Control device for an internal combustion engine

Abstract

The present application aims to suppress the accumulation of deposits in an intake port and an intake valve, and to suppress the deterioration of NV performance. A control device is a control device of an internal combustion engine provided with an intake port injection valve that injects fuel into an intake port, and an in-cylinder injection valve that injects fuel into a cylinder, the control device executing fuel injection using the intake port injection valve in a first state where a vehicle equipped with the internal combustion engine is in running and the internal combustion engine is in an idle state, or in a second state where the duration of stopping of the vehicle is less than a threshold value set in advance and the internal combustion engine is in an idle state, and executing fuel injection using only the in-cylinder injection valve in an idle state other than the first state and the second state.

Description

Technical Field

[0001] This invention relates to a control device for an internal combustion engine. Background Technology

[0002] Previously, internal combustion engines equipped with both port injection valves and in-cylinder injection valves were known (see, for example, Patent Document 1). Patent Document 1 proposes a technique that uses a port injection valve to inject fuel, preventing fuel adhering to the intake port or intake valve from becoming deposits. Specifically, Patent Document 1 proposes a scheme that uses only the in-cylinder injection valve in the idling state of the internal combustion engine.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-321707

[0006] The problem that the invention aims to solve

[0007] However, the fuel injected from the in-cylinder injection valve is pressurized by a high-pressure pump. This high-pressure pump is sometimes a source of noise and vibration (NV). Therefore, as described in Patent Document 1, if only the in-cylinder injection valve is used when the internal combustion engine is idling, noise or vibration accompanying the operation of the high-pressure pump will always be generated during idling. As a result, NV becomes a problem. Summary of the Invention

[0008] Therefore, the problem with the control device for the internal combustion engine disclosed in this specification is to suppress the accumulation of deposits in the intake port and intake valves, and to suppress the deterioration of NV performance.

[0009] The aforementioned problem is achieved by a control device for an internal combustion engine, which includes an intake port injection valve for injecting fuel into an intake port and an in-cylinder injection valve for injecting fuel into the cylinder. The control device performs fuel injection using the intake port injection valve when the vehicle equipped with the internal combustion engine is in a first state and the internal combustion engine is idling, or when the vehicle is stopped for a duration less than a preset threshold and the internal combustion engine is idling. When the vehicle is in an idling state other than the first state or the second state, it performs fuel injection using only the in-cylinder injection valve.

[0010] In the control device of the internal combustion engine constructed as described above, when the control device determines whether it is in the second state, the threshold includes a first threshold and a second threshold lower than the first threshold. During one stroke of the internal combustion engine from start to stop, if there is no execution history of fuel injection using only the in-cylinder injection valve, the control device selects the first threshold; if the execution history exists, the control device selects the second threshold.

[0011] Invention Effects

[0012] The control device for the internal combustion engine disclosed in this specification can suppress the accumulation of deposits in the intake port and intake valves, and can suppress the deterioration of NV performance. Attached Figure Description

[0013] Figure 1 This is a schematic diagram showing the general structure of an engine system with a control device for an internal combustion engine in an application implementation.

[0014] Figure 2 This is a schematic diagram showing the general structure of an internal combustion engine, illustrating the control device for an internal combustion engine in an application implementation.

[0015] Figure 3 This is a flowchart illustrating an example of control performed by the control device of an internal combustion engine in an embodiment.

[0016] Explanation of reference numerals in the attached figures

[0017] 1…Internal Combustion Engine, 5…ECU, 5a…Injection Pattern Selection Unit, 10…Fuel Supply System, 12…Intake Manifold, 13…Air Filter, 14…Exhaust Manifold, 16…Air Flow Meter, 18…Throttle Valve, 20…Cylinder Block, 20a…Cylinder, 20a1…Combustion Chamber, 21…Cylinder Head, 22…Piston, 23…Fuel Tank, 24…Low-Pressure Pump, 25…Low-Pressure Pipe, 25a…Branch Pipe, 26…Low-Pressure Delivery Pipe, 27…Intake Injection Valve, 31…Intake Port, 32…Exhaust Port, 36…High-Pressure Delivery Pipe, 37…In-Cylinder Injection Valve, 40…High-Pressure Pump, 60…Purification System, 71…Accelerator Opening Sensor, 72…Vehicle Speed ​​Sensor, 73…Speed ​​Sensor, 74…Water Temperature Sensor, 100…Engine System, CP…Cam Detailed Implementation

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part are sometimes not shown to be exactly the same as the actual dimensions, ratios, etc. In addition, according to the drawings, detailed parts are sometimes omitted in the depiction.

