JP2008223600A - Fuel injection control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress torque shocks in a start of combustion when an engine is restarted in a hybrid vehicle or the like. <P>SOLUTION: When a diesel engine having a compression pressure changing means such as a throttle valve of the hybrid vehicle or the like is restarted, cranking is started at low compression pressure, the compression pressure is increased after an engine revolution speed has reached a compression pressure restoration speed, injection is started as the injection pressure of a fuel injection valve reaches injection start pressure or higher, and pilot injection timing in the injection is controlled to an advanced side as the compression pressure is lower, and controlled to a retarded side as the compression pressure is gradually restored. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine for a vehicle, in particular, a hybrid vehicle using a motor and an engine as a prime mover, or an idle stop vehicle that starts after restarting the engine with a starter motor after the engine is stopped by waiting for a signal, etc. The present invention relates to fuel injection control when starting (cranking) the engine.

  In Patent Document 1, in an engine equipped with a compression pressure changing means such as a decompression, at the time of restart, cranking is performed while reducing the compression pressure in a region including a resonance point with the drive system, whereby engine torque fluctuations and vibrations are detected. Is reduced.

Moreover, misfire prevention at the time of the first explosion is aimed at by starting fuel injection after returning the reduced compression pressure.
JP 2003-113723 A

  In the configuration in which fuel injection is started after returning the compression pressure as in Patent Document 1, misfire at the start of combustion can be prevented, but torque shock that occurs at the start of combustion at the high compression pressure (first explosion) becomes a problem. It was.

  The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to provide an engine fuel injection control device capable of avoiding a torque shock at the start of combustion while smoothly starting cranking. .

In order to solve the above problems, the present invention provides:
In an engine having fuel injection means for performing main injection and pilot injection,
Means is provided for changing the pilot injection timing according to the compression pressure in the cylinder.

  With such a configuration, it is possible to ensure good combustion stability even at a low compression pressure by changing the pilot injection timing according to the compression pressure.

  As a result, combustion can be started at a low compression pressure, and torque shock at the start of combustion can be reduced.

  FIG. 1 shows a power train of a system in which the present invention is applied to an idle stop vehicle and restarted by a starter motor after the engine is stopped at the time of temporary stop.

  The engine 1 is started by ignition and combustion of fuel cranked by a starter motor 2 and injected by a fuel injection valve (injector) 3.

  The starter motor 2, the fuel injection valve 3, and the like are controlled by an ECM (engine controller) 4.

  FIG. 2 shows various signals input to the ECM 4 and various control signals output based on these signals.

  The ECM 4 includes an atmospheric pressure detection signal PA from the atmospheric pressure sensor 31, a cooling water temperature detection signal TW from the water temperature sensor 32, a rail pressure (fuel pressure in the common rail) detection signal PR from the fuel pressure sensor 33, and a rotation speed sensor 34. Is input to the starter motor 2 based on these input signals, and a main injection instruction signal and a pilot injection instruction signal are output to the fuel injection valve 3. Is provided with a compression pressure change means 35, a compression pressure means change control signal is output to the compression pressure change means.

  FIG. 3 shows an example of a power train in which the present invention is applied to a hybrid vehicle.

  An output shaft of the engine 1 is connected to a first motor / generator 6 via a clutch 5, and an output shaft thereof is connected to a transmission 7.

  The first inverter 8 converts DC power from the battery 9 into AC power and outputs the AC power to the first motor / generator 6 to drive the first motor / generator 6 as a motor, and the first motor / generator 6 generates the generator. , The battery 9 is charged by converting the generated power from the first motor / generator 6 into DC power.

  Further, the engine 1 includes a second motor / generator 11 for starting the engine that is linked to the engine 1 via a belt 10, and further includes a second inverter 12 between the second motor / generator 11 and the battery 9. .

  The engine 1 is controlled by an engine controller (ECM) 13, the first motor / generator 6 and the first inverter 8 are controlled by a first motor controller (MC) 14, and the second motor / generator 11 and the second inverter 12 are 2, the ECM 13, the first MC 14, and the second MC 15 are integrally controlled by a command from the hybrid controller (HCM) 16.

  FIG. 4 shows the input / output state of the HCM 16.

  FIG. 5 shows an example of the engine 1.

  The engine 1 is a diesel engine, and intake air is drawn into the cylinder 28 from an air cleaner 22 through an intake passage 23, a collector 24, an intake manifold 25, and an intake valve 26 that is driven to open and close by an intake cam 26.

