JP3557987B2 - Fuel injection device for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art There is known a fuel injection device for an internal combustion engine in which a main injection is performed at a time interval after a sub-injection, for example, a pilot injection is completed in one combustion cycle (see JP-A-6-129296).
[0003]
[Problems to be solved by the invention]
However, such a pilot injection has a considerably short fuel injection period, so that the opening / closing operation of the fuel injection valve at this time becomes unstable. As a result, there is a risk that the timing interval between the pilot injection and the main injection may deviate from the target timing interval because the injection start timing or the injection completion timing of the pilot injection deviates from the target timing. There is. That is, for example, when the injection completion timing of the pilot injection is later than the regular timing, the timing interval between the pilot injection and the main injection is shorter than the regular timing interval, and as a result, the pilot injection is actually completed. Although the fuel injection is not performed, the main injection is started, so that the actual fuel injection amount deviates from the normal fuel injection amount.
[0004]
Such a problem can also occur when the sub-injection is performed multiple times.
SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device for an internal combustion engine that can maintain a timing interval between fuel injections at a target timing interval.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a fuel injection system for an internal combustion engine, which performs a main injection after performing a sub-injection in one combustion cycle or performs a sub-injection after performing a main injection. The device detects the actual timing interval between the main injection and the sub-injection, When the deviation amount of the timing interval from the target timing interval is larger than a certain value, Correcting the fuel injection timing of the sub injection while maintaining the fuel injection timing of the main injection so that the timing interval becomes the target timing interval However, the fuel injection timing of the sub-injection is not corrected when the deviation amount is smaller than a certain value. Like that. That is, in the first aspect, the timing interval between the main injection and the sub-injection is maintained at the target timing interval. In this case, since the fuel injection timing of the main injection is maintained, the timing interval between the main injection and the sub-injection is corrected without affecting, for example, combustion or engine output torque.
[0006]
According to a second aspect of the present invention, the main injection is performed after the second and first sub-injections are sequentially performed in one combustion cycle, or the first injection is performed after the main injection is performed. And a fuel injection device for an internal combustion engine configured to perform the second sub-injection, wherein an actual timing interval between the first sub-injection and the main injection is detected, and this timing interval is set as a target timing. While maintaining the fuel injection timing of the main injection so that Vice In addition to correcting the fuel injection timing of the injection by the correction amount, the first Vice Injection and second Vice In order to maintain the timing interval between injection and injection, the second Vice The fuel injection timing of the injection is corrected. That is, in the second invention, the fuel injection timing of the first sub-injection is changed such that the timing interval between the first sub-injection and the main injection becomes a target timing interval. However, when the fuel injection timing of the first sub-injection is changed, the first Vice Injection and second Vice The timing interval between injections is undesirably changed. Therefore, in the second invention, the fuel injection timing of the second sub-injection is changed by an amount corresponding to the correction of the fuel injection timing of the first sub-injection. Vice Injection and second Vice The timing interval between injections is maintained.
[0007]
According to a third aspect of the present invention, the main injection is performed after the second and first sub-injections are sequentially performed within one combustion cycle, or the first injection is performed after the main injection is performed. And a fuel injection device for an internal combustion engine configured to perform the second sub-injection, wherein an actual timing interval between the first sub-injection and the second sub-injection is detected, and the timing interval is determined as a target. While maintaining the fuel injection timing of the first sub-injection so that the timing interval becomes Vice The fuel injection timing of the injection is corrected. That is, in the third aspect, the fuel injection timing of the second sub-injection is changed such that the timing interval between the first sub-injection and the second sub-injection becomes a target timing interval. In this case, 1 Because the fuel injection timing of 1 The timing interval between the sub injection and the main injection is maintained.
[0008]
According to a fourth aspect of the present invention, there is provided an internal combustion engine which performs a main injection after performing a sub-injection in one combustion cycle or performs a sub-injection after performing a main injection in one combustion cycle. In the fuel injection device, the actual fuel injection period of the sub-injection is detected, and the fuel injection start timing of the sub-injection and the fuel injection completion timing are determined so that the sub-injection fuel injection period becomes the target fuel injection period. Of these, the one far from the main injection is corrected while the one near the main injection is maintained. That is, in the fourth aspect, the fuel injection period of the sub-injection is maintained at the target fuel injection period. Here, of the fuel injection start timing and the fuel injection completion timing of the sub injection, whichever is closer to the main injection, that is, when the main injection is performed after the sub injection is performed, the fuel injection completion timing and the main injection are performed. When the sub-injection is performed after the injection, the fuel injection start timing is maintained, so that the timing interval between the main injection and the sub-injection is maintained.
