JP6304115B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device.

  Some in-vehicle engines include an injector that performs fuel injection by opening a needle valve by energizing an electromagnetic solenoid. In addition, at the start of fuel injection of such an injector, it is known that a large current is caused to flow through the electromagnetic solenoid by discharging from the capacitor, thereby improving the responsiveness of the needle valve opening operation and thus the responsiveness of the injector. ing.

  On the other hand, when performing multiple fuel injections in one compression / expansion stroke per cylinder, so-called multi-injection, the interval from one injection to the next is narrowed and the capacitor is not fully charged. It can happen that an injection is started. As a result, a delay occurs in the opening of the needle valve at the start of the next injection, which may deteriorate the injection control. Therefore, conventionally, in the fuel injection control device described in Patent Document 1, when the interval from the previous injection in the multi-injection is narrow and the charging voltage of the capacitor at the start of injection is insufficient, the discharge start timing of the capacitor is advanced. Thus, a delay in the actual injection start timing with respect to the required injection start timing is suppressed.

  As is well known, in an engine, a small amount of fuel may be injected to improve exhaust properties. However, the injection amount that can ensure the injection amount accuracy has a lower limit due to the mechanical factors of the injector, and the realization of fuel injection of a smaller amount than a certain level has been hindered. That is, when the needle valve is fully opened, it collides with other parts and bounces by its reaction. Therefore, immediately after the valve is fully opened, the lift amount of the needle valve pulsates, increasing the variation in the injection amount. The effect of such a bounce motion becomes more prominent as the injection amount is smaller. Therefore, it has been difficult to ensure the accuracy of the injection amount when the injection amount is smaller than a certain amount.

  On the other hand, in recent years, a partial lift injection technique has been proposed as a technique that realizes high-accuracy trace fuel injection by avoiding the deterioration of the injection amount accuracy due to the bounce motion of the needle valve as described above. The partial lift injection is a fuel injection performed by shortening the energization time for the electromagnetic solenoid than the time required for the needle valve to be fully opened. In such partial lift injection, since the injection is finished before the needle valve is fully opened and bounces, a very small amount of injection can be performed with high accuracy.

  By adopting such partial lift injection technology, it is possible to realize fuel injection in an unprecedented form. For example, in each cylinder, most of the required amount of fuel is injected during the intake stroke by full lift injection until the needle valve is fully opened, and then a small amount of fuel is injected by partial lift injection at a predetermined timing in the compression stroke It is a form to do. By the way, according to the fuel injection in such a form, it is possible to improve the combustion state of the fuel by forming an air-fuel mixture having a locally high concentration in the vicinity of the spark plug in the combustion chamber at the time of ignition. It becomes. In an engine that adopts the partial lift injection technology, as in this example, it is considered to perform multi-injection of full lift injection and partial lift injection at a timing significantly different from the full lift injection.

JP 2005-171928 A

  By the way, in order to reduce the number of parts, there is a case where injectors of a plurality of cylinders share a capacitor. In such an engine, when performing full lift injection and partial lift injection multi-injection as described above, the start timing of full lift injection by an injector of a cylinder and the start of partial lift injection by an injector of a cylinder different from that cylinder The interval with the time may be narrowed. In such a case, the capacitor whose charging voltage has dropped due to the discharge at the start of the previous injection may not be sufficiently charged by the start of the subsequent injection, and the opening of the needle valve is delayed due to insufficient voltage. There is a risk that the quantity accuracy will deteriorate.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide a fuel injection control device capable of suppressing deterioration in injection amount accuracy due to insufficient charging of a capacitor at the start of injection. There is.

  In the fuel injection control device that solves the above-described problem, the needle valve is opened by discharging from the capacitor to the electromagnetic solenoid to start fuel injection, and the needle valve is fully opened in the partial lift injection in which the needle valve is not fully opened. This is applied to an engine in which an injector that performs full lift injection up to is provided for each cylinder. The fuel injection control device includes an energization control unit that performs energization control of the injector so as to start discharging of the capacitor at a required injection start timing set in accordance with an operation state of the engine. Further, the energization control unit in the fuel injection control device calculates a time difference between the required injection start timings for the partial lift injection and the full lift injection performed by the two injectors sharing the capacitor, and calculates the difference. When the time difference is less than the specified time, the required injection start timing of at least one of the partial lift injection and the full lift injection is corrected so that the time difference becomes larger.

  In the fuel injection control device, the required injection start timing of partial lift injection by one injector among the injectors of each cylinder of the engine, and the required injection start timing of full lift injection by another injector sharing the condenser with the injector. When the time difference becomes smaller than the specified value, the required injection start timing of at least one of the partial lift injection and the full lift injection is corrected so that the time difference becomes larger. For this reason, it is possible to suppress the shortage of the charging time of the capacitor, and thus suppress the deterioration of the injection amount accuracy due to the insufficient charging of the capacitor at the start of injection.

  The effect of insufficient charging of the capacitor on the injection amount accuracy is relatively large in partial lift injection where the injection amount is small in the first place. Therefore, full lift injection with a large amount of injection in the first place may be tolerable as long as the capacitor is insufficiently charged. On the other hand, if the required injection start time is changed from the time set according to the operating state of the engine, the combustion state may deteriorate in some cases. Therefore, the energization control unit in the fuel injection control device corrects the required injection start timing when the required injection start timing of the partial lift injection is later than the required injection start timing of the full lift injection, and the partial lift It is desirable not to perform the injection when the required injection start timing of injection is earlier than the required injection start timing of the full lift injection. In such a case, the required injection start timing is corrected only when the injection that may cause insufficient charging of the capacitor is partial lift injection. Therefore, it is possible to achieve both suppression of deterioration of combustion due to change in the required injection start timing and suppression of decrease in injection amount accuracy.

  Further, in the full lift injection having a longer injection time than the partial lift injection, the influence of the correction of the required injection start timing on the combustion state is relatively small. Therefore, the energization control unit in the fuel injection control device corrects the required injection start timing by correcting the required injection start timing of the full lift injection while maintaining the required injection start timing of the partial lift injection. It is desirable to do so. In such a case, the correction of the required injection start timing is applied only to the full lift injection and not to the partial lift injection. Therefore, it is possible to achieve both suppression of deterioration of combustion due to change in the required injection start timing and suppression of decrease in injection amount accuracy.

  Note that the energization control unit in the fuel injection control device preferably corrects the required injection start timing when the time difference is less than the time required for full charge of the capacitor. In such a case, since the required injection start timing is corrected only when the capacitor is insufficiently charged at the start of injection, the required injection start timing is unnecessary when there is no risk of deterioration of the injection amount accuracy due to insufficient charging of the capacitor. Correction can be avoided.

