Control device and control method for internal combustion engine

Abstract

A control device and a control method of an internal combustion engine are provided. The internal combustion engine has an intake port injection valve, an in-cylinder injection valve, and a supercharger. The internal combustion engine is controlled in such a manner that, when a ratio of a fuel amount injected from the intake port injection valve with respect to a total fuel amount for which fuel burns once in a cylinder is set as an intake port injection ratio, the intake port injection ratio is set smaller and a start timing of injecting fuel from the intake port injection valve is delayed, in comparison with a case where a condition is not satisfied, in a case where the condition is satisfied in an internal combustion engine operating range where an operating state in which the supercharger performs supercharging and a valve overlap period are larger than zero.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control device and a control method for an internal combustion engine. BACKGROUND

[0002] The internal combustion engine disclosed in Japanese Patent Application Publication No. 2014-134144 has an intake port injection valve, an in-cylinder injection valve, and a supercharger. The intake port injection valve injects fuel into an intake passage. The in-cylinder injection valve directly injects fuel into a cylinder without passing through the intake passage. The intake port injection valve and the in-cylinder injection valve inject fuel at an injection ratio determined for each internal combustion engine operating range. The supercharger supercharges intake air. When supercharging based on the supercharger is performed, the pressure of the intake passage becomes higher than the pressure of an exhaust passage. Also, the internal combustion engine has an intake valve and an exhaust valve. Also, the internal combustion engine has a valve overlap period in which the intake valve and the exhaust valve are both in an open state.

[0003] In the internal combustion engine described in Japanese Patent Application Publication No. 2014-134144, the valve overlap period is entered when supercharging based on the supercharger is performed. In this case, as above, the pressure of the intake passage is higher than the pressure of the exhaust passage, so intake air flowing from the intake passage into the cylinder directly leaks to the exhaust passage. When the intake port injection valve comes to an injection timing and injects fuel into the intake passage in this situation, the fuel leaks to the exhaust passage along with the intake air.

[0004] Here, as a countermeasure for preventing the leakage of fuel, it is considered to start fuel injection based on the intake port injection valve after the valve overlap period ends. However, in a case where the injection ratio from the intake port injection valve is large, the following concern exists. That is, when fuel injection from the intake port injection valve is started after the valve overlap period ends, the intake port injection valve can not be able to inject the required amount of fuel before the intake valve is closed. SUMMARY

[0005] To solve the above problem, according to a first aspect of the present disclosure, a control device for an internal combustion engine is provided. The internal combustion engine has an intake port injection valve that injects fuel into an intake passage, an in-cylinder injection valve that directly injects fuel into a cylinder without passing through the intake passage, and a supercharger that supercharges intake air. The control device is configured to, when a ratio of an amount of fuel injected from the intake port injection valve to a total amount of fuel supplied for combustion of fuel in the cylinder is set as an intake port injection ratio, set the intake port injection ratio smaller and delay a start timing of fuel injection from the intake port injection valve in a case where a condition of being in an operating state in which the supercharger is supercharging and being in an internal combustion engine operating range in which a valve overlap period is larger than zero is satisfied, compared to a case where the condition is not satisfied.

[0006] To address the above-described problems, according to a second aspect of the present disclosure, there is provided a control method of an internal combustion engine. The internal combustion engine has an intake port injection valve that injects fuel toward an intake passage, an in-cylinder injection valve that injects fuel directly into a cylinder without passing through the intake passage, and a supercharger that supercharges intake air. The control method includes the steps of: when a ratio of an amount of fuel injected from the intake port injection valve with respect to a total fuel amount for combustion of fuel supplied in the cylinder at one time is set as an intake port injection ratio, in a case where a condition of being in an operating state in which the supercharger is supercharging and being in a valve overlap period larger than zero is satisfied, setting the intake port injection ratio to be smaller than in a case where the condition is not satisfied, and delaying a start timing of fuel injection from the intake port injection valve. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic configuration diagram of an internal combustion engine.

[0008] Figure 2 is a graph showing an example of a ratio map.

[0009] Figure 3 is a graph showing an example of setting of a fuel injection amount based on a first treatment.

[0010] Figure 4 is a graph showing an example of setting of a fuel injection amount based on a second treatment.

[0011] Figure 5 is a flowchart showing processing steps of specific injection control. DETAILED DESCRIPTION

[0012] Hereinafter, an embodiment of a control device of an internal combustion engine will be described with reference to the drawings.

[0013] Schematic Configuration of Internal Combustion Engine

[0014] As shown in Figure 1 , a vehicle 300 has an internal combustion engine 1. The internal combustion engine 1 is a drive source of the vehicle 300. The internal combustion engine 1 has four cylinders 18, four pistons 6, four connecting rods 19, and a crankshaft 7. Note that, in Figure 1 , only one of the four cylinders 18 is shown. The same applies to the pistons 6 and the connecting rods 19.

[0015] The cylinder 18 is a space in which a mixture of fuel and intake air (hereinafter referred to as intake air.) is combusted. The piston 6 is provided for each cylinder 18. The piston 6 is located in the cylinder 18. The piston 6 moves reciprocally in the cylinder 18. The piston 6 is linked to the crankshaft 7 via the connecting rod 19. The crankshaft 7 rotates in accordance with the operation of the piston 6.

[0016] The internal combustion engine 1 has four spark plugs 5. Note that only one of the four spark plugs 5 is shown in Figure 1 The spark plugs 5 are provided for each cylinder 18. The front end of the spark plug 5 is located in the cylinder 18. The spark plug 5 ignites the mixture in the cylinder 18.

[0017] The internal combustion engine 1 has four in-cylinder injection valves 20 and a first fuel passage 24. Note that only one of the four in-cylinder injection valves 20 is shown in Figure 1 The in-cylinder injection valve 20 is provided for each cylinder 18. The in-cylinder injection valve 20 directly injects fuel into the cylinder 18 without passing through the intake passage 3 described later. The first fuel passage 24 connects each in-cylinder injection valve 20 with a fuel tank. The first fuel passage 24 supplies fuel to each in-cylinder injection valve 20. The fuel tank stores fuel. Note that the illustration of the fuel tank is omitted in Figure 1

[0018] The internal combustion engine 1 has an intake passage 3, an intercooler 60, a throttle valve 29, four intake port injection valves 4, and a second fuel passage 25. Note that only one of the four intake port injection valves 4 is shown in Figure 1 The intake passage 3 is a passage for introducing intake air to each cylinder 18. The intake passage 3 is connected to each cylinder 18. The intercooler 60 is located midway in the intake passage 3. The intercooler 60 cools the intake air. The throttle valve 29 is located on the downstream side from the intercooler 60 as viewed in the intake passage 3. The throttle valve 29 is capable of adjusting the opening degree. When the opening degree of the throttle valve 29 is changed, the amount GA of the intake air flowing in the intake passage 3 is changed. That is, the throttle valve 29 adjusts the amount GA of the intake air flowing in the intake passage 3. The intake port injection valve 4 is located on the downstream side from the throttle valve 29 as viewed in the intake passage 3. The intake port injection valve 4 is provided for each cylinder 18. The intake port injection valve 4 injects fuel into the intake passage 3. The second fuel passage 25 branches from the first fuel passage 24 and is connected to each intake port injection valve 4. The second fuel passage 25 supplies fuel to each intake port injection valve 4. The pressure of the fuel supplied to the intake port injection valve 4 (hereinafter referred to as the port fuel pressure) PP is different from the pressure of the fuel supplied to the in-cylinder injection valve 20 (hereinafter referred to as the in-cylinder fuel pressure) PD.

[0019] The internal combustion engine 1 has an exhaust passage 8 and a catalyst 70. The exhaust passage 8 is a passage for discharging exhaust gas from the cylinder 18. The exhaust passage 8 is connected to each cylinder 18. The catalyst 70 is located midway in the exhaust passage 8. The catalyst 70 purifies the exhaust gas flowing in the exhaust passage 8.

[0020] ​The internal combustion engine 1 has a turbocharger 50. The turbocharger 50 is arranged across the intake passage 3 and the exhaust passage 8. The turbocharger 50 has a compressor impeller 51, a turbine 52, a bypass passage 21, and a waste gas valve (hereinafter referred to as WGV.) 22. The compressor impeller 51 is located on the upstream side of the intake passage 3 as viewed from the intercooler 60. The turbine 52 is located on the upstream side of the exhaust passage 8 as viewed from the catalyst 70. The turbine 52 rotates according to the flow of exhaust gas. The compressor impeller 51 rotates integrally with the turbine 52. At this time, the compressor impeller 51 compresses and delivers the intake air. That is, the intake air is pressurized by the rotation of the compressor impeller 51. The bypass passage 21 connects the upstream side portion of the exhaust passage 8 as viewed from the turbine 52 to the downstream side portion. That is, the bypass passage 21 is a passage that bypasses the turbine 52. The WGV 22 is located at the downstream end of the bypass passage 21. The opening of the WGV 22 can be adjusted. When the opening WV of WGV22 changes, the amount of exhaust flowing in the bypass passage 21 changes. That is, WGV22 adjusts the amount of exhaust flowing in the bypass passage 21. The smaller the opening WV of WGV22, the less exhaust flows in the bypass passage 21. In this case, the amount of exhaust passing through turbine 52 increases, thus increasing the rotational speed of turbine 52 and compressor wheel 51. Consequently, the boost pressure increases.

