JP2016133099A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of suppressing generation of particulate matters by properly changing a fuel injection timing according to an operating state of an internal combustion engine.SOLUTION: An ECU 60 includes an injection timing correction portion 63 for correcting a fuel injection timing set by a reference injection timing setting portion 61, when an acceleration determination portion 62 determines that a vehicle is in an accelerated state. When a temperature in a cylinder 12 is low, the injection timing correction portion 63 corrects the fuel injection timing to be close to a termination time of an intake stroke in comparison with a case when the temperature in the cylinder 12 is high.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for an internal combustion engine that is used for traveling of a vehicle and injects fuel directly into a cylinder.

  For the purpose of improving the fuel efficiency of internal combustion engines and reducing harmful substances in exhaust gas, studies are underway to optimize the combustion of fuel in the cylinder.

  For example, the following Patent Document 1 describes a control device for an internal combustion engine that temporarily changes the timing of fuel injection by an injector. Specifically, the control device disclosed in Patent Document 1 below temporarily changes the fuel injection timing during transient operation for increasing or decreasing the fuel injection amount, and the injected fuel adheres to the cylinder or piston in a liquid state. It is to suppress.

  It is known that fuel adhering in a liquid state in a cylinder becomes a factor that generates PM (Particuculate Matter) in a combustion stroke of an internal combustion engine. In addition, PM may be caused by insufficient mixing of fuel and air in the cylinder and incomplete combustion of the fuel. The control device of Patent Document 1 described below is intended to suppress the occurrence of PM by suppressing the fuel from adhering to the cylinder in a liquid state.

JP-A-9-68071

  In recent internal combustion engines, combustion control has become more sophisticated and complicated. For example, internal combustion engines that burn fuel in a lean state in a cylinder are widespread, contributing to improved fuel efficiency.

  In addition, the use of internal combustion engines that employ EGR (Exhaust Gas Recirculation) technology is also increasing. In the EGR technique, a part of exhaust gas generated by combustion of fuel in a cylinder is taken into the intake side of the internal combustion engine. Thereby, it becomes possible to improve fuel consumption and to suppress generation of harmful nitrogen oxides.

  In recent internal combustion engines that have become more sophisticated and complicated in this way, it is not possible to optimize the combustion of fuel in the cylinder by simply changing the fuel injection timing temporarily. Was insufficient. If the fuel injection timing is excessively delayed (the fuel injection timing is excessively changed toward the end of the intake stroke), the time from the end of the injection to the ignition is shortened, so that the mixture of fuel and air is sufficiently mixed On the other hand, there is a possibility that a large amount of PM is generated. On the other hand, if the fuel injection timing is excessively advanced (the fuel injection timing is changed excessively toward the start of the intake stroke), the fuel is injected with the injector and the piston close to each other. A large amount of PM may also be generated. That is, in a recent internal combustion engine in which the operation state changes in a complicated manner, the fuel injection timing becomes too late or too early in the operation state, and there is a problem that PM generation cannot be sufficiently suppressed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to control the fuel injection timing appropriately according to the operating state of the internal combustion engine to suppress the generation of particulate matter. To provide an apparatus.

  In order to solve the above-described problem, a control device according to the present invention is a control device (60) for an internal combustion engine (10) that is used for traveling of a vehicle and directly injects fuel into a cylinder (12). The reference injection timing setting means (61) for setting the fuel injection timing, the acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state, and the acceleration determination means determine that the vehicle is in the acceleration state. An injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means. The injection timing correction means corrects the fuel injection timing closer to the end of the intake stroke when the temperature in the cylinder is low than when the temperature in the cylinder is high.

  In the present invention, when the temperature in the cylinder is low, fuel is injected at a time closer to the end of the intake stroke than when the temperature in the cylinder is high. In other words, if the temperature in the cylinder is low and the fuel tends to remain liquid, the fuel is injected at a time close to the end of the intake stroke, so that the fuel is discharged in a state where the injector and the piston are largely separated in the cylinder. Can be injected. Thereby, it is possible to suppress the fuel from adhering to the piston in a liquid state, and as a result, it is possible to suppress the generation of particulate matter.