  Furthermore, it is preferable that the energization control unit in the fuel injection control device corrects the required injection start timing so that the time difference is equal to or longer than a time required for full charge of the capacitor. In such a case, the required injection start timing can be corrected so that the injection can be started with the capacitor being fully charged.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole structure of the fuel-injection control apparatus of 1st Embodiment. The figure which shows transition of the injection command signal, the discharge switch operation signal, the constant current switch operation signal, the injector drive current, and the nozzle lift amount at the time of fuel injection in the fuel injection control device. The graph which shows the relationship between the energization time of an injector, the fuel injection quantity, and its dispersion | variation. The flowchart of the injection command routine performed in the said fuel-injection control apparatus. An example of the control mode of the fuel injection control device of the first embodiment when the full lift injection is started after the partial lift injection is started and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. An example of the control mode of the fuel injection control device of the first embodiment when the partial lift injection is started after the start of the full lift injection and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. The flowchart of the injection command routine performed in the fuel-injection control apparatus of 2nd Embodiment. An example of the control mode of the fuel injection control device of the second embodiment when the full lift injection is started after the partial lift injection is started and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. An example of the control mode of the fuel injection control device of the second embodiment when the partial lift injection is started after the start of the full lift injection and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. The flowchart of the injection command routine performed in the fuel-injection control apparatus of 3rd Embodiment. An example of the control mode of the fuel injection control device of the third embodiment in the case where the full lift injection is started after the partial lift injection is started and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. An example of the control mode of the fuel injection control device of the third embodiment when the partial lift injection is started after the start of the full lift injection and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. The flowchart of the injection command routine performed in the fuel-injection control apparatus of 4th Embodiment. An example of the control mode of the fuel injection control device of the fourth embodiment in the case where the full lift injection is started after the partial lift injection is started and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown. An example of the control mode of the fuel injection control device of the fourth embodiment when the partial lift injection is started after the start of the full lift injection and the time difference between the required injection timings of both injections is less than the full charge time of the capacitor. Time chart shown.

(First embodiment)
Hereinafter, a first embodiment of a fuel injection control device will be described in detail with reference to FIGS.
The fuel injection control device of the present embodiment shown in FIG. 1 controls the injection operation of four injectors INJ1 to INJ4 installed in each cylinder of a vehicle-mounted four-cylinder engine. In the drawing, the sectional structure of only the injector INJ4 installed in the fourth cylinder of the engine is shown, and the sectional structure of the injectors INJ1 to INJ3 of the first to third cylinders is omitted. Have the same structure.

  Each of the injectors INJ1 to INJ4 incorporates an electromagnetic solenoid 21. The electromagnetic solenoid 21 is provided inside the housing 20 of each injector INJ1 to INJ4 and includes a fixed core 22, an electromagnetic coil 23, and a movable core 24. The fixed core 22 is fixed to the housing 20 and magnetized in response to energization to the electromagnetic coil 23 provided around the fixed core 22. The movable core 24 is provided adjacent to the fixed core 22 inside the housing 20 so as to be displaceable in the vertical direction in the figure. A needle valve 25 is integrally connected to the movable core 24 so as to be displaceable. In addition, a spring 26 is provided inside the housing 20 to constantly urge the movable core 24 toward the side (lower side in the figure) that is separated from the fixed core 22. A fuel chamber 29 into which pressurized fuel is introduced from the outside is formed inside the housing 20.

  On the other hand, a nozzle body 27 is attached to the distal end portion (lower end portion in the drawing) of the housing 20 so as to surround the periphery of the distal end portion of the needle valve 25. A slit-shaped injection hole 28 that communicates the inside and the outside of the nozzle body 27 is formed at the tip of the nozzle body 27. On the other hand, a fuel chamber 29 into which pressurized fuel is introduced from the outside is formed inside the housing 20.

  In the injectors INJ1 to INJ4, the needle valve 25 is displaceable in a range from a fully closed position where the tip of the needle valve 25 abuts (sits) to the nozzle body 27 to a fully open position where the movable core 24 abuts the fixed core 22. Yes. When the tip of the needle valve 25 is lifted from the nozzle body 27, the injection hole 28 is communicated with the fuel chamber 29, and the fuel introduced into the fuel chamber 29 is injected outside through the injection hole 28. On the other hand, when the needle valve 25 is displaced to the fully closed position and is seated on the nozzle body 27, the communication between the injection hole 28 and the fuel chamber 29 is blocked, and the fuel injection is stopped. In the following description, the displacement amount of the needle valve 25 from the fully closed position is referred to as a nozzle lift amount.

  The energization of the injectors INJ1 to INJ4 to the electromagnetic solenoid 21 (electromagnetic coil 23) is performed from the battery 15 and the capacitor 16. The capacitor 16 stores a high-voltage current for quickly opening the needle valve 25 by accelerating the excitation of the electromagnetic solenoid 21, and charging is performed through a booster circuit 19 that boosts the supply voltage of the battery 15.

  On the other hand, the fuel injection control device includes an electronic control unit 10. The electronic control unit 10 temporarily stores a central processing unit that performs various arithmetic processes related to fuel injection control, a read-only memory that stores control programs and data, arithmetic results of the central processing unit, sensor detection results, and the like. A readable / writable memory and an input / output port for sending / receiving signals to / from the outside are provided.

  The input port of the electronic control unit 10 includes a fuel pressure sensor 11 that detects the pressure (fuel pressure PF) of fuel supplied to the injectors INJ1 to INJ4, and a crank angle sensor that detects the rotational phase (crank angle) of the crankshaft of the engine. 12. An accelerator pedal sensor 13 for detecting an accelerator pedal depression amount (accelerator pedal depression amount ACCP) is connected. In addition to this, various sensors for detecting the operating status of the engine and the vehicle are connected to the input port. The electronic control unit 10 calculates the engine speed NE from the detection result of the crank angle sensor 12.

  On the other hand, the drive circuits 14 of the injectors INJ1 to INJ4 are connected to the output ports of the electronic control unit 10, respectively. Each drive circuit 14 includes a microcomputer (hereinafter referred to as a microcomputer) 14A, a discharge switch 14B, and a constant current switch 14C. The discharge switch 14B connects and disconnects the energization path from the capacitor 16 to the electromagnetic solenoid 21 of the corresponding injectors INJ1 to INJ4 according to the opening / closing thereof. The constant current switch 14C connects and disconnects the energization path from the battery 15 to the electromagnetic solenoids 21 of the corresponding injectors INJ1 to INJ4 according to the opening / closing thereof. On the other hand, the microcomputer 14A monitors the current (injector drive current) flowing through the electromagnetic solenoids 21 of the corresponding injectors INJ1 to INJ4, and according to the monitoring result and the injection command signal received from the electronic control unit 10, the discharge switch 14B and the constant current switch 14C are operated.