[0009]
According to a fifth aspect of the present invention, a main injection is performed after the second and first sub-injections are sequentially performed within one combustion cycle, or a first injection is performed after the main injection is performed. And an actual fuel injection period of the first sub-injection is detected in the fuel injection device of the internal combustion engine configured to perform the second sub-injection, and the fuel injection period of the first sub-injection is targeted. In the first sub-injection, the fuel injection start timing and the fuel injection completion timing of the first sub-injection are corrected while maintaining the one closer to the main injection and correcting the one far from the main injection by the correction amount. In order to maintain the timing interval between the injection and the second sub-injection, the second Vice The fuel injection timing of the injection is corrected. That is, in the fifth aspect, the fuel injection period of the first sub-injection is maintained at the target fuel injection period. Here, the closer of the fuel injection start timing and the fuel injection completion timing of the first sub-injection to the main injection is maintained, so that the timing interval between the main injection and the first sub-injection is maintained. On the other hand, the fuel injection start timing and the fuel injection completion timing of the first sub-injection which are farther from the main injection are changed, so that the timing interval between the first sub-injection and the second sub-injection is preferable. Will be changed without. Therefore, in the fifth invention, the fuel injection timing of the second sub-injection is changed by an amount corresponding to the correction of the fuel injection period of the first sub-injection, and the timing between the first sub-injection and the second sub-injection is changed. Target spacing is maintained.
[0010]
According to a sixth aspect of the present invention, a main injection is performed after the second and first sub-injections are sequentially performed within one combustion cycle, or a first injection is performed after the main injection is performed within one combustion cycle. And an actual fuel injection period of the second sub-injection is detected in the fuel injection device of the internal combustion engine configured to perform the second sub-injection, and the fuel injection period of the second sub-injection is targeted. During the period, the fuel injection start timing and the fuel injection completion timing of the second sub-injection are corrected while maintaining the one closer to the main injection and the one farther from the main injection. That is, in the sixth aspect, the fuel injection period of the second sub-injection is maintained at the target fuel injection period. Here, of the fuel injection start timing and the fuel injection completion timing of the second sub-injection, the one closer to the main injection is maintained, so that the timing interval between the first sub-injection and the second sub-injection is maintained. Is done.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a case where the present invention is applied to a diesel engine. However, the present invention can be applied to a spark ignition type engine.
Referring to FIG. 1, the engine body 1 includes, for example, four cylinders # 1, # 2, # 3, and # 4. Each cylinder is connected to a common surge tank 3 via a corresponding intake branch pipe 2, and the surge tank 3 is connected via an intake duct 4 and an intercooler 5 to an outlet of a supercharger, for example, a compressor 6 c of an exhaust turbocharger 6. Connected to the unit. The inlet of the compressor 6c is connected to an air cleaner 8 via an air suction pipe 7. A throttle valve 10 driven by an actuator 9 is arranged in the intake duct 4 between the surge tank 3 and the intercooler 5. A variable nozzle mechanism 6v whose opening area can be changed is attached to the exhaust gas inlet of the exhaust turbine 6t. If the area of the exhaust gas inlet of the exhaust turbine 6t is reduced by the variable nozzle mechanism 6v, the supercharging pressure can be increased even during low engine speed operation where the exhaust pressure is low.
[0012]
On the other hand, each cylinder is connected to the inlet of the exhaust turbine 6t of the exhaust turbocharger 6 through the exhaust manifold 11 and the exhaust pipe 12, and the outlet of the exhaust turbine 6t is connected to the NO through the exhaust pipe 13. _X An exhaust throttle valve 18 driven by an actuator 17 is disposed in an exhaust pipe 13 connected to a casing 15 containing a reduction catalyst 14 and connected to an exhaust pipe 16. NO _X The reduction catalyst 14 includes, for example, a zeolite supporting copper. This NO _X If the reducing catalyst 14 contains a reducing agent such as HC or CO in the exhaust gas that flows into the reducing catalyst 14, even if the gas is in an oxidizing atmosphere, the NO. _X Can be reduced. The combustion order of the engine 1 is # 1- # 3- # 4- # 2.
[0013]
Each cylinder has a fuel injection valve 20 for directly injecting fuel into the cylinder. Each fuel injection valve 20 is connected to a fuel pump 22 whose discharge amount can be controlled via a common fuel pressure accumulation chamber or a common rail 21. The fuel pump 22 is connected to a fuel tank (not shown) via a low-pressure pump (not shown). Fuel discharged from the fuel pump 22 is supplied to the common rail 21 and then to each fuel injection valve 20. . The discharge amount of the fuel pump 22 is controlled so that the fuel pressure in the common rail 21 becomes a predetermined target fuel pressure. The target fuel pressure can be determined, for example, according to the engine operating state.