  In order to solve the above problems, a control device according to the present invention is a control device (60) for an internal combustion engine (10) that is used to travel a vehicle and directly injects fuel into a cylinder (12). A reference injection timing setting means (61) for setting a reference fuel injection timing, an acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state, and an acceleration determination means that the vehicle is in an acceleration state And an injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means when determined. The injection timing correction means corrects the fuel injection timing closer to the start of the intake stroke when the rotational speed of the internal combustion engine is large than when the rotational speed of the internal combustion engine is small.

  In the present invention, when the rotational speed of the internal combustion engine is large, fuel is injected at a time closer to the start of the intake stroke than when the rotational speed of the internal combustion engine is small. In other words, if the internal combustion engine has a high engine speed and it is difficult to ensure a sufficient amount of time for mixing the fuel and air in the cylinder, the time is secured by injecting the fuel near the start of the intake stroke. be able to. Thereby, fuel and air are sufficiently mixed in the cylinder, and as a result, generation of particulate matter can be suppressed.

  In order to solve the above-described problem, a control device according to the present invention is a control device for an internal combustion engine that is used for traveling of a vehicle and directly injects fuel into a cylinder, and sets a reference fuel injection timing. Reference injection timing setting means (61), acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state, and reference injection timing when the acceleration determination means determines that the vehicle is in an acceleration state Injection timing correction means (63) for correcting the fuel injection timing set by the setting means. The injection timing correction means corrects the fuel injection timing closer to the end of the intake stroke when the pressure in the cylinder is high than when the pressure in the cylinder is low.

  When the pressure in the cylinder increases, mixing of the injected fuel and air tends to slow down. In the present invention, when the pressure in the cylinder is high, the fuel is injected at a time near the end of the intake stroke, thereby suppressing the fuel from adhering to the piston in a liquid state as the mixing is slowed down. it can. Thereby, fuel and air are sufficiently mixed in the cylinder, and as a result, generation of particulate matter can be suppressed.

  In order to solve the above problems, a control device according to the present invention is a control device (60) for an internal combustion engine (10) that is used to travel a vehicle and directly injects fuel into a cylinder (12). A reference injection timing setting means (61) for setting a reference fuel injection timing, an acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state, and the acceleration determination means indicate that the vehicle is in an acceleration state. And an injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means, and the injection timing correction means when the tumble flow in the cylinder is small The fuel injection timing is corrected so that it is closer to the end of the intake stroke than when the tumble flow is large.

  In the cylinder, a tumble flow that is a vertical vortex of the air-fuel mixture is generated. When this tumble flow decreases, the mixing of the injected fuel and air tends to slow down. In the present invention, when the tumble flow in the cylinder is small, the fuel is injected at the time near the end of the intake stroke, thereby suppressing the fuel from adhering to the piston in the liquid state as the mixing is slowed down. Can do. Thereby, fuel and air are sufficiently mixed in the cylinder, and as a result, generation of particulate matter can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus which can change generation | occurrence | production of a particulate matter by changing fuel injection timing appropriately according to the driving | running state of an internal combustion engine can be provided.

1 is a schematic configuration diagram of a drive system to which an ECU according to an embodiment of the present invention is applied. It is a control block diagram for demonstrating the functional block of ECU shown in FIG. It is a flowchart which shows the control by ECU which concerns on embodiment of this invention. It is a figure which shows the map used when determining the correction amount based on cooling water temperature or fuel temperature. It is a figure which shows the map used when determining the correction amount based on cooling water temperature or fuel temperature. It is a figure which shows the map used when determining the correction amount based on an engine speed. It is a figure which shows the map used when determining the correction amount based on an EGR rate. It is a figure which shows the map used when determining the correction amount based on the amount of tumble flow. It is a figure which shows the map used when determining the correction amount based on the VVT control amount.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  The ECU 60 according to the present embodiment controls an in-cylinder injection engine (internal combustion engine) 10 mounted on a vehicle (not shown). First, the schematic configuration of the drive system of the engine 10 will be described in detail with reference to FIG. As the engine 10 of the present embodiment, a multi-cylinder spark ignition reciprocating engine is assumed, but in FIG. 1, only one cylinder 12 is shown for convenience of explanation.