  FIG. 2 shows an example of a control mode at the time of fuel injection in the fuel injection control device of this embodiment. The figure shows the transition of the injection command signal output from the electronic control unit 10 to the drive circuit 14, the operation signal of the microcomputer 14A for the discharge switch 14B, and the operation signal of the microcomputer 14A for the constant current switch 14C. Has been. Further, the figure also shows the transition of the current flowing through the electromagnetic solenoid 21 (injector drive current) and the nozzle lift amount of the needle valve 25.

  For each fuel injection, the electronic control unit 10 generates and outputs a rectangular wave injection command signal to the drive circuit 14 of the injectors INJ1 to INJ4 that perform the fuel injection. In the figure, the injection command signal is output so that it is turned on from time-off at time t1, and is kept on until time t4, and then turned off.

  Receiving this injection command signal, the microcomputer 14A of the drive circuit 14 turns on the discharge switch 14B in response to the switching of the injection command signal from OFF to ON at time t1. Thereby, the electric charge stored in the capacitor 16 is discharged to the electromagnetic solenoid 21. In response to the excitation of the electromagnetic solenoid 21 by the discharge, the injector drive current increases, and the movable core 24 is attracted to the magnetized fixed core 22 against the urging force of the spring 26. As a result, the needle valve 25 is lifted from the nozzle body 27 and fuel injection is started.

  On the other hand, when the injector drive current reaches the specified peak current Ip at time t2, the microcomputer 14A operates the discharge switch 14B to turn off, and then keeps the injector drive current in the vicinity of the specified hold current Im. 14C is opened and closed. When the injection command signal switches from on to off at time t4, the microcomputer 14A stops energization of the electromagnetic solenoid 21 by holding the constant current switch 14C off. In response to the demagnetization of the fixed core 22, the movable core 24 is separated from the fixed core 22 by the biasing force of the spring 26. When the needle valve 25 reaches the fully closed position, the fuel injection is stopped.

  In the figure, the needle valve 25 reaches the fully open position at time t3. The needle valve 25 reaches the fully open position when the movable core 24 abuts against the fixed core 22, but a bounce motion occurs in the needle valve 25 due to a reaction at the end of the abutment. Therefore, immediately after time t3 when the needle valve 25 reaches full open, a pulsation occurs in the nozzle lift amount. The amplitude and period of the pulsation of the nozzle lift amount after such full opening changes from time to time. On the other hand, the fuel injection amount per unit time from the injectors INJ1 to INJ4 changes in correlation with the nozzle lift amount. Therefore, the bounce motion of the needle valve 25 when fully opened is a factor that deteriorates the fuel injection amount accuracy.

  FIG. 3 shows the relationship between the fuel injection amounts of injectors INJ1 to INJ4 and their variations, and the energization time of electromagnetic solenoid 21. In the drawing, “T0” is an energization time necessary for starting the lift of the needle valve 25, and “Tpmax” is an energization time necessary for lifting the needle valve 25 to the fully open position. In the interval from T0 to Tpmax, the amount of nozzle lift during energization changes, so the rate of change of the fuel injection amount with respect to the energization time becomes relatively large. On the other hand, in the section after Tpmax, since the nozzle lift amount is maintained at the fully opened amount, the rate of change of the fuel injection amount with respect to the energization time is relatively small. In the following description, a section of energization time from T0 to Tpmax in which the needle valve 25 does not fully open is referred to as a “partial lift (P / L) section”. A section of energization time after Tpmax when the needle valve 25 is fully opened is referred to as a “full lift (F / L) section”.

  There is a certain degree of variation in the time from the start of energization to the start of lift of the needle valve 25, and this variation causes variations in the fuel injection amount in the partial lift section. However, the variation in the fuel injection amount in the partial lift section decreases as the energization time increases. On the other hand, immediately after the energization time enters the full lift section, the variation in the fuel injection amount temporarily increases due to the bounce motion of the needle valve 25 described above. The influence of such a bounce movement becomes relatively small as the energization time increases. For this reason, the variation in the fuel injection amount once increased immediately after entering the full lift section decreases as the energization time increases. Therefore, if the energization time of the electromagnetic solenoid 21 is set longer than a specified time (full lift injection minimum energization time Tfmin) longer than Tpmax and fuel injection is performed, variation in the fuel injection amount can be suppressed to an allowable upper limit value or less. .

  On the other hand, as described above, even in the partial lift section, the variation in the fuel injection amount is relatively small during the energization time immediately before entering the full lift section. Therefore, even when the fuel solenoid is injected with the energization time of the electromagnetic solenoid 21 set in a range not less than a specified time (partial lift minimum energization time Tpmin) and less than Tpmax, the variation in the fuel injection amount is suppressed to an allowable upper limit value or less. be able to. That is, by setting the energization time in such a range and performing fuel injection in which the needle valve 25 does not reach full open, so-called partial lift injection, a small amount of fuel injection can be performed with high accuracy. In the fuel injection control device of this embodiment, a small amount of fuel injection by such partial lift injection is performed as necessary.

Next, details of fuel injection control in the fuel injection control device of the present embodiment will be described.
The electronic control unit 10 performs a required injection amount that is a fuel injection amount necessary for generating a torque corresponding to the required torque in accordance with the required torque of the engine calculated from the accelerator pedal depression amount ACCP or the like for each specified control cycle. Q is calculated. Furthermore, the electronic control unit 10 calculates a required injection start timing TS, which is a required value of the crank angle at which the injection is started, according to the engine speed NE, the engine load, and the like. In this fuel injection control device, there is a case where multi-injection is performed in which fuel necessary for generating torque corresponding to the required torque is divided into a plurality of times and injected depending on the operating state of the engine. In that case, the electronic control unit 10 individually calculates the required injection amount Q and the required injection start timing TS for each of the plurality of injections. Then, the electronic control unit 10 generates an injection command signal based on the calculated required injection amount Q and the required injection start timing TS. The injection command signal is turned on at the required injection start timing TS of each injection, and is generated to be turned off after being maintained on for the required injection time TAU from that point.

  On the other hand, as described above, discharging of the capacitor 16 to the electromagnetic solenoids 21 of the injectors INJ1 to INJ4 is started when the injection command signal is turned on. Therefore, in this fuel injection control apparatus, the injectors INJ1 to INJ4 are configured so that the electronic control unit 10 that generates the injection command signal starts discharging the capacitor 16 at the required injection start timing TS set according to the operating state of the engine. This corresponds to an energization control unit that performs energization control.

  In this fuel injection control apparatus, as one of the injection modes of multi-injection, there are cases where fuel injection is performed in two parts, that is, main injection during the intake stroke and minute injection during the compression stroke. In this injection mode, most of the required fuel is injected during the intake stroke, while a small amount of fuel is injected during the compression stroke to form an air-fuel mixture in the cylinder with a locally high fuel concentration in the vicinity of the spark plug. This is done for the purpose of improving the combustion state of the fuel. Incidentally, the main injection during the intake stroke at this time is performed by full lift injection, and a small amount of fuel injection during the compression stroke is performed by partial lift injection.