[0014]
Each fuel injection valve 20 is provided with, for example, an electromagnetic actuator. When the electromagnetic actuator is energized, a needle (not shown) of the fuel injection valve 20 rises to open the fuel injection valve 20, and as a result, fuel injection starts. Is done. On the other hand, when the electromagnetic actuator is deenergized, the needle descends and the fuel injection valve 20 closes, and as a result, fuel injection is stopped. Therefore, the fuel injection start timing, the fuel injection completion timing, and the fuel injection period of each fuel injection can be detected by detecting the needle raising / lowering operation or the needle lift amount.
[0015]
Still referring to FIG. 1, the exhaust manifold 11 and the intake duct 4 downstream of the throttle valve 10 are connected to each other via an exhaust gas recirculation (hereinafter, referred to as EGR) passage 23, and are driven by an actuator 24 in the EGR passage 23. EGR control valve 25 is arranged.
An electronic control unit (ECU) 30 is composed of a digital computer, and is connected to a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, and always connected via a bidirectional bus 31. It has a B-RAM (backup RAM) 35, an input port 36, and an output port 37 connected to a power supply. A water temperature sensor 38 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine body 1. An intake pressure sensor 39 that generates an output voltage proportional to the pressure in the intake duct 4 and an intake temperature sensor that generates an output voltage proportional to the intake air temperature in the intake duct 4 are provided in the intake duct 4 downstream of the throttle valve 10. 40 are arranged. For example, a needle lift sensor 41 that generates an output voltage proportional to the needle lift amount is attached to the fuel injection valve 20 of the first cylinder # 1. A fuel pressure sensor 42 that generates an output voltage proportional to the fuel pressure in the common rail 21 is attached to the common rail 21. The depression amount sensor 43 generates an output voltage proportional to the depression amount of an accelerator pedal (not shown). The output voltages of these sensors 38, 39, 40, 41, 42, 43 are input to the input port 36 via the corresponding AD converters 44, respectively. The input port 36 is connected to a crank angle sensor 45 that generates an output pulse every time the crankshaft rotates, for example, by 30 °. The CPU 34 calculates the engine speed N based on the output pulse of the crank angle sensor 45, and calculates the intake air amount Ga based on the output voltage of the intake pressure sensor 39.
[0016]
On the other hand, the output port 37 is connected to the variable nozzle mechanism 6v, the actuators 9, 17, 24, the fuel injection valves 20, and the fuel pump 22 via the corresponding drive circuits 46, respectively.
By the way, when the common rail 21 is provided, it becomes possible to inject fuel a plurality of times in one combustion cycle of each cylinder. Therefore, in this embodiment, apart from the main injection that is performed around the compression top dead center to generate the engine output torque, the sub-injection is performed at a timing interval from the main injection to the advance side or the retard side at a time interval. I have to. The sub-injection includes pilot injection, post-injection, and HC supply injection.
[0017]
The pilot injection is to inject a small amount of fuel prior to the main injection. The pilot injection is performed, for example, in a compression stroke before the main injection, that is, for example, at about 0 ° crank angle (hereinafter, referred to as CA) from 70 before compression top dead center (hereinafter, referred to as BTDC). When it is large, it forms a premixed gas, and when it is small, it forms an ignition source for igniting and burning fuel by main injection. It is also possible to perform a plurality of pilot injections, so that both pilot injection for forming a premixed gas and pilot injection for forming an ignition source can be performed. Multiple injections can be performed. In the present embodiment, it is possible to perform two pilot injections, that is, the first pilot injection preceding and the second pilot injection performed after the completion of the first pilot injection.
[0018]
The post-injection is performed after the main injection is completed in order to completely combust HC in the combustion gas or exhaust gas and reduce soot discharged from the engine. This post-injection is preferably performed while the combustion flame remains in the combustion chamber. For example, the post-injection is performed at about -30 ° CA from BTDC0 after completion of the main injection (0 to 30 ° CA after compression top dead center). .
[0019]
NO for HC supply injection _X This is for supplying HC (hydrocarbon) as a reducing agent to the reduction catalyst 14. This HC supply injection is performed, for example, from BTDC-150 after the completion of the main injection or the post-injection to about −210 ° CA. The fuel from the HC supply injection is NO _X NO reaching the reduction catalyst 14 and flowing _X To reduce.