  As shown in FIG. 1, the drive system includes an in-cylinder injection engine 10 that uses gasoline as fuel, various sensors that use the engine 10 for control, various actuators, an ECU (control device) 60, and the like. Has been.

  The engine 10 includes a cylinder 12 formed by a cylinder block 11. The cylinder block 11 is provided with a cooling water channel 11a. The engine 10 is cooled by the cooling water flowing through the cooling water channel 11a. The cooling water channel 11a is provided with a cooling water temperature sensor 11b. The cooling water temperature sensor 11b detects the temperature of the cooling water flowing through the cooling water channel 11a.

  A piston 13 is accommodated in the cylinder 12. The piston 13 has a cavity (depression) 13a for generating a swirl flow that is a spiral vortex and a tumble flow T that is a vertical vortex on the top surface.

  A crankshaft as an output shaft (not shown) is rotated by reciprocating movement of the piston 13 in the cylinder 12. A crank angle sensor 12a that outputs a rectangular crank angle signal for every predetermined crank angle (for example, at a cycle of 30 ° CA) is disposed on the outer peripheral side of the crankshaft, and the rotation angle of the crankshaft can be detected. ing.

  A cylinder head 15 is fixed to the upper end surface of the cylinder block 11. A combustion chamber 16 is formed between the cylinder head 15 and the upper surface of the piston 13.

  An intake port 17 and an exhaust port 18 that open to the combustion chamber 16 are formed in the cylinder head 15. The intake port 17 and the exhaust port 18 are configured to be opened and closed by an intake valve 21 and an exhaust valve 22 driven by cams 21a and 22a, respectively.

  The intake valve 21 is provided with a variable valve timing mechanism 21b. The variable valve timing mechanism 21b adjusts the valve timing, which is the timing at which the intake valve 21 opens and closes. The exhaust valve 22 is provided with a variable valve timing mechanism 22b. The variable valve timing mechanism 21b adjusts the valve timing, which is the timing at which the exhaust valve 22 opens and closes.

  An intake pipe 23 is connected to the intake port 17. The intake port 17 guides air taken from the outside of the vehicle to each cylinder 12 of the engine 10. An exhaust pipe 24 is connected to the exhaust port 18. The exhaust pipe 24 guides exhaust gas exhausted from each cylinder 12 of the engine 10 to the outside of the vehicle.

  The intake pipe 23 is provided with a surge tank 23a whose passage area is enlarged (expanded diameter). The surge tank 23a prevents intake pulsation and intake interference. The intake pipe 23 is provided with an air flow meter 31. The air flow meter 31 detects the amount of air sucked through an air cleaner (not shown) at the most upstream portion of the intake pipe 23.

  A throttle valve 32 and a throttle opening sensor 32a are provided on the downstream side of the air flow meter 31. The throttle valve 32 is an electronically controlled on / off valve that is electronically adjusted by an actuator such as a DC motor. The throttle opening sensor 32a detects the opening and movement (opening fluctuation) of the throttle valve 32. By changing the opening degree of the throttle valve 32, the amount of air sent to the surge tank 23a provided on the downstream side thereof can be adjusted.

  The surge tank 23a is provided with an intake pipe pressure sensor 23b. The intake pipe pressure sensor 23b detects intake pipe pressure (intake pipe negative pressure or the like). In the vicinity of the intake port 17, an airflow control valve 17a is provided. The air flow control valve 17a controls air flow strength such as swirl flow strength and tumble flow strength in the cylinder 12 which affects the flame propagation speed and the like.