  FIG. 4 shows a flowchart of an injection command routine related to generation of the injection command signal as described above. The processing of this routine is executed for each specified crank angle by the electronic control unit 10 during engine operation.

  When the processing of this routine is started, first, in step S100, the current engine speed NE and fuel pressure PF are read. Subsequently, in step S101, a required injection start timing TS and a required injection amount Q of each scheduled injection are read in a period from the present to the next execution time of this routine (hereinafter referred to as a target period).

  In the subsequent step S102, for each injection scheduled in the target period, a required injection time TAU, which is the energization time of the electromagnetic solenoid 21 required for fuel injection for the required injection amount Q, is calculated based on the engine speed NE and the fuel pressure PF. The It should be noted that the energization time of the electromagnetic solenoid 21 required for the injection for the required injection amount Q is in a range in which the variation in the fuel injection amount cannot be suppressed below the allowable upper limit value, that is, the range exceeding Tpmin and less than the full lift injection minimum energization time Tfmin. If so, the required injection time TAU is set to the full lift injection minimum energization time Tfmin. In the following description, the required injection time of the i-th injection in the target period is described as TAU [i], and the required injection start timing TS is described as TS [i] (i is an arbitrary natural number).

  Subsequently, in step S103, the value of the counter n is set to “1”. Thereafter, the processing from step S104 to step S111 is repeatedly executed until it is determined in step S111 that the value of the counter n has reached the scheduled number of injections in the target period.

  In step S104, it is determined whether or not the nth injector in the target period and the next (n + 1) th injector are different cylinder injectors. Here, if the injectors of the different cylinders perform these two injections (YES), the process proceeds to step S105, and if the same injector performs (NO), the process proceeds to step S110.

  When the process proceeds to step S105, it is determined in step S105 whether any of the nth injection and the (n + 1) th injection in the target period is a partial lift injection. Specifically, it is determined whether any of the required injection time TAU [n] of the nth injection and the required injection time TAU [n + 1] of the (n + 1) th injection is less than Tpmax. Here, if either the nth or n + 1th injection is a partial lift injection (YES), the process proceeds to step S106; otherwise, both the nth and n + 1th injections are full lift. If it is injection (NO), the process proceeds to step S110.

  When the process proceeds to step S106, a time difference ΔT between the required injection start timings TS [n] and TS [n + 1] for the nth injection and the n + 1th injection is calculated in step S106. Specifically, the time difference ΔT calculates the difference in crank angle between the required injection start timings TS [n] and TS [n + 1] and calculates the time required for the rotation of the crankshaft at the difference at the current engine speed NE. It is calculated by doing.

  In the subsequent step S107, it is determined whether or not the time difference ΔT is less than the full charge time TC of the capacitor 16. The full charge time TC is a time required for full charge of the capacitor 16, more specifically, a charge time of the capacitor 16 required until the capacitor 16 is fully discharged after being fully discharged. If the time difference ΔT is less than the full charge time TC (YES), the process proceeds to step S108. If the time difference ΔT is equal to or greater than the full charge time TC (NO), the process proceeds to step S110.

  When the process proceeds to step S108, in step S108, the crank angle conversion value of the difference (= TC−ΔT) of the time difference ΔT with respect to the full charge time TC is set as the value of the correction amount ΔTS. That is, the crankshaft rotation angle at the time difference ΔT at the current engine speed NE is calculated, and the calculated value is set as the value of the correction amount ΔTS. In subsequent step S109, the required injection start timing TS [n + 1] of the (n + 1) th injection in the target period is corrected to the retard side by the correction amount ΔTS, and then the process proceeds to step S110.

  When the process proceeds to step S110, 1 is added to the value of the counter n in step S110. Then, in the next step S111, it is determined whether or not the value of the counter n has reached the scheduled number of injections in the target period. If the value of the counter n is not the same as the scheduled number of injections in the target period (NO), the process returns to step S104, and the processes of steps S104 to S110 are executed again. On the other hand, if the value of the counter n is the same as the scheduled number of injections in the target period (YES), the process proceeds to step S112. In step S112, the required injection start timings TS [1], TS [2],..., Required injection times TAU [1], TAU [2],. In response to this, after the injection command signals of the injectors INJ1 to INJ4 are generated, the processing of this routine is terminated.

  In the above routine, for each injection scheduled in the target period, the time difference ΔT of the required injection start timing TS with the next injection in the target period is calculated. Then, it is determined whether or not all of the following requirements (A) to (C) are satisfied. If all of the requirements (A) to (C) are satisfied, the injection and the next injection request The required injection start timing TS of the next injection is corrected to the retard side so that the time difference ΔT of the injection start timing TS becomes the full charge time TC of the capacitor 16. That is, in this routine, the time difference ΔT between the required injection start timings TS is calculated for the partial lift injection and the full lift injection respectively performed by the two injectors INJ1 to INJ4 sharing the capacitor 16. When the calculated time difference ΔT is less than the full charge time TC of the capacitor 16, the required injection start timing TS of either the partial lift injection or the full lift injection is corrected so that the time difference ΔT becomes larger. .

(B) The injection following the injection in the target period is performed by an injector of a cylinder different from the injector that performs the injection.
(B) Either the injection or the injection next to the injection is performed by partial lift injection.

(C) The time difference ΔT between the required injection start timing TS of the injection and the required injection start timing TS of the next injection is less than the full charge time TC of the capacitor 16.
Then, the effect | action of the fuel-injection control apparatus of this embodiment is demonstrated.

  As described above, in the fuel injection control device of the present embodiment, multi-injection of main injection during the intake stroke by full lift injection and micro injection during the compression stroke by partial lift injection may be performed. In such a case, the time difference between the required injection start timing TS of full lift injection during the intake stroke of a certain cylinder and the required injection start timing TS of partial lift injection during the compression stroke of another cylinder becomes small. For this reason, the capacitor 16 whose charging voltage has decreased due to the discharge at the start of the previous injection cannot be sufficiently charged by the start of the subsequent injection, and the opening of the needle valve 25 is delayed and the injection amount accuracy may deteriorate. There is. That is, when the time difference ΔT between the required injection start timings TS of the partial lift injection and the full lift injection at this time is less than the full charge time TC of the capacitor 16, in the injection to be started later in both injections, the capacitor at the start of the injection The charging voltage of 16 becomes lower than the value at the time of full charging, and the valve opening of the needle valve 25 is delayed. The required injection time TAU is set on the assumption that the charging voltage of the capacitor 16 at the start of injection is a value at the time of full charging. Therefore, when the charging voltage of the capacitor 16 at the start of injection becomes lower than the value at the time of full charge, the injection amount accuracy is deteriorated.