[0021] The internal combustion engine 1 has multiple intake valves 9, multiple intake rocker arms 15, an intake camshaft 11, and an intake valve variable device 13. It should be noted that... Figure 1 Only one of the multiple intake valves 9 is shown in the diagram. The same applies to the intake rocker arm 15. Intake valves 9 are provided for each cylinder 18. The intake valve 9 is located at the connection port of the cylinder 18 in the intake passage 3. The intake valve 9 is connected to the intake camshaft 11 via the intake rocker arm 15. The intake valve 9 operates according to the rotation of the intake camshaft 11. Through this operation, the intake valve 9 opens and closes the aforementioned connection port of the intake passage 3. The rotation of the crankshaft 7 is transmitted to the intake camshaft 11. That is, the intake camshaft 11 rotates in conjunction with the crankshaft 7. The intake valve variable device 13 changes the relative rotational position (hereinafter referred to as crank position) Scr of the intake camshaft 11 and the crankshaft 7. As a result, the opening and closing timing of the intake valve 9 changes relative to the crank position Scr. The intake valve variable device 13 is an electric type driven by an electric motor.

[0022] The internal combustion engine 1 has multiple exhaust valves 10, multiple exhaust rocker arms 16, an exhaust camshaft 12, and an exhaust valve variable device 14. It should be noted that... Figure 1In the present embodiment, only one of the plurality of exhaust valves 10 is shown. The same applies to the exhaust rocker arm 16. The exhaust valve 10 is provided for each cylinder 18. The exhaust valve 10 is located at a connection port of the cylinder 18 in the exhaust passage 8. The exhaust valve 10 is linked to the exhaust camshaft 12 via the exhaust rocker arm 16. The exhaust valve 10 operates in accordance with the rotation of the exhaust camshaft 12. By this operation, the exhaust valve 10 opens and closes the aforementioned connection port of the exhaust passage 8. The exhaust camshaft 12 rotates in conjunction with the crankshaft 7, like the intake camshaft 11. The exhaust valve variable device 14 changes the relative rotational position of the exhaust camshaft 12 with respect to the crank position Scr. As a result, the opening and closing timing of the exhaust valve 10 with respect to the crank position Scr changes. The exhaust valve variable device 14 is electrically controlled by a motor.

[0023] The internal combustion engine 1 has a crank position sensor 34, an air flow meter 31, a first fuel pressure sensor 32, and a second fuel pressure sensor 33. Also, the internal combustion engine 1 has an intake cam position sensor 35, an exhaust cam position sensor 36, an opening degree sensor 37, and an atmospheric pressure sensor 30. The crank position sensor 34 detects the crank position Scr. The air flow meter 31 detects the amount GA of intake air that flows into the intake passage 3 from the outside. The first fuel pressure sensor 32 detects the port fuel pressure PP. The second fuel pressure sensor 33 detects the in-cylinder fuel pressure PD. The intake cam position sensor 35 detects the rotational position CG of the intake camshaft 11. The exhaust cam position sensor 36 detects the rotational position CE of the exhaust camshaft 12. The opening degree sensor 37 detects the opening degree WV of the WGV 22. The atmospheric pressure sensor 30 detects the atmospheric pressure L at the altitude at which the internal combustion engine 1 is located. Each of the sensors repeatedly outputs a signal corresponding to the information detected by itself to the control device 100 described later.

[0024] The vehicle 300 has an accelerator pedal 27, an accelerator sensor 28, and a vehicle speed sensor 38. The accelerator pedal 27 is a foot pedal that is stepped on by an occupant. The accelerator sensor 28 detects the amount of stepping on the accelerator pedal 27 as an accelerator operation amount ACCP. The vehicle speed sensor 38 detects the running speed of the vehicle 300 as a vehicle speed SP. Each of the sensors repeatedly outputs a signal corresponding to the information detected by itself to the control device 100 described later.

[0025] <Outline of Control Device>

[0026] As Figure 1As shown, the vehicle 300 has a control device 100. The control device 100 can be configured as one or more processors that execute various processes in accordance with a computer program (software). The processors include a CPU 110 and a memory 120 such as a RAM and a ROM. The memory 120 stores program codes or instructions configured in such a manner that the CPU 110 executes processes. The memory 120, i.e., the computer readable medium, includes a so-called available medium that can be accessed by a general-purpose or special-purpose computer.

[0027] The control device 100 calculates the following parameters at all times based on detection signals received from various sensors. The control device 100 calculates the rotational speed of the crankshaft 7, i.e., the engine speed NE, based on the crank position Scr detected by the crank position sensor 34. Also, the control device 100 calculates the engine load factor KL based on the engine speed NE and the amount GA of intake air detected by the air flow meter 31. The engine load factor KL indicates the ratio of the amount of intake air flowing into the cylinders at the present engine speed NE to the amount of intake air flowing into the cylinders when the engine 1 is stably operated with the throttle valve 29 fully open at the present engine speed NE. Note that the amount of intake air flowing into the cylinders is the amount GA of intake air that flows into each cylinder 18 during the intake stroke.

[0028] <Control over WGV>

[0029] The control device 100 controls various parts of the internal combustion engine 1 based on the detection signals received from the various sensors described above and the various parameters calculated based on the detection signals. For example, the control device 100 calculates a target value of the internal combustion engine load factor KL, i.e., a target load factor, based on the accelerator operation amount ACCP and the like. Then, the control device 100 controls the throttle valve 29 and the WGV 22 in such a manner that the target load factor can be achieved. When controlling the WGV 22, the control device 100 refers to a supercharging map stored in advance. The supercharging map shows the relationship between the internal combustion engine load factor KL and the opening degree WV of the WGV 22 and the atmospheric pressure L. The supercharging map is made, for example, based on experiments or simulations. The supercharging map is as follows. When observed at the same atmospheric pressure L, the WGV 22 is fully open in the case where the internal combustion engine load factor KL is smaller than a certain threshold value, and the opening degree WV of the WGV 22 is smaller than the full opening in the case where the internal combustion engine load factor KL is equal to or greater than the certain threshold value. In detail, in the case where the internal combustion engine load factor KL is equal to or greater than the threshold value described above, the greater the internal combustion engine load factor KL is than the threshold value described above, the smaller the opening degree WV of the WGV 22 is. The threshold value in the supercharging map at which the WGV 22 is switched from the full opening to the opening smaller than the full opening is called a supercharging start load factor KLA. When the internal combustion engine operating state in which the internal combustion engine load factor KL is equal to or greater than the supercharging start load factor KLA is reached, the supercharger 50 is supercharged. In the supercharging map, the lower the atmospheric pressure L is, the smaller the supercharging start load factor KLA is. Thus, the lower the atmospheric pressure L is, the smaller the accelerator operation amount ACCP at which the supercharging state is switched is. That is, the relationship of the parameters is determined in such a manner that the responsiveness of the internal combustion engine output with respect to the accelerator operation amount ACCP indicated by the driver does not decrease even in an environment where the atmospheric pressure L is low due to the low oxygen density and the internal combustion engine output tends to be small. The control device 100 calculates the opening degree WV of the WGV 22 corresponding to the target load factor as a target opening degree based on the supercharging map described above. Then, the control device 100 controls the WGV 22 in such a manner that the actual opening degree WV of the WGV 22 coincides with the target opening degree.

[0030] <About Fuel Injection>

[0031] The control device 100 controls the intake port injection valve 4 and the in-cylinder injection valve 20. The control device 100 performs fuel injection from both the intake port injection valve 4 and the in-cylinder injection valve 20, or from only one of them. The control device 100 changes the ratio of the amount of fuel injected from the intake port injection valve 4 to the total fuel amount Fall for fuel combustion once in one cylinder 18, that is, the intake port injection ratio R, according to the engine operating state. The intake port injection ratio R takes a value of "0" or more and "1" or less. The intake port injection ratio R of "1" means that the total fuel amount Fall is injected all through the intake port injection valve 4. The intake port injection ratio R of "0" means that the total fuel amount Fall is injected all through the in-cylinder injection valve 20. The intake port injection ratio R greater than "0" and less than "1" means that fuel injection is performed with both the intake port injection valve 4 and the in-cylinder injection valve 20. Note that the total fuel amount Fall for fuel combustion once is the total fuel amount supplied to one cylinder 18 in one cycle of the engine 1. One cycle of the engine 1 is the series of periods in which each of the intake stroke, compression stroke, combustion stroke, and exhaust stroke is entered once in one cylinder 18.