  A catalyst 35 is provided in the exhaust pipe 24. The catalyst 35 is composed of a three-way catalyst or the like, and purifies CO, HC, NOx, etc. in the exhaust gas. An oxygen concentration sensor 35 a is provided on the upstream side of the catalyst 35. The oxygen concentration sensor 35a is, for example, a linear detection type A / F sensor, a binary detection type O2 sensor, or the like, and detects the air-fuel ratio or rich / lean of the air-fuel mixture using the exhaust gas discharged from the cylinder 12 as a detection target. To do.

  An injector 27 is attached to the combustion chamber 16 in the cylinder 12. The injector 27 is an electromagnetically driven actuator that directly injects fuel supplied for combustion in the combustion chamber 16 into the cylinder 12. Here, for the sake of convenience, only the injector 27 provided in one cylinder 12 is illustrated, but such an injector 27 is provided for each cylinder 12 of the engine 10. Each injector 27 of the engine 10 is connected to the fuel tank 41, and the fuel in the fuel tank 41 pumped up by the fuel pump 42 is supplied to each injector 27 through the fuel pipe 43. Yes.

  Further, an in-cylinder pressure sensor 19 and a spark plug 28 are attached to the combustion chamber 16. The cylinder pressure sensor 19 detects the pressure in the cylinder 12. The spark plug 28 ignites (sparks ignition) the fuel in the air-fuel mixture when a high voltage is applied at a predetermined ignition timing based on an instruction from the ECU 60.

  A fuel pressure sensor 44 and a fuel temperature sensor 45 are provided in the middle of the fuel pipe 43. The fuel pressure sensor 44 detects the pressure of the fuel supplied by the fuel pipe 43. The fuel temperature sensor 45 detects the temperature of the fuel supplied by the fuel pipe 43. The fuel pressure sensor 44 and the fuel temperature sensor 45 allow the fuel pressure and temperature of each injector 27 of the engine 10 to be managed.

  In the intake stroke of the engine 10, air is introduced from the intake pipe 23 into the combustion chamber 16 by the opening operation of the intake valve 21. At this time, fuel is directly injected into the cylinder 12 from the injector 27. The sucked air is mixed with fuel in the cylinder 12. The air-fuel mixture is ignited by the spark plug 28 in a compressed state, and ignited and burned. The exhaust gas generated by this combustion is discharged from the combustion chamber 16 to the exhaust pipe 24 by the opening operation of the exhaust valve 22.

  Furthermore, this drive system also includes an EGR device for returning a part of the high-temperature exhaust gas to the intake system as EGR gas. This EGR device has an EGR pipe 51, an EGR valve 52, and an EGR sensor 53. The EGR pipe 51 is a pipe provided to communicate the intake pipe 23 and the exhaust pipe 24. The EGR valve 52 is an electromagnetic valve that adjusts the flow path cross-sectional area of the EGR pipe 51 according to the valve opening. The EGR sensor 53 determines the ratio (EGR rate) of the exhaust gas recirculated to the intake system by the EGR pipe 51 out of the exhaust gas discharged from the combustion chamber 16 to the exhaust pipe 24 based on the opening degree of the EGR valve 52. To detect. In the EGR device, based on such a configuration, a part of the exhaust gas is recirculated to the intake system through the EGR pipe 51, and the generation of NOx is suppressed by lowering the combustion temperature.

  In addition to the above sensors, the vehicle (not shown) is provided with various sensors for vehicle control. For example, an accelerator opening sensor 54 that detects an operation amount (accelerator opening) of an accelerator pedal by the driver is provided.

  A part or all of the ECU 60 is configured as an analog circuit or a digital processor including a memory (not shown). In any case, a functional control block is configured in the ECU 60 in order to fulfill the function of outputting a control signal based on the received electrical signal.

  Next, the ECU 60 will be described in detail with reference to FIG. FIG. 2 shows the ECU 60 as a functional control block diagram. The software module incorporated in the analog circuit or digital processor constituting the ECU 60 does not necessarily have to be divided into the control blocks shown in FIG. 2, and may be configured to function as a plurality of control blocks. Of course, it may be further subdivided. If the ECU 60 is configured to execute a processing flow described later, the actual configuration inside the ECU 60 can be changed as appropriate by those skilled in the art.

