JP4622569B2 - In-cylinder direct injection internal combustion engine - Google Patents

Description

  The present invention relates to a direct injection type internal combustion engine.

Conventionally, an in-cylinder direct injection internal combustion engine having a fuel injection valve that injects fuel directly into a combustion chamber has been proposed (see, for example, Patent Document 1).
JP-A-2002-161790 (page 1-6, FIG. 1-12)

  In the technique of Patent Document 1, the fuel injection valve is controlled to inject fuel into the combustion chamber a plurality of times in one cycle. Thereby, it can prevent that fuel adheres to the wall surface of a combustion chamber.

  However, the technique of Patent Document 1 always tends to be controlled so that the fresh air-fuel mixture in the combustion chamber is dispersed. For this reason, when EGR is performed, combustion in the combustion chamber may not be stable, and thus EGR resistance tends to be insufficient. In addition, for example, knocking is likely to occur in the operating state on the low speed and high load side, so that the anti-knocking property tends to be insufficient.

  An object of the present invention is to provide an in-cylinder direct injection internal combustion engine that can prevent fuel from adhering to the wall surface of a combustion chamber and can improve EGR resistance and knocking resistance.

  The direct injection type internal combustion engine according to the present invention includes a combustion chamber, a fuel injection valve, and a control unit. The fuel injection valve directly injects fuel into the combustion chamber. A control part switches a 1st injection pattern and a 2nd injection pattern according to a driving | running state, and controls a fuel injection valve so that a fuel is injected in a combustion chamber in multiple times in 1 cycle. The first injection pattern is a pattern for dispersing the fresh air mixture in the combustion chamber. The second injection pattern is a pattern for concentrating the fresh air mixture in the combustion chamber.

In this direct injection internal combustion engine, the control unit controls the fuel injection valve to inject the fuel into the combustion chamber a plurality of times in one cycle. For this reason, it is possible to prevent the fuel from adhering to the wall surface of the combustion chamber. Further, since the control unit switches between the first injection pattern and the second injection pattern according to the operation state, if the fuel injection valve is controlled by the second injection pattern when EGR is performed, the combustion in the combustion chamber Can be stabilized. Thereby, EGR resistance can be improved. Alternatively, when knocking is likely to occur (for example, in the operating state on the low speed and high load side), if the fuel injection valve is controlled with the second injection pattern, the occurrence of knocking can be suppressed. Thereby, knocking resistance can be improved.
In this direct injection type internal combustion engine, when the fuel injection valve is controlled by the first injection pattern, the control unit equally divides the time during which the swirling flow of fresh air in the combustion chamber makes one rotation, and performs a plurality of times. When the fuel injection valve is controlled to inject fuel into the combustion chamber at the timing when the injection interval is set to the equally divided time, and when the fuel injection valve is controlled by the second injection pattern, fresh air in the combustion chamber The fuel injection valve is controlled so that the fuel injection valve injects fuel into the combustion chamber at the timing when the swirl flow makes one rotation .

  In the direct injection internal combustion engine according to the present invention, not only can fuel be prevented from adhering to the wall surface of the combustion chamber, but also EGR resistance can be improved when EGR is performed, and knocking can be achieved. When it is easy to generate | occur | produce, knocking resistance can be improved. That is, fuel can be prevented from adhering to the wall surface of the combustion chamber, and EGR resistance and knocking resistance can be improved.

<First Embodiment>
FIG. 1 is a sectional view of a direct injection type internal combustion engine according to the first embodiment of the present invention.

(Schematic configuration of a direct injection internal combustion engine)
The in-cylinder direct injection internal combustion engine 1 mainly includes a combustion chamber 63, an intake / exhaust mechanism, a fuel injection valve 27, an EGR (Exhaust Gas Recirculation) device 30, a spark plug 29, and an ECU (control unit) 40.

  The combustion chamber 63 is a chamber surrounded by the cylinder head 20, the cylinder block 10 and the piston 3. The cylinder head 20 is formed with an intake port 23 for supplying fresh air to the combustion chamber 63 and an exhaust port 24 for discharging burned gas from the combustion chamber 63 as exhaust gas.

  As an intake / exhaust mechanism, the intake collector 51 and the intake manifold 52 are located upstream of the intake port 23. An intake valve 21 is disposed downstream of the intake port 23. On the other hand, the exhaust manifold 91 is located downstream of the exhaust port 24. An exhaust valve 22 is disposed upstream of the exhaust port 24. The intake cam shaft 21b / exhaust cam shaft 22b fixed to the intake cam shaft 21b / exhaust cam shaft 22b rotating in conjunction with the rotation of the crankshaft are arranged above the intake valve 21 / exhaust valve 22. Then, the intake valve 21 / exhaust valve 22 are opened and closed.

  The EGR device 30 is provided between the exhaust manifold 91 (exhaust system) and the intake collector 51 (intake system), and recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51.

  The fuel injection valve 27 is a valve that directly injects gasoline fuel into the combustion chamber 63. The fuel injection valve 27 is provided so as to extend from the cylinder head 20 at the upper center of the combustion chamber 63 into the combustion chamber 63. The tip of the fuel injection valve 27 protrudes into the combustion chamber 63.

  The spark plug 29 is provided so as to extend from the cylinder head 20 at the upper center of the combustion chamber 63 into the combustion chamber 63. A tip end portion 29 a (ignition part) of the spark plug 29 protrudes into the combustion chamber 63.

  The ECU 40 is electrically connected to the fuel injection valve 27, the spark plug 29, the EGR device 30, and the like.

(Schematic operation of a direct injection internal combustion engine)
In the direct injection internal combustion engine 1, fresh air is introduced into the intake port 23 via the intake collector 51 and the intake manifold 52. Further, in the operation state in which EGR is performed (see the first control region A1 and the second control region A2 in FIG. 2), the exhaust gas (burned gas) recirculated by the EGR device 30 is converted into the intake collector 51 and the intake manifold 52. Are further introduced into the intake port 23 via.

  In the intake stroke, the intake valve 21 is opened by the intake cam 21a, and fresh air introduced into the intake port 23 is introduced from the intake port 23 into the main combustion chamber 63. Therefore, a tumble flow (vertical vortex) of fresh air stratified in the main combustion chamber 63 is formed.

  On the other hand, pressurized fuel is supplied to the fuel injection valve 27. When controlled in a split injection mode, which will be described later, the fuel injection valve 27 injects fuel into the fresh air introduced into the combustion chamber 63 a plurality of times during the intake stroke or the compression stroke. Alternatively, when controlled in a stratified combustion mode to be described later, the fuel injection valve 27 injects fuel once into fresh air introduced into the combustion chamber 63 during the compression stroke. Thereby, a fresh air mixture is generated in the combustion chamber 63.

  Further, in the compression stroke, the piston 3 rises and the fresh air mixture in the combustion chamber 63 is compressed. The fresh air mixture in the combustion chamber 63 is ignited and burned at a predetermined timing by the tip portion 29a of the spark plug 29.

  In the expansion stroke, the piston 3 is pushed down by the combustion pressure generated by burning the fresh air mixture.

  In the exhaust stroke, the exhaust valve 22 is opened by the exhaust cam 22a, and the burned gas burned in the main combustion chamber 63 is discharged as exhaust gas to the exhaust manifold 91 via the exhaust port 24. Here, in an operation state in which EGR is performed (see the first control region A1 and the second control region A2 in FIG. 2), the EGR device 30 recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51.

  The ECU 40 supplies a control signal to the fuel injection valve 27, the spark plug 29, the EGR device 30, and the like to perform various controls. The ECU 40 executes logic for performing various controls. For example, the ECU 40 executes predetermined logic in an electric circuit, software, or both.

(Detailed configuration of EGR device)
The EGR device 30 mainly includes a first reflux pipe 31, an EGR amount adjustment valve 32, and a second reflux pipe 33.