[0019] (Implementation Method)

[0020] First, refer to Figure 1 and Figure 2 This describes the general structure of the engine system 100 and the internal combustion engine 1 of the control device for the internal combustion engine 1 in the application embodiment. The engine system 100 includes the internal combustion engine 1, the fuel supply system 10, and the ECU (Electronic Control Unit) 5.

[0021] Reference Figure 2 Internal combustion engine 1 is a four-stroke engine that ignites a mixture of fuel and air. Internal combustion engine 1 has a cylinder block 20 and a cylinder head 21. In internal combustion engine 1, the cylinder head 21 is mounted on the cylinder block 20, and a crankcase (not shown) is mounted below the cylinder block 20. A piston 22 is housed within a cylinder 20a disposed in the cylinder block 20. Figure 2 Only one cylinder, 20a, is depicted in the reference. Figure 1 The internal combustion engine 1 has a 4-cylinder intake injection valve 27 and a cylinder injection valve 37. That is, the internal combustion engine 1 is a 4-cylinder engine. However, the number of cylinders in the internal combustion engine 1 is not limited to this, and it can also be 3 cylinders, 6 cylinders, or other numbers of cylinders. In addition, the cylinder arrangement can also adopt conventional arrangements such as inline or V-type.

[0022] Piston 22 is connected to crankshaft via connecting rod. Piston 22 is slidably disposed within cylinder 20a. Combustion chamber 20a1 is defined by cylinder block 20, cylinder head 21 and piston 22.

[0023] An intake port 31 and an exhaust port 32 are connected to the cylinder head 21. An intake passage 12 is connected upstream of the intake port 31. An exhaust passage 14 is connected downstream of the exhaust port 32.

[0024] An air filter 13, an air flow meter 16, a throttle body 18, and an intake injection valve 27 are sequentially arranged from the upstream side of the intake passage 12. The air filter 13 removes dust and other contaminants from the air in the intake passage 12 to purify the air. The air flow meter 16 detects the air flow rate in the intake passage 12. The throttle body 18 regulates the air flow rate. The larger the opening of the throttle body 18, the greater the air flow rate. The smaller the opening of the throttle body 18, the smaller the air flow rate. The intake injection valve 27 injects fuel into the intake port 31. A catalyst 29 is installed in the exhaust passage 14.

[0025] The cylinder head 21 is equipped with an intake valve 17, an exhaust valve 19, a spark plug 30, and a cylinder injection valve 37. The intake valve 17 and exhaust valve 19 are opened and closed via a valve mechanism (not shown). When the intake valve 17 is open, the intake port 31 communicates with the combustion chamber 20a1. When the exhaust valve 19 is open, the exhaust port 32 communicates with the combustion chamber 20a1. The spark plug 30 generates a spark between electrodes at its front end, igniting the air-fuel mixture in the combustion chamber 20a1. The cylinder injection valve 37 injects fuel into the combustion chamber 20a1. The internal combustion engine 1 includes a camshaft 15 (see reference). Figure 1 The camshaft 15 is linked with the crankshaft to drive the intake valve 17 or the exhaust valve 19, and the crankshaft is linked with the piston 22.

[0026] ECU5 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), backup RAM, and other storage devices. (See reference...) Figure 1 The ECU 5 includes an injection pattern selection unit 5a. For fuel injection, the injection pattern selection unit 5a selects whether to use the intake port injection valve 27 or the in-cylinder injection valve 37. The ECU 5 functions as the control device for the internal combustion engine. The ECU 5 performs calculations and various controls based on programs and mappings stored in the CPU, ROM, or other storage devices. RAM is a memory that temporarily stores the results of CPU calculations and data input from various sensors, while backup RAM is a non-volatile memory that stores data that should be saved when the internal combustion engine 1 stops.