  The ECU 60 is electrically connected to various sensors such as the coolant temperature sensor 11b and various actuators such as the airflow control valve 17a. The ECU 60 includes a reference injection timing setting unit (reference injection timing setting unit) 61, an acceleration determination unit (acceleration determination unit) 62, and an injection timing correction unit (injection timing correction unit) 63.

  The reference injection timing setting unit 61 is a part that sets a timing for injecting fuel from the injector 27 into the cylinder 12 during the intake stroke of the engine 10. As will be described later, the fuel injection timing is determined after various corrections are made based on the operating state of the engine 10, but the reference injection timing setting unit 61 uses the reference injection timing as a reference before the correction is made. Set.

  The acceleration determination unit 62 is a part that determines whether or not the vehicle on which the engine 10 is mounted is in an accelerated state. Specifically, the acceleration determination unit 62 determines that the vehicle is in an accelerated state based on an increase in the throttle opening detected by the throttle opening sensor 32a, an increase in the accelerator opening detected by the accelerator opening sensor 54, or the like. It is determined whether or not there is.

  The injection timing correction unit 63 is a part that corrects the reference injection timing set by the reference injection timing setting unit 61. Specifically, the injection timing correction unit 63 shifts the timing at which the injector 27 injects fuel from the reference injection timing to the advance side (the start time side of the intake stroke of the engine 10), or the retard side ( Correction is made to shift to the end of the intake stroke of the engine 10). Through this correction, the timing (fuel injection timing) at which fuel is injected from the injector 27 into the cylinder 12 in the intake stroke of the engine 10 is determined.

  Next, the determination of the fuel injection timing by the ECU 60 will be described with reference to FIGS. In the following, for the sake of simplicity, it will be described in detail that the processing performed by each part such as the reference injection timing setting unit 61 of the ECU 60 is performed by the ECU 60 as a whole. In this description, the description will be made mainly with reference to FIG. 3 showing a flowchart, and FIGS. 4 to 9 will be referred to as appropriate.

  FIG. 3 shows a routine executed by the ECU 60. The ECU 60 repeatedly executes this routine at a predetermined cycle (for example, 10 ms cycle) while the engine 10 is operating.

  First, the ECU 60 sets a reference injection timing in step S101. Here, a map for setting the reference injection timing based on the operating state of the engine 10 is stored in the memory of the ECU 60. The ECU 60 sets the reference injection timing by comparing the values obtained from the various sensors described above with the map.

  Next, in step S102, the ECU 60 determines whether or not the vehicle on which the engine 10 is mounted is in an accelerated state. When it is determined that the vehicle is not in an accelerated state (S102: NO), the ECU 60 ends this routine without correcting the reference injection timing. In this case, the ECU 60 injects fuel from the injector 27 at the reference injection timing set in step S101.

  On the other hand, if it is determined in step S102 that the vehicle is in an accelerated state (S102: YES), the amount of fuel injected from the injector 27 into the cylinder 12 increases in order to increase the output of the engine 10. There is a growing concern that a large number of PMs are generated during the combustion stroke. That is, it can be estimated that correction of the reference injection timing is necessary to suppress the occurrence of PM. In this case, the ECU 60 proceeds to step S103.

  Next, in step S103, the ECU 60 corrects the reference injection timing based on the coolant temperature. Here, a map as shown in FIG. 4 is stored in the memory of the ECU 60. The ECU 60 compares the cooling water temperature detected by the cooling water temperature sensor 11b with the map, determines a correction amount based on the cooling water temperature, and performs correction.

  As shown in FIG. 4, in the map, the correction amount is determined so that the fuel injection timing is retarded when the temperature of the cooling water is low compared to when the temperature of the cooling water is high. The correction amount is a deviation amount from the reference injection timing. The correction amount is set so as to increase toward the retard side as the temperature of the cooling water decreases.