  Incidentally, the multiple fuel injections by the single injector in the multi-injection are set to be performed at a time longer than the full charging time TC of the capacitor 16. Further, in this fuel injection control device, the proximity of the fuel injection start timing between the cylinders until the capacitor 16 is insufficiently charged is the main injection during the intake stroke by full lift injection and the micro injection during the compression stroke by partial lift injection. This is limited to multi-injection.

  In the fuel injection control device of this embodiment, the electronic control unit 10 calculates the time difference ΔT of the required injection start timing TS of each injection in the generation target period when generating the injection command signal. When the partial lift injection and the full lift injection are performed during the target period, the electronic control unit 10 determines that the time difference ΔT is greater if the required injection start timing TS and the time difference ΔT are less than the full charge time TC of the capacitor 16. The required injection start time TS is corrected so as to increase.

  FIG. 5 shows how the required injection start time TS is set when the full lift injection of the injector B is started after the partial lift injection of the injector A is started. As shown by the solid line in the figure, when the time difference ΔT between the required injection start timings TS of both injections set according to the engine operating condition is less than the full charge time TC, the time difference between them as shown by the broken line in the figure. The required injection start timing TS for full lift injection of the injector B is corrected to the retard side so that ΔT extends to the full charge time TC. Therefore, even when the injection of the injector B is started, the charging voltage of the capacitor 16 is restored to the value at the time of full charging.

  FIG. 6 shows how the required injection start time TS is set when the partial lift injection of the injector B is started after the full lift injection of the injector A is started. As shown by the solid line in the figure, when the time difference ΔT between the required injection start timings TS of both injections set according to the engine operating condition is less than the full charge time TC, the time difference between them as shown by the broken line in the figure. The required injection start timing TS of the partial lift injection of the injector B is corrected to the retard side so that ΔT extends to the full charge time TC. Therefore, also in this case, the charging voltage of the capacitor 16 is restored to the value at the time of full charging even when the injection of the injector B is started.

According to the fuel injection control apparatus of the present embodiment described above, the following effects can be obtained.
(1) In the fuel injection control device of the present embodiment, the time difference ΔT between the required injection start timings TS for partial lift injection and full lift injection respectively performed by two of the injectors INJ1 to INJ4 sharing the capacitor 16 is Calculated. When the time difference ΔT is less than the full charge time TC of the capacitor 16, the required injection start timing TS is corrected so that the time difference ΔT becomes larger. Therefore, even when the time difference ΔT of the required injection start timing TS set according to the engine operating condition is less than the full charge time TC, insufficient charging of the capacitor 16 at the start of injection is suppressed. Therefore, the deterioration of the injection amount accuracy due to insufficient charging of the capacitor 16 at the start of injection can be suitably suppressed.

  (2) In the fuel injection control device of the present embodiment, the required injection start timing TS is corrected when the time difference ΔT between the required injection start timing TS for full lift injection and partial lift injection is less than the full charge time TC of the capacitor 16. Yes. Therefore, it can be avoided that the required injection start timing TS is unnecessarily corrected when there is no risk of deterioration in the injection amount accuracy due to insufficient charging of the capacitor 16.

  (3) In the fuel injection control device of the present embodiment, the required injection timing is corrected so that the time difference ΔT between the required injection start timings TS for full lift injection and partial lift injection becomes the full charge time TC of the capacitor 16. Is going. Therefore, the required injection start timing TS can be corrected so that the injection can be started with the capacitor 16 being fully charged.

(Second Embodiment)
Next, a second embodiment of the fuel injection control device will be described in detail with reference to FIGS. In the present embodiment and each of the embodiments described later, the same reference numerals are given to configurations common to the above-described embodiment, and detailed description thereof is omitted.

  The effect of insufficient charging of the capacitor 16 at the start of injection on the injection amount accuracy is relatively large in partial lift injection with a small injection amount in the first place. Therefore, for full lift injection with a large injection amount, the capacitor 16 is charged. Some deficiencies may be acceptable. On the other hand, if the required injection start time TS is corrected from the time set according to the operating condition of the engine, the combustion state may deteriorate in some cases. Therefore, in the fuel injection control device of the present embodiment, the capacitor 16 may be insufficiently charged even when the time difference ΔT between the required injection start timings TS of full lift injection and partial lift injection is less than the full charge time TC of the capacitor 16. The required injection start timing TS is corrected only when a certain injection is a partial lift injection.

  FIG. 7 shows a flowchart of an injection command routine executed in the fuel injection control apparatus of this embodiment. The processing of this routine is executed for each specified crank angle by the electronic control unit 10 during engine operation.

  When the processing of this routine is started, first, in step S200, the current engine speed NE and fuel pressure PF are read. Subsequently, in step S201, the required injection start timing TS and the required injection amount Q of each injection scheduled during the injection command signal generation target period from the present time to the next execution of this routine are read. In the subsequent step S202, for each injection scheduled in the target period, the required injection time TAU, which is the energization time of the electromagnetic solenoid 21 required for fuel injection for the required injection amount Q, is calculated based on the engine speed NE and the fuel pressure PF. Calculated.

  Subsequently, after the value of the counter n is set to “1” in step S203, the processes in steps S204 to S211 are performed until it is determined in step S211 that the value of the counter n has reached the scheduled number of injections in the target period. Repeatedly executed. That is, in step S204, it is determined whether or not the nth injector performing the injection and the n + 1th injector in the target period are different cylinder injectors. If the injectors of different cylinders perform these two injections (YES), the process proceeds to step S205. If the same injector performs (NO), the process proceeds to step S210.

  When the process proceeds to step S205, it is determined in step S205 whether or not the (n + 1) th injection in the target period is a partial lift injection. Specifically, it is determined whether or not the required injection time TAU [n + 1] of the (n + 1) th injection is less than Tpmax. If the (n + 1) th injection is a partial lift injection (YES), the process proceeds to step S206; otherwise, that is, if the (n + 1) th injection is a full lift injection (NO), the process proceeds to step S210. Is advanced.

  When the process proceeds to step S206, in step S206, a time difference ΔT between the required injection start timings TS [n] and TS [n + 1] of the nth injection and the n + 1th injection is calculated. Specifically, the time difference ΔT is calculated by converting the difference in crank angle between the required injection start times TS [n] and TS [n + 1] according to the engine speed NE.

  In the subsequent step S207, it is determined whether or not the time difference ΔT is less than the full charge time TC of the capacitor 16. If the time difference ΔT is less than the full charge time TC (YES), the process proceeds to step S208. If the time difference ΔT is equal to or greater than the full charge time TC (NO), the process proceeds to step S210.

  When the process proceeds to step S208, the crank angle conversion value of the difference (= TC−ΔT) of the time difference ΔT with respect to the full charge time TC is set as the value of the correction amount ΔTS in step S208. Then, in the subsequent step S209, after the required injection start timing TS [n + 1] of the (n + 1) th injection in the target period, which is performed as the partial lift (P / L) injection, is corrected to the retard side by the correction amount ΔTS, The process proceeds to step S210.

