JP2008196387A - Control device for cylinder injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably inject fuel even when heavy supercharging is performed. <P>SOLUTION: A control device 30 for an internal combustion engine 1 provided with a supercharger and a fuel injection valve 11 directly injecting fuel into a combustion chamber, is provided with injection control means 303, 304 controlling the fuel injection valve to injecting fuel with dividing into a plurality of times of injection in a suction stroke when load and speed of the internal combustion engine is in a low speed and heavy load area, and an injection period setting means 302 setting injection period per one injection shortest injection period or longer but shorter than stable injection period. The fuel injection valve includes a swirl valve forming swirl. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to the technical field of a control device that controls the operation of, for example, a direct injection internal combustion engine that injects fuel directly into a combustion chamber.

  Patent Documents 1 to 4 disclose a cylinder injection type internal combustion engine with a supercharger. In these in-cylinder injection type internal combustion engines, the fuel is injected into the combustion chamber in a plurality of times. By dividing the fuel injection into the combustion chamber into a plurality of times, the fuel combustibility can be improved and the gas temperature of the exhaust gas can be increased. Furthermore, in the cylinder injection type internal combustion engine disclosed in Patent Document 4, when knocking occurs, fuel injection is divided into a plurality of times to suppress the occurrence of knocking.

JP 2000-54894 A JP 2002-2-6446 A JP 2003-161185 A Japanese Patent Laid-Open No. 9-1226028

  On the other hand, when high supercharging is performed by the supercharger, knocking is assumed to occur particularly in a state where the rotational speed of the internal combustion engine is low. For this reason, in order to avoid the occurrence of knocking, it is necessary to shift the ignition timing to the delay side (that is, the top dead center side of the compression process). However, since the ignition timing shifts to the top dead center side of the compression process, it is necessary to ignite in a state where the in-cylinder pressure (that is, the gas pressure in the combustion chamber) has increased, and as a result, the voltage required for ignition is reduced. It will be high. For this reason, if the voltage required for ignition cannot be maintained due to some factor, a technical problem that ignition cannot be performed may occur.

  The present invention has been made in view of, for example, the above-described conventional problems. For example, a control device for a direct injection internal combustion engine that enables fuel injection to be suitably performed even when high supercharging is performed. The issue is to provide.

  A control device for a direct injection internal combustion engine according to the present invention is a control device for an internal combustion engine comprising a supercharger and a fuel injection valve for directly injecting fuel into a combustion chamber, wherein the rotational speed and load of the internal combustion engine Is in the range of low rotation and high load (specifically, the range indicated by the region (a) shown in the drawings to be described later), the fuel is divided into a plurality of times and injected in the intake process. In this way, the injection control means for controlling the fuel injection valve and the injection period per injection of the fuel that is divided and injected into the plurality of times are the lowest that the fuel injection valve can inject the fuel. An injection period setting means that sets the spray injection angle of the injected fuel to be less than a stable injection period that is equal to or longer than a minimum injection period that indicates time, and the fuel injection valve includes a swirl valve that forms a swirl flow Including.

  According to the control device for a direct injection internal combustion engine of the present invention, when the rotation speed and the load are in the range of low rotation and high load by the control of the injection control means (that is, the rotation speed of the internal combustion engine is relatively In the case of high supercharging in a low rotation state), fuel injection is performed in a plurality of times in the intake process. That is, fuel split injection is performed.

  At this time, by the operation of the injection period setting means, the injection period per injection out of a plurality of injections is set to be not less than the minimum injection period and less than the stable injection period. Here, the “minimum injection period” is the minimum injection period necessary for realizing controllable fuel injection in the fuel injection valve, and the fuel injection valve appropriately controls, for example, the injection amount. While indicating the minimum time required to inject fuel. In addition, the “stable injection period” is the minimum injection period required for realizing injection that stabilizes (or maximizes) the fuel spread angle in the combustion chamber. That is, if fuel is injected in an injection period that is equal to or longer than the stable injection period, the fuel spread angle in the combustion chamber is maximized (that is, the fuel is sufficiently dispersed in the combustion chamber), while the injection is less than the stable injection period. If fuel is injected in a period, the spread angle of the fuel in the combustion chamber does not become maximum (that is, the fuel is not sufficiently dispersed in the combustion chamber). In other words, in the present invention, the injection period per fuel injection is set to a time such that the fuel spread angle in the combustion chamber is not stabilized while the fuel injection is suitably controlled. In other words, the injection period per fuel injection is set to such a time that fuel injection is suitably controlled while fuel is not sufficiently dispersed in the combustion chamber.

  Furthermore, in the present invention, since the swirl valve is used as the fuel injection valve, a range that is longer than the minimum injection period and less than the stable injection period as compared to the case where other valves other than the swirl valve are used as the fuel injection valve. This time can be secured relatively large. That is, it can be avoided that the minimum injection period and the stable injection period are substantially the same value. For this reason, as described above, the injection period per injection is suitably set to such a time that fuel injection in the combustion chamber is insufficient while the fuel injection is suitably controlled. be able to.

  Thus, in the present invention, one injection is performed so that fuel is not sufficiently dispersed in the combustion chamber. For this reason, the mixing of the fuel in the combustion chamber deteriorates, and as a result, the combustion speed decreases. Thereby, the ignition timing can be shifted to the advance side (that is, advanced).

  Furthermore, since fuel split injection is performed in the intake process, an increase in the temperature in the combustion chamber (particularly, the gas temperature in the combustion chamber) in the compression step can be suppressed by the vaporization latent heat effect of the fuel in the combustion chamber. For this reason, the temperature in the combustion chamber can be lowered, and as a result, the occurrence of knocking can be avoided or suppressed. Thereby, in order to avoid or suppress the occurrence of knocking, there is almost no need to shift the ignition timing to the delay side (that is, to retard), and as a result, the ignition timing is relatively shifted to the advance side (that is, Advance).

  Thus, according to the present invention, even when high supercharging is performed in a low rotation state, control for avoiding or suppressing knocking by simply shifting the ignition timing to the delay side (so-called retard control). The ignition timing is shifted to the advance side (specifically, the compression timing is shifted from the compression top dead center to the advance side) as compared with the ignition timing when the ignition timing control means described below is performed). Can do. Therefore, ignition can be performed in a state where the in-cylinder pressure is relatively low (that is, a state where the in-cylinder pressure is not increased), and as a result, the voltage required for ignition can be reduced. Thereby, the technical problem that ignition cannot be performed can be preferably solved.

  In one aspect of the control device for a direct injection internal combustion engine of the present invention, the injection period setting means has an injection period of the fuel to be injected last among the fuels divided and injected into the plurality of times. Injecting the last of the fuels divided and injected into the plurality of times so as to be longer than the injection period of the fuel other than the fuel injected last among the fuels divided and injected in the plurality of times Set the fuel injection period.

  According to this aspect, the adjustment of the fuel injection amount is performed in the last one of the plurality of injections. That is, the above-described divided injection can be suitably performed without changing the total amount of injected fuel.

  Furthermore, in consideration of the fact that the last one of the plurality of injections is likely to be performed near the end of the intake process, the latent effect of vaporization of the fuel in the combustion chamber can be relatively enhanced. As a result, the temperature in the combustion chamber can be lowered. As a result, the occurrence of knocking can be avoided or suppressed, and as a result, the ignition timing can be relatively shifted to the advance side (that is, advanced).

  Another aspect of the control apparatus for a direct injection internal combustion engine according to the present invention includes a knocking detection means for detecting the occurrence of knocking, and an ignition timing in the combustion chamber when the occurrence of the knocking is detected. Ignition timing control means for delaying or advancing by a predetermined amount determined according to each of the number and the load, and when the occurrence of knocking is detected, the injection control means The fuel injection valve is controlled so as to change the fuel injection mode according to each of the above.