[0027] An accelerator opening sensor 71, a vehicle speed sensor 72, a rotational speed sensor 73, and a coolant temperature sensor 74 are electrically connected to the ECU5. The accelerator opening sensor 71 detects the opening of an accelerator (not shown). In this embodiment, when the detection value of the accelerator opening sensor 71 is zero, it is determined that the internal combustion engine 1 is idling. The vehicle speed sensor 72 detects the speed of the vehicle equipped with the engine system 100 including the internal combustion engine 1. When the detection value of the vehicle speed sensor 72 is zero, it is determined that the vehicle is stationary. The rotational speed sensor 73 detects the rotational speed Ne of the internal combustion engine. It can also be determined that the internal combustion engine 1 is idling if the rotational speed Ne is lower than a specified speed. Alternatively, the determination of whether the internal combustion engine 1 is idling can be made by appropriately combining the detection value of the accelerator opening sensor 71 and the rotational speed Ne. The coolant temperature sensor 74 detects the temperature of the coolant circulating in the internal combustion engine 1. Based on the detection value of the coolant temperature sensor 74, it is determined whether the preheating of the internal combustion engine 1 is complete. In addition, other known methods can also be used to determine the completion of preheating of the internal combustion engine 1.

[0028] Reference Figure 1The fuel supply system 10 includes a fuel tank 23, a low-pressure pump 24, a low-pressure pipe 25, a low-pressure delivery pipe 26, a high-pressure delivery pipe 36, a high-pressure pump 40, and a purification system 60.

[0029] Gasoline is stored in fuel tank 23. Low-pressure pump 24 pressurizes the fuel and discharges it through low-pressure pipe 25. The fuel discharged into low-pressure pipe 25 is supplied to intake injection valve 27 via low-pressure delivery pipe 26, and is also supplied to high-pressure pump 40 via branch pipe 25a branching from low-pressure pipe 25.

[0030] The high-pressure pump 40 pressurizes the fuel supplied from the branch pipe 25a and discharges it to the high-pressure delivery pipe 36. The fuel pressurized by the high-pressure pump 40 is then supplied to the in-cylinder injection valve 37 via the high-pressure delivery pipe 36.

[0031] The high-pressure pump 40 is equipped with a cylinder 41, a plunger 42, a pressurization chamber 43, a suction passage 45, a discharge passage 47, a safety passage 49, a suction valve 50, a discharge valve 56, and a safety valve 57.

[0032] The plunger 42 reciprocates within the cylinder 41 in a drive linkage with the internal combustion engine 1. Specifically, the plunger 42 is forced by a spring toward the cam CP, which rotates together with the camshaft 15, and reciprocates within the cylinder 41 by the rotation of the cam CP.

[0033] The pressurization chamber 43 is defined by the cylinder 41 and the plunger 42. As the plunger 42 rises, the volume of the pressurization chamber 43 decreases, and as the plunger 42 falls, the volume of the pressurization chamber 43 increases.

[0034] The intake passage 45 connects to the pressurization chamber 43 via a branch pipe 25a branching from the low-pressure pipe 25. A pulsation damper 44 is installed in the intake passage 45 to suppress fuel pressure pulsations. The safety passage 49 connects the pressurization chamber 43 to the high-pressure delivery pipe 36. The discharge passage 47 connects the safety passage 49, which is closer to the pressurization chamber 43 than the discharge valve 56, to the safety passage 49, which is closer to the high-pressure delivery pipe 36 than the discharge valve 56. That is, the discharge passage 47 bypasses the safety valve 57.

[0035] The intake valve 50, also known as an overflow valve, is an electromagnetically driven on / off valve located on the fuel inlet side of the pressurization chamber 43, switching the connection between the intake passage 45 and the pressurization chamber 43. The intake valve 50 has a valve core 51, a coil 55 that drives the valve core 51, and a spring 53 that always applies force to the valve core 51 in the opening direction. The energization of the coil 55 is controlled by the ECU 5. When the coil 55 is energized, the valve core 51 overcomes the force of the spring 53 and cuts off the intake passage 45 and the pressurization chamber 43. When the coil 55 is not energized, the valve core 51 remains open due to the force of the spring 53.

[0036] The discharge valve 56 is provided on the discharge passage 47 and is a check valve that allows fuel to flow from the pressurization chamber 43 side to the high-pressure delivery pipe 36 side but restricts fuel flow in the opposite direction. Specifically, the discharge valve 56 opens when the fuel pressure in the pressurization chamber 43 becomes higher than the fuel pressure in the high-pressure delivery pipe 36 by a predetermined level.