[0020]
FIG. 2A schematically shows the fuel injection timing of each fuel injection operation in the form of a valve opening period of the fuel injection valve 20. Here, j represents the order or type of fuel injection that can be performed in one combustion cycle of each cylinder, that is, j = 1 indicates the first pilot injection, j = 2 indicates the second pilot injection, and j = 3 indicates main injection, j = 4 indicates post-injection, and j = 5 indicates HC supply injection.
[0021]
While the main injection is always performed in one combustion cycle of each cylinder, whether or not the pilot injection, the post-injection, and the HC supply injection are performed is determined depending on the engine operating state. Therefore, the number of fuel injections performed in one combustion cycle of each cylinder can be changed between one and five. For example, in the example shown in FIG. 2B, fuel injection is performed only four times in one combustion cycle of each cylinder, and in the example shown in FIG. 2C, it is performed only three times.
[0022]
The fuel injection timing of each fuel injection of each cylinder is obtained, for example, in the form of a crank angle from the intake top dead center of the first cylinder. That is, referring to FIG. 3 showing each fuel injection of the first cylinder, the crank angle from the intake top dead center of the first cylinder is the j-th (j = 1, 2, 3, 4, 5) fuel injection. At the fuel injection start time ST (j), the fuel injection valve 20 is opened for the j-th fuel injection, and is kept open for the fuel injection period TAU (j) of the j-th fuel injection. When the fuel injection completion time FIN (j) of the fuel injection reaches the fuel injection valve 20, the fuel injection valve 20 is closed. Therefore, the fuel injection timing is determined when the fuel injection start timing and the fuel injection completion timing are determined. Note that the same applies to the fuel injection of other cylinders, so that the description is omitted.
[0023]
Next, a method of calculating the fuel injection timing of each fuel injection will be described with reference to FIG. In this embodiment, first, the fuel injection start timing ST (3) of the main injection and the fuel injection period TAU (3) are calculated. ST (3) and TAU (3) are, for example, the optimal fuel injection start timing and fuel injection period for making the engine output torque equal to the required torque, and correspond to the engine speed N and the accelerator pedal depression amount DEP, respectively. It is stored in the ROM 32 in advance in the form of a map as a function. Next, the fuel injection completion timing FIN (3) of the main injection is calculated by increasing or retarding the fuel injection period TAU (3) from the fuel injection start timing ST (3) (FIN (3) = ST (3). ) + TAU (3)).
[0024]
Next, the fuel injection completion timing FIN (2) of the second pilot injection is calculated by decreasing or advancing the fuel injection start timing ST (3) of the main injection by the second timing interval INT (2). (FIN (2) = ST (3) -INT (2)). Next, the fuel injection start timing ST (2) of the second pilot injection is decreased or advanced from the fuel injection completion timing FIN (2) of the second pilot injection by the fuel injection period TAU (2) of the second pilot injection. 2) is calculated (ST (2) = FIN (2) -TAU (2)).
[0025]
Next, the fuel injection completion timing FIN (1) of the first pilot injection is decreased or advanced by the first timing interval INT (1) from the fuel injection start timing ST (2) of the second pilot injection. It is calculated (FIN (1) = ST (2) -INT (1)). Next, the fuel injection start timing ST (1) of the first pilot injection is reduced by decreasing or advancing the fuel injection period TAU (1) of the first pilot injection from the fuel injection completion timing FIN (1) of the first pilot injection. 1) is calculated (ST (1) = FIN (1) -TAU (1)).
[0026]
The timing intervals INT (1), INT (2) and the fuel injection periods TAU (1), TAU (2) are the timing intervals and the fuel injection periods required to form a good premixed fuel or ignition source. For example, the data is stored in the ROM 32 in advance in the form of a map as a function of the engine speed N and the depression amount DEP of the accelerator pedal, respectively.
Next, the fuel injection start timing ST (4) of the post-injection is calculated by increasing or retarding the fuel injection completion timing FIN (3) of the main injection by the third timing interval INT (3) (ST (ST ( 4) = FIN (3) + INT (3)). Next, the post-injection fuel injection completion timing FIN (4) is calculated by increasing or retarding the post-injection fuel injection period TAU (4) from the post-injection fuel injection start time ST (4) (FIN (4)). 4) = ST (4) + TAU (4)). The timing interval INT (3) and the fuel injection period TAU (4) are the timing interval and the fuel injection period required to reduce HC discharged from the cylinder, and include the engine speed N and the amount of depression of the accelerator pedal. Each of them is stored in the ROM 32 in advance in the form of a map as a function of the DEP.