  The first recirculation pipe 31 is connected to the exhaust manifold 91 in a branched manner so that a part of the exhaust gas (burned gas) of the exhaust manifold 91 can be taken in. An EGR amount adjustment valve 32 is provided downstream of the first reflux pipe 31.

  The second recirculation pipe 33 is connected to the intake collector 51 so as to merge, and the recirculated exhaust gas can be guided to the intake collector 51. An EGR amount adjustment valve 32 is provided upstream of the second reflux pipe 33.

  The EGR amount adjusting valve 32 is disposed between the first return pipe 31 and the second return pipe 33, and exhaust gas that flows through the first return pipe 31 and the second return pipe 33 and flows into the intake collector 51. Adjust the amount. The EGR amount adjusting valve 32 is an electrically controlled valve that electrically drives the valve element by a step motor, and is controlled by the total number of pulse signals (hereinafter referred to as step number) input from the ECU 40 to the step motor. Opening is determined. The step motor is sometimes called a stepping motor, a stepper, a pulse motor, or the like.

(Detailed operation of EGR device)
In an operation state in which EGR is performed (see the first control region A1 and the second control region A2 in FIG. 2), the EGR amount adjustment valve 32 is opened. Thereby, a part of the exhaust gas of the exhaust manifold 91 is recirculated to the intake collector 51 via the first recirculation pipe 31, the EGR amount adjusting valve 32, and the second recirculation pipe 33.

  Here, the EGR amount, which is the amount of exhaust gas recirculated, is adjusted by the opening degree of the EGR amount adjusting valve 32. That is, if the opening degree of the EGR amount adjustment valve 32 is large, the EGR amount increases, and if the opening degree of the EGR amount adjustment valve 32 is small, the EGR amount decreases. The amount of EGR is controlled so as to increase when the engine load is low compared to when the engine load is high.

  In an operating state in which EGR is not performed (see the third control region A3 and the fourth control region A4 in FIG. 2), the EGR amount adjustment valve 32 is closed. Thereby, a part of the exhaust gas of the exhaust manifold 91 is not supplied before the EGR amount adjusting valve 32 and is not recirculated to the intake collector 51.

(Detailed configuration of ECU)
The ECU 40 mainly includes a load calculation unit 41, a speed calculation unit 42, a fuel injection control unit 43, an ignition timing control unit 44, an EGR control unit 45, and a storage unit 47. The load calculation unit 41, the speed calculation unit 42, the fuel injection control unit 43, the ignition timing control unit 44, and the EGR control unit 45 are a CPU or the like. The storage unit 47 is a ROM, a RAM, or the like, and stores programs, map information (see FIG. 2), and the like.

  The ECU 40 not only executes logic for performing various controls, but also executes logic for controlling the fuel injection valve 27.

(Detailed operation of ECU)
The ECU 40 includes a crank angle signal detected by a crank angle sensor (not shown), a coolant temperature signal detected by a water temperature sensor (not shown), and an accelerator opening detected by an accelerator opening sensor (not shown). A degree signal is input. The load calculation unit 41 and the speed calculation unit 42 receive these signals. The load calculation unit 41 calculates the engine load based on these signals. The speed calculation unit 42 calculates the engine speed based on these signals.

  The fuel injection control unit 43 receives engine load information from the load calculation unit 41 and receives engine speed information from the speed calculation unit 42. Further, the fuel injection control unit 43 refers to the storage unit 47 and receives map information (see FIG. 2) from the storage unit 47. The fuel injection control unit 43 generates an injection period control signal based on engine load and engine speed information, map information (see FIG. 2), and the like. Thus, the fuel injection valve 27 injects a predetermined injection amount of fuel into the combustion chamber 63 at a predetermined injection timing based on the injection period control signal. That is, the fuel injection control unit 43 of the ECU 40 switches between the first injection pattern and the second injection pattern according to the operating state (engine load and engine speed), and injects the fuel into the combustion chamber 63 a plurality of times in one cycle. Thus, the fuel injection valve 27 is controlled. Here, the first injection pattern is a pattern for dispersing the fresh air mixture in the combustion chamber 63. The second injection pattern is a pattern for concentrating the fresh air mixture in the combustion chamber 63.

  The ignition timing control unit 44 receives engine load information from the load calculation unit 41, receives engine speed information from the speed calculation unit 42, and generates an ignition timing control signal based on the engine load and engine speed information. . Thereby, the spark plug 29 generates a spark at a predetermined timing based on the ignition timing control signal.

  The EGR control unit 45 receives engine load information from the load calculation unit 41 and receives engine speed information from the speed calculation unit 42. Further, the EGR control unit 45 refers to the storage unit 47 and receives map information (see FIG. 11) from the storage unit 47. The EGR control unit 45 generates an EGR control signal based on information on the engine load and engine speed, map information (see FIG. 11), and the like. Thereby, the EGR amount adjustment valve 32 of the EGR device 30 is closed or opened at a predetermined opening based on the EGR control signal.

(Control of direct injection internal combustion engine)
The control of the direct injection type internal combustion engine 1 will be described with reference to FIGS.

  Map information referred to by the fuel injection control unit 43 and the EGR control unit 45 of the ECU 40 is shown in FIG. The map information shows the relationship between the engine load and engine speed and the control area. That is, the control area is divided into a first control area A1, a second control area A2, a third control area A3, and a fourth control area A4. The first control region A1 is a region on the relatively low speed and low load side, and is a region where the fuel injection valve 27 is controlled in the stratified combustion mode. The operation state in the first control region A1 is an operation state in which stratified combustion is performed, and is an operation state in which EGR is performed. The second control region A2 is a region on the relatively low speed and low load side, but is a region where the engine load is higher or the engine speed is higher than the first control region A1, and the fuel injection valve 27 is controlled in the split injection mode. Area. The operation state in the second control region A2 is an operation state in which EGR is performed. The third control region A3 is a region on the relatively low speed and high load side, and is a region where the fuel injection valve 27 is controlled in the split injection mode. The operation state in the third control region A3 is an operation state in which EGR is not performed, and is an operation state in which knocking easily occurs. The fourth control region A4 is a region on the relatively high speed side or the high load side, and is a region in which the fuel injection valve 27 is controlled in the split injection mode. The operation state in the fourth control region A2 is an operation state in which EGR is not performed.

((Control in the first control area A1))
The first control region A1 is a region where normal stratified combustion is performed. That is, in the first control region A1, the fuel injection valve 27 is controlled in the stratified combustion mode. Specifically, the fuel injection control unit 43 of the ECU 40 causes the fuel injection valve 27 to inject fuel once into the fresh air introduced into the combustion chamber 63 during the compression stroke (the injection timing and the injection amount). (Injection time)) is determined, and an injection period control signal is generated. As a result, the fuel injection valve 27 injects fuel once into the fresh air in the combustion chamber 63 based on the injection period control signal. For this reason, a stratified fresh air mixture is formed in the combustion chamber 63. As a result, the engine air-fuel ratio (the air-fuel ratio of the combustion chamber 63 as a whole) is significantly leaned, while the air-fuel ratio in the vicinity of the spark plug 29 is locally enriched and stable combustion is performed. .

((Control in Second Control Area A2))
Control in the second control region A2 will be described with reference to FIGS. Here, the second control region A2 is a region in which the fuel injection valve 27 is controlled by the EGR-resistant pattern (second injection pattern) in the split injection mode. FIG. 3 is a timing chart showing an injection period (injection timing and injection amount (injection time)) when the fuel injection valve 27 injects fuel in an EGR-resistant pattern.