  The temperature of the cooling water has a correlation with the temperature in the cylinder 12 of the engine 10. When the temperature of the cooling water is low, that is, when the temperature in the cylinder 12 is low, the fuel injected into the cylinder 12 tends to remain liquid. In this case, in the combustion stroke of the engine 10, there is an increased concern that a large number of PMs are generated.

  Therefore, the ECU 60 causes the cylinder 27 to inject fuel from the injector 27 when the temperature in the cylinder 12 is low compared to when the temperature in the cylinder 12 is high, closer to the end of the intake stroke of the engine 10. The fuel can be injected in a state where the injector 27 and the piston 13 are largely separated from each other. Thereby, it is possible to suppress the fuel from adhering to the piston 13 in a liquid state, and as a result, it is possible to suppress the generation of PM.

  Next, in step S104, the ECU 60 corrects the reference injection timing based on the rotational speed of the engine 10. Here, a map as shown in FIG. 5 is stored in the memory of the ECU 60. The ECU 60 compares the rotation speed of the engine 10 calculated from the detection value of the crank angle sensor 12a with the map, determines a correction amount based on the rotation speed of the engine 10, and performs correction.

  As shown in FIG. 5, in the map, the correction amount is determined so that the fuel injection timing is on the advance side when the rotational speed of the engine 10 is large compared to when the rotational speed of the engine 10 is small. The correction amount is a deviation amount from the reference injection timing. The correction amount is set so as to increase on the advance side with an increase in the rotational speed of the engine 10 in a range equal to or higher than the predetermined rotational speed, and is delayed with a decrease in the rotational speed of the engine 10 in a range below the predetermined rotational speed. It is set to increase on the corner side.

  When the rotational speed of the engine 10 is large, it is difficult to ensure time for sufficiently mixing fuel and air in the cylinder 12. In this case, in the combustion stroke of the engine 10, there is an increased concern that a large number of PMs are generated.

  Therefore, the ECU 60 causes the cylinder 27 to inject fuel from the injector 27 at a time closer to the start of the intake stroke of the engine 10 when the rotational speed of the engine 10 is larger than when the rotational speed of the engine 10 is small. The time required to sufficiently mix the fuel and air in 12 can be secured. Thereby, fuel and air are sufficiently mixed in the cylinder 12, and as a result, generation of PM can be suppressed.

  Next, in step S105, the ECU 60 corrects the reference injection timing based on the EGR rate. Here, a map as shown in FIG. 6 is stored in the memory of the ECU 60. The ECU 60 compares the EGR rate detected by the EGR sensor 53 with the map, determines a correction amount based on the EGR rate, and performs correction.

  As shown in FIG. 6, in this map, the correction amount is determined so that the fuel injection timing is retarded when the EGR rate is low compared to when the EGR rate is high. The correction amount is a deviation amount from the reference injection timing. The correction amount is set to increase toward the advance side as the EGR rate increases.

  When the EGR rate is low, the flow rate of the high-temperature exhaust gas recirculated to the intake system of the engine 10 is small, the temperature in the cylinder 12 becomes low, and the fuel injected into the cylinder 12 tends to remain liquid. In this case, in the combustion stroke of the engine 10, there is an increased concern that a large number of PMs are generated.

  Therefore, when the EGR rate is low, the ECU 60 causes the fuel to be injected from the injector 27 at a time closer to the end of the intake stroke of the engine 10 than when the EGR rate is high. The fuel can be injected in a state where the piston 13 is largely separated. Thereby, it is possible to suppress the fuel from adhering to the piston 13 in a liquid state, and as a result, it is possible to suppress the generation of PM.

  Next, in step S106, the ECU 60 corrects the reference injection timing based on the pressure in the cylinder 12. Here, a map as shown in FIG. 7 is stored in the memory of the ECU 60. The ECU 60 compares the pressure in the cylinder 12 detected by the in-cylinder pressure sensor 19 with the map, determines a correction amount based on the pressure in the cylinder 12, and performs correction.