[0027]
Next, the fuel injection start timing ST (5) of the HC supply injection is calculated by increasing or retarding the fuel injection completion timing FIN (4) of the post-injection by the fourth timing interval INT (4) ( ST (5) = FIN (4) + INT (4)). Next, the fuel injection completion timing FIN (5) of the HC supply injection is increased or delayed from the fuel injection start time ST (5) of the HC supply injection by the fuel injection period TAU (5) of the HC supply injection. It is calculated (FIN (5) = ST (5) + TAU (5)). The timing interval INT (4) and the fuel injection period TAU (5) are NO _X NO discharged from the reduction catalyst 14 _X The time interval and fuel injection period required to reduce the amount _X NO flowing into the reduction catalyst 14 _X It is stored in the ROM 32 in advance in the form of a map as a function of the intake air amount Ga representing the amount and the engine speed N.
[0028]
Therefore, generally speaking, in one combustion cycle, the main injection is performed after the second and first sub-injections are sequentially performed, or the first and second sub-injections are sequentially performed after the main injection is performed. In this case, first, the fuel injection timing of the main injection is obtained, then the fuel injection timing of the first sub-injection is obtained based on the fuel injection timing of the main injection, and the second fuel injection timing is obtained based on the fuel injection timing of the first sub-injection. That is, the fuel injection timing of the sub injection is determined.
[0029]
However, for example, the fuel injection period of the second pilot injection is considerably shorter than the fuel injection period of the main injection. Further, the second timing interval between the second pilot injection and the main injection may be set to be considerably short. For this reason, as described at the beginning, the opening / closing operation of the fuel injection valve 20 becomes unstable, and as a result, the actual second timing interval deviates from the second timing interval calculated from the target map. There is fear.
[0030]
Therefore, in the present embodiment, the actual second timing interval AINT (2) is detected, and the fuel injection of the second pilot injection is performed such that the actual timing interval becomes the target timing interval INT (2). The timing is corrected.
Specifically, the actual second temporal interval AINT (2) is larger than the target second temporal interval INT (2) plus a small constant value x (INT (2) + x). At times, the fuel injection completion timing FIN (2) of the second pilot injection is increased or retarded by a small constant value a. As a result, the second temporal interval AINT (2) is reduced. However, in this state, the fuel injection period of the second pilot injection is extended by a, so that the fuel injection period of the second pilot injection is maintained in order to maintain the fuel injection period TAU (2) of the second pilot injection. The start timing ST (2) is increased or retarded by a.
[0031]
However, in this state, the first timing interval INT (1) between the second pilot injection and the first pilot injection is extended by a. Therefore, the fuel injection completion timing FIN (1) of the first pilot injection is increased or retarded by a in order to maintain the first timing interval INT (1). Further, the fuel injection start timing ST (1) of the first pilot injection is increased or retarded by a in order to maintain the fuel injection period TAU (1) of the first pilot injection.
[0032]
On the other hand, when the actual second temporal interval AINT (2) is smaller than the target second temporal interval INT (2) obtained by subtracting x (INT (2) -x), FIN ( 2) is reduced or advanced by a, and ST (2) is reduced or advanced by a. FIN (1) and ST (1) are reduced or advanced by a.
[0033]
Accordingly, the actual second timing interval AINT (2) is made to coincide with the target timing interval. At this time, the first timing interval and the fuel injection period TAU (1) of the first and second pilot injections are set. 1) and TAU (2) are prevented from changing. Further, in this case, the second timing interval is corrected while maintaining the fuel injection timing of the main injection. Therefore, the second timing interval AINT (2) can be corrected without having the greatest effect on the generation of engine output torque, combustion, or exhaust performance.
[0034]
FIG. 4 shows a routine for calculating the fuel injection timing of the first and second pilot injections in this embodiment. This routine is executed by interruption every predetermined set time.
Referring to FIG. 4, first, at step 100, the fuel injection start timing ST (3) of the main injection is calculated. In the following step 101, the target second timing interval INT (2) and the fuel injection period TAU (2) of the second pilot injection are calculated from the map. In the subsequent step 102, the target fuel injection completion timing FIN (2) and fuel injection start timing ST (2) of the second pilot injection are calculated. In the subsequent step 103, the target fuel injection completion timing FIN (1) and fuel injection start timing ST (1) of the first pilot injection are calculated from the map. In the following step 105, the actual second timing interval AINT (2) is calculated. In the following step 106, it is determined whether or not AINT (2) is greater than INT (2) + x. When AINT (2)> INT (2) + x, the process proceeds to step 107, where FIN (2) and ST (2) are increased or retarded by a. In the following step 108, FIN (1) and ST (1) are increased or retarded by a.