  When the process proceeds to step S210, 1 is added to the value of the counter n in step S210. Then, in the next step S211, it is determined whether or not the value of the counter n has reached the scheduled number of injections in the target period. Here, if the value of the counter n is not the same as the scheduled number of injections in the target period (NO), the process returns to step S204, and the processes of steps S204 to S210 are executed again.

  On the other hand, if the value of the counter n is the same as the scheduled number of injections in the target period (YES), the process proceeds to step S212. In step S212, the required injection start times TS [1], TS [2],..., Required injection times TAU [1], TAU [2],. In response to this, after the injection command signals of the injectors INJ1 to INJ4 are generated, the processing of this routine is terminated.

Then, the effect | action of the fuel-injection control apparatus of this embodiment is demonstrated.
FIG. 8 shows how the required injection start timing TS is set when the full lift injection of the injector B is started after the partial lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. At this time, the injection in which the insufficient charging of the capacitor 16 affects the injection amount accuracy is the full lift injection of the injector B. In such a case, in the fuel injection control device of the present embodiment, the required injection start timing TS is not corrected. Therefore, the charging voltage of the capacitor 16 at the start of full lift injection of the injector B becomes lower than the value at the time of full charging, and the injection amount accuracy of the injection is deteriorated to some extent. However, in the full lift injection with a large injection amount, the variation in the injection amount due to the deterioration in accuracy is relatively small, so the influence of the deterioration on the combustion state remains relatively small.

  FIG. 9 shows how the required injection start time TS is set when the partial lift injection of the injector B is started after the full lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. At this time, the injection in which the insufficient charging of the capacitor 16 affects the injection amount accuracy is the partial lift injection of the injector B. In partial lift injection with a small injection amount, the deterioration of the injection amount accuracy due to insufficient charging of the capacitor 16 at the start of injection is relatively large. In this respect, in such a case, the fuel injection control apparatus of the present embodiment performs the partial lift injection of the injector B so that the time difference ΔT between the required injection start timings TS of the full lift injection and the partial lift injection becomes the full charge time TC. The required injection timing is corrected. Therefore, the partial lift injection of the injector B is also started in a state where the charging voltage of the capacitor 16 becomes a value at the time of full charging.

According to the fuel injection control device of the present embodiment described above, in addition to the effects described in (1) to (3) above, the following effects can be further achieved.
(4) In the fuel injection control device of the present embodiment, the required injection start timing TS is corrected only when the injection that may cause insufficient charging of the capacitor 16 at the start of injection is partial lift injection. Therefore, it is possible to achieve both suppression of deterioration of combustion due to change of the required injection start timing TS and suppression of decrease in injection amount accuracy.

(Third embodiment)
Next, a third embodiment of the fuel injection control device will be described in detail with reference to FIGS.

  If the required injection start time TS for correcting the shortage of charging of the capacitor 16 at the start of injection as described above is corrected, the required injection start time TS deviates from the optimal time according to the operating condition of the engine. There is a risk of deteriorating the combustion state. However, in the full lift injection having a longer injection time than the partial lift injection, the influence of the correction of the required injection start timing TS on the combustion state is relatively small. Therefore, in the fuel injection control device of this embodiment, the request for full lift injection is applied so that the correction of the required injection start timing TS is applied only to full lift injection, that is, while the required injection start timing TS of partial lift injection is maintained. The injection timing is corrected.

  FIG. 10 shows a flowchart of an injection command routine executed in the fuel injection control device of this embodiment. The processing of this routine is executed for each specified crank angle by the electronic control unit 10 during engine operation.

  When the processing of this routine is started, first, in step S300, the current engine speed NE and fuel pressure PF are read. Subsequently, in step S301, the required injection start timing TS and the required injection amount Q of each injection scheduled during the injection command signal generation target period from the present time to the execution time of the next routine are read. In step S302, for each injection scheduled for the target period, the required injection time TAU, which is the energization time of the electromagnetic solenoid 21 required for fuel injection for the required injection amount Q, is calculated based on the engine speed NE and the fuel pressure PF. Calculated.

  Subsequently, after the value of the counter n is set to “1” in step S303, the processes in steps S304 to S312 are performed until it is determined in step S313 that the value of the counter n has reached the scheduled number of injections in the target period. Repeatedly executed. That is, in step S304, it is determined whether or not the nth injector for the target period and the n + 1th injector for different cylinders are different cylinders. Here, if the injectors of different cylinders perform these two injections (YES), the process proceeds to step S305, and if the same injector performs (NO), the process proceeds to step S312.

  When the process proceeds to step S305, in step S305, a time difference ΔT between the required injection start timings TS [n] and TS [n + 1] of the nth injection and the n + 1th injection in the target period is calculated. In subsequent step S306, it is determined whether or not the time difference ΔT is less than the full charge time TC of the capacitor 16. If the time difference ΔT is less than the full charge time TC (YES), the process proceeds to step S307. If the time difference ΔT is equal to or greater than the full charge time TC (NO), the process proceeds to step S312.

  When the process proceeds to step S307, in step S307, the crank angle conversion value of the difference (= TC−ΔT) of the time difference ΔT with respect to the full charge time TC is set as the value of the correction amount ΔTS. In step S308, it is determined whether or not the nth injection is a partial lift injection. Specifically, it is determined whether or not the required injection time TAU [n] for the nth injection is less than Tpmax.

  If the nth injection is a partial lift injection (S308: YES), the process proceeds to step S309. In the fuel injection control device according to the present embodiment, when multi-injection of partial lift injection and full lift injection is performed, partial lift injection is performed during the compression stroke of each cylinder, and partial lift injection is performed during the intake stroke. Never done. Therefore, in this case, the (n + 1) th injection is a full lift injection. When the process proceeds to step S309, in step S309, the required injection start timing TS [n + 1] of the (n + 1) th injection performed as the full lift injection is corrected to the retard side by the correction amount ΔTS, and then the process proceeds to step S312. Is advanced.

  On the other hand, if the n-th injection is not a partial lift injection (S307: NO), it is determined in step S310 whether the (n + 1) th injection is a partial lift injection. Specifically, it is determined whether or not the required injection time TAU [n + 1] of the (n + 1) th injection is less than Tpmax. If the (n + 1) th injection is a partial lift injection (YES), the process proceeds to step S311. In this case, the nth injection is full lift injection. When the process proceeds to step S311, the requested injection start timing TS [n] of the nth injection performed as full lift injection is corrected to the correction amount ΔTS advance angle side in step S311 and then the process proceeds to step S312. Is advanced.