[0037] During the suction stroke of the high-pressure pump 40, the suction valve 50 opens, the plunger 42 descends, and fuel is filled into the pressurization chamber 43 from the branch pipe 25a via the suction passage 45. During the pressurization stroke, the suction valve 50 closes, and as the plunger 42 rises, the volume of the pressurization chamber 43 decreases, and the fuel in the pressurization chamber 43 is pressurized. During the discharge stroke, when the fuel pressure acting on the discharge valve 56 from the pressurization chamber 43 side increases due to the fuel pressure acting on the discharge valve 56 from the high-pressure delivery pipe 36 side and the spring force of the discharge valve 56, the discharge valve 56 opens, and the pressurized fuel is supplied to the high-pressure delivery pipe 36.

[0038] Safety valve 57 is located on safety passage 49 and is a check valve that allows fuel to flow from the high-pressure delivery pipe 36 side to the pressurization chamber 43 side but restricts fuel flow in the opposite direction. When the fuel pressure in the high-pressure delivery pipe 36 rises excessively to a level that could cause an anomaly in the high-pressure delivery pipe 36 or the in-cylinder injection valve 37, safety valve 57 opens, thereby preventing anomalies from occurring in the high-pressure delivery pipe 36 or the in-cylinder injection valve 37.

[0039] It is believed that the high-pressure pump 40 will generate noise and vibration during its operation, thereby affecting the NV performance of the internal combustion engine 1. Furthermore, the structure of the high-pressure pump 40 in this embodiment is an example, and other forms of high-pressure pumps known in the prior art may also be used.

[0040] The purification system 60 includes a purification passage 61, a carbon canister 62, and a purification valve 63. The carbon canister 62 is connected to the fuel tank 23 and adsorbs evaporated fuel (vapor). The purification passage 61 connects the carbon canister 62 and the intake passage 12. The purification valve 63 is provided in the purification passage 61. By opening the purification valve 63, the fuel captured by the carbon canister 62 is introduced into the intake passage 12 through the purification passage 61. A purification concentration detection unit 64 is provided on the carbon canister 62 to detect the concentration of purified fuel. The method for detecting the concentration of purified fuel can be not only the method using the purification concentration detection unit 64, but also various methods known in the art. For example, the concentration of purified fuel can also be detected based on the A / F value when purified fuel is introduced into the intake passage 12 after the purification valve 63 is opened.

[0041] Next, refer to Figure 3An example of the control performed by the ECU 5 and the injection mode selection unit 5a included in the engine system 100 will be described. Before describing the specific control example, the control will first be briefly explained. The injection mode selection unit 5a selects the injection valve to be used to suppress the deterioration of the NV performance of the internal combustion engine 1, and at the same time suppress the deposition of deposits in the intake port 31 and intake valve 17. When the intake port injection valve 27 is used, deposits may accumulate.

[0042] The injection pattern selection unit 5a determines whether it is in the first state. In the first state, the vehicle equipped with the internal combustion engine 1 is in motion and the internal combustion engine 1 is idling. If it is determined that it is in the first state, intake injection is performed using the intake port injection valve 27.

[0043] The injection pattern selection unit 5a determines whether the vehicle is in a second state. In the second state, the vehicle's parking duration ts is less than a preset threshold and the internal combustion engine 1 is idling. If the vehicle is determined to be in the second state, intake injection is performed using the intake injection valve 27.

[0044] That is, in the first or second state, it is difficult for deposits to accumulate. Therefore, in these cases, the intake port injection valve 27 is used. At this time, fuel injection from the in-cylinder injection valve 37 is avoided. As a result, the generation of noise and vibration accompanying the operation of the high-pressure pump 40 that supplies fuel to the in-cylinder injection valve 37 is suppressed, and the deterioration of the NV performance of the internal combustion engine 1 is avoided.

[0045] On the other hand, in idling conditions other than the first and second states, fuel injection is performed using only the in-cylinder injection valve 37. In idling conditions other than the first and second states, if intake injection using the intake port injection valve 27 is performed, deposits may accumulate. Therefore, in this case, fuel injection using only the in-cylinder injection valve 37 is performed to suppress deposit accumulation.

[0046] In this way, the injection pattern selection unit 5a subdivides the idling state of the internal combustion engine 1 based on the ease of deposit accumulation, and selects an appropriate injection pattern that can suppress deposit accumulation and suppress the deterioration of NV performance.

[0047] In this embodiment, both determining whether it is the first state and determining whether it is the second state are performed, but either one can be determined. Hereinafter, based on... Figure 3 The flowchart shown illustrates an example of control.