[0035]
On the other hand, when AINT (2) ≦ INT (2) + x in step 106, the process then proceeds to step 109, where it is determined whether or not AINT (2) is smaller than INT (2) −x. When AINT (2) ≧ INT (2) −x, the processing cycle ends. When AINT (2) <INT (2) −x, the process proceeds to step 110, where FIN (2) and ST (2) are only a. It is reduced or advanced. In the following step 111, FIN (1) and ST (1) are reduced or advanced by a.
[0036]
Further, the actual first temporal interval AINT (1) is detected, and the first temporal interval AINT (1) is set to be the target first temporal interval INT (1). The fuel injection timing of the pilot injection can be corrected.
Specifically, the actual first temporal interval AINT (1) is larger than the target first temporal interval INT (1) plus a small constant value y (INT (1) + y). At times, the fuel injection completion timing FIN (1) of the first pilot injection is increased or retarded by a small constant value b. In order to maintain the fuel injection period TAU (1) of the first pilot injection, the fuel injection start timing ST (1) of the first pilot injection is increased or retarded by b. On the other hand, when the actual first temporal interval AINT (1) is smaller than the target first temporal interval INT (1) minus y (INT (1) -y), FIN ( 1) is reduced or advanced by b, and ST (1) is reduced or advanced by b.
[0037]
In this case, the first timing interval is corrected while maintaining the fuel injection timing of the second pilot injection. Therefore, there is no need to re-correct the second temporal interval INT (2).
FIG. 5 shows a routine for calculating the fuel injection timing of the first pilot injection in the present embodiment. This routine is executed, for example, following the routine of FIG.
[0038]
Referring to FIG. 5, first, at step 120, the actual first temporal interval AINT (1) is calculated. In the following step 121, it is determined whether or not AINT (1) is greater than INT (1) + y. When AINT (1)> INT (1) + y, the process proceeds to step 122, where FIN (1) and ST (1) are increased or retarded by b.
[0039]
On the other hand, if AINT (1) ≦ INT (1) + x in step 121, the process then proceeds to step 123, where it is determined whether AINT (1) is smaller than INT (1) −y. When AINT (1) ≧ INT (1) -y, the processing cycle is terminated, and when AINT (1) <INT (1) -y, the process proceeds to step 124, where FIN (1) and ST (1) are only b. It is reduced or advanced.
[0040]
Next, another embodiment will be described.
As described above, when the opening / closing operation of the fuel injection valve 20 becomes unstable, the actual fuel injection period may deviate from the fuel injection period calculated from the target map. Therefore, in the present embodiment, the actual fuel injection period ATAU (2) of the second pilot injection is detected, and the actual fuel injection period ATAU (2) of the second pilot injection is set as the target fuel injection period TAU (2). ), The fuel injection timing of the second pilot injection is corrected.
[0041]
Specifically, a small constant value z is added to the fuel injection period TAU (2) of the second pilot injection in which the actual fuel injection period ATAU (2) of the second pilot injection is targeted (TAU (2 ) + Z), the fuel injection start timing ST (2) of the second pilot injection is increased or retarded by c while the fuel injection completion timing FIN (2) of the second pilot injection is maintained. As a result, the fuel injection period ATAU (2) of the second pilot injection is shortened.
[0042]
However, in this state, the first temporal interval INT (1) between the second pilot injection and the first pilot injection is extended by c. Therefore, the fuel injection completion timing FIN (1) of the first pilot injection is increased or retarded by c in order to maintain the first timing interval INT (1). Further, the fuel injection start timing ST (1) of the first pilot injection is increased or retarded by c in order to maintain the fuel injection period TAU (1) of the first pilot injection.
[0043]
On the other hand, z is subtracted from the fuel injection period TAU (2) of the second pilot injection in which the actual fuel injection period ATAU (2) of the second pilot injection is targeted (TAU (2) -z). If smaller than ST (2), ST (2) is reduced or advanced by c while FIN (2) is maintained. FIN (1) and ST (1) are reduced or advanced by c.
[0044]
Therefore, the actual fuel injection period ATAU (2) of the second pilot injection is made to coincide with the target fuel injection period. At this time, the first timing interval INT (1) and the fuel injection of the first pilot injection are set. The period TAU (1) is prevented from changing. Further, in this case, the fuel injection start timing ST (2) of the second pilot injection and the fuel injection completion timing FIN (2), which is closer to the fuel injection timing of the main injection, that is, the fuel injection completion timing FIN (2) is While being maintained, the one far from the fuel injection timing of the main injection, that is, the fuel injection start timing ST (2) is corrected. Therefore, the fuel injection period TAU (2) of the second pilot injection can be corrected without changing the second timing interval INT (2) or the fuel injection timing of the main injection.