[0032] The control device 100 stores a ratio map in advance. The ratio map determines a base value of the intake port injection ratio R, that is, a basic intake port injection ratio RB, for each engine operating range defined by the engine speed NE and the engine load factor KL. The basic intake port injection ratio RB is the optimum intake port injection ratio R under standard atmospheric pressure. The ratio map is made, for example, on the basis of experiments or simulations. The ratio map is as follows. As Figure 2As shown, in the high-rotation engine operating range in which the engine speed NE is the first value NE1 or more, the basic intake port injection ratio RB is "0" regardless of the magnitude of the engine load factor KL. That is, in this engine operating range, fuel injection is performed only from the in-cylinder injection valve 20. On the other hand, in the low-rotation or medium-rotation engine operating range (hereinafter referred to as the prescribed rotation range) in which the engine speed NE is less than the first value NE1, the basic intake port injection ratio RB is changed depending on the magnitude of the engine load factor KL. Hereinafter, the setting of the basic intake port injection ratio RB in the prescribed rotation range will be described. In the low-load engine operating range in the prescribed rotation range in which the engine load factor KL is less than the first load factor KL1, the basic intake port injection ratio RB is "0". In the high-load engine operating range in which the engine load factor KL is the second load factor KL2 or more, the basic intake port injection ratio RB is also "0". That is, in the low-load or high-load engine operating range, as in the high-rotation engine operating range, fuel injection is performed only from the in-cylinder injection valve 20. On the other hand, in the medium-load engine operating range in the prescribed rotation range in which the engine load factor KL is the first load factor KL1 or more and less than the second load factor KL2, the basic intake port injection ratio RB is greater than "0". In detail, in the first medium-load range Y1 in the medium-load engine operating range in which the engine load factor KL is less than the specific load factor KLY, the basic intake port injection ratio RB is greater than "0" and less than "0.5". That is, in this first medium-load range Y1, fuel injection is performed from both the intake port injection valve 4 and the in-cylinder injection valve 20, and the amount of fuel injected from the in-cylinder injection valve 20 is greater than that from the intake port injection valve 4. On the other hand, in the second medium-load range Y2 in the medium-load engine operating range in which the engine load factor KL is the specific load factor KLY or more, the basic intake port injection ratio RB is "0.5" or more and less than "1". That is, in this second medium-load range Y2, fuel injection is performed from both the intake port injection valve 4 and the in-cylinder injection valve 20, and the amount of fuel injected from the intake port injection valve 4 is greater than that from the in-cylinder injection valve 20.

[0033] Note that the engine operating range such as the medium-load, high-load in the ratio map and the boost start load factor KLA are in the following relationship. The boost start load factor KLA2 in the case where the atmospheric pressure L is close to the standard atmospheric pressure is slightly smaller than the second load factor KL2. That is, in the region at a low altitude where the atmospheric pressure L is close to the standard atmospheric pressure, as a whole, the opportunity of performing the boost in the high-load engine operating range in which the intake port injection ratio R is "0" is more. Note that in the case where the atmospheric pressure L is less than the standard atmospheric pressure, the boost start load factor KLA is greater than the second load factor KL2. That is, in the region at a high altitude where the atmospheric pressure L is less than the standard atmospheric pressure, as a whole, the opportunity of performing the boost in the medium-load engine operating range in which the intake port injection ratio R is greater than "0" is more. Figure 2In the middle, B indicates the supercharged engine operating range in a region at a low altitude. Then, as explained in the above supercharging map, the lower the atmospheric pressure L, the smaller the supercharge start load factor KLA. Therefore, the lower the atmospheric pressure L compared to the standard atmospheric pressure, the smaller the supercharge start load factor KLA compared to the second load factor KL2. Also, there can be a region at a certain degree of high altitude, for example, 1000 m in the altitude range of the road, in which the supercharge start load factor KLA1 is slightly smaller than the certain load factor KLY. Therefore, as indicated by the range of A in Figure 2 the low load engine operating range. Also, in the region at a high altitude, not only the high load engine operating range in which the basic intake port injection ratio RB is "0", but also the opportunity for supercharging in the second middle load range Y2 in which the basic intake port injection ratio RB is "0.5" or more and less than "1" becomes more. Note that in the following description, the engine operating ranges of low load, middle load, and high load are all based on the ratio map.

[0034] <Regarding the opening and closing timing of the intake valve and the exhaust valve>

[0035] The control device 100 controls the intake valve variable device 13. Thereby, the control device 100 adjusts the opening and closing timing of the intake valve 9, that is, the intake valve timing. In the present embodiment, the control device 100 processes the state in which the intake valve timing is the timing of the most retarded angle side as the initial value of "0". Also, the control device 100 adjusts the intake valve timing by the amount of advance angle from this initial value. The control device 100 calculates the target value of the amount of advance angle of the intake valve timing, that is, the target advance angle amount, based on the engine speed NE and the engine load factor KL, and the like, when adjusting the intake valve timing. Then, the control device 100 controls the intake valve variable device 13 in such a manner that the actual amount of advance angle of the intake valve timing coincides with the target advance angle amount. A certain one of the four cylinders 18 is referred to as a reference cylinder. The control device 100 stores in advance the crank position Scr at which the intake valve 9 of the reference cylinder becomes the opening timing when the intake valve timing is the initial value. Therefore, the control device 100 can grasp the crank position Scr at which the intake valve 9 of the reference cylinder becomes the opening timing in the present situation by calculating the crank position Scr that is advanced by the target advance angle amount with respect to this crank position Scr. Similarly, the control device 100 stores in advance the crank position Scr at which the intake valve 9 of the reference cylinder becomes the closing timing when the intake valve timing is the initial value. Therefore, the control device 100 can grasp the crank position Scr at which the intake valve 9 of the reference cylinder becomes the closing timing in the present situation.

[0036] Further, the control device 100 controls the exhaust valve variable device 14. Thereby, the control device 100 adjusts the opening and closing timing of the exhaust valve 10, that is, the exhaust valve timing. In the present embodiment, the control device 100 treats the state where the exhaust valve timing is the timing of the most advanced angle side as "0" as an initial value. Further, the control device 100 adjusts the exhaust valve timing by adjusting the amount of retardation of the exhaust valve timing from the initial value. The control device 100 calculates a target value of the amount of retardation of the exhaust valve timing, that is, a target amount of retardation, on the basis of the engine speed NE and the engine load factor KL and the like when adjusting the exhaust valve timing. Then, the control device 100 controls the exhaust valve variable device 14 in such a manner that the actual amount of retardation of the exhaust valve timing coincides with the target amount of retardation. Note that the control device 100 stores in advance the crank positions Scr at which the exhaust valve 10 of the reference cylinder becomes the opening timing and the closing timing when the exhaust valve timing is the initial value. Therefore, the control device 100, like the case of the intake valve 9, can grasp the crank positions Scr at which the exhaust valve 10 of the reference cylinder becomes the opening timing and the closing timing in the present situation.

[0037] The control device 100 changes the valve overlap period VO in which both the intake valve 9 and the exhaust valve 10 are in the open state according to the engine operating range by adjusting the amount of advance of the intake valve timing and the amount of retardation of the exhaust valve timing. Specifically, the control device 100 increases the amount of advance of the intake valve timing in the medium load and high load engine operating ranges compared to the low load engine operating range. Further, the control device 100 increases the amount of retardation of the exhaust valve timing in the medium load and high load engine operating ranges compared to the low load engine operating range. Thereby, the control device 100 makes the valve overlap period VO longer and delays the end timing VOE of the valve overlap period VO in the medium load and high load engine operating ranges compared to the low load engine operating range. The end timing VOE of the valve overlap period VO is the closing timing of the exhaust valve 10. Note that the control device 100 basically makes the valve overlap period VO larger than "0" in each engine operating range, but sometimes makes the valve overlap period VO "0" in the low load engine operating range.

[0038] Here, as described above, the middle load and high load engine operating ranges are engine operating ranges in which supercharging based on the supercharger 50 is performed. That is, the control device 100 lengthens the valve overlap period VO in the engine operating ranges in which supercharging is performed. When supercharging based on the supercharger 50 is performed, the pressure of the intake passage 3 becomes higher than the pressure of the exhaust passage 8. If both the intake valve 9 and the exhaust valve 10 are brought to the open valve state at this time, the engine output is increased by performing the air exchange of introducing intake air into the cylinder 18 and scavenging exhaust gas from the cylinder 18. In this regard, it is effective to lengthen the valve overlap period VO when supercharging based on the supercharger 50 is performed. Note that the control device 100 sometimes lengthens the valve overlap period VO when supercharging based on the supercharger 50 is not performed, as in the middle load engine operating range in a region having a low altitude, for example. This is to achieve a reduction in NOx and an improvement in fuel economy by improving the effect of so-called internal exhaust gas recirculation.