  As shown in FIG. 3, the fuel injection valve 27 is required to inject fuel within an injectable period (DT). The injectable period (DT) is a period between the advance angle limit (CA1) and the retard angle limit (CA2), and is a period included in the intake stroke and the compression stroke. That is, in the second control region A2, the fuel injection is performed by the fuel injection valve 27 toward the tumble flow of fresh air formed in the combustion chamber 63 during the period included in the intake stroke and the compression stroke. A tumble flow of fresh air mixture is formed in the chamber 63. Then, the fresh air mixture in the combustion chamber 63 swirls in the combustion chamber 63 in a tumble flow. Here, the time (crank angle unit) in which the tumble flow makes one rotation is shown as a period (RT) from timing (CA3) to timing (CA4) in FIG.

  Further, according to the specifications, the fuel injection valve 27 needs to inject fuel at an interval longer than the minimum injection interval (DImin), and needs to inject the fuel at a minimum injection amount (minimum injection time Tmin) or more. Further, the fuel injection valve 27 needs to inject the fuel at a maximum injection amount (maximum injection time Tmax) or less in order to prevent the fuel from adhering to the wall surface 63a of the combustion chamber 63.

When the ECU 40 controls the fuel injection valve 27 with an EGR-resistant pattern, the fuel injection valve 27 injects fuel into the combustion chamber 63 at the same phase as the tumble flow of fresh air in the combustion chamber 63. To control. That is, the ECU 40
DI = 360 ° ÷ TR (1)
The injection interval in the crank angle unit is determined by the following formula. Here, DI indicates the injection interval. TR indicates the tumble ratio,
TR = (rotational speed of the tumble flow) / (rotational speed of the engine). It is. Further, the ECU 40
T = Tall ÷ DN (3)
The injection time in units of crank angle is determined by the following formula. Here, T indicates the injection time per time, and Tall indicates the total injection time corresponding to the required total injection amount. DN indicates the number of injections,
DT ÷ RT ≦ DN (4)
Is the smallest integer that satisfies. However, as mentioned above,
DI ≧ DImin (5)
Tmin ≦ T ≦ Tmax (6)
Must be satisfied. The injection timing is such that the fresh air mixture in the combustion chamber 63 is concentrated in the vicinity of the tip portion 29a of the spark plug 29 at the timing when the tip portion 29a of the spark plug 29 is ignited (hereinafter referred to as ignition timing). Selected. That is, the ECU 40 satisfies the expressions (1) to (6), and the injection period (the injection timing and the injection timing) is such that the fresh air mixture in the combustion chamber 63 is concentrated in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. Volume (injection time)). If there is an injection that falls outside the injectable period (DT), the ECU 40 adds the amount outside the injectable period (DT) to the advance timing and resets the injection period. Further, if the injection amount after the addition exceeds the maximum injection amount, the ECU 40 resets the injection period by adding the amount exceeding the maximum injection amount to the retarded timing. Then, the ECU 40 determines the injection period within the injectable period (DT).

For example, in the case shown in FIG. 3, the injection interval is DI5 (= RT) according to the equation (1). Since the number of injections (DN) is 2, the injection time is
T5 = Tall ÷ 2 (7)
It becomes. And
DI5 ≧ DImin (9)
Tmin ≦ T5 ≦ Tmax (10)
It is. Thereby, ECU40 determines the injection period which satisfy | fills Formula (1)-(6) to injection timing CA3, CA4 and injection time T5.

For example, in the case shown in FIG. 4, the injection interval is DI5 (= RT) according to the equation (1). Since the injection time is the number of injections (DN) is 2,
T5 = Tall ÷ 2 (11)
It becomes. However, the injection at the second injection timing (CA6) reaches the retardation limit (CA2) in the middle of the injection time T5 and exceeds the injectable period (DT). Therefore, the injection time T6 corresponding to the injectable period (DT) is added to the one-advance-side injection timing (CA5). The injection time of the injection timing (CA5) is reset to T5 + T6.
Tmin ≦ T5 + T6 ≦ Tmax (12)
It is. Thereby, ECU40 determines the injection period which satisfy | fills Formula (1)-(6) to injection timing CA5, CA6 and injection time T5 + T6, T5-T6.

For example, in the case shown in FIG. 5, the injection interval is DI5 (= RT) according to the equation (1). Since the injection time is the number of injections (DN) is 2,
T5 = Tall ÷ 2 (13)
It becomes. However, the injection at the second injection timing (CA8) reaches the retardation limit (CA2) in the middle of the injection time T5 and exceeds the injectable period (DT). Therefore, the injection time T7 corresponding to the injection possible period (DT) is added to the one-advance-side injection timing (CA7), and the injection period is reset. The injection time of the injection timing (CA7) is T5 + T7.
T5 + T7> Tmax (14)
It is. Therefore, the injection time for exceeding the maximum injection amount Tmax T8 = T5 + T7−Tmax (15)
Is added to the one-retarded injection timing (CA8), the injection timing (CA8) is advanced by time T8, and reset to the injection timing (CA18). Moreover, the injection time of the injection timing (CA18) is T5-T7 + T8. Thereby, ECU40 determines the injection period which satisfy | fills Formula (1)-(6) to injection timing CA7, CA18 and injection time Tmax, T5-T7 + T8.

  In these cases, the distribution of the fresh air mixture in the combustion chamber 63 is as shown in FIG. That is, the fuel injected at the first injection timing (CA3, CA5, CA7) rides on the tumble flow and swirls in the combustion chamber 63 as a fresh air mixture F5. The fuel injected at the second injection timing (CA4, CA6, CA18) takes a tumble flow and swirls in the combustion chamber 63 as a fresh air mixture F6. In this manner, the fresh air mixtures F5 and F6 in the combustion chamber 63 are swirled at positions that are in phase with each other in the tumble flow. In FIG. 6, portions other than the cylinder block 10, the cylinder head 20, and the piston 3 are not shown.

  Further, as the injection timing (CA3, CA4, CA5, CA6, CA7, CA18), a timing is selected such that the fresh air mixture in the combustion chamber 63 is concentrated in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. ing. Therefore, the fresh air mixtures F5 and F6 in the combustion chamber 63 are swirled so as to concentrate in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. Thereby, the ignitability of the fresh air mixture and the initial combustion speed in the combustion chamber 63 are improved.

  Even when the number of injections DN = 3, as shown in FIG. 7, the fresh air mixtures F7, F8, and F9 in the combustion chamber 63 are swirled at the same phase in the tumble flow. Further, the fresh air mixtures F7, F8, and F9 in the combustion chamber 63 are swirled so as to concentrate in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. Thereby, the ignitability of the fresh air mixture and the initial combustion speed in the combustion chamber 63 are improved.

((Control in the third control region A3))
Control in the third control region A3 will be described with reference to FIGS. Here, the third control region A3 is a region in which the fuel injection valve 27 is controlled with a knocking resistant pattern (second injection pattern) in the split injection mode. FIG. 8 is a timing chart showing an injection period (injection timing and injection amount (injection time)) when the fuel injection valve 27 injects fuel in a knocking resistant pattern.

  The control in the third control region A3 is basically the same as “((control in the second control region A2))” described above, but differs in the following points.

  The time (crank angle unit) for the tumble flow to make one rotation is shown as a period (RT) from timing (CA11) to timing (CA12) in FIG.

  The injection timing is selected such that the fresh air mixture in the combustion chamber 63 concentrates on the intake side (near the intake valve 21) at the ignition timing. That is, the ECU 40 satisfies the expressions (1) to (6) and sets the injection period (injection timing and injection amount (injection time)) so that the fresh air mixture in the combustion chamber 63 is concentrated on the intake side at the ignition timing. Set.

  For example, in the case illustrated in FIG. 8, the ECU 40 determines an injection period that satisfies the expressions (1) to (6) as the injection timings CA11 and CA12 and the injection time T5.