  As shown in FIG. 7, in this map, the correction amount is determined so that the fuel injection timing is retarded when the pressure in the cylinder 12 is high compared to when the pressure in the cylinder 12 is low. The correction amount is a deviation amount from the reference injection timing.

  When the pressure in the cylinder 12 increases, mixing of the injected fuel and air tends to slow down. For this reason, mixing of the fuel and air in the cylinder 12 becomes insufficient, and there is an increased concern that a large number of PMs are generated in the combustion stroke of the engine 10.

  Therefore, the ECU 60 mixes fuel by injecting fuel from the injector 27 when the pressure in the cylinder 12 is high compared to when the pressure in the cylinder 12 is low, at a time closer to the end of the intake stroke of the engine 10. It is possible to suppress the fuel from adhering to the piston 13 while being in a liquid state with the slowing of the fuel. Thereby, fuel and air are sufficiently mixed in the cylinder 12, and as a result, generation of PM can be suppressed.

  Next, in step S107, the ECU 60 corrects the reference injection timing based on the tumble rate in the cylinder 12. Here, a map as shown in FIG. 8 is stored in the memory of the ECU 60. The ECU 60 calculates a tumble rate that is a ratio of the tumble flow in the cylinder 12 by a known method based on the rotational speed of the engine 10, the load, and the opening degree of the airflow control valve 17a. Then, the ECU 60 compares the tumble rate with the map and determines a correction amount based on the tumble rate.

  As shown in FIG. 8, in this map, the correction amount is determined so that the fuel injection timing is retarded when the tumble rate in the cylinder 12 is small compared to when the tumble rate in the cylinder 12 is large. To do. The correction amount is a deviation amount from the reference injection timing.

  When the tumble rate in the cylinder 12 is small, that is, when the amount of tumble flow is small, mixing of the injected fuel and air tends to be slowed down. Thereby, mixing of the fuel and air in the cylinder 12 becomes insufficient, and a concern that a large number of PMs are generated in the combustion stroke of the engine 10 increases.

  Therefore, when the tumble rate in the cylinder 12 is small, the ECU 60 injects fuel from the injector 27 at a time closer to the end of the intake stroke of the engine 10 than when the tumble rate is large. Thereby, it can suppress that a fuel adheres to the piston 13 with liquid state with the slowing of mixing. Therefore, fuel and air are sufficiently mixed in the cylinder 12, and as a result, generation of PM can be suppressed.

  Next, in step S108, the ECU 60 corrects the basic injection timing based on the control amount of the variable valve timing mechanism 21b of the intake valve 21. Here, a map as shown in FIG. 9 is stored in the memory of the ECU 60. The ECU 60 compares the control amount of the variable valve timing mechanism 21b with the map, determines a correction amount based on the control amount of the variable valve timing mechanism 21b, and performs correction.

  When the control amount of the variable valve timing mechanism 21b is small, the amount of exhaust gas taken into the cylinder 12 via the EGR pipe 51 is smaller than when the control amount is large. By reducing the amount of hot exhaust gas taken into the cylinder 12, the temperature in the cylinder 12 is difficult to rise, and the fuel injected into the cylinder 12 tends to remain liquid. In this case, in the combustion stroke of the engine 10, there is an increased concern that a large number of PMs are generated.

  Therefore, the ECU 60 determines the correction amount so that the fuel injection timing is retarded when the control amount of the variable valve timing mechanism 21b is small compared to when the control amount of the variable valve timing mechanism 21b is large. Thereby, it is possible to suppress the fuel from adhering to the piston 13 in a liquid state, and as a result, it is possible to suppress the generation of PM.

  Next, the ECU 60 limits correction based on the ignition timing of the spark plug 28 in step S109. If the above-described correction of the reference fuel injection timing from step S103 to step S108 is not appropriate due to the relationship with the ignition timing of the spark plug 28, the output of the engine 10 is reduced. May cause adverse effects. Therefore, in this step S109, from the viewpoint of the ignition timing of the spark plug 28, when the correction from step S103 to step S108 is excessive, the correction is limited.