  According to this aspect, even when the occurrence of knocking is detected, the occurrence of knocking is avoided or suppressed by changing the fuel injection mode according to the state of the rotation speed and the load. be able to. The mode of fuel injection will be described in detail below.

  In the aspect of the control device for the direct injection internal combustion engine that changes the fuel injection mode when the occurrence of knocking is detected as described above, the rotational speed and the load are in the range of low rotation and high load (specifically, If the occurrence of knocking is detected in the region (a range indicated by a region (a) shown in the drawings), the ignition timing control means sets the predetermined amount to 0. The injection period setting means sets an injection period per injection of the fuel to be injected divided into a plurality of times to be not less than the minimum injection period and less than a stable injection period, and the injection control means The fuel injection valve may be controlled to reduce the fuel pressure of the fuel and increase the number of divisions of the fuel injection as compared to a case where the occurrence of knocking is not detected. Good.

  When the rotation speed and load are in the range of low rotation and high load, the ignition timing is shifted to the advance side by split injection as described above. Therefore, if the normal retard control or the like is simply performed due to the occurrence of knocking, the ignition timing shifted to the advance side will be shifted uniformly to the delay side, which is not preferable.

  Therefore, with this configuration, the divided injection in which the injection period per injection is within the minimum injection period and less than the stable injection period is in a state where the fuel pressure is reduced and the number of divided injections is increased. Since it is performed in a state, it is possible to further reduce fuel dispersion due to a decrease in fuel pressure while maintaining the fuel injection amount. Thereby, since the combustion speed can be further reduced, MBT (Minimum spark advance for Best Torque) shifts to the advance side. On the other hand, since the ignition timing is not shifted to the delay side or the advance side, the amount of ignition timing delay with respect to MBT increases. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state where the ignition timing is shifted to the delay side by the retard control. Thereby, the occurrence of knocking can be avoided or suppressed. On the other hand, the above-described split injection maintains the state in which the absolute ignition timing is shifted to the advance side (specifically, the state shifted from the compression top dead center to the advance side). Can be ignited in a relatively low state, and as a result, the voltage required for ignition can be lowered.

  In the aspect of the control device for the direct injection internal combustion engine in which the injection control means controls the fuel injection valve so as to reduce the fuel pressure as described above, the injection control means changes the state of the intake valve from the open state to the closed state. You may comprise so that the said fuel injection valve may be controlled so that the injection of the said fuel may be complete | finished at a time.

  With this configuration, fuel can be injected until the intake valve is closed, so that fuel can be injected even in a part of the compression process following the intake process. Thereby, since the combustion speed can be further reduced, MBT (Minimum spark advance for Best Torque) shifts to the advance side. For this reason, as described above, while avoiding or suppressing the occurrence of knocking, it is possible to suitably enjoy the effect that the voltage required for ignition can be lowered.

  Furthermore, since the end timing of injection is matched with the time when the intake valve is closed, the start timing of injection can be relatively delayed. Thereby, generation | occurrence | production of the smoke by the adhesion of the fuel to a piston top surface can be avoided or suppressed. Furthermore, in the intake process, considering that the fuel dispersion in the combustion chamber may be promoted by the agitation effect due to the airflow (in other words, the effect of suppressing the fuel spread angle may be reduced), the injection start timing is set. By relatively delaying, fuel can be injected even in a part of the compression process, and as a result, a state where fuel dispersion is insufficient can be realized more suitably. Thereby, the combustion rate can be further reduced.

  In the aspect of the control apparatus for the direct injection internal combustion engine that changes the fuel injection mode when the occurrence of knocking is detected as described above, the rotation speed and the load are changed from low rotation and medium load to medium rotation and medium high. When the occurrence of knocking is detected in the range of the load (specifically, the range shown in the region (b) shown in the drawings described later), the ignition timing control means The timing is delayed by a second predetermined amount that is smaller than the first predetermined amount that is the predetermined amount when the rotational speed and the load are in the range of low rotation and high load, and the injection period setting means The injection period per injection of the fuel that is injected in a divided manner is set to be not less than the minimum injection period and less than the stable injection period, and the injection control means may cause the fuel to be injected a plurality of times in the intake process. Split It may be configured to control the fuel injection valve to inject Te.

  If comprised in this way, dispersion | distribution of a fuel can be made insufficient by the division | segmentation injection from which the injection period per injection becomes the time more than the minimum injection period and less than the stable injection period. As a result, the combustion speed can be reduced, so that the MBT shifts toward the advance side. For this reason, the amount of delay of the ignition timing with respect to MBT increases. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state where the ignition timing is shifted to the delay side by the retard control. Thereby, the occurrence of knocking can be avoided or suppressed.

  On the other hand, the ignition timing is shifted to the delay side by a relatively small second predetermined amount. Specifically, the ignition timing is shifted to the delay side by a second predetermined amount that is smaller than the first predetermined amount used when the rotation speed and load are in the range of low rotation and high load. Even if the rotation speed and load are in the range of low rotation and medium load to medium rotation and medium and high load, ignition is performed by the first predetermined amount used when the rotation speed and load are in the range of low rotation and high load. If the timing is shifted to the delay side, the supercharging pressure increases due to an increase in the exhaust gas temperature, and as a result, the occurrence of knocking cannot be avoided or suppressed. However, according to the present invention, since the ignition timing is shifted to the delay side by a relatively small second predetermined amount, an increase in the supercharging pressure can be suppressed by suppressing an increase in the exhaust gas temperature, As a result, the occurrence of knocking can be avoided or suppressed.

  In the aspect of the control device for the direct injection internal combustion engine that changes the fuel injection mode when the occurrence of knocking is detected as described above, the rotational speed and the load are changed from the medium rotation and the high load to the high rotation and the high load. When the occurrence of knocking is detected in the range of the load (specifically, the range shown in the region (c) shown in the drawings described later), the ignition timing control means The timing is delayed by a second predetermined amount smaller than the first predetermined amount that is the predetermined amount when the rotation speed and the load are low rotation and high load, and the injection period setting means is divided into the plurality of times The injection period per one injection of the fuel to be injected is set to be equal to or longer than the stable injection period, and the injection control means injects the fuel divided into a plurality of times in the intake step Fuel injection It may be configured to control the valve.

  If comprised in this way, dispersion | distribution of fuel can fully be performed by the division | segmentation injection from which the injection period per injection becomes more than a stable injection period. The ignition timing is shifted to the delay side by a relatively small second predetermined amount. Thereby, it is possible to improve the knock margin by increasing the combustion speed, and it is possible to suppress the increase in the supercharging pressure by suppressing the increase in the exhaust gas temperature. As a result, the occurrence of knocking can be avoided or suppressed.

  In order to suppress an increase in the exhaust gas temperature, a measure for increasing or decreasing the total fuel injection amount may be considered. However, when the total fuel injection amount is increased, the smoke emission amount increases, and when the total fuel injection amount is decreased, the combustion becomes unstable (that is, high supercharging). Therefore, ignition failure occurs), which is not preferable. Therefore, as described above, it is preferable that fuel is sufficiently dispersed by split injection in which the injection period per injection is equal to or longer than the stable injection period.

  In the aspect of the control apparatus for the direct injection internal combustion engine that changes the fuel injection mode when the occurrence of knocking is detected as described above, the rotational speed and the load are low to medium and low to high. When the occurrence of knocking is detected in the middle load range (specifically, the range shown in the region (d) shown in the drawings to be described later), the ignition timing control means The second position which is the predetermined amount when the rotation speed and the load are in the range of low rotation and medium load to medium rotation and medium high load or in the range of medium rotation and high load to high rotation and high load. You may comprise so that it may delay by 1st predetermined amount larger than fixed_quantity | quantitative_assay.