  As the injection timing (CA11, CA12), the timing at which the fresh air mixture in the combustion chamber 63 is concentrated on the intake side at the ignition timing is selected. Therefore, the fresh air mixtures F10 and F11 in the combustion chamber 63 shown in FIG. 9 are swirled so as to concentrate on the intake side at the ignition timing. As a result, the combustion period of the fresh air mixture is shortened on the intake side (in the vicinity of the intake valve 21) where knocking is likely to occur, so that the occurrence of knocking is effectively suppressed.

  Even when the number of injections DN = 3, as shown in FIG. 10, the fresh air mixtures F12, F13, F14 in the combustion chamber 63 are swirled so as to concentrate on the intake side at the ignition timing. As a result, the combustion period of the fresh air mixture is shortened on the intake side (in the vicinity of the intake valve 21) where knocking is likely to occur, so that the occurrence of knocking is effectively suppressed.

((Control in Fourth Control Area A4))
Control in the fourth control region A4 will be described with reference to FIGS. Here, the fourth control region A4 is a region in which the fuel injection valve 27 is controlled by the dispersion pattern (first injection pattern) in the split injection mode. FIG. 11 is a timing chart showing an injection period (injection timing and injection amount (injection time)) when the fuel injection valve 27 injects fuel in a dispersion pattern.

  As shown in FIG. 11, the fuel injection valve 27 is required to inject fuel within the injectable period (DT). The injectable period (DT) is a period between the advance angle limit (CA1) and the retard angle limit (CA2), and is a period included in the intake stroke and the compression stroke. That is, in the fourth control region A4, the fuel injection is performed by the fuel injection valve 27 toward the tumble flow of fresh air formed in the combustion chamber 63 during the period included in the intake stroke and the compression stroke. A tumble flow of fresh air mixture is formed in the chamber 63. Then, the fresh air mixture in the combustion chamber 63 swirls in the combustion chamber 63 in a tumble flow. Here, the time during which the tumble flow makes one rotation (crank angle unit) is shown as a period (RT) from the advance limit (CA1) to the timing (CA15) in FIG.

  Further, according to the specifications, the fuel injection valve 27 needs to inject fuel at an interval longer than the minimum injection interval (DImin), and needs to inject the fuel at a minimum injection amount (minimum injection time Tmin) or more. Further, the fuel injection valve 27 needs to inject the fuel at a maximum injection amount (maximum injection time Tmax) or less in order to prevent the fuel from adhering to the wall surface 63a of the combustion chamber 63.

When the ECU 40 controls the fuel injection valve 27 in a distributed pattern, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63. To control. That is, the ECU 40
DI = 360 ° ÷ N ÷ TR (16)
The injection interval in the crank angle unit is calculated by the following formula. Here, DI indicates the injection interval, and N indicates the number of divisions. TR indicates the tumble ratio,
TR = (rotational speed of the tumble flow) / (rotational speed of the engine) (17) It is. Further, the ECU 40
T = Tall ÷ DN (18)
The injection time in the crank angle unit is calculated by the following formula. Here, T indicates the injection time per time, and Tall indicates the total injection time corresponding to the required total injection amount. DN indicates the number of injections,
DT ÷ DI ≦ DN (19)
Is the smallest integer that satisfies. However, as mentioned above,
DI ≧ DImin (20)
Therefore, the number of divisions N is
RT ÷ DImin ≧ N (21)
The largest integer value that satisfies is selected first. Also,
Tmin ≦ T ≦ Tmax (22)
Must be satisfied. That is, the ECU 40 obtains the maximum value of N that satisfies the equations (16) to (22), and determines the injection period (injection timing and injection amount (injection time)) within the injectable period (DT).

For example, in the case shown in FIG. 11, when N = 4, the injection interval is DI4 and the injection time is T4. But,
DI4 <DImin (23)
And equation (20) cannot be satisfied. That is, since the maximum value of N that satisfies the equation (21) is N = 3, N = 3 is first selected as the number of divisions. Then, since the injection interval is DI3 and the number of injections (DN) is 5 from Equation (16), the injection time is T3 = Tall ÷ 5 (24)
It becomes. And
DI3 ≧ DImin (25)
Tmin ≦ T3 ≦ Tmax (26)
It is. Thereby, ECU40 calculates | requires the maximum value of N which satisfy | fills Formula (16)-(22) as N = 3. Here, if the first injection timing is the advance angle limit (CA1), the injection at the fifth injection timing (CA17) reaches the delay angle limit (CA2) in the middle of the injection time T3 and can be injected. The period (DT) is exceeded. Therefore, the injection at the fifth injection timing is canceled, and the number of injections (DN) is reduced from 5 times to 4 times. And the injection time T3a = Tall ÷ 4 (27)
And the injection period is reset. Further, the first to fourth injection timings are left as they are. Thus, ECU40 determines the injection period which satisfy | fills Formula (16)-(22) to injection timing CA1, CA13, CA14, CA15, and injection time T3a. Here, the number of injections DN (four times in the case of FIG. 11) is equal to or more than the number of injections (DN = 2 in the case of FIGS. 3 to 5) when controlled in the second control region A2. The number of injections when controlled to the third control region A3 (DN = 2 in the case of FIG. 8) is greater than or equal to.

  In this case, the distribution of the fresh air mixture in the combustion chamber 63 is as shown in FIG. That is, the fuel injected at the first injection timing (CA1) rides in the tumble flow and swirls in the combustion chamber 63 as a fresh air mixture F1. The fuel injected at the second injection timing (CA13) takes the tumble flow and swirls in the combustion chamber 63 as a fresh air mixture F2. The fuel injected at the third injection timing (CA14) takes a tumble flow and swirls in the combustion chamber 63 as a fresh air mixture F3. In this manner, the fresh air mixtures F1 to F3 in the combustion chamber 63 are swirled at positions where the phase is equally divided (here, divided into three) in the tumble flow.

  When the number of divisions N = 2, as shown in FIG. 11, the injection interval is determined as DI2, the injection timings are determined as CA1, CA16, CA15, and the injection time is determined as T2. Then, as shown in FIG. 13, the fresh air mixtures F4 and F5 in the combustion chamber 63 turn at a position where the phase is equally divided (here, divided into two) in the tumble flow.

(Control flow in a direct injection internal combustion engine)
A control flow in the direct injection type internal combustion engine will be described with reference to a flowchart shown in FIG. Such control is performed together with other controls in the direct injection type internal combustion engine 1.

  In step S1, the operating state (engine load, engine speed) is detected. That is, the ECU 40 detects a crank angle signal detected by a crank angle sensor (not shown), a cooling water temperature signal detected by a water temperature sensor (not shown), and an accelerator opening sensor (not shown). An accelerator opening signal or the like is input. The load calculation unit 41 and the speed calculation unit 42 receive these signals. The load calculation unit 41 calculates the engine load based on these signals. The speed calculation unit 42 calculates the engine speed based on these signals.

  The fuel injection control unit 43 of the ECU 40 receives engine load information from the load calculation unit 41 and receives engine speed information from the speed calculation unit 42. Further, the fuel injection control unit 43 refers to the storage unit 47 and receives map information (see FIG. 2) from the storage unit 47. The fuel injection control unit 43 determines an operation mode and an injection pattern based on information on engine load and engine speed, map information (see FIG. 2), and the like.

  In step S2, the ECU 40 determines which operation mode is in effect. That is, if it is determined that the operation mode is the split injection mode, the process proceeds to step S3, and if it is determined that the operation mode is the stratified combustion mode, the process proceeds to step S9.

  In step S3, an injection pattern is read. That is, the fuel injection control unit 43 of the ECU 40 determines an injection pattern based on information on the engine load and engine speed, map information (see FIG. 2), and the like, and reads the contents from the storage unit 47.

  In step S4, the ignition timing is read. That is, the fuel injection control unit 43 of the ECU 40 receives ignition timing information from the ignition timing control unit 44.