[0039] <About Normal Injection Control>

[0040] The control device 100 performs normal injection control when the specific conditions described later are not established during operation of the engine 1. The control device 100 first calculates the total fuel amount Fall for combustion of fuel supplied to one cylinder 18 in the normal injection control, based on the present engine speed NE and engine load factor KL, and the like. Next, the control device 100 calculates the basic intake port injection ratio RB corresponding to the present engine speed NE and engine load factor KL in the ratio map. Then, the control device 100 calculates the fuel injection amount of the intake port injection valve 4, that is, the basic port injection amount FPB, corresponding to the basic intake port injection ratio RB, based on the total fuel amount Fall and the basic intake port injection ratio RB. Also, the control device 100 calculates the fuel injection amount of the in-cylinder injection valve 20, that is, the basic in-cylinder injection amount FDB, corresponding to the basic intake port injection ratio RB, based on the total fuel amount Fall and the basic intake port injection ratio RB. Then, the control device 100 injects the fuel of the basic port injection amount FPB from the intake port injection valve 4. Also, the control device 100 injects the fuel of the basic in-cylinder injection amount FDB from the in-cylinder injection valve 20. The control device 100 sequentially performs such fuel injection in the four cylinders 18. The control device 100 repeatedly performs the normal injection control consisting of the above series of processes. Note that the control device 100 sets the start timing of fuel injection of the intake port injection valve 4 (hereinafter referred to as the port injection timing. ) FPS to be a timing that is prompt after the opening of the intake valve 9 in the normal injection control. Also, the control device 100 sets the start timing of fuel injection of the in-cylinder injection valve 20 (hereinafter referred to as the in-cylinder injection timing. ) FDS to be a proper timing corresponding to the basic in-cylinder injection amount FDB in the normal injection control.

[0041] <Summary of specific injection control>

[0042] The control device 100 performs specific injection control when specific conditions are satisfied. The specific conditions are that both of the following items are satisfied.

[0043] (A) The internal combustion engine is in an operating state in which the supercharger 50 is performing supercharging.

[0044] (B) The internal combustion engine is in an operating range in which the valve overlap period VO is larger than "0".

[0045] Item (A) is a state in which the internal combustion engine load factor KL is equal to or greater than the supercharging start load factor KLA. Also, with regard to item (B), as described above, in the internal combustion engine operating range in which the supercharger 50 is performing supercharging, i.e., the medium load and high load internal combustion engine operating range, the valve overlap period VO is larger than "0". Therefore, if item (A) is satisfied, item (B) is necessarily satisfied.

[0046] Then, when the valve overlap period VO is entered while supercharging based on the supercharger 50 is being performed, breathing is promoted, but on the other hand, the following phenomenon also occurs. That is, intake air flowing from the intake passage 3 into the cylinder 18 directly leaks to the exhaust passage 8. At this time, if the intake port injection valve 4 comes to the injection timing and injects fuel into the intake passage 3, the fuel leaks to the exhaust passage 8 together with the intake air. The specific injection control is dedicated fuel injection control for preventing such leakage of fuel. In the specific injection control, specifically, the intake port injection ratio R is set to be smaller than in the normal injection control, and the start timing of fuel injection from the intake port injection valve 4 is delayed.

[0047] The control device 100 performs two processes in the specific injection control on the basis of setting the intake port injection ratio R to be small. The control device 100 corrects the basic intake port injection ratio RB in the first process in accordance with the atmospheric pressure L of the place where the vehicle 300 is located. Note that the reason for performing the correction taking the atmospheric pressure L into account is described in the Effect column described later. The control device 100 stores a correction map as information for performing the correction corresponding to the atmospheric pressure L in advance. The correction map shows the relationship between the atmospheric pressure L and a correction value H for correcting the intake port injection ratio R. The correction map is made on the basis of, for example, experiments or simulations. In the correction map, the lower the atmospheric pressure L, the smaller the correction value H. Note that the correction value H is a value of "1" or less. The control device 100 calculates a value obtained by multiplying the correction value H by the basic intake port injection ratio RB as a corrected intake port injection ratio RM. Thus, when the same basic intake port injection ratio RB is taken as the subject, the lower the atmospheric pressure L, the smaller the corrected intake port injection ratio RM. In other words, the corrected intake port injection ratio RM is set to a value of the lower the atmospheric pressure L, the greater the drop from the basic intake port injection ratio RB. The first process resets the intake port injection ratio R to the corrected intake port injection ratio RM of the lower the atmospheric pressure L, the greater the drop from the basic intake port injection ratio RB.

[0048] The control device 100 performs the second process only when the blowby of fuel cannot be completely prevented even if the first process is performed. The fuel injection amount of the intake port injection valve 4 corresponding to the corrected intake port injection ratio RM is referred to as a set port injection amount FPU. Also, the amount of fuel that can be injected from the intake port injection valve 4 in the period from the start timing FPS of fuel injection from the intake port injection valve 4, that is, the port injection timing FPS, to the closing of the intake valve 9 is referred to as an allowable port injection amount FPA. The control device 100 injects the allowable port injection amount FPA from the intake port injection valve 4 instead of the set port injection amount FPU in the second process. Also, the control device 100 compensates for the difference between the allowable port injection amount FPA and the set port injection amount FPU with injection from the in-cylinder injection valve 20. That is, the control device 100 resets the intake port injection ratio R in the second process in such a manner that the amount of fuel injected from the intake port injection valve 4 becomes the allowable port injection amount FPA instead of the corrected intake port injection ratio RM calculated in the first process.

[0049] The control device 100 stores in advance a port injection map as information required on the basis of the calculation of the allowable port injection amount FPA. Fuel injection during constant injection from the intake port injection valve 4 at a constant port fuel pressure PP. At this time, the amount of fuel injected from the intake port injection valve 4 is called an injectable amount. The injectable amount varies depending on the injection period. The port injection map shows the relationship between the injection period and the injectable amount for each port fuel pressure PP. The injection period and the injectable amount in the port injection map and the port fuel pressure PP are in the following relationship. When observed at a certain port fuel pressure PP, the longer the injection period, the greater the injectable amount. Also, if the injection period is the same, the higher the port fuel pressure PP, the greater the injectable amount. The port injection map is made on the basis of, for example, experiments or simulations.

[0050] The control device 100 calculates the port injection timing FPS specific to the specific injection control. In the present embodiment, the control device 100 sets the end timing VOE of the valve overlap period VO, i.e., a late timing within the valve overlap period VO, as the port injection timing FPS. The end timing VOE of the valve overlap period VO is the closing timing of the exhaust valve 10. The port injection timing FPS determined by the specific injection control by the control device 100 is a timing later than the port injection timing FPS of the normal injection control. Note that the port injection timing FPS of the normal injection control as a comparative object here is the port injection timing FPS when the normal injection control is performed in a condition where only item (B) of items (A) to (B) is satisfied. The reason for taking the normal injection control in a condition where only (B) is satisfied as a comparative object of the specific injection control will be described later. Then, the condition where only item (B) of items (A) to (B) is satisfied is a condition as follows. For example, it is a condition when the vehicle 300 is located at a place such as a lowland where the atmospheric pressure L is close to the standard atmospheric pressure and the engine operating range is within the second middle load range Y2. Or, it is a condition where the engine operating range is within the first middle load range Yl regardless of the atmospheric pressure L at which the vehicle 300 is located. In these cases, since (A) is not satisfied, the specific condition does not hold. However, the length of the valve overlap period VO and the end timing VOE determined by the engine operating range are substantially the same as in the condition where the specific condition holds, i.e., in the highland and in the supercharged middle load range Y2. Here, in the condition where the specific condition does not hold, the problem of blow-by of fuel does not occur, and thus fuel injection by the intake port injection valve 4 can be started before the end timing VOE of the valve overlap period VO. Therefore, the port injection timing FPS of the normal injection control in the condition where only (B) is satisfied is set to be earlier than the end timing VOE of the valve overlap period VO. In contrast to this, the control device 100 sets the end timing VOE of the valve overlap period VO as the port injection timing FPS in the specific injection control in order to avoid blow-by of fuel. That is, in the specific injection control, the port injection timing FPS is delayed compared to the normal injection control in the condition where the length of the valve overlap period VO and the end timing VOE are the same.

[0051] It should be noted that the example of a normal injection process performed under condition (B) is cited as a comparison object with the injection timing FPS of a specific injection control for the following reasons. The condition of performing normal injection processing is a condition where the specific process does not occur. That is, a condition where only one of items (A) or (B) is satisfied, i.e., the first condition, or a condition where neither item (A) nor (B) is satisfied, i.e., the second condition. Here, regarding the first condition, in the setting of the valve overlap period VO in this embodiment, a condition where only item (A) is satisfied does not occur. Therefore, the first condition actually only exists where only item (B) is satisfied. Furthermore, regarding the second condition, a condition where neither item (A) nor (B) is satisfied is a condition where the internal combustion engine 1 is in the low-load operating range of the internal combustion engine. Here, as... Figure 2 As shown, within the low-load operating range of the internal combustion engine, the intake port injection ratio R is "0", and no fuel injection is performed from the intake port injection valve 4. That is, under the condition that neither item (A) nor (B) is satisfied, there is no port injection timing FPS. Based on this situation, as a comparison with the port injection timing FPS of a specific control process, the port injection timing FPS of a normal injection process that only satisfies (B) is exemplified.