  When the rotation speed and the load are in the range from low to medium rotation and low load to high rotation and medium load, both the ignition request voltage and the exhaust gas temperature have a margin. Therefore, the occurrence of knocking can be avoided or suppressed by shifting the ignition timing to the delay side by a relatively large first predetermined amount.

  In the aspect of the control apparatus for the direct injection internal combustion engine having the knocking detection means as described above, when the rotation speed and the load are in the range of low rotation and high load, or from low rotation and medium load to medium rotation and medium high load. When the occurrence of knocking is detected in the range, the apparatus further includes a determination unit that determines whether or not the occurrence of knocking is avoided, and when the determination by the determination unit is performed, the injection period The setting means may be configured to set an injection period per injection of the fuel to be injected divided into a plurality of times to be equal to or longer than the stable injection period.

  If comprised in this way, dispersion | distribution of fuel can fully be performed by the division | segmentation injection from which the injection period per injection becomes more than a stable injection period. Thereby, since a combustion rate can be increased, MBT shifts to the delay side. That is, MBT can be brought close to the absolute position of the ignition timing. For this reason, the delay amount of the ignition timing with respect to MBT is reduced. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state where the ignition timing is shifted to the advance side by the retard control. Thereby, it can be suitably determined whether or not the occurrence of knocking is avoided.

  If the determination by the determination means is performed and the ignition timing control means shifts the absolute position of the ignition timing to the advance side, the fuel is steamed from the early combustion due to the advance of the ignition timing, and as a result , Smoke emissions will increase. Therefore, when the determination by the determination means is performed, the ignition timing is shifted to the advanced side by the retard control due to the increase in the combustion speed caused by setting the injection period per injection to be equal to or longer than the stable injection period. It is preferable to realize the same state as the above state.

  In the aspect of the control device for the direct injection internal combustion engine provided with the knocking detection means as described above, when the rotation speed and the load are in the range of medium rotation and high load to high rotation and high load, or low and medium rotation and low And determining means for determining whether or not the occurrence of knocking has been avoided after the occurrence of knocking is detected in a range of high rotation and medium load from the load, and the determination by the determining means is performed. In this case, the ignition timing control means may be configured to advance the delayed ignition timing.

  If comprised in this way, it can be determined suitably whether generation | occurrence | production of knocking was avoided.

  The operation and other advantages of the present invention will become more apparent from the embodiments described below.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In the following embodiments, description will be given of a case where the control device for a direct injection internal combustion engine of the present invention is applied to a direct injection type engine.

(1) Basic Configuration First, the basic configuration of the in-cylinder injection engine according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a block diagram conceptually showing the basic configuration of the in-cylinder injection engine according to this embodiment. FIG. 2 is a conceptual cross-sectional view of the in-cylinder injection engine according to this embodiment. FIG. 3 is a cross-sectional view conceptually showing a cross section of an injector provided in the direct injection type engine according to the present embodiment.

  As shown in FIG. 1, the cylinder head portion of the cylinder 2 of the direct injection type engine 1 according to the present embodiment is provided with an injector 11 together with a spark plug (not shown) for each cylinder.

  As shown in FIG. 2, the injector 11 is attached to the cylinder 2 at an angle, for example, and injects fuel directly into the cylinder 2 (that is, in the combustion chamber). Further, for example, a cavity 6 is formed at the top of the piston 5 that reciprocates in the cylinder 2. The fuel injected from the injector 11 flows through the cylinder 2 as a swirl flow or a tumble flow through the cavity 6.

  Further, as shown in FIG. 3, the injector 11 includes a swirl valve that injects fuel from the injection hole 113 after a swirl flow is formed in the sack portion 112. In the present embodiment, a groove is provided in the needle 111 of the injector 11, and a swirling flow is formed by the fuel flowing into the sack portion 112 through the groove.

  In FIG. 1 again, the fuel is supplied to the injector 11 via the fuel supply unit 14. More specifically, the fuel supply unit 14 is connected to the fuel tank 16 while being connected to the injector 11 via the fuel pipe 15. The fuel supply unit 14 includes, for example, a high-pressure fuel pump (not shown), and high-pressure fuel can be supplied to the injector 11 by the high-pressure fuel pump. At this time, the fuel supply unit 14 includes a pressure regulating valve that regulates the fuel supplied from the high-pressure fuel pump to a desired pressure. The fuel whose pressure is adjusted in the pressure regulating valve is supplied to the injector 11 and then injected into the cylinder 2 at the pressure adjusted in the pressure regulating valve (or at a pressure corresponding to the pressure adjusted in the pressure regulating valve). .

  The fuel injection operation from the injector 11 is controlled by the operation of the ECU 30 (particularly, the operation of the injection period setting unit 302, the injection number setting unit 303, the injection control unit 304, etc. provided in the ECU 30). The operation of a spark plug (not shown) is controlled by the operation of the ECU 30 (particularly, the operation of the ignition timing control unit 305 and the like provided in the ECU 30). The operation of the fuel supply unit 14 (that is, the pressure adjustment) is controlled by the operation of the ECU 30 (particularly, the operation of the fuel pressure setting unit 301 provided in the ECU 30). Details of these operations will be described later (see FIG. 4 and the like).

  Then, the air taken into the combustion chamber 5 through the intake manifold 3 and the intake port 7 (see FIG. 2) and the fuel injected from the injector 11 are mixed in the combustion chamber 5, and an unillustrated spark plug is connected. By sparking, the mixed gas burns in the combustion chamber 5. The exhaust gas after combustion is discharged to the outside of the in-cylinder injection type engine 1 through the exhaust port 8 (see FIG. 2) and the exhaust manifold 4.

  Under the present circumstances, the knocking sensor 12 is provided for the cylinder head part of the cylinder 2 of the cylinder injection type engine 1 which concerns on this embodiment for every cylinder. The knocking sensor 12 can detect the occurrence of knocking for each cylinder. When the occurrence of knocking is detected, a knocking detection signal indicating that the occurrence of knocking has been detected is output from the knocking sensor 12 to the ECU 30.

  Further, as shown in FIG. 1, the direct injection engine 1 includes an exhaust turbine 21, a compressor 22, a rotor shaft 23, an air cleaner 24, and an intercooler 25.

  Exhaust gas discharged from the cylinder 2 of the in-cylinder injection engine 1 is sprayed to the exhaust turbine 21 via the exhaust manifold 4. The exhaust turbine 21 is rotated by the exhaust gas. As the exhaust turbine 21 rotates, the compressor 22 connected to the exhaust turbine 21 via the rotor shaft 23 also rotates in the same manner. At this time, the intake air supplied to the compressor 12 via the air cleaner 24 is compressed by the rotation of the compressor 22 and then passes through the intercooler 25 and the temperature thereof is lowered. Thereafter, the compressed intake air is supplied into the cylinder 2 of the direct injection engine 1 through the intake manifold 3.

  The injector 11 constitutes one specific example of the “fuel injection valve” in the present invention, and the fuel pressure setting unit 301, the injection number setting unit 303, and the injection control unit 304 of the “injection control means” in the present invention. One specific example is configured, the injection period setting unit 302 is one specific example of the “injection period setting unit” in the present invention, and the ignition timing control unit 305 is the “ignition timing control unit” in the present invention. The knocking sensor 12 constitutes a specific example of “knocking detection means” and “determination means” in the present invention.