  In step S5, the total injection amount (total injection time) is calculated. That is, the fuel injection control unit 43 of the ECU 40 calculates a required total injection amount (total injection time Tall) based on information on the engine load and engine speed and map information (see FIG. 2).

  In step S6, the injection possible period (DT) is read. In other words, the fuel injection control unit 43 of the ECU 40 refers to the storage unit 47 and receives information on the injection possible period (DT) from the storage unit 47.

  In step S7, the maximum injection amount / minimum injection amount / minimum injection interval are read. That is, the fuel injection control unit 43 of the ECU 40 refers to the storage unit 47 and stores information on the maximum injection amount (maximum injection time Tmax), the minimum injection amount (minimum injection time Tmin), and the minimum injection interval (DImin). Receive from.

  In step S8, an injection period calculation process is performed.

  In step S9, the injection period (injection timing and injection amount (injection time)) is determined. That is, the fuel injection control unit 43 of the ECU 40 determines an injection period so that the fuel injection valve 27 injects fuel once into fresh air introduced into the combustion chamber 63 in the compression stroke, and generates an injection period control signal. Generate. As a result, the fuel injection valve 27 injects fuel once into the fresh air in the combustion chamber 63 based on the injection period control signal. For this reason, a stratified fresh air mixture is formed in the combustion chamber 63. As a result, the engine air-fuel ratio (the air-fuel ratio of the combustion chamber 63 as a whole) is significantly leaned, while the air-fuel ratio in the vicinity of the spark plug 29 is locally enriched and stable combustion is performed. .

  Next, the details of the injection period calculation process S8 will be described using the flowchart shown in FIG.

  In step S11, the ECU 40 determines which injection pattern is used. That is, if it is determined that the injection pattern is a dispersion pattern, the process proceeds to step S12, and if it is determined that the injection pattern is an anti-EGR pattern / anti-knocking pattern, the process proceeds to step S21.

  In step S12, the number of divisions is selected. That is, the ECU 40 selects the maximum value of N (integer) that satisfies the equation (21) as the division number N.

  In step S13, the injection interval and the injection time are calculated. That is, the ECU 40 calculates the injection interval in units of crank angles using the equations (16), (17) and the like. Further, the ECU 40 calculates the injection time in units of crank angles using the total injection amount (total injection time Tall) calculated in step S5 and the equations (18) and (19).

  In step S14, the ECU 40 determines whether or not the injection interval and the injection time satisfy the constraint conditions. That is, it is determined whether the injection interval satisfies Expression (20) and the injection time satisfies Expression (22) at the same time. If it is determined that the conditions are satisfied simultaneously, the process proceeds to step S16. If it is determined that the conditions are not satisfied simultaneously, the process proceeds to step S15.

  In step S15, the number of divisions is changed. That is, the ECU 40 newly sets the number of divisions N (N−1) obtained by reducing the number of divisions by 1 as the number of divisions N.

  In step S16, an injection period (injection timing and injection amount (injection time)) is temporarily set. That is, the ECU 40 sets the first injection timing to the advance angle limit (CA1). Then, the ECU 40 sets the first injection time (injection amount) and the second and subsequent injection timings / injection times (injection amount) based on the injection interval and the injection time.

  In step S17, the ECU 40 determines whether or not the injection period is within the injectable period (DT). That is, if it is determined that the injection period is within the injectable period (DT), the process proceeds to step S19. If it is determined that the injection period is not within the injectable period (DT), the process proceeds to step S18.

In step S18, the injection period is reset. That is, the ECU 40 cancels the injection at the injection timing that exceeds the injectable period (DT). Then, the ECU 40 newly sets the number of injections reduced by the number of canceled injections (DN-1 when only one is canceled) as the injection number DN. The ECU 40 uses the equation (18) to recalculate the injection time and reset the injection period. In step S19, the injection period is determined. That is, the ECU 40 determines the injection period and generates an injection period control signal. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63 based on the injection period control signal. For this reason, as shown in FIG. 12, the fresh air mixtures F1, F2, and F3 in the combustion chamber 63 are swirled at positions where the phase is equally divided (here, divided into three) in the tumble flow. Alternatively, as shown in FIG. 13, the fresh air mixtures F4 and F5 in the combustion chamber 63 are swirled at positions where the phase is equally divided (here, divided into two) in the tumble flow.

  In step S21, the injection interval / injection time is calculated. That is, the ECU 40 calculates the injection interval in units of crank angles using the formulas (1) and (2). In addition, the ECU 40 calculates the injection time in units of crank angles using the total injection amount (total injection time Tall) calculated in step S5 and the equations (3) and (4).

  In step S22, the ECU 40 determines whether or not the injection interval and the injection time satisfy the constraint conditions. That is, it is determined whether or not the injection interval satisfies Expression (5) and the injection time satisfies Expression (6) at the same time. If it is determined that they are satisfied simultaneously, the process proceeds to step S23, and if it is determined that they are not satisfied simultaneously, the process proceeds to step S21.

  In step S23, an injection period (injection timing and injection amount (injection time)) is temporarily set. That is, when the ECU 40 determines that the injection pattern is an ERG-resistant pattern, the timing at which the fresh air mixture in the combustion chamber 63 concentrates in the vicinity of the tip portion 29a of the ignition plug 29 at the first ignition timing is determined. At the injection timing. Alternatively, when the ECU 40 determines that the injection pattern is an anti-knocking pattern, the first time is set so that the fresh air mixture in the combustion chamber 63 concentrates on the intake side (near the intake valve 21) at the ignition timing. At the injection timing. Then, the ECU 40 sets the first injection time (injection amount) and the second and subsequent injection timings / injection times (injection amount) based on the injection interval and the injection time.

  In step S24, the ECU 40 determines whether or not the injection period is within the injectable period (DT). That is, if it is determined that the injection period is within the injectable period (DT), the process proceeds to step S28, and if it is determined that the injection period is not within the injectable period (DT), the process proceeds to step S25.

  In step S25, the injection period is reset. That is, the ECU 40 resets the injection period by adding the amount outside the injection possible period (DT) to the advance timing (see FIGS. 4 and 5).

  In step S26, it is determined whether or not the injection amount (injection time) exceeds the maximum injection amount (maximum injection time Tmax). If it is determined that it has exceeded, the process proceeds to step S27, and if it is determined that it does not exceed, the process proceeds to step S28.

  In step S27, the injection period is reset. That is, the ECU 40 resets the injection period by adding the amount exceeding the maximum injection amount to the retarded timing (see FIG. 5).

  In step S28, the injection period is determined. That is, the ECU 40 determines the injection period and generates an injection period control signal. Accordingly, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing that is in phase with the tumble flow of fresh air in the combustion chamber 63 based on the injection period control signal. For this reason, the fresh air mixture in the combustion chamber 63 turns at a position where the phase is the same in the tumble flow. Specifically, when the injection pattern is an ERG-resistant pattern, as shown in FIGS. 6 and 7, the fresh air mixtures F5, F6, F7, F8, and F9 in the combustion chamber 63 are in the combustion chamber 63 at the ignition timing. The air-fuel mixture swirls at a position where the fresh air-fuel mixture is concentrated in the vicinity of the tip portion 29a of the spark plug 29. Alternatively, when the injection pattern is a knocking resistant pattern, as shown in FIGS. 9 and 10, the fresh air mixture F10, F11, F12, F13, and F14 in the combustion chamber 63 is mixed with the fresh air mixture in the combustion chamber 63 at the ignition timing. It turns at a position where the air is concentrated on the intake side (near the intake valve 21).