  A piston 29 is inserted into the cylinder 28, and fuel is injected and supplied by the fuel injection valve 3. The combustion exhaust is discharged to the exhaust passage 33 through an exhaust valve 32 that is opened and closed by an exhaust cam 31.

  A part of the exhaust is introduced into the EGR passage 34 as EGR gas, and is returned to the intake manifold 25 while the EGR amount is controlled by the EGR valve 35.

  And as a compression pressure change means, at least 1 is provided among the following each means.

  The throttle valve 36 is composed of a butterfly valve, for example, and reduces the cross-sectional area of the intake passage 23 to reduce the pressure downstream of the valve {see FIG. 6A}.

  The intake shut-off valve 37 is constituted by a butterfly valve, a flap valve, a poppet valve, etc., and shuts off the intake passage continuously or in a predetermined section in one cycle to lower the pressure downstream of the valve {see FIG. 6B} .

  The intake valve characteristic variable means (intake valve opening / closing timing variable means or intake valve operating angle variable means) 38 changes the valve center angle by changing the phase of the intake cam or uses a plurality of cams having different profiles. The amount of air flowing into the cylinder in the intake stroke is changed using another known variable valve mechanism such as a switcher {see FIG. 6C}. The continuously variable type has no step when changing the cylinder internal pressure, and the switching type has the advantage that the compression pressure can be changed quickly.

  FIG. 7 shows a flow of the first embodiment in which the at least one compression pressure changing means performs the change control of the compression pressure at the time of engine start (cranking) and the fuel injection control according to the compression pressure.

  In step S101, it is determined whether engine start control is being performed. Note that “during engine start control” is defined as from the start of cranking to the end of operation of the compression pressure changing means.

  Here, the compression pressure at the start of cranking is set to the minimum in order to reduce the cranking torque and suppress the vibration, so that the vibration can be suppressed even if the compression pressure is increased as the engine speed increases. Then, the compression pressure is recovered (increased), and after the compression pressure has recovered to an appropriate value, fuel injection is started to suppress misfire.

  Therefore, when it is determined in step S101 that the engine start control is being performed, the engine speed NE and the rail pressure (fuel pressure) PR are read in step S102, and the operation amount of the compression pressure changing means is set in step S103. Specifically, according to the map characteristics shown in FIG. 8, after the cranking starts, compression is performed according to the increase in the engine rotational speed NE so that the compression pressure increases (recovers) after reaching a predetermined compression pressure recovery rotational speed. Increase the operating amount of the pressure changing means.

  Next, in step S104, it is determined whether the rail pressure PR is equal to or higher than the injection start pressure PRs at which fuel can be injected.

  When it is determined that PR ≧ PRs, the process proceeds to step S105, it is determined whether the operation amount PD of the compression pressure changing means has reached the injection start permission operation amount PDp, and after determining that it has reached, the process proceeds to step S106. Allow fuel injection. If it is determined in step S104 that PR <PRs, or if it is determined in step S105 that PD <PDp, fuel injection is not permitted in step S108. The injection start permission operation amount PDp is set within a compression pressure range in which stable combustion is possible.

  When the fuel injection is permitted, the process proceeds to step S107, and the pilot injection timing is adjusted according to the operation amount PD of the compression pressure changing means.

  Here, as shown in FIG. 8, the operation amount PD of the compression pressure changing means increases from the initial value of the injection start permission operation amount PDp according to the increase in the engine rotational speed NE, and the compression pressure is accordingly increased. Increase.

  On the other hand, as shown in the map characteristics of FIG. 9, the pilot injection timing is on the advance side when the compression pressure is low, and is retarded as the compression pressure increases. In the present invention, the pilot injection timing is set so as to ensure stable combustion by starting the combustion by the main injection in the combustion process by the pilot injection, and the generated torque is ensured. Since the ignition delay time due to is large and the ignition delay time decreases as the compression pressure increases, the pilot injection timing is retarded.

  Therefore, after the start of injection is permitted, the pilot injection timing is gradually delayed from the advance side as the compression pressure increases as the operation amount PD of the compression pressure changing means increases in accordance with the increase in the engine speed NE. Horned.

  According to the above control, the cranking torque can be reduced by maintaining the compression pressure as low as possible in a region where the engine speed is relatively low including the resonance point of the engine mount and drive system within a predetermined period from the start of cranking. As a result, it is possible to suppress engine torque fluctuations and vibrations that are problematic in the early stages of cranking.