(2-1) First Operation Example Next, a first operation example (particularly, an operation related to fuel injection) of the direct injection type engine 1 according to the present embodiment will be described with reference to FIGS. 4 to 8. Proceed. FIG. 4 is a flowchart conceptually showing an overall flow of the first operation example of the direct injection type engine 1 according to the present embodiment, and FIG. 5 is a range of low rotation and high load. FIG. 6 is a graph conceptually showing the region (a), FIG. 6 is a graph conceptually showing an injection period-injection amount (spray spread angle) characteristic in fuel injection from the injector 11, and FIG. 8 is a timing chart conceptually showing respective modes of split injection and batch injection, and FIG. 8 is a graph showing combustion speed, knock margin and ignition timing when fuel split injection and batch injection are performed, respectively. It is.

  As shown in FIG. 4, first, the operation of the ECU 30 determines whether the current load (that is, torque) and rotational speed of the in-cylinder injection engine 1 are in the range of low rotation and high load (that is, , Whether or not it is in the area (a)) is determined (step S101).

  Here, with reference to FIG. 5, the description will be made on the region (a) which is a range of low rotation and high load.

  The operating state of the direct injection engine 1 according to the present embodiment can be specified by the load (torque) and the rotational speed. As shown in FIG. 5, the region (a) is a region indicating that the load and the rotational speed of the direct injection type engine 1 according to the present embodiment are in a low rotation state and a high load state. When the load and the rotational speed of the direct injection engine 1 according to the present embodiment are in the region (a), the ignition timing is generally shifted to the delay side (that is, the compression top dead center side).

  The specific numerical values of the region (a) are the specifications and characteristics of the in-cylinder injection engine 1 according to the present embodiment (further, the various component parts included in the in-cylinder injection engine 1 according to the present embodiment). Specifications and characteristics), and the specifications and characteristics of the vehicle including the in-cylinder injection engine 1 according to the present embodiment, for each in-cylinder injection engine 1 according to the present embodiment or in-cylinder injection type according to the present embodiment. It is preferably set in advance for each vehicle including the engine 1. And it is preferable that the mapping (load-rotation number mapping) which can identify such an area | region (a) is stored in the memory in ECU30. The determination in step S101 is preferably performed based on this mapping.

  In FIG. 4 again, if it is determined as a result of the determination in step S101 that the current load and rotation speed of the direct injection engine 1 are in the region (a) (step S101: Yes), the injector 11 The fuel injection is performed in a state divided into a plurality of times. That is, fuel injection is continuously performed a plurality of times from the injector 11. In this case, first, an injection period per one fuel injection is set by the operation of the injection period setting unit 302 (step S102).

  Here, the setting operation of the injection period per injection will be described with reference to FIG.

  As shown in FIG. 6, due to the specifications of the injector 11, the injection period and the injection amount do not have a proportional relationship until the injection period exceeds the minimum injection period etau_min. That is, when the injection period is equal to or shorter than the minimum injection period etau_min, it is difficult to control the injection amount, so the injection period needs to be set to be equal to or longer than the minimum injection period etau_min. If the injection period is equal to or longer than the minimum injection period etau_min, the injection period and the injection amount have a substantially proportional relationship, so that the injection amount can be controlled by the injection period.

  On the other hand, the spray spread angle (that is, the spread angle of the fuel injected from the injector 11 in the combustion chamber) has a relatively short injection period (specifically, the injection period is equal to or less than the minimum injection period etau_min + α). In some cases, it becomes larger as the injection period becomes longer. Therefore, when fuel is injected with a relatively short injection period, fuel dispersion in the combustion chamber is insufficient. When the injection period is relatively long (specifically, the injection period is not less than the minimum injection period etau_min + α), the spray spread angle is substantially constant regardless of the length of the injection period. Therefore, when fuel is injected with a relatively long injection period, the fuel in the combustion chamber is sufficiently dispersed.

  In the present embodiment, the operation of the injection period setting unit 302 sets the injection period per injection to be equal to or longer than the minimum injection period etau_min and less than the minimum injection period etau_min + α. That is, in the present embodiment, the injection period per injection is set to a period that can realize a state where fuel is not sufficiently dispersed in the combustion chamber.

  In FIG. 4 again, subsequently, the number of fuel injections is set by the operation of the injection number setting unit 303 (step S103). Here, based on the total amount of fuel to be injected into the combustion chamber and the injection amount per fuel injection derived from the injection period per fuel injection set in step S102, The number of times is set. Specifically, the number of fuel injections is set by dividing the total amount of fuel to be injected into the combustion chamber by the injection amount per injection. For example, if the total amount of fuel to be injected into the combustion chamber is 0.65 ml and the injection amount per fuel injection is 0.13 ml, the number of fuel injections is 0.5 / 0.13 = 5. Set to times.

It should be noted that, based on the total amount of fuel to be injected into the combustion chamber and the injection amount per injection, it is sufficiently conceivable that fractions are generated by simple division. For example, the case where the total amount of fuel to be injected into the combustion chamber is 0.55 ml and the injection amount per injection is 0.13 ml is considered as an example. In this case, it is preferable to increase the injection period (that is, the injection amount) in the last one injection among the plurality of injections. In other words, the total amount of fuel actually injected into the combustion chamber is injected into the combustion chamber by increasing the injection period (that is, the injection amount) in the last one injection among the plurality of injections. It is preferable to match the total amount of fuel to be used. For example, after performing the first to third injections by setting the injection period so that the injection amount becomes 0.13 ml, the final (that is, the fourth) injection becomes the injection amount 0.16 ml. Thus, it is preferable to set the injection period. That means
Thereafter, an injection start timing, which is a timing for starting fuel injection, is set (step S104). It is preferable that an appropriate timing is set as the injection start timing so that fuel injection is performed at a timing at which fuel injection is completed in the intake process.

  Thereafter, by the operation of the injection control unit 304, based on the injection period per injection set in step S102, the number of fuel injections set in step S103, and the injection start time set in step S104, The operation of the injector 11 is controlled so that fuel split injection is actually performed (step S105). As a result, fuel is injected from the injector 11 into the combustion chamber.

  On the other hand, as a result of the determination in step 101, when it is determined that the current load and rotation speed of the direct injection type engine 1 are not in the region (a) (step S101: No), the fuel injection from the injector 11 is performed. Is performed in a collective state (step S106). That is, fuel injection is performed only once from the injector 11. In this case, the total amount of fuel injected into the combustion chamber is the same as when split injection is performed.

  Here, with reference to FIG. 7, the respective modes of fuel split injection and batch injection will be described in more detail.

  As shown in the upper side of FIG. 7, when fuel split injection is performed, the injection control unit 304 operates so that the injection period per injection is not less than the minimum injection period etau_min and the minimum injection period etau_min + α. A plurality of drive pulses for driving the injector 11 are generated so as to be less. The plurality of generated drive pulses are output from the injection control unit 304 to the injector 11. Here, an example in which fuel is injected from the injector 11 at the timing when the drive pulse is in the ON state will be described.

  Similarly, as shown in the lower side of FIG. 7, when the fuel is collectively injected, the operation of the injection control unit 304 causes the total amount of fuel to be injected into the combustion chamber to be injected at a time. As realized, one drive pulse for driving the injector 11 is generated. One generated drive pulse is output from the injection control unit 304 to the injector 11.

  As described above, according to the present embodiment, the injection period per injection is a time during which the fuel is suitably dispersed while the fuel is not sufficiently dispersed in the combustion chamber. Set to

  Further, in the present embodiment, since the injector 11 includes a swirl valve, the minimum injection period etau_min and the minimum injection period are compared with the case where a valve other than the swirl valve is used for the injector 11. A relatively large range of less than etau_min + α can be secured. In other words, it is possible to avoid a state where the period α approaches zero as much as possible (that is, the period α is relatively long). For this reason, as described above, the injection period per injection is suitably set to such a time that fuel injection in the combustion chamber is insufficient while the fuel injection is suitably controlled. be able to.