(Characteristics of in-cylinder direct injection internal combustion engine)
(1)
Here, the ECU 40 controls the fuel injection valve 27 to inject fuel into the combustion chamber 63 a plurality of times in one cycle. This prevents fuel from adhering to the wall surface 63a of the combustion chamber 63. Further, since the ECU 40 switches between the dispersion pattern, the anti-EGR pattern, and the anti-knocking pattern according to the operation state, if the fuel injection valve 27 is controlled with the anti-EGR pattern when the EGR is performed, Combustion stabilizes. Thereby, the EGR resistance is improved. Alternatively, when knocking is likely to occur, if the fuel injection valve 27 is controlled with a knocking resistant pattern, the occurrence of knocking is suppressed. Thereby, knocking resistance improves.

  Thus, not only is the fuel prevented from adhering to the wall surface 63a of the combustion chamber 63, but EGR resistance is improved when EGR is performed, and knock resistance is improved when knocking is likely to occur. To do. That is, the fuel is prevented from adhering to the wall surface 63a of the combustion chamber 63, and the EGR resistance and the knocking resistance are improved.

(2)
Here, when the fuel injection valve 27 is controlled in a dispersion pattern, the ECU 40 causes the fuel injection valve 27 to supply fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63. Control to inject. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63.

  For this reason, the fresh air mixture in the combustion chamber 63 turns at a position where the phase is equally divided in the tumble flow. As a result, the fresh air mixture in the combustion chamber 63 is dispersed at positions where the phases are equally divided in the tumble flow.

(3)
Here, when the ECU 40 controls the fuel injection valve 27 with the anti-EGR pattern / anti-knocking pattern, the fuel injection valve 27 is in the combustion chamber 63 at the same timing as the tumble flow of fresh air in the combustion chamber 63. Control to inject fuel into the inside. Thus, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing that is in phase with the tumble flow of fresh air in the combustion chamber 63.

  For this reason, the fresh air mixture in the combustion chamber 63 turns at a position where the phase is the same in the tumble flow. As a result, the fresh air mixture in the combustion chamber 63 is concentrated at the same phase in the tumble flow.

(4)
Here, the EGR device 30 recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51 when the operating state belongs to the second control region A2. The ECU 40 controls the fuel injection valve 27 with an anti-EGR pattern when the EGR device 30 recirculates a part of the exhaust gas of the exhaust manifold 91 to the intake collector 51. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 in an EGR-resistant pattern when EGR is performed.

  For this reason, even when EGR is performed, the combustion in the combustion chamber 63 is stabilized. As a result, the EGR resistance is improved.

(5)
Here, the EGR device 30 recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51 when the operating state belongs to the second control region A2. At this time, in the combustion chamber 63, the fresh air mixture may be difficult to ignite, and the combustion speed of the fresh air mixture may be slow. That is, when EGR is performed, the combustion in the combustion chamber tends to become unstable.

  Even in this case, when the EGR device 30 recirculates a part of the exhaust gas of the exhaust manifold 91 to the intake collector 51, the ECU 40 causes the fresh air mixture in the combustion chamber 63 in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. Control to focus on. As a result, the fresh air mixtures F5, F6, F7, F8, and F9 in the combustion chamber 63 rotate so as to concentrate in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. For this reason, since the ignitability and initial combustion speed of the fresh air mixture in the combustion chamber 63 are improved, the combustion in the combustion chamber 63 is stabilized even when EGR is performed. As a result, the EGR resistance is improved.

(6)
Here, when the engine load is high and the engine speed is slow (when the operating state belongs to the third control region A3), the ECU 40 controls the fuel injection valve 27 with a knocking resistant pattern. That is, when knocking is likely to occur, the ECU 40 controls with a knocking resistant pattern. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 in a knocking-resistant pattern when knocking is likely to occur.

  For this reason, since the combustion period of the fresh air mixture in the combustion chamber 63 is shortened, the occurrence of knocking is suppressed. As a result, the knocking resistance is improved.

(7)
Here, when the engine load is high and the engine speed is slow (when the operating state belongs to the third control region A3), knocking tends to occur easily on the intake side of the combustion chamber 63 (near the intake valve 21). is there.

  Even in this case, when the engine load is high and the engine speed is slow, the ECU 40 controls the fresh air mixture in the combustion chamber 63 to concentrate on the intake side at the ignition timing. As a result, the fresh air mixture F10, F11, F12, F13, and F14 in the combustion chamber 63 turns so as to concentrate on the intake side at the ignition timing. For this reason, since the combustion period of the fresh air mixture is shortened on the intake side where knocking is likely to occur, the occurrence of knocking is effectively suppressed. As a result, the knocking resistance is improved.

(8)
Here, the ECU 40 performs control so that the number of injections (DN) in the dispersion pattern is equal to or more than the number of injections (DN) in the anti-EGR pattern / anti-knocking pattern. For this reason, when the fuel injection valve 27 is controlled by the dispersion pattern, the fresh air mixture in the combustion chamber 63 is dispersed. Further, when the fuel injection valve 27 is controlled with an EGR-resistant pattern / anti-knocking-resistant pattern, the fresh air mixture in the combustion chamber 63 is concentrated.

(Modification of the first embodiment)
(A) Since it is necessary to avoid that the fuel injected by the fuel injection valve 27 is exhausted as it is, the advance angle limit (CA1) is preferably the timing after the exhaust valve 22 is closed.

  In the latter half of the compression stroke, the tumble flow (longitudinal vortex) in the combustion chamber 63 may be attenuated. Therefore, it is preferable that the retard limit (CA2) is the timing in the first half of the compression stroke.

  Furthermore, in the control in the first control region A1, it is preferable that the timing at which the fuel injection valve 27 injects fuel is before the ignition timing and in the latter half of the compression stroke. This is because, when the ignition timing and the injection timing are close, it is easy to ignite in a state where the fresh air mixture is stratified in the combustion chamber 63. In the control in the first control region A1, the fuel injection valve 27 may be controlled to inject the fuel a plurality of times.

  Then, in the control in the third control region A3, if knocking occurs more easily on the exhaust side than on the intake side, the injection timing is such that the fresh air mixture in the combustion chamber 63 is concentrated on the exhaust side at the ignition timing. Timing may be selected. That is, when the engine load is high and the engine speed is slow, the ECU 40 may control the fresh air mixture in the combustion chamber 63 to concentrate on the exhaust side at the ignition timing. Even in this case, the fresh air mixture in the combustion chamber 63 swirls so as to concentrate on the exhaust side at the ignition timing. For this reason, since the combustion period of the fresh air mixture is shortened on the exhaust side where knocking is likely to occur, the occurrence of knocking is effectively suppressed. As a result, the knocking resistance is improved.

  (B) As shown in FIG. 16, the map information stored in the storage unit 47a may store the second control area A2a instead of the second control area A2, and the map information stored in the fourth control area A4. Instead, the fourth control area A4a may be stored. Here, the second control region A2a is a region in which the fuel injection control unit 43 of the ECU 40 controls the engine air-fuel ratio leaner than the stoichiometric air-fuel ratio (except for the first control region A1). In addition, a lean-resistant pattern that is the same pattern as the EGR-resistant pattern is employed as the ejection pattern.

  When the engine air-fuel ratio is controlled to be leaner than the stoichiometric air-fuel ratio, the fresh air mixture may be difficult to ignite in the combustion chamber 63, and the combustion speed of the new air mixture may be slow. For this reason, the expansion of the lean limit tends to be insufficient.

  Even in this case, when the engine air-fuel ratio is controlled to be leaner than the stoichiometric air-fuel ratio, the ECU 40 performs control so that the fresh air mixture in the combustion chamber 63 is concentrated in the vicinity of the tip portion 29 a of the spark plug 29 at the ignition timing. . As a result, the fresh air mixture in the combustion chamber 63 swirls so as to concentrate in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. For this reason, since the ignitability of the fresh air mixture and the initial combustion speed in the combustion chamber 63 are improved, the lean limit is expanded.

  (C) The tumble flow (longitudinal vortex) may be controlled by the shape of the top surface of the piston 3.