[0048] In step S1, the injection mode selection unit 5a determines whether the internal combustion engine 1 is started. If a positive determination is made in step S1 (determined as "yes"), the process proceeds to step S2. On the other hand, if a negative determination is made in step S1 (determined as "no"), the process of step S1 is repeated.

[0049] In step S2, the injection mode selection unit 5a starts timing the parking duration ts. When the determination is "yes" in step S1, the timing of the parking duration ts typically starts immediately since the vehicle is currently parked. After the processing in step S2, the injection mode selection unit 5a proceeds to step S3.

[0050] In step S3, the injection pattern selection unit 5a determines whether the internal combustion engine 1 is in an idling state. This determination is made because idling can sometimes lead to deposit buildup, and also because the operation of the high-pressure pump 40 can easily affect NV performance during idling. In this embodiment, the injection pattern selection unit 5a determines that the internal combustion engine 1 is in an idling state when the detection value of the accelerator opening sensor 71 is zero. That is, a "yes" determination is made. If the determination is "yes" in step S3, the process proceeds to step S4. On the other hand, if the determination is "no" in step S3, the process proceeds to step S13.

[0051] In step S4, the injection pattern selection unit 5a determines whether the vehicle is continuously stationary. This determination is made because it is believed that the accumulation pattern of deposits differs depending on whether the vehicle is moving or stationary. Furthermore, it is assumed that the impact on NV performance accompanying the operation of the high-pressure pump 40 varies. In this embodiment, when the detection value of the vehicle speed sensor 72 is zero, the injection pattern selection unit 5a determines that the vehicle is continuously stationary. That is, a "yes" determination is made. If the determination is "yes" in step S4, the process proceeds to step S5. On the other hand, if the determination is "no" in step S4, the process proceeds to step S14. Furthermore, the "no" determination in step S4 corresponds to the first state.

[0052] In step S5, the injection pattern selection unit 5a determines whether the preheating of the internal combustion engine 1 is complete. This determination is made because it is believed that the accumulation pattern of deposits varies depending on the preheating state of the internal combustion engine 1. More specifically, deposits are unlikely to accumulate when the preheating of the internal combustion engine 1 is not yet complete. Deposits tend to accumulate when the preheating of the internal combustion engine 1 is complete. In this embodiment, when the detection value of the water temperature sensor 74 is higher than a predetermined threshold used for preheating determination, the injection pattern selection unit 5a determines that the internal combustion engine 1 has completed preheating. That is, a "yes" determination is made. If the determination is "yes" in step S5, the process proceeds to step S6. On the other hand, if the determination is "no" in step S5, the process proceeds to step S13.

[0053] In step S6, the injection pattern selection unit 5a determines whether there is an execution history of in-cylinder injection. The execution history of in-cylinder injection refers to the history of whether in-cylinder injection was performed in step S10, which will be described later. Here, if it is determined in step S11, which will be described later, that the internal combustion engine 1 has stopped, the history is reset in step S12. Therefore, the history is the history of one stroke from the start of the internal combustion engine 1 to its stop. This determination is performed to change the threshold for the vehicle's stopping duration ts based on the execution history of in-cylinder injection. If it is determined to be "yes" in step S6, the process proceeds to step S7. On the other hand, if it is determined to be "no" in step S6, the process proceeds to step S17. In step S7, a first threshold is selected. In step S17, a second threshold is selected.

[0054] Both the first and second thresholds are included in the threshold for the vehicle's parking duration ts. The second threshold is lower (shorter) than the first threshold. First, the rationale for setting the threshold for the vehicle's parking duration ts will be explained.

[0055] In a parked vehicle, when the internal combustion engine 1 is idling, it is considered that deposits are prone to build up. However, on the other hand, if in-cylinder injection valve 37 is used exclusively to avoid deposit buildup, NV performance may deteriorate. Therefore, when idling for a short duration ts, intake port injection valve 27 is permitted, while when idling for a long duration ts, in-cylinder injection valve 37 is used. This allows for the simultaneous suppression of deposit buildup and the prevention of NV performance deterioration.