[0045]
FIG. 6 shows a routine for calculating the fuel injection timing of the first and second pilot injections in the present embodiment. This routine is executed by interruption every predetermined set time.
Referring to FIG. 6, first, at step 130, the fuel injection start timing ST (3) of the main injection is calculated. In the following step 131, the target second timing interval INT (2) and the fuel injection period TAU (2) of the second pilot injection are calculated from the map. In the following step 132, the fuel injection completion timing FIN (2) and the fuel injection start timing ST (2) which are the targets of the second pilot injection are calculated. In the following step 133, the target fuel injection completion timing FIN (1) and fuel injection start timing ST (1) of the first pilot injection are calculated from the map. In the following step 135, the actual fuel injection period ATAU (2) of the second pilot injection is calculated. In the following step 136, it is determined whether or not ATAU (2) is larger than TAU (2) + z. If ATAU (2)> TAU (2) + z, then the routine proceeds to step 137, where ST (2) is increased or retarded by c. In the following step 138, FIN (1) and ST (1) are increased or retarded by c.
[0046]
On the other hand, if ATAU (2) ≦ TAU (2) + z in step 136, the process then proceeds to step 139, where it is determined whether ATAU (2) is smaller than TAU (2) -z. When ATAU (2) ≧ TAU (2) -z, the processing cycle is ended, and when ATAU (2) <TAU (2) -z, the process proceeds to step 110, where ST (2) is reduced or advanced by c. You. In the following step 111, FIN (1) and ST (1) are reduced or advanced by c.
[0047]
Further, the actual first pilot injection fuel injection period ATAU (1) is detected, and the actual first pilot injection fuel injection period ATAU (1) is targeted for the first pilot injection fuel injection period TAU. The fuel injection timing of the first pilot injection can be corrected so as to satisfy (1).
More specifically, a value obtained by adding a small constant value w to the fuel injection period TAU (1) of the first pilot injection in which the actual fuel injection period ATAU (1) of the first pilot injection is targeted (TAU (1 When it is larger than (+ w), the fuel injection start timing ST (1) of the first pilot injection is increased or retarded by d while the fuel injection completion timing FIN (1) of the first pilot injection is maintained. On the other hand, w is subtracted from the fuel injection period TAU (1) of the first pilot injection in which the actual fuel injection period ATAU (1) of the first pilot injection is targeted (TAU (1) -w). If smaller than ST (1), ST (1) is reduced or advanced by d while FIN (1) is maintained.
[0048]
In this case, the fuel injection period TAU (1) is corrected while maintaining the fuel injection completion timing FIN (1) of the first pilot injection. Therefore, it is not necessary to re-correct the first timing interval INT (1) or the fuel injection timing of the second pilot injection.
FIG. 7 shows a routine for calculating the fuel injection timing of the first pilot injection in the present embodiment. This routine is executed, for example, following the routine of FIG.
[0049]
Referring to FIG. 7, first, at step 150, the actual fuel injection period ATAU (1) of the first pilot injection is calculated. In the following step 151, it is determined whether or not ATAU (1) is larger than TAU (1) + w. If ATAU (1)> TAU (1) + w, then the routine proceeds to step 152, where ST (1) is increased or retarded by d.
[0050]
On the other hand, when ATAU (1) ≦ TAU (1) + w in step 151, the process then proceeds to step 153, where it is determined whether ATAU (1) is smaller than TAU (1) −w. When ATAU (1) ≧ TAU (1) -w, the processing cycle is ended, and when ATAU (1) <TAU (1) -w, the process proceeds to step 154, where ST (1) is reduced or advanced by b. You.
[0051]
In the same manner as in the above-described embodiments, a third timing interval INT (3) between the main injection and the post-injection, and a fourth timing interval INT between the post-injection and the HC supply injection. (4) The fuel injection period TAU (4) of the post injection and the fuel injection period TAU (5) of the HC supply injection can also be corrected. In this case, the third temporal interval INT (3) corresponds to the second temporal interval INT (2), and the fourth temporal interval INT (4) corresponds to the first temporal interval INT (1). Corresponding. The post-injection fuel injection period TAU (4) corresponds to the second pilot injection fuel injection period TAU (2), and the HC supply injection fuel injection period TAU (5) corresponds to the first pilot injection fuel injection period TAU (5). This corresponds to the injection period TAU (1).