  As described above, the fuel injection timing is determined by correcting the reference fuel injection timing from step S103 to step S108 and limiting the correction in step S109. By injecting fuel from the injector 27 at the fuel injection timing determined in this manner, the fuel injection timing can be made ideal in suppressing the generation of PM.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. Each element included in each of the specific examples described above and their arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed.

  For example, in step S103 described above, the temperature of the cooling water is used as an index having a correlation with the temperature in the cylinder 12 of the engine 10. Instead, as shown in parentheses in FIGS. The fuel temperature may be used as an index.

  That is, when the fuel temperature is low and the temperature in the cylinder 12 is low, the ECU 60 injects fuel from the injector 27 toward the end of the intake stroke of the engine 10 so that the injector 27 and the piston 13 are connected in the cylinder 12. The fuel can be injected in a state of being largely separated. Thereby, it is possible to suppress the fuel from adhering to the piston 13 in a liquid state, and as a result, it is possible to suppress the generation of PM.

10: Engine (internal combustion engine)
12: Cylinder 60: ECU (control device)
61: Reference injection timing setting unit (reference injection timing setting means)
62: Acceleration determination unit (acceleration determination means)
63: Injection timing correction unit (injection timing correction means)
T: Tumble flow

Claims (7)

A control device (60) for an internal combustion engine (10) used to travel a vehicle and directly injecting fuel into a cylinder (12),
Reference injection timing setting means (61) for setting a reference fuel injection timing;
Acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state;
Injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means when the acceleration determination means determines that the vehicle is in an acceleration state;
The injection timing correction means corrects the fuel injection timing so that it is closer to the end of the intake stroke when the temperature in the cylinder is low than when the temperature in the cylinder is high. Control device.   The injection timing correction means corrects the fuel injection timing closer to the end of the intake stroke when the temperature of the cooling water for cooling the cylinder is low than when the temperature of the cooling water is high. The control device according to claim 1.   The injection timing correction means corrects the fuel injection timing closer to the end of the intake stroke when the temperature of the fuel injected into the cylinder is low than when the temperature of the fuel is high. The control device according to claim 1.   The fuel injection timing correction means is configured such that when the amount of exhaust gas sucked into the cylinder during the intake stroke after being exhausted from the cylinder during the exhaust stroke is small, the fuel is compared with when the amount of exhaust gas is large. The control device according to claim 1, wherein the correction is performed so that the injection timing approaches the end of the intake stroke. A control device (60) for an internal combustion engine (10) used to travel a vehicle and directly injecting fuel into a cylinder (12),
Reference injection timing setting means (61) for setting a reference fuel injection timing;
Acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state;
Injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means when the acceleration determination means determines that the vehicle is in an acceleration state;
The injection timing correction means corrects the fuel injection timing closer to the start of the intake stroke when the rotational speed of the internal combustion engine is larger than when the rotational speed of the internal combustion engine is small. Control device characterized. A control device for an internal combustion engine that is used to travel a vehicle and directly injects fuel into a cylinder,
Reference injection timing setting means (61) for setting a reference fuel injection timing;
Acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state;
Injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means when the acceleration determination means determines that the vehicle is in an acceleration state;
The injection timing correction means corrects the fuel injection timing closer to the end of the intake stroke when the pressure in the cylinder is higher than when the pressure in the cylinder is low. Control device. A control device (60) for an internal combustion engine (10) used to travel a vehicle and directly injecting fuel into a cylinder (12),
Reference injection timing setting means (61) for setting a reference fuel injection timing;
Acceleration determination means (62) for determining whether or not the vehicle is in an acceleration state;
Injection timing correction means (63) for correcting the fuel injection timing set by the reference injection timing setting means when the acceleration determination means determines that the vehicle is in an acceleration state;
The injection timing correction means performs correction so that the fuel injection timing is closer to the end of the intake stroke when the tumble flow in the cylinder is small than when the tumble flow is large. apparatus.

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