  Thus, in the present embodiment, when fuel split injection is performed, one injection is performed so that fuel is not sufficiently dispersed in the combustion chamber. For this reason, the mixing of the fuel in the combustion chamber is deteriorated. As a result, as shown in FIG. 8A, the combustion speed is reduced as compared with the case where the fuel is collectively injected. Thereby, the ignition timing can be shifted to the advance side (that is, advanced).

  Furthermore, since fuel split injection is performed in the intake process, an increase in the temperature in the combustion chamber (particularly, the gas temperature in the combustion chamber) in the compression step can be suppressed by the vaporization latent heat effect of the fuel in the combustion chamber. For this reason, the temperature in the combustion chamber can be lowered, and as a result, the occurrence of knocking can be avoided or suppressed. Specifically, as shown in FIG. 8B, the knock margin (that is, the MBT-ignition timing) can be made smaller than in the case where the fuel is injected all at once. Thereby, in order to avoid or suppress the occurrence of knocking, there is almost no need to shift the ignition timing to the delay side (that is, retard), and as a result, the ignition timing is relatively shifted to the advance side (that is, Advance).

  Thus, according to the present embodiment, even when high supercharging is performed in a low rotation state (that is, when the load and the rotation speed of the direct injection engine 1 are in the region (a)), FIG. As shown in (c), the ignition timing is shifted to the advance side as compared with the case where the fuel is collectively injected (specifically, the ignition timing is shifted from the compression top dead center to the BDC side which is the advance side). Can do. Therefore, ignition can be performed in a state where the in-cylinder pressure is relatively low (that is, a state where the in-cylinder pressure is not increased), and as a result, the voltage required for ignition can be reduced. Thereby, the technical problem that ignition cannot be performed can be preferably solved.

  In addition, according to the present embodiment, the total amount of fuel actually injected into the combustion chamber by increasing the injection period (that is, the injection amount) in the last one injection among the plurality of injections. Can be matched to the total amount of fuel to be injected into the combustion chamber. Thereby, the above-described divided injection can be suitably performed without changing the total amount of fuel injected into the combustion chamber. Furthermore, in consideration of the fact that the last one of the plurality of injections is likely to be performed near the end of the intake process, the latent effect of vaporization of the fuel in the combustion chamber can be relatively enhanced. As a result, the temperature in the combustion chamber can be lowered. Thereby, since the occurrence of knocking can be avoided or suppressed, the ignition timing can be relatively shifted to the advance side (that is, advanced).

(2-2) Second Operation Example Next, a second operation example of the direct injection type engine 1 according to the present embodiment will be described with reference to FIGS. 9 to 14. FIG. 9 is a flowchart conceptually showing an overall flow of the second operation example of the direct injection type engine 1 according to the present embodiment. FIG. 10 is specified by the load (torque) and the rotational speed. 11 is a graph conceptually showing an operating state of the in-cylinder injection type engine 1. FIG. 11 is a graph conceptually showing fuel pressure reduction control, and FIG. 12 is an injection in fuel injection from the injector 11. FIG. 13 is a graph conceptually showing a period-injection amount (spray spread angle) characteristic, FIG. 13 is a timing chart conceptually showing an aspect of fuel injection in the second operation example, and FIG. It is a graph which shows retard amount.

  The second operation example shows an operation when the occurrence of knocking is detected when the first operation example is performed. This second operation example may be performed in parallel with the first operation example described above, or may be performed subsequent to the first operation example. In the flowchart shown in FIG. 9, the description of the first operation example is omitted, but actually, the first operation example is performed in parallel with the operation of FIG. 9, or in step S201 in FIG. The first operation example is performed in the previous stage.

  As shown in FIG. 9, first, it is determined whether or not knocking has occurred by monitoring the output of the knocking sensor 12 by the operation of the ECU 30 (step S201).

  As a result of the operation in step S201, when it is determined that knocking has not occurred (step S201: No), the operation is terminated.

  On the other hand, if it is determined that knocking has occurred as a result of the operation in step S201 (step S201: Yes), then the current load and speed of the in-cylinder injection engine 1 are determined by the operation of the ECU 30. Is in the range of low rotation and high load (that is, whether it is in the region (a)) (step S202). That is, the same operation as step S101 in the first operation example is performed.

  As shown in FIG. 10, the region (a) in step S <b> 202 of FIG. 9 indicates that the load and the rotational speed of the direct injection type engine 1 according to the present embodiment are in a low rotation state and a high load state. This is a region that is substantially the same as the region (a) in FIG.

  Further, specific numerical values and the like of the region (a) (further, the region (b), the region (c), and the region (d) described later) are the specifications and characteristics of the direct injection engine 1 according to the present embodiment. (Furthermore, according to the specifications and characteristics of various components included in the in-cylinder injection engine 1 according to the present embodiment) and the specifications and characteristics of the vehicle including the in-cylinder injection engine 1 according to the present embodiment. It is preferably set in advance for each in-cylinder injection engine 1 according to the embodiment or for each vehicle including the in-cylinder injection engine 1 according to the present embodiment. And mapping (load-rotation speed mapping) which can identify such an area | region (a), an area | region (b), an area | region (c), and an area | region (d) is stored in the memory in ECU30. preferable. The determination in step S202 (further, step S212, step S222, and step S232 described later) is preferably performed based on this mapping.

  As a result of the determination in step S202, when it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (a) (step S202: Yes), subsequently, the fuel pressure setting unit 301 The fuel pressure reduction control is performed by the operation (step S203). Specifically, as shown in FIG. 11, the fuel pressure is set to a fuel pressure FP_B that is smaller than the fuel pressure in the first operation example (the fuel pressure used in operations other than the operations in steps S203 to S207) FP_A. The fuel pressure set here is output to the fuel supply unit 14, and the fuel supply unit 14 controls the pressure regulating valve so as to supply the fuel at the set fuel pressure.

  Subsequently, in the same manner as the operation in step S102 in the first operation example, the injection period per one fuel injection is set by the operation of the injection period setting unit 302 (step S204). Here, as in the operation of step S102 in the first operation example, the injection period per one fuel injection is the injection period A shown in FIG. 12 (that is, the minimum injection period etau_min and the minimum injection period etau_min + α). Is set to a period that is less than).

  Thereafter, in the same manner as the operation in step S103 in the first operation example, the number of fuel injections is set by the operation of the injection number setting unit 303 (step S205).

  Subsequently, an injection start timing which is a timing at which fuel injection is started is set (step S206). Here, the injection start timing is set so that the import valve 7 changes from the open state to the closed state almost simultaneously with the end of the last injection of the plurality of injections. In other words, the end timing of the last injection of the plurality of injections is set first, and the injection start timing is set by calculating backward from there.

  Thereafter, similarly to the operation in step S105 in the first operation example, the operation of the injection control unit 304 causes the fuel pressure FP_A set in step S203, the injection period A per injection set in step S204, and step S205. Based on the number of fuel injections set in step S1 and the injection start timing set in step S206, the operation of the injector 11 is controlled so that split fuel injection is actually performed (step S207).

  Specifically, as shown in the upper side of FIG. 13, the operation of the injection control unit 304 causes the injection period per injection to be not less than the minimum injection period etau_min and less than the minimum injection period etau_min + α, and multiple times A plurality of drive pulses for driving the injector 11 are generated so that the import valve 7 changes from the open state to the closed state almost simultaneously with the end of the last injection. The plurality of generated drive pulses are output from the injection control unit 304 to the injector 11. As a result, fuel is injected from the injector 11 into the combustion chamber.

  On the other hand, as a result of the determination in step S202, when it is determined that the current load and rotation speed of the direct injection engine 1 are not in the region (a) (step S202: No), the operation of the ECU 30 is subsequently performed. Therefore, whether or not the current load and the rotational speed of the direct injection type engine 1 are in the range of low rotation and medium load to medium rotation and medium and high load (that is, whether or not in the region (b) shown in FIG. 10) Is determined (step S212).