[0052] The control device 100 calculates the in-cylinder injection timing FDS specific to the specific injection control. The in-cylinder injection timing FDS is the start timing of fuel injection from the in-cylinder injection valve 20 as described above. Here, the fuel injection amount from the in-cylinder injection valve 20 corresponding to the corrected port injection ratio RM calculated in the first process is referred to as the set in-cylinder injection amount FDU. The control device 100 determines the in-cylinder injection timing FDS based on the set in-cylinder injection amount FDU both in the case where the second process is performed after the first process and in the case where the second process is not performed. The control device 100 determines the in-cylinder injection timing FDS as a timing that takes into account the following aspects. Fuel injected from the in-cylinder injection valve 20 into the cylinder 18 is atomized in the cylinder 18. The heat of vaporization at this time cools the surroundings of the spark plug 5. Therefore, when the in-cylinder injection timing FDS is made as close as possible to the ignition timing set at a point near the compression top dead center, ignition can be performed in a state where the surroundings of the spark plug 5 are at a relatively low temperature by using the heat of vaporization described above. This is effective in suppressing damage to the spark plug 5. On the other hand, if fuel is injected from the in-cylinder injection valve 20 when the piston 6 is at a position near the top dead center, the fuel adheres to the top surface of the piston 6 and the fuel becomes difficult to atomize. In this case, there is an increase in fuel that is directly discharged to the exhaust passage 8 in an unburned state. Therefore, from the viewpoint of exhaust emission, it is preferable to set a timing as far back as possible from the compression top dead center, such as when the piston 6 is at a position near the bottom dead center, as the in-cylinder injection timing FDS. The control device 100 determines the in-cylinder injection timing FDS as a timing that is optimal in injecting the set in-cylinder injection amount FDU from the in-cylinder injection valve 20, taking into account the protection of the spark plug 5, exhaust emission, and the like. Here, the period required to inject the set in-cylinder injection amount FDU from the in-cylinder injection valve 20 is referred to as the necessary period. In the present embodiment, the control device 100 sets a crank position Scr that is the necessary period back from a predetermined prescribed crank position as the in-cylinder injection timing FDS. The prescribed crank position is determined as a crank position Scr that is the most optimal as a reference in determining the in-cylinder injection timing FDS from the viewpoint described above, based on, for example, experiments or simulations, in the period from the bottom dead center to the top dead center of the piston 6 in the compression stroke. The control device 100 has the prescribed crank position with respect to the reference cylinder stored in advance. The details of the method of determining the in-cylinder injection timing FDS are described later. Note that the in-cylinder injection timing FDS set by the control device 100 is a timing after the end timing VOE of the valve overlap period VO in association with the following matter. The matter is adjusting the correction value H of the correction map in a manner that avoids the set in-cylinder injection amount FDU that is the basis for calculating the necessary period from becoming excessive.

[0053] The control device 100 pre-stores the in-cylinder injection map as the information needed to calculate the aforementioned necessary period. The in-cylinder injection map is created for the in-cylinder injection valve 20 in the same way as the port injection map. That is, the in-cylinder injection map shows the relationship between the injection period and the injectable quantity according to each in-cylinder fuel pressure PD. Here, the injectable quantity is the amount of fuel injected by the in-cylinder injection valve 20 during a constant injection period at a constant in-cylinder fuel pressure PD. The basic relationships of the parameters in the in-cylinder injection map are the same as those in the port injection map. The in-cylinder injection map is created based on, for example, experiments or simulations.

[0054] <Specific processing details for injection control>

[0055] During the operation of the internal combustion engine 1, the control device 100 repeatedly determines whether a specific condition is met. If the specific condition is met, the control device 100 cancels normal injection control and performs specific injection control. The control device 100 repeatedly performs specific injection control during the period in which the specific condition is met. At this time, the control device 100 performs specific injection control once per cycle of the internal combustion engine 1. In this specific injection control, the reference cylinder is set to the cylinder 18 that initiates fuel injection first out of the four cylinders 18.

[0056] like Figure 5 As shown, when the control device 100 initiates specific injection control, it first performs step S110. In step S110, the control device 100 calculates the total fuel quantity Fall for primary combustion in one cylinder 18. The control device 100 refers to the latest internal combustion engine speed NE and the latest internal combustion engine load rate KL, etc. Then, the control device 100 calculates the total fuel quantity Fall based on these. For example, the control device 100 stores a mapping representing the relationship between the internal combustion engine speed NE, the internal combustion engine load rate KL, and the total fuel quantity Fall. The control device 100 calculates the total fuel quantity Fall based on such a mapping. After calculating the total fuel quantity Fall, the control device 100 proceeds to step S120.

[0057] In step S120, the control device 100 calculates the corrected intake port injection ratio RM. Specifically, the control device 100 refers to the latest internal combustion engine speed NE, the latest internal combustion engine load rate KL, and the ratio mapping. Then, the control device 100 calculates the basic intake port injection ratio RB corresponding to the latest internal combustion engine speed NE and the latest internal combustion engine load rate KL based on the ratio mapping. Next, the control device 100 refers to the latest atmospheric pressure L and the correction mapping. Then, the control device 100 calculates the correction value H corresponding to the latest atmospheric pressure L based on the correction mapping. Then, the control device 100 multiplies the basic intake port injection ratio RB calculated according to the ratio mapping with the correction value H calculated according to the correction mapping. Then, the control device 100 sets the obtained value as the corrected intake port injection ratio RM. Then, the control device 100 causes the process to proceed to step S130.

[0058] In step S130, the control device 100 calculates the set port injection quantity FPU. The set port injection quantity FPU, as described above, is the fuel injection quantity of the intake port injection valve 4 corresponding to the corrected intake port injection ratio RM. Specifically, in step S130, the control device 100 multiplies the total fuel quantity Fall calculated in step S110 by the corrected intake port injection ratio RM calculated in step S120. The control device 100 then sets the obtained value as the set port injection quantity FPU. The control device 100 then proceeds to step S140.

[0059] In step S140, the control device 100 calculates the set in-cylinder injection quantity FDU. The set in-cylinder injection quantity FDU, as described above, is the fuel injection quantity of the in-cylinder injection valve 20 corresponding to the corrected intake port injection ratio RM. Specifically, in step S140, the control device 100 subtracts the set intake port injection quantity FDU calculated in step S130 from the total fuel quantity Fall calculated in step S110. Then, the control device 100 sets the obtained value as the set in-cylinder injection quantity FDU. Then, the control device 100 proceeds to step S150. It should be noted that the processes in steps S120, S130, and S140 constitute the first step in specific injection control.

[0060] In step S150, the control device 100 calculates the start timing of fuel injection by the intake port injection valve 4, that is, the port injection timing FPS. The control device 100 first calculates the port injection timing FPS with respect to the reference cylinder. Specifically, the control device 100 refers to the latest value of the target retardation angle amount for adjusting the amount of retardation of the exhaust valve timing. Also, the control device 100 refers to the crank position Scr at which the exhaust valve 10 of the reference cylinder becomes the closed valve timing when the exhaust valve timing is the initial value. Then, the control device 100 calculates the crank position Scr that is retarded from this crank position Scr by the target retardation angle amount as the crank position Scr at which the exhaust valve 10 of the reference cylinder becomes the closed valve timing under the present situation. Then, the control device 100 sets the calculated crank position Scr as the crank position Scr of the port injection timing FPS in the reference cylinder. Then, the control device 100 calculates the port injection timing FPS with respect to the three cylinders 18 other than the reference cylinder. Specifically, the control device 100 sets the crank position Scr that is advanced by 180 degrees from the port injection timing FPS of the reference cylinder in order of the cylinders 18 that enter the combustion stroke as the crank position Scr of the port injection timing FPS with respect to each cylinder 18. Then, the control device 100 causes the process to proceed to step S160.

[0061] In step S160, the control device 100 calculates the start timing of fuel injection by the in-cylinder injection valve 20, i.e., the in-cylinder injection timing FDS. The control device 100 first calculates the in-cylinder injection timing FDS with respect to the reference cylinder. Specifically, the control device 100 refers to the latest in-cylinder fuel pressure PD, the set in-cylinder injection amount FDU calculated in step S140, and the in-cylinder injection map. Then, the control device 100 calculates, as a necessary period, an injection period corresponding to the latest in-cylinder fuel pressure PD and the set in-cylinder injection amount FDU, based on the in-cylinder injection map. At this time, the control device 100 can apply the set in-cylinder injection amount FDU as an injectable amount in the in-cylinder injection map. Note that the necessary period is the period required to inject the set in-cylinder injection amount FDU from the in-cylinder injection valve 20, as described above. After calculating the necessary period, the control device 100 calculates a necessary crank amount that converts the necessary period into the amount of rotation of the crankshaft 7. The control device 100 calculates the necessary crank amount based on the necessary period and the latest engine speed NE. Then, the control device 100 refers to the above-described prescribed crank position of the reference cylinder, which is stored in advance. Then, the control device 100 calculates, as the crank position Scr of the in-cylinder injection timing FDS in the reference cylinder, a crank position Scr that is traced back from the prescribed crank position by the necessary crank amount. Then, the control device 100 calculates the in-cylinder injection timing FDS with respect to the three cylinders 18 other than the reference cylinder. Specifically, the control device 100 sets, as the crank position Scr of the in-cylinder injection timing FDS with respect to each cylinder 18, a crank position Scr that is advanced by 180 degrees from the in-cylinder injection timing FDS of the reference cylinder, in the order of the cylinders 18 that enter the combustion stroke. Then, the control device 100 advances the process to step S170.