[0056] Next, the first threshold and the second threshold will be explained. During one stroke from the start of the internal combustion engine 1 to its stop, if the in-cylinder injection of step S10 is not performed, the first threshold is selected. During one stroke from the start of the internal combustion engine 1 to its stop, if the in-cylinder injection of step S10 is performed, the second threshold is selected. That is, if the second threshold is selected, in-cylinder injection using the in-cylinder injection valve 37 is performed prior to this. Therefore, it can be assumed that the vehicle occupants have experienced the noise and vibration accompanying the operation of the high-pressure pump 40 and have become accustomed to the operation of the high-pressure pump 40. In this case, in order to emphasize the suppression of deposit accumulation and to switch to in-cylinder injection using the in-cylinder injection valve 37 earlier, the second threshold is selected.

[0057] After the processing in step S7, the spray pattern selection unit 5a proceeds to step S8. After the processing in step S17, the spray pattern selection unit 5a proceeds to step S18.

[0058] In step S8, the injection pattern selection unit 5a determines whether the parking duration ts is greater than or equal to a first threshold. If the determination is "yes" in step S8, the process proceeds to step S9. On the other hand, if the determination is "no" in step S8, the process proceeds to step S13. Furthermore, the case where the determination is "no" in step S8 corresponds to the second state.

[0059] In step S9, ECU5 determines whether purification treatment in the purification system 60 is not required. Specifically, ECU5 determines whether the purification concentration detected by the purification concentration detection unit 64 is lower than a predetermined threshold. This determination is made because, when purification treatment is required, if in-cylinder injection using the in-cylinder injection valve 37 is performed, it may sometimes conflict with the minimum injection quantity of the in-cylinder injection valve 37. That is, by performing purification treatment, the injection quantity of the in-cylinder injection valve 37 is reduced, but this may sometimes conflict with the minimum injection quantity of the in-cylinder injection valve 37. As a result, it is conceivable that the injection quantity of the in-cylinder injection valve 37 cannot be properly controlled. By making this determination, the requirements for purification treatment and an appropriate fuel injection quantity can be achieved. If the determination in step S9 is "yes", the process proceeds to step S10. On the other hand, if the determination in step S9 is "no", the process proceeds to step S13.

[0060] In step S10, the injection pattern selection unit 5a selects the in-cylinder injection valve 37 and performs in-cylinder injection. This suppresses the accumulation of deposits. After the processing in step S10, the injection pattern selection unit 5a proceeds to step S11.

[0061] In step S11, the injection mode selection unit 5a determines whether the internal combustion engine 1 has stopped. If the determination is "yes" in step S11, the process proceeds to step S12. On the other hand, if the determination is "no" in step S11, the process from step S3 onwards is repeated.

[0062] In step S12, the injection pattern selection unit 5a resets the history of the stroke. Therefore, the processing after step S1 is repeated the next time the internal combustion engine 1 is started.

[0063] Next, step S13 will be explained. In step S13, the injection pattern selection unit 5a performs inlet injection using the inlet injection valve 27. Step S13 is performed if the determination in steps S3, S5, S8, and S9 is "No". Additionally, step S13 is also performed if the determination in step S18 (described later) is "No". In step S13, by performing inlet injection using the inlet injection valve 27, the deterioration of NV performance is suppressed.

[0064] Furthermore, the reason for proceeding to step S13 when the determination in step S3 is "no" is that it is considered difficult for deposits to accumulate when the internal combustion engine 1 is not idling. Additionally, if step S13 is executed when the determination in step S3 is "no," then in-cylinder injection via the in-cylinder injection valve 37 can be used depending on the state of the internal combustion engine 1. This is because, when the internal combustion engine 1 is not idling, the operating noise of the high-pressure pump 40 is considered not to cause significant disturbance to the vehicle occupants.

[0065] Furthermore, the reason for executing step S13 when the result in step S5 is "no" is that it is believed that deposits are difficult to accumulate when the preheating of the internal combustion engine 1 has not yet been completed.

[0066] Furthermore, the reason for performing step S13 when the determination is "no" in step S8 and when the determination is "no" in step S18 is that, in a parked vehicle, if the internal combustion engine 1 is in an idling state and the parking duration ts is short, it is considered that deposits are unlikely to accumulate.

[0067] After the processing in step S13, the spray pattern selection unit 5a proceeds to step S11. The processing after step S11 is the same as after step S10, so its detailed description is omitted here.