  On the other hand, when it is determined in step S310 that the (n + 1) th injection is not a partial lift injection, the process proceeds to step S312. Note that the n-th injection and the (n + 1) -th injection at this time are full lift injections.

  When the process proceeds to step S312, 1 is added to the value of the counter n in step S312. Then, in the next step S313, it is determined whether or not the value of the counter n has reached the scheduled number of injections in the target period. If the value of the counter n is not the same as the scheduled number of injections in the target period (NO), the process returns to step S304, and the processes of steps S304 to S311 are executed again. On the other hand, if the value of the counter n is the same as the scheduled number of injections in the target period (YES), the process proceeds to step S314. In step S314, the required injection start times TS [1], TS [2]..., The required injection times TAU [1], TAU [2],. In response to this, after the injection command signals of the injectors INJ1 to INJ4 are generated, the processing of this routine is terminated.

Then, the effect | action of the fuel-injection control apparatus of this embodiment is demonstrated.
FIG. 11 shows how the required injection start timing TS is set when the full lift injection of the injector B is started after the partial lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. At this time, in the fuel injection control device of the present embodiment, as shown by the broken line in the drawing, the required injection start timing TS of the full lift injection of the injector B is maintained while maintaining the required injection start timing TS of the partial lift injection of the injector A. However, the time difference ΔT between the required injection start timings TS of the full lift injection and the partial lift injection is corrected so as to become the full charge time TC.

  FIG. 12 shows how the required injection start time TS is set when the partial lift injection of the injector B is started after the full lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. At this time, in the fuel injection control device of the present embodiment, as shown by the broken line in the figure, the required injection start timing TS of the full lift injection of the injector A is maintained while maintaining the required injection start timing TS of the partial lift injection of the injector B. However, the time difference ΔT between the required injection start timings TS of the full lift injection and the partial lift injection is corrected so as to become the full charge time TC.

According to the fuel injection control device of the present embodiment described above, in addition to the effects described in (1) to (3) above, the following effects can be further achieved.
(5) In the fuel injection control device of the present embodiment, when the time difference ΔT between the required injection start timing TS for full lift injection and partial lift injection is less than the full charge time TC of the capacitor 16, the required injection start timing TS for partial lift injection is set. While being maintained, the required injection start timing TS of full lift injection is corrected so that the time difference ΔT becomes larger. Therefore, the correction of the required injection start timing TS is applied only to the full lift injection in which the influence of the change in the required injection start timing TS on the combustion state is smaller, and is not applied to the partial lift injection in which the same effect is larger. Therefore, it is possible to achieve both suppression of deterioration of combustion due to change of the required injection start timing TS and suppression of decrease in injection amount accuracy.

(Fourth embodiment)
Next, a fourth embodiment of the fuel injection control device will be described in detail with reference to FIGS.

  As described above, in full lift injection with a large injection amount, the effect of insufficient charging of the capacitor 16 at the start of injection on the injection amount accuracy is smaller than with partial lift injection with a small injection amount. Further, in the full lift injection with a long injection time, the influence of the change in the required injection start timing TS on the combustion state is smaller than in the partial lift injection with a short injection time. Therefore, in the present embodiment, even when the capacitor 16 is insufficiently charged at the start of injection, the required injection start timing TS is corrected only when the injection is partial lift injection, and the correction is performed for full lift injection. This is applied only to the required injection start timing TS.

  FIG. 13 shows a flowchart of an injection command routine executed in the fuel injection control apparatus of this embodiment. The processing of this routine is executed for each specified crank angle by the electronic control unit 10 during engine operation.

  When the processing of this routine is started, first, in step S400, the current engine speed NE and fuel pressure PF are read. Subsequently, in step S401, the required injection start timing TS and the required injection amount Q of each injection scheduled in the injection command signal generation target period from the present time to the next execution of this routine are read. In the subsequent step S402, for each injection scheduled for the target period, the required injection time TAU, which is the energization time of the electromagnetic solenoid 21 required for fuel injection for the required injection amount Q, is calculated based on the engine speed NE and the fuel pressure PF. Calculated.

  Subsequently, after the value of the counter n is set to “1” in step S403, the processing in steps S404 to S411 is performed until it is determined in step S411 that the value of the counter n has reached the scheduled number of injections in the target period. Repeatedly executed. That is, in step S404, it is determined whether or not the nth injector performing the injection in the target period and the n + 1th injector performing are different cylinders. If the injectors of different cylinders perform these two injections (YES), the process proceeds to step S405. If the same injector performs (NO), the process proceeds to step S410.

  When the process proceeds to step S405, it is determined in step S405 whether or not the (n + 1) th injection in the target period is a partial lift injection. Specifically, it is determined whether or not the required injection time TAU [n + 1] of the (n + 1) th injection is less than Tpmax. If the (n + 1) th injection is a partial lift injection (YES), the process proceeds to step S406. The n-th injection at this time is full lift injection.

  On the other hand, if the (n + 1) th injection is not a partial lift injection (NO), the process proceeds to step S410. In this case, the case where the nth and n + 1th injections are both full lift injections and the case where the nth injection is partial lift injections and the n + 1th injection is full lift injections are included.

  When the process proceeds to step S406, a time difference ΔT between the required injection start timings TS [n] and TS [n + 1] of the nth injection and the n + 1th injection in the target period is calculated. Then, in the subsequent step S407, it is determined whether or not the time difference ΔT is less than the full charge time TC of the capacitor 16. If the time difference ΔT is less than the full charge time TC (YES), the process proceeds to step S408. If the time difference ΔT is equal to or greater than the full charge time TC (NO), the process proceeds to step S410.

  When the processing proceeds to step S408, in step S408, a crank angle converted value of the difference (= TC−ΔT) of the time difference ΔT with respect to the full charge time TC is set as the value of the correction amount ΔTS. In subsequent step S409, the required injection start timing TS [n] of the nth injection performed as full lift injection is corrected to the correction amount ΔTS advance angle side, and then the process proceeds to step S410.

  When the process proceeds to step S410, 1 is added to the value of the counter n in step S410. Then, in the next step S411, it is determined whether or not the value of the counter n has reached the scheduled number of injections in the target period. Here, if the value of the counter n is not the same as the scheduled number of injections in the target period (NO), the process returns to step S404, and the processes of steps S404 to S409 are executed again. On the other hand, if the value of the counter n is the same as the scheduled number of injections in the target period (YES), the process proceeds to step S412. In step S412, the required injection start timings TS [1], TS [2]..., The required injection times TAU [1], TAU [2]. After the injection command signals of the injectors INJ1 to INJ4 are generated, the current routine is terminated.

Then, the effect | action of the fuel-injection control apparatus of this embodiment is demonstrated.
FIG. 14 shows how the required injection start time TS is set when the full lift injection of the injector B is started after the partial lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. However, at this time, the fuel injection control apparatus of the present embodiment does not correct the required injection start timing TS for both the partial lift injection of the injector A and the full lift injection of the injector B.