[0062] In step S170, the control device 100 calculates the allowable port injection amount FPA. As described above, the allowable port injection amount FPA is the amount of fuel that can be injected from the intake port injection valve 4 in the period from the port injection timing FPS to the closing timing of the intake valve 9. As a specific process of step S170, the control device 100 first calculates the closing timing of the intake valve 9 of the reference cylinder. Specifically, the control device 100 refers to the latest value of the target advance angle amount for adjusting the advance angle amount of the intake valve timing. Also, the control device 100 refers to the crank position Scr at which the intake valve 9 of the reference cylinder becomes the closing timing when the intake valve timing is the initial value. Then, the control device 100 calculates the crank position Scr that is advanced from this crank position Scr by the target advance angle amount as the crank position Scr at which the intake valve 9 of the reference cylinder becomes the closing timing. Then, the control device 100 calculates the allowable rotation amount. The allowable rotation amount is the magnitude of the rotation angle by which the crankshaft 7 rotates in the period from the crank position Scr of the port injection timing FPS of the reference cylinder calculated in step S150 to the crank position Scr of the closing timing of the intake valve 9 of the reference cylinder. After the control device 100 calculates the allowable rotation amount, the control device 100 converts the allowable rotation amount into a unit of time on the basis of the latest engine speed NE and the allowable rotation amount. Then, the control device 100 sets the obtained value as the allowable period. Then, the control device 100 refers to the latest port fuel pressure PP and the port injection map. Then, the control device 100 calculates the injectable amount corresponding to the latest port fuel pressure PP and the allowable period on the basis of the port injection map. At this time, the control device 100 can apply the above-described allowable period to the injection period in the port injection map. After the control device 100 calculates the injectable amount according to the port injection map, the control device 100 sets the calculated value as the allowable port injection amount FPA. Then, the control device 100 causes the process to proceed to step S180.

[0063] In step S180, the control device 100 determines whether the allowable port injection amount FPA calculated in step S170 is equal to or greater than the set port injection amount FPU calculated in step S130. The control device 100 causes the process to proceed to step S190 when the allowable port injection amount FPA is equal to or greater than the set port injection amount FPU (step S180: YES).

[0064] In step S190, the control device 100 calculates the target port injection amount FPF. The target port injection amount FPF is the target value of the amount of fuel injected from the intake port injection valve 4. As a specific process of step S190, the control device 100 calculates the set port injection amount FPU calculated in step S130 directly as the target port injection amount FPF. Then, the control device 100 causes the process to proceed to step S200.

[0065] In step S200, the control device 100 calculates the target in-cylinder injection quantity FDF. The target in-cylinder injection quantity FDF is a target value for the amount of fuel injected from the in-cylinder injection valve 20. As a specific process in step S200, the control device 100 directly uses the set in-cylinder injection quantity FDU calculated in step S140 as the target in-cylinder injection quantity FDF to calculate the target in-cylinder injection quantity. Then, the control device 100 causes the process to proceed to step S300.

[0066] On the other hand, in step S180, if the allowable injection quantity FPA is less than the set injection quantity FPU (step S180: No), the control device 100 proceeds to step S210. Then, in step S210, the control device 100 calculates the target injection quantity FPF. Specifically, the control device 100 calculates the target injection quantity FPF using the allowable injection quantity FPA calculated in step S170. Then, the control device 100 proceeds to step S220. It should be noted that the processes in steps S210 and S220 are the second processing steps for specific injection control.

[0067] In step S220, the control device 100 calculates the target in-cylinder injection quantity FDF. Specifically, the control device 100 calculates the difference N by subtracting the allowable in-cylinder injection quantity FPA calculated in step S170 from the set injection quantity FPU calculated in step S130. Then, the control device 100 calculates the target in-cylinder injection quantity FDF by adding the difference N and the set injection quantity FDU calculated in step S140. Then, the control device 100 proceeds to step S300. It should be noted that the control device 100 rapidly performs the series of processes described above from step S110 to step S220 before the start of fuel injection relative to the reference cylinder.

[0068] In step S300, fuel injection is performed from each intake port injection valve 4 and each cylinder injection valve 20. Specifically, the port injection timing FPS of each cylinder 18 calculated by the control device 100 in step S150 begins fuel injection from each intake port injection valve 4. At that time, the control device 100 injects fuel of the target port injection quantity FPF from each intake port injection valve 4. Furthermore, the cylinder injection timing FDS of each cylinder 18 calculated by the control device 100 in step S160 begins fuel injection from each cylinder injection valve 20. At that time, the control device 100 injects fuel of the target cylinder injection quantity FDF from each cylinder injection valve 20. After completing fuel injection into the four cylinders 18, the control device 100 temporarily terminates the series of processes for specific injection control. Then, the control device 100 performs the process of step S110 again.

[0069] <The Role of the Implementation Method>

[0070] If already used Figure 2 As explained, when atmospheric pressure L decreases, the operating range of the internal combustion engine where the turbocharger 50 performs turbocharging expands towards the operating range of a low-load internal combustion engine. As a result, the opportunity for turbocharging also increases within the second load range Y2, where the basic intake injection ratio RB is set relatively high. On the other hand, within the operating range of the internal combustion engine where the turbocharger 50 performs turbocharging, the valve overlap period VO is set to be longer. Therefore, when the turbocharger 50 performs turbocharging in an environment with low atmospheric pressure L and fuel injection is performed directly using the basic intake injection ratio RB, the following problems occur. That is, as... Figure 3 As shown in (a), the fuel injection quantity of the intake port injection valve 4 corresponding to the basic intake port injection ratio RB, i.e., the basic port injection quantity FPB, is quite large. Therefore, in order to inject this basic port injection quantity FPB from the intake port injection valve 4 before the valve closing time GVE of the intake valve 9, it is necessary to do the following: that is, fuel injection of the intake port injection valve 4 needs to start before the end time VOE of the valve overlap period. In this case, the fuel injected from the intake port injection valve 4 during the valve overlap period will leak into the exhaust passage 8.

[0071] Therefore, in the first step of specific injection control, the inlet injection ratio R is reset based on atmospheric pressure L. That is, the control device 100 calculates a corrected inlet injection ratio RM that decreases more significantly from the basic inlet injection ratio RB as atmospheric pressure L decreases (step S120). Figure 3 As shown in (b), if the fuel injection quantity from the intake injection valve 4 corresponding to the corrected intake injection ratio RM, i.e., the setpoint injection quantity FPU, is... Figure 3 If the permissible port injection quantity FPA shown in (c) is below, the following becomes possible. That is, even when fuel injection based on the port injection valve 4 starts from the end timing VOE of the valve overlap period VO, the port injection valve 4 can inject the set port injection quantity FPU before the valve closing timing GVE of the intake valve 9. Therefore, when the set port injection quantity FPU is below the permissible port injection quantity FPA (step S180: Yes), the control device 100 sets the set port injection quantity FPU to the final target port injection quantity FPF (step S190). Furthermore, the control device 100 starts fuel injection from the end timing VOE of the valve overlap period VO. On the other hand, the control device 100 uses fuel injection from the in-cylinder injection valve 20 to compensate for the amount of fuel injection reduced from the port injection valve 4. That is, the control device 100 sets the fuel injection quantity from the in-cylinder injection valve 20, which corresponds to the corrected intake port injection ratio RM, as the target in-cylinder injection quantity FDF (step S200). Furthermore, the control device 100 starts fuel injection from the in-cylinder injection valve 20 at the optimal timing.

[0072] Therefore, as described above, in the first treatment, the intake injection ratio R is corrected based on atmospheric pressure L. Accompanying this correction, Figure 4 The basic orifice jet volume FPB shown in (a) is reduced to Figure 4 The set nozzle injection volume of the FPU is shown in (b). However, as Figure 4 As shown in (b), the set nozzle injection volume of the FPU may sometimes be higher than that. Figure 4 The permissible injection quantity FPA shown in (c) is higher. This situation may occur, for example, when the total fuel quantity Fall is higher, or when the internal combustion engine speed NE is higher and the period from the end timing VOE of the valve overlap period to the closing timing GVE of the intake valve 9 is shorter. When the set injection quantity FPU is higher than the permissible injection quantity FPA, the following problem occurs. That is, if Figure 4 As shown in (b), if the set port injection quantity FPU is injected before the valve closing time GVE of the intake valve 9, fuel injection from the intake port injection valve 4 needs to begin before the end time VOE of the valve overlap period. In this case, the fuel injected from the intake port injection valve 4 during the valve overlap period will leak into the exhaust passage 8. That is, the problem of fuel leakage still occurs.