[0068] Next, step S14 will be explained. In step S14, the injection pattern selection unit 5a performs intake port injection using the intake port injection valve 27 in the same manner as in step S13. Step S14 is performed when the condition determined as "no" in step S4 is met, i.e., when the vehicle is in motion. When the vehicle is in motion, even if the internal combustion engine 1 is idling, the airflow in the intake passage 12 is considered to be faster than when the vehicle is stationary. Therefore, it is considered that deposit accumulation is unlikely to occur. Therefore, intake port injection using the intake port injection valve 27 is permitted and implemented. When performing step S14, cylinder injection using the cylinder injection valve 37 can be used in conjunction with the state of the internal combustion engine 1 and the vehicle speed. For example, when the vehicle speed is high, the operating noise of the high-pressure pump 40 is usually not noticeable, and in this case, cylinder injection can be used in conjunction with it. Of course, when the cylinder injection valve 37 is not used, the deterioration of NV performance caused by the operation of the high-pressure pump 40 is suppressed. After the processing in step S14, the spray pattern selection unit 5a proceeds to step S15.

[0069] In step S15, the injection mode selection unit 5a determines whether the vehicle equipped with the internal combustion engine 1 is stopped. This determination is performed because the injection mode needs to be selected again when the vehicle is stopped. If the determination is "yes" in step S15, the process starting from step S2 is repeated. That is, after stopping, the counting of the stopping duration ts is restarted, and subsequent processes are performed. On the other hand, if the determination is "no" in step S15, intake injection using the intake port injection valve 27 continues. After the process in step S16, the injection mode selection unit 5a proceeds to step S11. The process after step S11 is the same as after step S10, so its detailed description is omitted here.

[0070] Next, steps S17 and S18 will be explained. After selecting the second threshold in step S17, in step S18, the injection pattern selection unit 5a determines whether the parking duration ts is greater than or equal to the second threshold. If the determination in step S18 is "yes", the process proceeds to step S9. On the other hand, if the determination in step S18 is "no", the process proceeds to step S13. Furthermore, the case where the determination in step S18 is "no" is equivalent to the second state. Since steps S9 and S13 are the same as described above, their detailed explanations are omitted here.

[0071] In addition, in this embodiment, such as Figure 3 As illustrated in the flowchart, the process includes multiple decision steps. The case where the decision is "yes" in step S3 and "no" in step S4 corresponds to the first state. Similarly, the case where the decision is "yes" in step S3 and "no" in step S8 corresponds to the second state. The case where the decision is "yes" in step S3 and "no" in step S18 also corresponds to the second state.

[0072] Other implementations only require the determination of at least one of the determination of being in the first state and the determination of being in the second state. That is, it can be a method that only uses the determination of being in the first state or a method that only uses the determination of being in the second state. Alternatively, it can be a method that appropriately combines the determination of being in the first state, the determination of being in the second state, and other determinations, such as the determination in step S5 and the determination in step S9.

[0073] [Effect]

[0074] According to this embodiment, when the internal combustion engine 1 is in the first state or the second state, intake injection using the intake port injection valve 27 is performed. Therefore, the deterioration of NV performance can be suppressed. Furthermore, when the internal combustion engine 1 is in an idling state other than the first and second states, in-cylinder injection using only the in-cylinder injection valve 37 is performed. This suppresses the accumulation of deposits.

[0075] Furthermore, according to this embodiment, by appropriately selecting the first threshold and the second threshold, the accumulation of deposits can be suppressed, thereby suppressing the deterioration of NV performance.

[0076] The above embodiments are merely examples for implementing the present invention, and the present invention is not limited thereto. Various modifications of these embodiments all fall within the scope of the present invention. Furthermore, as can be understood from the above description, various other embodiments may exist within the scope of the present invention.

Claims

1. A control device for an internal combustion engine, the internal combustion engine comprising an intake injection valve for injecting fuel into an intake port and an in-cylinder injection valve for injecting fuel into a cylinder, wherein, When the control device is in a first state where the vehicle equipped with the internal combustion engine is in motion and the internal combustion engine is idling, or in a second state where the duration of the vehicle's stop is less than a preset threshold and the internal combustion engine is idling, it performs fuel injection using the intake port injection valve. When the vehicle is in an idling state other than the first state and the second state, it performs fuel injection using only the cylinder injection valve.

2. The control device for an internal combustion engine according to claim 1, wherein, When the control device determines whether it is in the second state, the threshold includes a first threshold and a second threshold that is lower than the first threshold. During one stroke of the internal combustion engine from start to stop, if there is no execution history of fuel injection using only the in-cylinder injection valve, the control device selects the first threshold; if the execution history exists, the control device selects the second threshold.

Images