  As a result of the determination in step S212, when it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (b) (step S212: Yes), subsequently, the ignition timing control unit 305 By this operation, the ignition timing is controlled so as to shift to the delay side by a relatively small retardation amount A shown in FIG. 14 (step S213). That is, retard control is performed.

  Subsequently, the injection period per one fuel injection is set by the operation of the injection period setting unit 302, similarly to the operation of step S102 in the first operation example (step S214). Here, as in the operation of step S102 in the first operation example, the injection period per one fuel injection is the injection period A shown in FIG. 12 (that is, the minimum injection period etau_min and the minimum injection period etau_min + α). Is set to a period that is less than).

  Thereafter, the number of times of fuel injection is set by the operation of the injection number setting unit 303, similarly to the operation of step S103 in the first operation example (step S215).

  Subsequently, an injection start timing, which is a timing at which fuel injection is started, is set (step S216). Here, it is preferable to set an appropriate timing as the injection start timing so that the fuel injection is performed at a timing at which the fuel injection is completed in the intake process.

  Thereafter, similarly to the operation in step S105 in the first operation example, the injection control unit 304 operates to inject the injection period A per injection set in step S214 and the number of fuel injections set in step S215. Based on the injection start timing set in step S216, the operation of the injector 11 is controlled so that the divided fuel injection is actually performed (step S217). That is, the operation of the injector 11 is controlled so that the fuel split injection is performed in a manner substantially similar to the fuel split injection in the first operation example.

  Specifically, as shown in the middle of FIG. 13, the injection control unit 304 operates so that the injection period per injection is equal to or longer than the minimum injection period etau_min and less than the minimum injection period etau_min + α. A plurality of drive pulses for driving the injector 11 are generated. The plurality of generated drive pulses are output from the injection control unit 304 to the injector 11. As a result, fuel is injected from the injector 11 into the combustion chamber.

  On the other hand, as a result of the determination in step S212, when it is determined that the current load and rotation speed of the direct injection engine 1 are not in the region (b) (step S212: No), the operation of the ECU 30 is subsequently performed. Thus, whether or not the current load and rotation speed of the direct injection engine 1 are in the range of medium rotation and high load to high rotation and high load (that is, in the region (c) shown in FIG. 10). Is determined (step S222).

  As a result of the determination in step S222, when it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (c) (step S222: Yes), the operation of step S213 is subsequently performed. Similarly, by the operation of the ignition timing control unit 305, the ignition timing is controlled so as to shift to the delay side by a relatively small retardation amount A shown in FIG. 14 (step S223).

  Subsequently, an injection period per one fuel injection is set by the operation of the injection period setting unit 302 (step S224). Here, the injection period per fuel injection is set to the injection period B shown in FIG. 12 (that is, the period that is equal to or longer than the minimum injection period etau_min + α).

  Thereafter, the number of times of fuel injection is set by the operation of the injection number setting unit 303 in the same manner as the operation of step S103 in the first operation example (step S225).

  Subsequently, similarly to the operation in step S216, an injection start timing that is a timing at which fuel injection is started is set (step S226). Here, similarly to the operation in step S216, it is preferable to set an appropriate timing as the injection start timing so that the fuel injection is performed at a timing at which the fuel injection is completed in the intake process.

  Thereafter, in the same manner as the operation in step S105 in the first operation example, the operation of the injection control unit 304 causes the injection period B per injection set in step S224, and the number of fuel injections set in step S225. Based on the injection start timing set in step S226, the operation of the injector 11 is controlled so that the divided fuel injection is actually performed (step S227).

  Specifically, as shown in the lower side of FIG. 13, by the operation of the injection control unit 304, a plurality of units for driving the injector 11 so that the injection period per injection becomes equal to or longer than the minimum injection period etau_min + α. Drive pulses are generated. For this reason, the pulse width of one drive pulse is larger than the pulse width of the drive pulse generated by the operation of step S217. The plurality of generated drive pulses are output from the injection control unit 304 to the injector 11. As a result, fuel is injected from the injector 11 into the combustion chamber.

  On the other hand, as a result of the determination in step S222, when it is determined that the current load and rotation speed of the direct injection type engine 1 are not in the region (c) (step S222: No), the operation of the ECU 30 is subsequently performed. Therefore, whether or not the current load and the rotational speed of the direct injection type engine 1 are in the range of low and medium rotations and low loads to high and medium loads (that is, in the region (d) shown in FIG. 10). No) is determined (step S232).

  As a result of the determination in step S232, when it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (d) (step S232: Yes), the ignition timing control unit 305 is subsequently performed. By this operation, the ignition timing is controlled so as to shift to the delay side by the relatively large retardation amount B shown in FIG. 14 (step S233). That is, the ignition timing is shifted further to the retard side than the ignition timing shifted to the retard side in steps S213 and S223. In this case, the fuel may not be divided and injected.

  On the other hand, as a result of the determination in step S232, when it is determined that the current load and rotation speed of the direct injection engine 1 are not in the region (d) (step S232: No), the operation is terminated.

  As described above, according to the second operation example, when knocking is detected, the occurrence of knocking is suppressed by changing the fuel injection mode according to the state of the rotation speed and the load. It can be avoided or suppressed. Hereinafter, the operation according to each state of the rotation speed and the load and the effect thereof will be described in more detail.

  First, when the rotation speed and load are in the range of low rotation and high load (that is, region (a)), the ignition timing is shifted to the advance side by the divided injection shown in the first operation example. Therefore, if the normal retard control or the like is simply performed due to the occurrence of knocking, the ignition timing shifted to the advance side will be shifted uniformly to the delay side, which is not preferable.

  Accordingly, in the second operation example, split injection in which the injection period per injection is the injection period A is performed in a state where the fuel pressure is reduced and the number of split injections is increased. While maintaining the injection amount, it is possible to further reduce fuel dispersion due to a decrease in fuel pressure. As a result, the combustion speed can be further reduced, so that the MBT shifts toward the advance side. On the other hand, since the ignition timing is not shifted to the delay side or the advance side, the amount of ignition timing delay with respect to MBT increases. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state where the ignition timing is shifted to the delay side by the retard control. Thereby, the occurrence of knocking can be avoided or suppressed. On the other hand, the above-described split injection maintains the state in which the absolute ignition timing is shifted to the advance side (specifically, the state shifted from the compression top dead center to the advance side). Can be ignited in a relatively low state, and as a result, the voltage required for ignition can be lowered.

  Further, since the fuel can be injected until the intake valve 7 is closed, the fuel can be injected even in a part of the compression process following the intake process. As a result, the combustion speed can be further reduced, so that the MBT shifts toward the advance side. For this reason, as described above, while avoiding or suppressing the occurrence of knocking, it is possible to suitably enjoy the effect that the voltage required for ignition can be lowered.

  Furthermore, since the end timing of injection is matched with the time when the intake valve is closed, the start timing of injection can be relatively delayed. Thereby, generation | occurrence | production of the smoke by the adhesion of the fuel to the top part of piston 5 can be avoided or suppressed. Furthermore, in consideration of the fact that in the intake process, the dispersion of the fuel in the combustion chamber may be promoted by the stirring effect due to the airflow (in other words, the effect of suppressing the fuel spread angle may be reduced), the injection start time By relatively delaying, it is possible to inject fuel even in a part of the compression process, and as a result, it is possible to more suitably realize a state where fuel dispersion is insufficient. Thereby, the combustion rate can be further reduced.

  Subsequently, when the rotation speed and load are in the range of low rotation and medium load to medium rotation and medium and high load (that is, region (b)), the injection period per injection becomes the injection period A. Divided injection can make fuel dispersion insufficient. That is, fuel split injection is performed in the same manner as the operation in the first operation example. As a result, the combustion speed can be reduced, so that the MBT shifts toward the advance side. For this reason, the amount of delay of the ignition timing with respect to MBT increases. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state where the ignition timing is shifted to the delay side by the retard control. Thereby, the occurrence of knocking can be avoided or suppressed.