[0073] Therefore, if the set jet volume FPU is greater than the allowable jet volume FPA (step S180: No), the control device 100 performs a second processing step. That is, if... Figure 4 As shown in (c), the control device 100 sets the permissible port injection quantity FPA to the final target port injection quantity FPF, instead of the set port injection quantity FPU (step S210). Furthermore, the control device 100 starts fuel injection from the intake port injection valve 4 at the end timing Voe of the valve overlap period VO. Thus, the intake port injection valve 4 can inject the required amount of fuel before the valve closing timing GVE of the intake valve 9. On the other hand, the control device 100 uses the in-cylinder injection valve 20 to compensate for the difference N between the set port injection quantity FPU and the permissible port injection quantity FPA. That is, the control device 100 adds the aforementioned difference N to the set in-cylinder injection quantity FDU and sets the result as the target in-cylinder injection quantity FDF (step S220). Then, the control device 100 injects this target in-cylinder injection quantity FDF from the in-cylinder injection valve 20. The in-cylinder injection timing FDS at this time is the same as in the first process. That is, when the control device 100 uses the in-cylinder injection valve 20 to compensate for the above-mentioned difference N, it does not need to recalculate the in-cylinder injection timing FDS, but uses the in-cylinder injection timing FDS calculated based on the set in-cylinder injection quantity FDU.

[0074] It should be noted that, in Figure 4In the present embodiment, an example is shown in which the in-cylinder injection timing FDS is set to a timing later than the closing timing GVE of the intake valve 9, but there can be cases in which the in-cylinder injection timing FDS is set to a timing earlier than the closing timing GVE of the intake valve 9. Also, ​ The injection amount, injection timing, opening / closing timing of each valve, etc. of each injection valve are schematically depicted for the purpose of easily explaining the effects in the case where the specific injection control is performed, and these do not necessarily agree with the actual ones.

[0075] <Effects of Embodiments>

[0076] (1) As described in the above effects, the control device 100 makes the intake port injection ratio R smaller by performing the two-stage treatment in the case where the internal combustion engine 1 is operated in an operating range in which fuel blow-by can occur. Also, the target port injection amount FPF is set to a value that is equal to or less than the allowable port injection amount FPA. In this case, even in the case where the port injection timing FPS is set to a timing after the end of the valve overlap period VO, the target port injection amount FPF can be injected from the intake port injection valve 4 before the closing timing of the intake valve 9. In the structure of this embodiment, by starting fuel injection from the intake port injection valve 4 at the end timing VOE of the valve overlap period VO, fuel blow-by can be prevented. Also, the control device 100 compensates for the entire amount by which the fuel injection amount from the intake port injection valve 4 is reduced by fuel injection from the in-cylinder injection valve 20. Therefore, the total fuel amount Fall for combustion of the fuel in the cylinder 18 does not change. Therefore, the effects of the variation in the torque of the internal combustion engine 1, etc. that accompany the decrease in the intake port injection ratio R are suppressed to a minimum.

[0077] (2) In the case where the amount of fuel injected from the in-cylinder injection valve 20 is large, the following concern exists. That is, the period required to inject the required amount of fuel from the in-cylinder injection valve 20 becomes long. Along with this, the in-cylinder injection timing FDS is set to a crank position that is correspondingly retrograded from the prescribed crank position. In this case, the in-cylinder injection timing FDS can become, for example, a timing that is correspondingly retrograded from the timing at which the piston 6 is at the bottom dead center of the compression stroke, that is, a timing at which the piston 6 is at a position close to the top dead center. When fuel injection is started at this timing, the amount of fuel adhering to the top surface of the piston 6 can become large. Also, the fuel becomes difficult to atomize. Thus, it is not preferable to excessively increase the amount of fuel injection from the in-cylinder injection valve 20. There is also a case where the correction value H used when the intake port injection ratio R is reduced in the first treatment of the specific injection processing is a value at which the amount of fuel injection from the in-cylinder injection valve 20 is not so large. Therefore, the amount of fuel injection of the intake port injection valve 4 reduced in the first treatment is also limited to some extent. Although the first treatment has such a limitation, in the specific injection processing, the intake port injection ratio R is reset in the second treatment in such a manner that the target port injection amount FPF becomes the allowable port injection amount FPA. Therefore, it is possible to reliably prevent blow-by of fuel.

[0078] Here, as explained in step S160 of the specific injection processing, complicated processing is correspondingly required to calculate the in-cylinder injection timing FDS. When the intake port injection ratio R is reset in the second treatment, the burden of processing of the control device 100 increases if the in-cylinder injection timing FDS is recalculated again from the final target in-cylinder injection amount FDF. In view of this, the present embodiment does not recalculate the in-cylinder injection timing FDS even in the case where the intake port injection ratio R is reset in the second treatment, but uses the existing in-cylinder injection timing FDS that has been calculated based on the set in-cylinder injection amount FDU. Therefore, although the above-described two-stage treatment is performed, it is possible to suppress the burden of processing of the control device 100 to the minimum.

[0079] <Modification Example>

[0080] Note that the above-described embodiment can be changed and implemented as follows. The above-described embodiment and the following modification examples can be combined with each other and implemented within a range where there is no technical contradiction.

[0081] The scheme of the second treatment of the specific injection control is not limited to the example of the above-described embodiment. That is, in step S210, a fuel amount smaller than the allowable port injection amount FPA can be set as the target port injection amount FPF, instead of directly setting the allowable port injection amount FPA as the target port injection amount FPF. In this case, as long as the difference between the total fuel amount Fall and the above-described target port injection amount FPF is compensated for by fuel injection from the in-cylinder injection valve 20, the total fuel amount Fall can be supplied to the cylinder 18.

[0082] The calculation method of the in-cylinder injection timing FDS in the specific injection control is not limited to the example of the above-described embodiment. The calculation method of the in-cylinder injection timing FDS can be a method that is capable of setting an appropriate timing on the basis of taking into account the protection of the spark plug 5, exhaust emission, and the like. Along with the change of the calculation method of the in-cylinder injection timing FDS, a timing different from the in-cylinder injection timing FDS calculated in the scheme of the above-described embodiment can be set as the in-cylinder injection timing FDS.

[0083] The in-cylinder injection timing FDS in the case of the second treatment in which the specific injection control is performed can also be recalculated on the basis of the target in-cylinder injection amount FDF calculated in the second treatment. In this case, fuel injection from the in-cylinder injection valve 20 can be started from a timing that is optimal for injecting the target in-cylinder injection amount FDF calculated in the second treatment.

[0084] The port injection timing FPS set in the specific injection control is not limited to the example of the above-described embodiment. The port injection timing FPS can also be set to a timing later than the end timing VOE of the valve overlap period VO. For example, the set port injection amount FPU can be set to be smaller than the allowable port injection amount FPA. In this case, even if the port injection timing FPS is set to a timing later than the end timing VOE of the valve overlap period VO, the set port injection amount FPU can be injected from the intake port injection valve 4 before the valve closing timing of the intake valve 9. Also, as in the modification example described later, in the case where the second treatment is abandoned or the like, the port injection timing FPS can be set halfway through the valve overlap period VO. In this case, as long as it is as late a timing as possible within the valve overlap period VO, the amount of fuel leakage of fuel to the exhaust passage 8 can be reduced as little as possible. The port injection timing FPS set in the specific injection control can be later than the port injection timing FPS set in the normal injection control.

[0085] The method of correction of the intake port injection ratio R in the first treatment of the specific injection control is not limited to the example of the above-described embodiment. When the intake port injection ratio R is corrected, a correction value H can be added or subtracted instead of being multiplied by the correction value H. As long as an appropriate correction value H is set to the correction map according to the method of correction. Regardless of the method of correction, as long as the corrected intake port injection ratio RM that is larger the lower the atmospheric pressure L is calculated.

[0086] In the above-described embodiment, the correction value H is determined with the intake port injection valve 4 among the in-cylinder injection valve 20 and the intake port injection valve 4 as the focus. Instead, the correction value H can be determined with the in-cylinder injection valve 20 as the focus. Specifically, in step S120, a value obtained by subtracting the basic intake port injection ratio RB from "1" is calculated as a basic in-cylinder injection ratio. Then, the basic in-cylinder injection ratio is multiplied by the correction value H to calculate a corrected in-cylinder injection ratio. Then, in step S130 and step S140, the fuel injection amount from each injection valve is determined according to the corrected in-cylinder injection ratio. The correction value H can be determined in a manner that enables such a scheme. In this case, the correction map can be one in which the correction value H is larger the lower the atmospheric pressure L is. At that time, the correction value H in the case where the correction is made by multiplication can be a value of "1" or more. Also, as the correction value H in the case where the correction is made by multiplication, for example, a value obtained by dividing the standard atmospheric pressure by the atmospheric pressure L of the place where the vehicle 300 is located can be adopted. In these cases, the lower the atmospheric pressure L is, the larger the magnitude at which the intake port injection ratio R is made smaller is set.