[0052]
In the above-described embodiment, the needle lift sensor 41 detects a change in the needle lift amount with respect to the crank angle, and thereby detects the actual timing interval and the actual fuel injection period. However, for example, an in-cylinder pressure sensor that generates an output signal representing the in-cylinder pressure is arranged in the cylinder to detect a change in the in-cylinder pressure with respect to the crank angle, thereby detecting an actual timing interval and an actual fuel injection period. You can also. Alternatively, an ion current detection glow that generates an output voltage proportional to the ion current generated when the combustion flame crosses the flame is disposed in the cylinder, and the change in the ion current with respect to the crank angle is detected, whereby the actual timing interval is determined. Alternatively, the actual fuel injection period may be detected.
[0053]
【The invention's effect】
The timing interval between fuel injections can be maintained at a target timing interval.
[Brief description of the drawings]
FIG. 1 is an overall view of an internal combustion engine.
FIG. 2 is a diagram for explaining a fuel injection timing and the number of fuel injections performed in one cylinder combustion cycle.
FIG. 3 is a schematic diagram showing a fuel injection timing of a fuel injection operation in one combustion cycle.
FIG. 4 is a flowchart showing a routine for calculating a fuel injection timing.
FIG. 5 is a flowchart showing a routine for calculating a fuel injection timing.
FIG. 6 is a flowchart illustrating a calculation routine of a fuel injection timing.
FIG. 7 is a flowchart showing a routine for calculating a fuel injection timing.
[Explanation of symbols]
1. Engine body
20 ... Fuel injection valve
21 ... Common rail

Claims (6)

In a fuel injection device for an internal combustion engine in which a main injection is performed after a sub-injection is performed or a sub-injection is performed after a main injection is performed in one combustion cycle, an actual timing between the main injection and the sub-injection The target interval is detected, and when the deviation amount of the timing interval from the target timing interval is larger than a predetermined value , the fuel injection timing of the main injection is adjusted so that the timing interval becomes the target timing interval. A fuel injection device for an internal combustion engine , wherein the fuel injection timing of sub-injection is corrected while maintaining the same, and the fuel injection timing of sub-injection is not corrected when the deviation amount is smaller than a predetermined value . A fuel injection device for an internal combustion engine in which the main injection is performed after the second and first sub-injections are sequentially performed in one combustion cycle, or the first and second sub-injections are sequentially performed after the main injection is performed The actual timing interval between the first sub-injection and the main injection is detected, and the first timing is maintained while maintaining the fuel injection timing of the main injection such that the timing interval becomes a target timing interval. secondary injection fuel injection timing of the is corrected by the correction amount, the fuel of the correction amount corresponding second auxiliary injection as timing intervals is maintained between the first sub-injection and the second sub-injection A fuel injection device for an internal combustion engine that corrects an injection timing. A fuel injection device for an internal combustion engine in which the main injection is performed after the second and first sub-injections are sequentially performed in one combustion cycle, or the first and second sub-injections are sequentially performed after the main injection is performed , The actual timing interval between the first sub-injection and the second sub-injection is detected, and the fuel injection timing of the first sub-injection is set so that the timing interval becomes a target timing interval. A fuel injection device for an internal combustion engine, wherein the fuel injection timing of the second sub- injection is corrected while maintaining the above. In a fuel injection device of an internal combustion engine that performs main injection after performing sub injection in one combustion cycle or performs sub injection after performing main injection, an actual fuel injection period of sub injection is detected. The fuel injection start time and the fuel injection completion time of the sub-injection are corrected so that the one far from the main injection is maintained, so that the fuel injection period of the sub-injection becomes the target fuel injection period. A fuel injection device for an internal combustion engine. A fuel injection device for an internal combustion engine in which the main injection is performed after the second and first sub-injections are sequentially performed in one combustion cycle, or the first and second sub-injections are sequentially performed after the main injection is performed In the above, the actual fuel injection period of the first sub-injection is detected, and the fuel injection start timing of the first sub-injection is set so that the fuel injection period of the first sub-injection becomes the target fuel injection period. Of the fuel injection completion timings, the one far from the main injection is corrected by the correction amount while the one closer to the main injection is corrected, and the timing interval between the first sub-injection and the second sub-injection is maintained. Thus, the fuel injection device for the internal combustion engine is configured to correct the fuel injection timing of the second sub- injection by the correction amount. A fuel injection device for an internal combustion engine in which the main injection is performed after the second and first sub-injections are sequentially performed in one combustion cycle, or the first and second sub-injections are sequentially performed after the main injection is performed. The actual fuel injection period of the second sub-injection is detected, and the fuel injection start timing of the second sub-injection is set so that the fuel injection period of the second sub-injection becomes the target fuel injection period. A fuel injection device for an internal combustion engine, wherein the fuel injection completion timing is corrected while maintaining the one closer to the main injection and correcting the one far from the main injection.

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