  On the other hand, the ignition timing is shifted to the delay side by a relatively small retardation amount A. Even if the rotation speed and load are in the range of low rotation and medium load to medium rotation and medium and high load, ignition is performed by the retard amount B used when the rotation speed and load are in the range of low rotation and high load. If the timing is shifted to the delay side, the supercharging pressure increases due to an increase in the exhaust gas temperature, and as a result, the occurrence of knocking cannot be avoided or suppressed. However, according to the second operation example, since the ignition timing is shifted to the delay side by a relatively small retardation amount A, the increase in the supercharging pressure can be suppressed by suppressing the increase in the exhaust gas temperature. As a result, the occurrence of knocking can be avoided or suppressed.

  Subsequently, when the rotation speed and load are in the range of medium rotation and high load to high rotation and high load (that is, region (c)), the injection period per injection becomes the injection period B. The fuel can be sufficiently dispersed by split injection. The ignition timing is shifted to the delay side by a relatively small retardation amount A. Thereby, it is possible to improve the knock margin by increasing the combustion speed, and it is possible to suppress the increase in the supercharging pressure by suppressing the increase in the exhaust gas temperature. As a result, the occurrence of knocking can be avoided or suppressed.

  When the rotation speed and load are in the range of medium rotation and high load to high rotation and high load (that is, region (c)), in order to suppress an increase in exhaust gas temperature, the total fuel injection amount Measures to increase or decrease can be considered. However, when the total fuel injection amount is increased, the smoke emission amount increases, and when the total fuel injection amount is decreased, the combustion becomes unstable (that is, high supercharging). Therefore, ignition failure occurs), which is not preferable. Therefore, as described above, it is preferable that fuel is sufficiently dispersed by split injection in which the injection period per injection is equal to or longer than the stable injection period.

  Subsequently, when the rotation speed and load are in the low and medium rotation and low to high rotation and medium load (that is, in the region (d)), both the ignition request voltage and the exhaust gas temperature become unstable. There is a margin compared to the voltage and exhaust gas temperature. Therefore, the occurrence of knocking can be avoided or suppressed by shifting the ignition timing to the delay side by a relatively large retardation amount B (that is, performing the conventional retard control).

(2-3) Third Operation Example Next, a third operation example of the direct injection type engine 1 according to the present embodiment will be described with reference to FIGS. 15 to 18. FIG. 15 is a flowchart conceptually showing an overall flow of the third operation example of the direct injection type engine 1 according to the present embodiment. FIG. 16 is a flowchart showing fuel injection in the third operation example. FIG. 17 is a timing chart conceptually showing one aspect, FIG. 17 is a timing chart conceptually showing another aspect of fuel injection in the third operation example, and FIG. 18 is shown in FIGS. It is explanatory drawing which shows notionally the shift of MBT at the time of injecting a fuel in the aspect.

  The third operation example shows an operation when it is determined whether or not the occurrence of knocking is avoided or suppressed when the second operation example is performed. The third operation example may be performed in parallel with the second operation example described above, or may be performed subsequent to the second operation example.

  As shown in FIG. 15, first, it is determined whether or not to determine whether or not knocking has been avoided or suppressed by the operation of the ECU 30 (step S301).

  As a result of the determination in step S301, if it is determined not to perform the operation of determining whether or not the occurrence of knocking has been avoided or suppressed (step S301: No), the operation ends.

  On the other hand, as a result of the determination in step S301, when it is determined that the determination operation of whether or not the occurrence of knocking is avoided or suppressed (step S301: Yes), subsequently, the current cylinder is determined by the operation of the ECU 30. Whether the load and the rotational speed of the internal injection type engine 1 are in the range of low rotation and high load or in the range of low rotation and medium load to medium rotation and medium and high load (that is, the region (a) shown in FIG. It is determined whether or not it is in the region (b) (step S302).

  As a result of the determination in step S302, when it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (a) or the region (b) (step S302: Yes), then, By the operation of the injection period setting unit 302, the injection period per one fuel injection is set to the injection period B shown in FIG. 12 (that is, the period that is not less than the minimum injection period etau_min + α) (step S303).

  When the current load and the rotational speed of the in-cylinder injection engine 1 are in the region (a) or the region (b), the injection period per one fuel injection is initially the injection shown in FIG. Period A is set. For this reason, the operation in step S303 is an operation of increasing the injection period per one fuel injection from the injection period A to the injection period B.

  Thereafter, by monitoring the output of the knocking sensor 12 by the operation of the ECU 30, it is determined whether or not the occurrence of knocking is avoided or suppressed (step S304). That is, as in step S201 in FIG. 9, it is determined whether or not knocking has occurred.

  On the other hand, as a result of the determination in step S302, if it is determined that the current load and rotation speed of the direct injection engine 1 are not in the region (a) or the region (b) (step S302: No), then, By the operation of the ECU 30, the current load and rotation speed of the in-cylinder injection engine 1 is in the range of medium rotation and high load to high rotation and high load, or from low and medium rotation and low load to high rotation and medium load. (That is, whether it is in the region (c) or the region (d) shown in FIG. 10) or not (step S312).

  As a result of the determination in step S312, if it is determined that the current load and rotation speed of the direct injection type engine 1 are in the region (c) or the region (d) (step S312: Yes), the ignition timing control is performed. The ignition timing is shifted to the advanced side by the operation of unit 305 (step S313).

  Thereafter, by monitoring the output of the knocking sensor 12 by the operation of the ECU 30, it is determined whether or not knocking has been avoided or suppressed (that is, whether or not knocking has occurred) (step S304).

  On the other hand, as a result of the determination in step S312, when it is determined that the current load and rotation speed of the direct injection type engine 1 are not in the region (c) or the region (d) (step S312: No), the operation is performed. Exit.

  As described above, according to the third operation example, when the current load and the rotational speed of the direct injection type engine 1 are in the region (a) or the region (b), the amount per injection is one. The fuel can be sufficiently dispersed by the divided injection in which the injection period is the injection period B (that is, the minimum injection period etau_min + α or more). As a result, the combustion speed can be increased, so that the MBT shifts to the delay side as shown in FIG. That is, MBT can be brought close to the absolute position of the ignition timing. For this reason, the delay amount of the ignition timing with respect to MBT is reduced. As a result, the relative position of the ignition timing with respect to MBT can realize the same state as the state in which the ignition timing is uniformly advanced and shifted by the retard control. Thereby, it can be suitably determined whether or not the occurrence of knocking is avoided.

  If the ignition timing control unit 305 shifts the absolute position of the ignition timing to the advance side, the fuel is steamed from the earlier combustion due to the advance of the ignition timing, resulting in an increase in smoke emissions. End up. Therefore, it is preferable to realize the same state as the state in which the ignition timing is shifted to the advance side by the retard control by increasing the combustion speed due to setting the injection period per injection to the injection period B. .

  On the other hand, when the current load and rotational speed of the direct injection engine 1 are in the region (c) or the region (d), the ignition timing control unit 305 moves the absolute position of the ignition timing forward. Even if it is shifted, there is no inconvenience that the smoke discharge amount increases. Therefore, in this case, it is possible to suitably determine whether or not the occurrence of knocking has been avoided or suppressed by uniformly shifting the absolute position of the ignition timing to the advance side by the ignition timing control unit 305. .