  FIG. 15 shows how the required injection start time TS is set when the partial lift injection of the injector B is started after the full lift injection of the injector A is started. As shown by the solid line in the figure, the time difference ΔT between the required injection start timings TS for both injections set according to the engine operating condition is less than the full charge time TC. At this time, in the fuel injection control device of the present embodiment, as shown by the broken line in the figure, the required injection start timing TS of the full lift injection of the injector A is maintained while maintaining the required injection start timing TS of the partial lift injection of the injector B. However, the time difference ΔT between the required injection start timings TS is corrected so as to become the full charge time TC.

According to the fuel injection control device of the present embodiment described above, the effects described in (1) to (5) above can be achieved.
In addition, each said embodiment can also be changed and implemented as follows.

  The correction of the required injection start timing TS in step S109 of FIG. 4 or step S209 of FIG. 7 is performed by correcting the required injection start timing TS [n] of the nth injection to the correction amount ΔTS advance angle side. It may be. Even in such a case, it is possible to avoid insufficient charging of the capacitor 16 at the start of injection by setting the time difference ΔT between the required injection start timings TS of partial lift injection and full lift injection as the full charge time TC of the capacitor 16.

  The correction of the required injection start timing TS in step S109 of FIG. 4 or step S209 of FIG. 7 is performed by setting the required injection start timing TS [n] of the nth injection to the advance side and the required injection start timing of the (n + 1) th injection. Alternatively, TS [n + 1] may be corrected to the retard side. Even in such a case, if the sum of these correction amounts is the difference of the time difference ΔT with respect to the full charge time TC (= TC−ΔT), the time difference ΔT between the required injection start timings TS for the partial lift injection and the full lift injection. Is the full charge time TC of the capacitor 16, it is possible to avoid insufficient charging of the capacitor 16 at the start of injection.

  In each of the above embodiments, the required injection start timing TS is corrected so that the time difference ΔT between the required injection start timing TS for partial lift injection and full lift injection becomes the full charge time TC of the capacitor 16. Specifically, in step S108 of FIG. 4, step S208 of FIG. 7, step S307 of FIG. 10, and step S408 of FIG. 13, the crank angle conversion value of the difference of the time difference ΔT with respect to the full charge time TC is set to the correction amount ΔTS. Set. In step S109 in FIG. 4, step S209 in FIG. 7, steps S309 and S311 in FIG. 10, and step S409 in FIG. 13, the required injection start timing TS is corrected by the correction amount ΔTS. The value of the correction amount ΔTS may be set in another manner, for example, a fixed value. In such a case, the time difference ΔT between the corrected partial lift injection and the required injection start timing TS of the full lift injection may be less than the full charge time TC or may be longer than the full charge time TC. Even if the time difference ΔT of the required injection start timing TS after the correction is less than the full charge time TC, if the time difference ΔT is larger than before the correction, the shortage of charging of the capacitor 16 at the start of injection becomes smaller. The deterioration of the injection amount accuracy is suppressed to some extent. Further, when the time difference ΔT of the corrected required injection start timing TS exceeds the full charge time TC, the required injection start timing TS is changed more than necessary, but the capacitor 16 at the start of injection is fully charged. State. Incidentally, if the correction amount ΔTS is set so that the time difference ΔT of the corrected required injection start timing TS is always equal to or longer than the full charge time TC, the required injection start timing is set so that the capacitor 16 at the start of injection is always fully charged. It is possible to correct TS.

  In each of the above embodiments, the required injection start timing TS is corrected when the time difference ΔT between the required injection start timing TS for partial lift injection and full lift injection is less than the full charge time TC of the capacitor 16. When the capacitor voltage at the start of injection is equal to or higher than a predetermined voltage lower than the value at the time of full charge, if the injection amount accuracy can be sufficiently secured, the time difference ΔT is less than the specified time shorter than the full charge time TC The required injection start time TS may be corrected. In consideration of the variation in the full charge time TC, the required injection start timing TS may be corrected when the time difference ΔT is less than the specified time longer than the full charge time TC.

  In each of the above embodiments, all of the injectors INJ1 to INJ4 are configured to share the single capacitor 16, but may be configured to include a plurality of capacitors shared by the plurality of injectors. In such a case, when the time difference between the required injection start times TS of the partial lift injection and the full lift injection is less than the specified time, the two injectors that perform the injection share the capacitor If the two injectors that perform these injections do not share a capacitor, they should not be performed.

  -Although the fuel-injection control apparatus of each said embodiment was applied to the 4-cylinder engine, it can apply similarly to the engine from which the number of cylinders differs.

  INJ1 to INJ4 ... injectors, 10 ... electronic control unit (energization controller), 11 ... fuel pressure sensor, 12 ... crank angle sensor, 13 ... accelerator pedal sensor, 14 ... drive circuit, 14A ... microcomputer, 14B ... discharge switch, 14C ... Constant current switch, 15 ... battery, 16 ... capacitor, 20 ... housing, 21 ... electromagnetic solenoid, 22 ... fixed core, 23 ... electromagnetic coil, 24 ... movable core, 25 ... needle valve, 26 ... spring, 27 ... nozzle body, 28 ... nozzle hole, 29 ... fuel chamber.

Claims (5)

An injector that opens the needle valve by discharging from the capacitor to the electromagnetic solenoid to start fuel injection and performs partial lift injection in which the needle valve does not fully open and full lift injection in which the needle valve fully opens is provided for each cylinder. Fuel injection control provided with an energization control unit which is applied to the engine provided in the engine and performs energization control of the injector so as to start discharging of the capacitor at a required injection start timing set in accordance with an operation state of the engine In the device
The energization control unit calculates a time difference between the required injection start timings for partial lift injection and full lift injection respectively performed by the two injectors sharing the capacitor, and the calculated time difference is less than a specified time. In addition, the required injection start timing of at least one of the partial lift injection and the full lift injection is corrected so that the time difference becomes larger.
A fuel injection control device. The energization control unit performs correction of the required injection start timing when the required injection start timing of the partial lift injection is later than the required injection start timing of the full lift injection, and the required injection start timing of the partial lift injection is Do not perform when it is earlier than the required injection start timing of full lift injection,
The fuel injection control device according to claim 1. The energization control unit performs the correction of the required injection start timing by correcting the required injection start timing of the full lift injection while maintaining the required injection start timing of the partial lift injection.
The fuel injection control device according to claim 1 or 2. The energization control unit corrects the required injection start timing when the time difference is less than the time required for full charge of the capacitor.
The fuel-injection control apparatus of any one of Claims 1-3. The energization control unit performs the correction of the required injection start timing so that the time difference is equal to or longer than the time required for full charge of the capacitor.
The fuel-injection control apparatus of any one of Claims 1-4.