  The EGR device 30 may have a configuration different from that of the first embodiment as long as a part of the exhaust gas in the exhaust system can be recirculated to the intake system.

<Second Embodiment>
FIG. 17 shows a cross-sectional view of a direct injection type internal combustion engine according to the second embodiment of the present invention.

  The direct injection internal combustion engine 100 has the same basic configuration as that of the first embodiment, but differs from the first embodiment in that an ECU (control unit) 140 is provided instead of the ECU 40.

  The storage unit 147 of the ECU 140 stores map information shown in FIG. 18 instead of the map information shown in FIG. The fuel injection control unit 143 refers to the storage unit 147 and receives map information (see FIG. 18) from the storage unit 147. When the fuel injection control unit 143 controls the fuel injection valve 27 with the dispersion pattern (fourth control region A104), the fuel injection amount at the advance side timing (first injection amount) is changed to the injection amount at the retard side timing. Increase compared to (second injection amount). In addition, when the fuel injection control unit 143 controls the fuel injection valve 27 with the anti-EGR pattern (second control region A102) and the anti-knocking pattern (third control region A103), the fuel injection amount (first injection timing) 1 injection amount) is made smaller than the injection amount (second injection amount) at the timing on the retard side. These points are different from the first embodiment.

(Control of direct injection internal combustion engine)
The control of the direct injection type internal combustion engine 100 will be described with reference to FIGS.

  The map information stores the second control area A102 instead of the second control area A2, the third control area A103 instead of the third control area A3, and the fourth control instead of the fourth control area A4. Area A104 is stored. Other points are basically the same as in the first embodiment.

((Control in the first control area A1))
This is the same as in the first embodiment.

((Control in Second Control Area A102))
The ECU 140 satisfies the formulas (1), (2), (5), and (6), and the injection period (in which the injection amount at the advance side timing is smaller than the injection amount at the retard side timing) The injection timing and the injection amount (injection time)) are set. This is different from the first embodiment.

  For example, in the case shown in FIG. 19, the injection timings CA9 and CA10 are selected as the timing at which the fresh air mixture in the combustion chamber 63 is concentrated in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. Then, ECU 140 assigns the maximum injection amount (maximum injection time Tmax) to the injection at timing CA10 that is the timing on the retard side. Further, ECU 140 assigns the remaining injection amount (injection time Tall-Tmax) to the injection at timing CA9, which is the advance side timing. This injection period satisfies the expressions (1), (2), (5), and (6), and is within the injection possible period (DT). Thereby, ECU140 determines injection timing CA9, CA10 and injection time Tall-Tmax, Tmax.

  Other points are the same as in the first embodiment.

((Control in the third control area A103))
The injection timing is selected so that the fresh air mixture in the combustion chamber 63 is concentrated on the intake side at the ignition timing.

  Other points are the same as “((control in second control region A102))”.

((Control in Fourth Control Area A104))
The ECU 140 satisfies the equations (16) to (22), and the injection period (injection timing and injection amount (injection time) is set so that the injection amount at the advance side timing becomes larger than the injection amount at the retard side timing. )) Is set. This is different from the first embodiment.

  For example, in the case shown in FIG. 20, the maximum value of N (integer) that satisfies the equation (21) is N = 2, so N = 2 is first selected as the number of divisions. Then, the injection interval is DI6 from equation (16). This injection interval DI6 satisfies the equation (20). Further, the number of times of injection DN is 3 from the equation (19). If the first injection timing is the advance limit (CA1), the second injection timing is CA19, and the third injection timing is CA20.

  Then, a minimum injection amount (minimum injection time Tmin) is assigned to the injection at each injection timing CA1, CA19, CA20. Next, the injection amount (injection time) at the first injection timing CA1, which is the advance side timing, is changed from the minimum injection amount (minimum injection time Tmin) to the maximum injection amount (maximum injection time Tmax). Further, the injection amount at the second injection timing CA19 is changed to the remaining injection amount (injection time Tall-Tmax-Tmin). The injection amount at the third injection timing CA20, which is the retard side timing, is kept at the minimum injection amount (minimum injection time Tmin). This injection period satisfies the equations (16) to (22), and is within the injectable period (DT). Thereby, ECU140 determines injection timing CA1, CA19, CA20 and injection time Tmax, Tall-Tmax-Tmin, Tmin.

  Other points are the same as in the first embodiment.

(Characteristics of in-cylinder direct injection internal combustion engine)
(1)
Here, the ECU 140 controls the fuel injection valve 27 to inject fuel into the combustion chamber 63 a plurality of times in one cycle. This prevents fuel from adhering to the wall surface 63a of the combustion chamber 63. In addition, since the ECU 140 switches between the dispersion pattern, the anti-EGR pattern, and the anti-knocking pattern according to the operation state, if the fuel injection valve 27 is controlled with the anti-EGR pattern when the EGR is performed, Combustion stabilizes. Thereby, the EGR resistance is improved. Alternatively, when knocking is likely to occur, if the fuel injection valve 27 is controlled with a knocking resistant pattern, the occurrence of knocking is suppressed. Thereby, knocking resistance improves.

  Thus, not only is the fuel prevented from adhering to the wall surface 63a of the combustion chamber 63, but EGR resistance is improved when EGR is performed, and knock resistance is improved when knocking is likely to occur. To do. That is, the fuel is prevented from adhering to the wall surface 63a of the combustion chamber 63, and the EGR resistance and the knocking resistance are improved.

(2)
Here, when controlling the fuel injection valve 27 with a dispersion pattern, the ECU 140 causes the fuel injection valve 27 to supply fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63. Control to inject. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing at which the phase is equally divided with respect to the tumble flow of fresh air in the combustion chamber 63.

  For this reason, the fresh air mixture in the combustion chamber 63 turns at a position where the phase is equally divided in the tumble flow. As a result, the fresh air mixture in the combustion chamber 63 is dispersed at positions where the phases are equally divided in the tumble flow.

(3)
Here, when the ECU 140 controls the fuel injection valve 27 with an anti-EGR pattern / anti-knocking pattern, the fuel injection valve 27 is in the combustion chamber 63 at the same timing as the tumble flow of fresh air in the combustion chamber 63. Control to inject fuel into the inside. Thus, the fuel injection valve 27 injects fuel into the combustion chamber 63 at a timing that is in phase with the tumble flow of fresh air in the combustion chamber 63.

  For this reason, the fresh air mixture in the combustion chamber 63 turns at a position where the phase is the same in the tumble flow. As a result, the fresh air mixture in the combustion chamber 63 is concentrated at the same phase in the tumble flow.

(4)
Here, the EGR device 30 recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51 when the operating state belongs to the second control region A2. The ECU 140 controls the fuel injection valve 27 with an EGR-resistant pattern when the EGR device 30 recirculates a part of the exhaust gas of the exhaust manifold 91 to the intake collector 51. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 in an EGR-resistant pattern when EGR is performed.

  For this reason, even when EGR is performed, the combustion in the combustion chamber 63 is stabilized. As a result, the EGR resistance is improved.

(5)
Here, the EGR device 30 recirculates a part of the exhaust gas in the exhaust manifold 91 to the intake collector 51 when the operating state belongs to the second control region A2. At this time, in the combustion chamber 63, the fresh air mixture may be difficult to ignite, and the combustion speed of the fresh air mixture may be slow. That is, when EGR is performed, the combustion in the combustion chamber tends to become unstable.

  Even in this case, when the EGR device 30 recirculates a part of the exhaust gas of the exhaust manifold 91 to the intake collector 51, the ECU 140 causes the fresh air mixture in the combustion chamber 63 to be near the tip portion 29a of the spark plug 29 at the ignition timing. Control to focus on. As a result, the fresh air mixtures F5, F6, F7, F8, and F9 in the combustion chamber 63 rotate so as to concentrate in the vicinity of the tip portion 29a of the spark plug 29 at the ignition timing. For this reason, since the ignitability and initial combustion speed of the fresh air mixture in the combustion chamber 63 are improved, the combustion in the combustion chamber 63 is stabilized even when EGR is performed. As a result, the EGR resistance is improved.