[0087] The second treatment of the specific injection control can be abandoned, and only the first treatment can be performed. If the first treatment is performed, the intake port injection ratio R can be made smaller in accordance with the atmospheric pressure L. Here, the set port injection amount FPU obtained by the first treatment is sometimes more than the allowable port injection amount FPA. In this case, as described in the above-described modification, the port injection timing FPS can be set within the valve overlap period VO. In this case, compared to the case where the first treatment is not performed, the intake port injection ratio R is made smaller by the first treatment, and thus the amount of fuel that leaks to the exhaust passage 8 can be reduced without being small.

[0088] The first process of the specific injection control can also be abandoned, and only the second process can be performed. That is, the correction corresponding to the atmospheric pressure L can also not be performed. For example, if the correction value H is handled as 1 in step S120, such a scheme can be realized. Specifically, in a case where the correction value H is set to 1, in step S180, the fuel injection amount from the intake port injection valve 4 corresponding to the basic intake port injection ratio RB, that is, the basic port injection amount FPB, and the allowable port injection amount FPA are compared. Then, in a case where the former is more than the latter (step S180: No), the second process is performed. Then, in step S210, the allowable port injection amount FPA is set as the target port injection amount FPF. Also, in step S220, the difference between the basic port injection amount FPB and the allowable port injection amount FPA is included in the target in-cylinder injection amount FDF. Such a scheme can also be employed.

[0089] In the case of abandoning the first process of the specific injection control and performing only the second process, as with the above-described modification example, the injection amount smaller than the allowable port injection amount FPA can also be set as the target port injection amount FPF. Also, the amount of the reduction can be included in the target in-cylinder injection amount FDF.

[0090] In the case of abandoning the first process of the specific injection control and performing only the second process, the in-cylinder injection timing FDS can also be set to either of the following. That is, the in-cylinder injection timing FDS can be calculated from the fuel injection amount from the in-cylinder injection valve 20 corresponding to the basic in-cylinder injection ratio RB, that is, the basic in-cylinder injection amount FDB. Also, the in-cylinder injection timing FDS can be calculated from the target in-cylinder injection amount FDF calculated in the second process. The port injection timing FPS can be set in a manner that enables the target port injection amount FPF to be injected before the valve closing timing of the intake valve 9.

[0091] In the specific injection control, the intake port injection ratio R can also be set to be smaller by a method different from the first process and the second process. For example, in the specific injection control, regardless of the atmospheric pressure L of the place where the vehicle 300 is located, a value obtained by reducing the basic intake port injection ratio RB by a predetermined fixed value can be calculated as the corrected intake port injection ratio RM. Also, fuel corresponding to the corrected intake port injection ratio RM can be injected from each injection valve. The specific injection control can be a content in which the intake port injection ratio R is set to be smaller and the port injection timing FPS is delayed compared to the normal injection control.

[0092] The calculation method of each valve timing calculated during the processing of the specific injection control is not limited to the example of the above-described embodiment. For example, each valve timing can be calculated using the detection values of the following sensors. The sensors are the crank position sensor 34, the intake cam position sensor 35, and the exhaust cam position sensor 36. Regardless of the method, as long as each valve timing can be appropriately calculated.

[0093] Each map can be a mathematical expression, not a table or a graph. Each map can only need to clearly show the relationship between the parameters defined in each map.

[0094] The adjustment scheme of each valve timing corresponding to the operating range of the internal combustion engine is not limited to the example of the above-described embodiment. Regardless of the adjustment scheme of each valve timing, fuel blow-by can occur when the valve overlap period VO is larger than "0" and the intake port injection ratio R is large at that time, based on the supercharging of the supercharger 50. In order to prevent this fuel blow-by, the specific injection control can be performed.

[0095] The contents of the ratio map, the contents of the supercharging map, and the setting method of the valve overlap period VO can sometimes be different from the example of the above-described embodiment. Also, in conjunction therewith, the relationship of the supercharging start load rate KLA, the basic intake port injection ratio RB, and the length of the valve overlap period VO can sometimes be different from the example of the above-described embodiment. In this case, the specific injection control can only need to be the contents of setting the intake port injection ratio R to be smaller than the usual injection control and delaying the port injection timing FPS.

[0096] Here, the initial values ​​of the intake valve timing and exhaust valve timing are set to the same scheme as in the above embodiment. In this case, regarding the reference cylinder, the intake valve timing set by the intake valve variable device 13 and the exhaust valve timing set by the exhaust valve variable device 14 have the following relationship. That is, the crank position Scr when the exhaust valve 10 becomes closed when the lag angle of the exhaust valve timing is maximized is located on the lag angle side compared to the crank position Scr when the intake valve timing is the initial value and the intake valve 9 becomes open. Then, specific injection control is performed when the lag angle of the exhaust valve timing is maximized and valve overlap is performed. Furthermore, the port injection timing FPS at this time is set to the end timing VOE of the valve overlap period VO, that is, the closing timing of the exhaust valve 10. This scheme is called the prescribed scheme. Here, in normal injection control, the timing immediately after the opening timing of the intake valve 9 is basically set as the port injection timing FPS. For example, the opening timing of the intake valve 9 and the port injection timing FPS of normal injection control are made approximately the same. In this case, the inlet injection timing FPS under normal injection control with the intake valve timing at its initial value is the most delayed timing under normal injection control. Compared to the inlet injection timing FPS at this time, the inlet injection timing FPS under specific injection control using the above-described scheme, even when the exhaust valve timing lag angle is at its maximum, is further behind the lag angle of the exhaust valve 10's closing timing. Therefore, if the premise that the intake valve 9's opening timing and the inlet injection timing FPS under normal injection control are approximately the same holds true, then the following applies. That is, if specific injection control is performed using the prescribed scheme, the inlet injection timing FPS of this specific injection control is later than the inlet injection timing FPS of normal injection control.

[0097] The overall structure of the internal combustion engine 1 is not limited to the example of the above embodiment. For example, the number of cylinders 18 can be changed. The intake valve variable device 13 can also be of the type driven by hydraulic pressure. The same applies to the exhaust valve variable device 14. Furthermore, for example, if the first treatment is not performed, the atmospheric pressure sensor 30 can be discarded. The internal combustion engine 1 only needs to have an intake port injection valve 4, an in-cylinder injection valve 20, and a turbocharger 50.

[0098] The overall structure of vehicle 300 is not limited to the examples of the above embodiments. For example, vehicle 300 may also have not only an internal combustion engine 1 but also a generator motor as the drive source of vehicle 300.

[0099] The control device 100 is not limited to a unit that executes software processing, such as a CPU, a GPU, a TPU, or the like. For example, the control device can also have a dedicated hardware circuit that performs hardware processing on at least a part of the content of the software processing performed in the above-described embodiments. The dedicated hardware circuit can be, for example, an ASIC or the like. That is, the control device can have a processing circuit having any one of the following (a) to (c).

[0100] (a) a processing circuit having a processing device that executes all of the above-described processing according to a program and a program storage device that stores the program.

[0101] (b) a processing circuit having a processing device that executes a part of the above-described processing according to a program and a program storage device and a dedicated hardware circuit that executes the remaining processing.

[0102] (c) a processing circuit having a dedicated hardware circuit that executes all of the above-described processing.

[0103] Here, the software execution device having the processing device and the program storage device and the dedicated hardware circuit can each be plural.

Claims

1. A control device for an internal combustion engine, The internal combustion engine has the following features: The intake injection valve injects fuel into the intake passage. The in-cylinder injection valve injects fuel directly into the cylinder without going through the intake passage; The turbocharger pressurizes the intake air; Atmospheric pressure sensor, to detect atmospheric pressure; and A fuel pressure sensor detects the fuel pressure at the air intake, which is the pressure of the fuel supplied to the air intake injection valve. The control device is configured to perform specific injection control as follows when the ratio of the amount of fuel injected from the intake port injection valve to the total amount of fuel supplied for one combustion cycle in the cylinder is set as the intake port injection ratio: When the condition of being in a turbocharged operating state and within the internal combustion engine operating range greater than zero during valve overlap is met, compared to a case where this condition is not met, the intake port injection ratio is set to be smaller, and the timing of the start of fuel injection from the intake port injection valve is delayed. In the specific injection control, The start timing is set to a time later than the valve overlap period, and the following processing is performed: the lower the latest atmospheric pressure detected by the atmospheric pressure sensor, the greater the reduction in the intake injection ratio is set, in order to calculate the intake injection ratio. The amount of fuel injected by the intake injection valve is defined as the permissible injection amount if fuel injection is performed from the intake injection valve during the period from the start timing to the valve closing timing, under the latest intake fuel pressure detected by the fuel pressure sensor. If the permissible port injection amount is less than the fuel injection amount of the intake port injection valve corresponding to the intake port injection ratio calculated in the process, the intake port injection ratio is reset instead of the intake port injection ratio calculated in the process, so that the amount of fuel injected from the intake port injection valve becomes the permissible port injection amount.

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