of each injection of the injector, the first injection number being a basic value of the number of times the injector is caused to perform fuel injection within the first injection range, and the second injection number being a basic value of the number of times the injector is caused to perform fuel injection within the second injection range; a first determination process, when referring to the first completion condition that a first total amount is injected in the first injection range, before the first injection process, determining whether the first completion condition is satisfied under a first assumption, the first total amount being the total amount of fuel injection allocated to the first injection range determined based on the basic injection amount and the first injection number, the first assumption being that the fuel injection amount per injection in the first injection range is set to the basic injection amount and fuel injection is performed for the first injection number; as well as A second determination process, when the second total amount of fuel injected in the second injection range is referred to as a second completion condition, before the second injection process, determines whether the second completion condition is satisfied under a second assumption, wherein the second total amount is a total amount of fuel injection allocated to the second injection range determined based on the basic injection amount and the second injection number, and the second assumption is that the fuel injection amount of each injection in the second injection range is set to the basic injection amount and fuel injection is performed for the second injection number, When the first completion condition is not satisfied under the first assumption, in the first injection process, the injector performs fuel injection of the first changed number of times by changing the fuel injection amount per time from the basic injection amount in such a manner that the first total amount can be injected within the first injection range by a first changed number of times less than the first injection number, When the second completion condition is not satisfied under the second assumption, in the second injection process, the injector injects fuel in an amount equal to the second changed number of times by changing the amount of fuel injection each time from the basic injection amount in such a manner that the second total amount can be injected within the second injection range with a second changed number of times which is less than the second injection number.

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