  In addition, when the load and rotation speed of the present in-cylinder injection engine 1 are in the region (a), a countermeasure for increasing the fuel pressure can be considered in order to increase the combustion speed. However, if the configuration for increasing the fuel pressure is adopted, if it is determined in step S304 in FIG. 15 that the occurrence of knocking is not avoided or suppressed, it is necessary to lower the fuel pressure again. This can lead to frequent fluctuations in fuel pressure. Therefore, as a more suitable measure, as described above, it is preferable to increase the injection amount per injection (that is, set to the injection period B).

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. A control device for an internal combustion engine is also included in the technical scope of the present invention.

It is a block diagram which shows notionally the basic composition of the cylinder injection type engine which concerns on this embodiment. It is sectional drawing which shows notionally the cross section of the cylinder injection type engine which concerns on this embodiment. It is sectional drawing which shows notionally the cross section of the injector with which the cylinder injection type engine which concerns on this embodiment is provided. It is a flowchart which shows notionally the whole flow of the 1st operation example of the cylinder injection type engine which concerns on this embodiment. It is a graph which shows notionally the field (a) which is the range of low rotation and high load. It is a graph which shows notionally the injection period-injection amount (spray spread angle) characteristic in the injection of the fuel from an injector. It is a timing chart which shows notionally each mode of division injection of fuel and collective injection. It is a graph which shows the combustion speed, knock margin, and ignition timing in case each of the division | segmentation injection of fuel and collective injection is performed. It is a flowchart which shows notionally the whole flow of the 2nd operation example of the cylinder injection type engine which concerns on this embodiment. It is a graph which shows notionally the operating state of the direct injection type engine specified by load (torque) and rotation speed. 5 is a graph conceptually showing fuel pressure reduction control. It is a graph which shows notionally the injection period-injection amount (spray spread angle) characteristic in the injection of the fuel from an injector. It is a timing chart which shows notionally the mode of fuel injection in the 2nd example of operation. It is a graph which shows the amount of retardation of ignition timing. It is a flowchart which shows notionally the whole flow of the 3rd operation example of the cylinder injection type engine which concerns on this embodiment. It is a timing chart which shows notionally one mode of fuel injection in the 3rd example of operation. 12 is a timing chart conceptually showing another aspect of fuel injection in the third operation example. It is explanatory drawing which shows notionally the shift of MBT at the time of injecting a fuel in the aspect shown in FIG.16 and FIG.17.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 In-cylinder injection type engine 2 Cylinder 3 Intake manifold 4 Exhaust manifold 5 Piston 6 Cavity 7 Intake port 8 Exhaust port 11 Injector 12 Knocking sensor 14 Fuel supply unit 15 Fuel line 16 Fuel tank 21 Exhaust turbine 22 Compressor 23 Rotor shaft 24 Air Cleaner 25 Intercooler 30 ECU
301 Fuel Pressure Setting Unit 302 Injection Period Setting Unit 303 Injection Number Setting Unit 304 Injection Control Unit 305 Ignition Timing Control Unit

Claims (10)

A control device for an internal combustion engine comprising a supercharger and a fuel injection valve that directly injects fuel into a combustion chamber,
An injection control means for controlling the fuel injection valve so as to divide and inject the fuel into a plurality of times in an intake process when the rotational speed and load of the internal combustion engine are in a range of low rotation and high load;
An injection period per injection of the fuel that is divided and injected into the plurality of times is equal to or longer than a minimum injection period that indicates a minimum time during which the fuel injection valve can inject the fuel. An injection period setting means for setting the spray spread angle to be less than a stable injection period where the spray spread angle starts to stabilize,
The control device for a direct injection internal combustion engine, wherein the fuel injection valve includes a swirl valve that forms a swirl flow.   The injection period setting means has an injection period of the fuel injected last among the fuel injected dividedly in the plurality of times, and is injected last in the fuel injected in the plurality of times. The fuel injection period of the last fuel to be injected among the fuels divided and injected into the plurality of times is set so as to be longer than the fuel injection period of fuel other than the fuel. The control apparatus for a cylinder injection type internal combustion engine according to claim. Knocking detection means for detecting occurrence of knocking;
Ignition timing control means for delaying or advancing the ignition timing in the combustion chamber by a predetermined amount determined according to each of the rotational speed and the load when the occurrence of knocking is detected,
When the occurrence of knocking is detected, the injection control means controls the fuel injection valve so as to change the fuel injection mode in accordance with each of the rotational speed and the load. The control device for a direct injection internal combustion engine according to claim 1 or 2, wherein the control device is an internal combustion engine. When the occurrence of knocking is detected when the rotation speed and the load are in the range of low rotation and high load,
The ignition timing control means sets the predetermined amount to 0,
The injection period setting means sets an injection period per injection of the fuel to be injected divided into a plurality of times to be not less than the minimum injection period and less than a stable injection period,
The injection control means controls the fuel injection valve so as to decrease the fuel pressure of the fuel and increase the number of divisions of the fuel injection as compared with a case where the occurrence of knocking is not detected. 4. The control apparatus for a direct injection internal combustion engine according to claim 3, wherein   5. The in-cylinder injection according to claim 4, wherein the injection control unit controls the fuel injection valve so as to end the fuel injection when the state of the intake valve changes from an open state to a closed state. 6. Type internal combustion engine control device. When the occurrence of knocking is detected when the rotation speed and the load are in the range of low rotation and medium load to medium rotation and medium high load,
The ignition timing control means delays the ignition timing by a second predetermined amount that is smaller than a first predetermined amount that is the predetermined amount when the rotation speed and the load are in a range of low rotation and high load,
The injection period setting means sets an injection period per injection of the fuel to be injected divided into a plurality of times to be not less than the minimum injection period and less than a stable injection period,
6. The in-cylinder according to claim 3, wherein the injection control unit controls the fuel injection valve so that the fuel is divided into a plurality of times and injected in an intake process. A control device for an injection type internal combustion engine. When the occurrence of knocking is detected when the rotation speed and the load are in the range of medium rotation and high load to high rotation and high load,
The ignition timing control means delays the ignition timing by a second predetermined amount smaller than a first predetermined amount that is the predetermined amount when the rotation speed and the load are low rotation and high load,
The injection period setting means sets an injection period per one injection of the fuel to be injected divided into a plurality of times to be equal to or more than the stable injection period,
The in-cylinder according to any one of claims 3 to 6, wherein the injection control means controls the fuel injection valve so that the fuel is divided into a plurality of times and injected in an intake process. A control device for an injection type internal combustion engine. When the occurrence of knocking is detected when the rotation speed and the load are in the range of low to medium rotation and low load to high rotation and medium load,
The ignition timing control means sets the ignition timing when the rotation speed and the load are in the range of low rotation and medium load to medium rotation and medium to high load or in the range of medium rotation and high load to high rotation and high load. The control apparatus for a direct injection internal combustion engine according to any one of claims 3 to 7, wherein the control is delayed by a first predetermined amount that is larger than a second predetermined amount that is the predetermined amount. The occurrence of knocking is detected after the occurrence of knocking is detected when the rotational speed and the load are in the range of low rotation and high load, or in the range of low rotation and medium load to medium rotation and medium high load. A determination means for determining whether or not it has been avoided;
When the determination by the determination unit is performed, the injection period setting unit sets the injection period per injection of the fuel that is divided and injected into the plurality of times to be equal to or more than the stable injection period. The control apparatus for a cylinder injection internal combustion engine according to any one of claims 4 to 6, wherein the control apparatus is a cylinder injection type internal combustion engine. The occurrence of knocking is detected when the rotation speed and the load are in the range of medium rotation and high load to high rotation and high load, or in the range of low to medium rotation and low load to high rotation and medium load. A determination means for determining whether or not the occurrence of the knocking is avoided later;
The control apparatus for a direct injection internal combustion engine according to claim 7 or 8, wherein when the determination by the determination means is made, the ignition timing control means advances the delayed ignition timing.

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