(6)
Here, the ECU 140 controls the fuel injection valve 27 with a knocking resistant pattern when the engine load is high and the engine speed is slow (when the operating state belongs to the third control region A103). That is, when knocking is likely to occur, ECU 140 controls with a knocking resistant pattern. Thereby, the fuel injection valve 27 injects fuel into the combustion chamber 63 in a knocking-resistant pattern when knocking is likely to occur.

  For this reason, since the combustion period of the fresh air mixture in the combustion chamber 63 is shortened, the occurrence of knocking is suppressed. As a result, the knocking resistance is improved.

(7)
Here, when the engine load is high and the engine speed is slow (when the operating state belongs to the third control region A103), knocking tends to occur on the intake side of the combustion chamber 63 (near the intake valve 21). is there.

  Even in this case, when the engine load is high and the engine speed is slow, the ECU 140 controls the fresh air mixture in the combustion chamber 63 to concentrate on the intake side at the ignition timing. As a result, the fresh air mixture F10, F11, F12, F13, and F14 in the combustion chamber 63 turns so as to concentrate on the intake side at the ignition timing. For this reason, since the combustion period of the fresh air mixture is shortened on the intake side where knocking is likely to occur, the occurrence of knocking is effectively suppressed. As a result, the knocking resistance is improved.

(8)
Here, the ECU 140 performs control so that the number of injections (DN) in the dispersion pattern is equal to or greater than the number of injections (DN) in the anti-EGR pattern / anti-knocking pattern. For this reason, when the fuel injection valve 27 is controlled by the dispersion pattern, the fresh air mixture in the combustion chamber 63 is dispersed. Further, when the fuel injection valve 27 is controlled with an EGR-resistant pattern / anti-knocking-resistant pattern, the fresh air mixture in the combustion chamber 63 is concentrated.

(9)
Here, when controlling the fuel injection valve 27 with the dispersion pattern, the ECU 140 increases the injection amount at the advance side timing compared to the injection amount at the retard side timing. Thereby, since mixing of the fuel injected by the combustion injection valve 27 and fresh air in the combustion chamber 63 is promoted, dispersion of the fresh air mixture in the combustion chamber 63 is promoted.

(10)
Here, when controlling the fuel injection valve 27 with the anti-EGR pattern / anti-knocking pattern, the ECU 140 reduces the injection amount at the advance side timing compared to the injection amount at the retard side timing. Thereby, since mixing with the fuel which the combustion injection valve 27 injected, and the fresh air of the combustion chamber 63 is suppressed, the fresh air mixture in the combustion chamber 63 concentrates effectively.

  The in-cylinder direct injection internal combustion engine according to the present invention has an effect of preventing fuel from adhering to the wall surface of the combustion chamber and improving EGR resistance and knocking resistance. It is useful as an internal direct injection internal combustion engine or the like.

1 is a cross-sectional view of a direct injection type internal combustion engine according to a first embodiment of the present invention. The figure which shows the map information in 1st Embodiment. The timing chart which shows the injection period in case a fuel injection valve injects a fuel with an EGR-proof pattern. The timing chart which shows the injection period in case a fuel injection valve injects a fuel with an EGR-proof pattern. The timing chart which shows the injection period in case a fuel injection valve injects a fuel with an EGR-proof pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in an EGR-proof pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in an EGR-proof pattern. The timing chart which shows the injection period in case a fuel injection valve injects a fuel with a knocking-resistant pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in a knocking-resistant pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in a knocking-resistant pattern. The timing chart which shows the injection period in case a fuel injection valve injects a fuel by a dispersion | distribution pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in a dispersion | distribution pattern. The figure which shows distribution of the fresh air mixture of the combustion chamber in a dispersion | distribution pattern. The flowchart which shows the flow of control in a direct injection type internal combustion engine. The flowchart which shows the flow of an injection period calculation process. The figure which shows the map information in the modification of 1st Embodiment. Sectional drawing of the direct injection type internal combustion engine which concerns on 2nd Embodiment of this invention. The figure which shows the map information in 2nd Embodiment. The timing chart which shows the injection period in case a fuel injection valve injects a fuel with an EGR-proof pattern. The timing chart which shows the injection period in case a fuel injection valve injects a fuel by a dispersion | distribution pattern.

Explanation of symbols

1,100 In-cylinder direct injection internal combustion engine 27 Fuel injection valve 29 Spark plug 29a Tip portion (ignition part)
30 EGR devices 40, 140 ECU (control unit)
63 Combustion chamber

Claims (8)

A combustion chamber;
A fuel injection valve for directly injecting fuel into the combustion chamber;
The first injection pattern for dispersing the fresh air mixture in the combustion chamber and the second injection pattern for concentrating the fresh air mixture in the combustion chamber are switched according to the operating state, and in the combustion chamber in one cycle. A control unit for controlling the fuel injection valve to inject the fuel a plurality of times;
With
When the fuel injection valve is controlled by the first injection pattern, the control unit equally divides the time during which the swirling flow of fresh air in the combustion chamber makes one rotation and divides the injection interval of multiple injections into the equal divisions. When the fuel injection valve controls the fuel injection valve to inject the fuel into the combustion chamber at the timing set to the time, and when the fuel injection valve is controlled by the second injection pattern, a plurality of fresh air in the combustion chamber Controlling the fuel injection valve to inject the fuel into the combustion chamber at the timing when the swirl flow makes one rotation of the injection interval of the round injection ;
In-cylinder direct injection internal combustion engine. An EGR device that recirculates part of the exhaust gas of the exhaust system to the intake system;
The control unit controls the fuel injection valve with the second injection pattern when the EGR device recirculates a part of the exhaust gas of the exhaust system to the intake system.
The in-cylinder direct injection internal combustion engine according to claim 1. An ignition unit for igniting the fresh air mixture in the combustion chamber;
When the EGR device recirculates a part of the exhaust gas of the exhaust system to the intake system, the control unit concentrates the fresh air mixture in the combustion chamber in the vicinity of the ignition unit at the timing when the ignition unit ignites. To control,
The in-cylinder direct injection internal combustion engine according to claim 2. The control unit controls the fuel injection valve with the second injection pattern when the engine load is high and the engine speed is low.
The in-cylinder direct injection internal combustion engine according to claim 1. An ignition unit for igniting the fresh air mixture in the combustion chamber;
The control unit controls the fresh air mixture in the combustion chamber to concentrate on the intake side at a timing when the ignition unit ignites when the engine load is high and the engine speed is low.
The in-cylinder direct injection internal combustion engine according to claim 4. When the control unit controls the fuel injection valve according to the first injection pattern, the fuel injection valve controls the fuel injection valve when the first number of times that the fuel injection valve controls the fuel injection valve to control the fuel injection valve. Control to be equal to or more than the second number of times of spraying
The in-cylinder direct injection internal combustion engine according to any one of claims 1 to 5. When the fuel injection valve is controlled by the first injection pattern, the control unit sets a first injection amount that is an amount by which the fuel injection valve injects the fuel at an advance timing to a retard timing. In the fuel injection valve, the fuel injection valve increases the second injection amount that is an amount of the fuel to be injected.
The in-cylinder direct injection internal combustion engine according to any one of claims 1 to 6. When the fuel injection valve is controlled by the second injection pattern, the control unit sets a first injection amount that is an amount by which the fuel injection valve injects the fuel at an advance timing to a retard timing. The fuel injection valve reduces the fuel injection amount to a second injection amount that is an amount by which the fuel is injected.
The in-cylinder direct injection internal combustion engine according to any one of claims 1 to 7.

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