  Next, the compression pressure recovery control is started, fuel injection is started when the compression pressure is restored to an appropriate value, and the pilot injection timing is changed in accordance with the recovery of the compression pressure. Can be secured.

  This makes it possible to start combustion at a low compression pressure, coupled with stable flammability, to further reduce the torque shock at the time of the first explosion, and then to stable combustion until the end of control at start-up while recovering the compression pressure Can be performed smoothly after starting.

  FIG. 10A shows the heat generation rate when pilot injection timing control according to the compression pressure according to the present invention is performed, and main combustion (combustion by main injection) in the combustion process in pilot combustion (combustion by pilot injection) ) Is started and the heat generation rate gradually increases, and rapid combustion can be suppressed and torque shock can be reduced. Note that the combustibility can be further stabilized by setting the injection timing so that the peak of the heat generation rate is near the top dead center and after the top dead center. FIG. 5B shows a case where the pilot injection timing is not controlled. Each combustion is separated, the heat generation rate in the main combustion increases rapidly, and the torque shock increases.

  In addition, it can be calculated | required by simple calculation by setting it as the structure which calculates | requires pilot injection timing etc. by a predetermined map as mentioned above.

  FIG. 11 shows a flow of a second embodiment in which an intake throttle such as the throttle valve 36 or the intake cutoff valve 37 is used as the compression pressure changing means.

  In steps S201 and 202, it is determined that the engine start control is being performed, and after reading the engine speed NE and the rail pressure PR, the intake throttle operation amount is set in step S203. The intake throttle operation amount is set by searching from a map having the characteristics shown in the middle of FIG. Specifically, for a predetermined time from the start of cranking until the engine speed reaches the compression pressure recovery speed, the intake throttle operation amount (intake passage opening area) is minimized, and the operation amount is reduced after reaching the compression pressure recovery speed. Increase.

  The compression pressure is proportional to the intake pressure on the downstream side of the intake throttle, and at the time of low rotation at the start of cranking, from the maximum at the intake pressure = atmospheric pressure to the minimum as the intake pressure decreases as the engine speed increases Decrease. When the intake throttle operation amount is increased after reaching the compression pressure recovery speed, the compression pressure also increases accordingly. However, the increase in the compression pressure causes a time delay and a primary time delay with respect to the increase in the operation amount. Increase with.

  Then, after determining in step S204 that the rail pressure PR has reached the injection start pressure PRs, in step S205, it is determined whether the elapsed time of the intake throttle operation (increase in the operation amount) has reached the injection start permission time. , The injection start is permitted in step S206.

  The pilot injection timing in step S207 is set by searching from a map having the characteristics shown in FIG. The time delay of the change in compression pressure is experimentally obtained in advance with respect to the change in the intake throttle operation amount shown in FIG. 12 (shown by the dotted line in FIG. 13), and the characteristic of the first order delay is applied to the setting of the pilot injection timing. .

  Thus, since the intake pressure and the compression pressure have a correlation as shown in FIG. 14, an intake pressure sensor may be provided and the pilot injection timing may be set based on the detected intake pressure value. FIG. 15 shows characteristics of pilot injection timing setting according to the intake pressure PA.

  FIG. 16 shows a flow of a third embodiment in which a variable lift valve that switches the intake valve lift amount in two stages is used as the intake valve characteristic varying means 38 that is a compression pressure changing means.

  In step S303, the lift amount of the variable lift valve is set. Specifically, as shown in the upper part of FIG. 17, the variable lift valve is controlled to a low lift until the start time of the compression pressure recovery control is reached according to the elapsed time (or engine speed) from the start of cranking. Then, after reaching the compression pressure recovery control start timing, the variable lift valve is switched to a high lift. Here, even when the variable lift valve is in a low lift, the lift amount is set to be equal to or higher than the compression pressure at which the start of fuel injection can be permitted.

  When it is determined in step S304 that the rail pressure PR has reached the injection start pressure PRs, the injection start is permitted in step S305. The variable lift valve at the start of injection is controlled to be a low lift, and then switched to a high lift after a predetermined time has elapsed.

  As shown in the lowermost stage of FIG. 17, the pilot injection timing is set at step S306. When the variable lift valve is controlled to a low lift, the pilot injection timing is fixed to the advance side, switched to a high lift, and the compression pressure is changed. In synchronism with the recovery, the angle is retarded by a predetermined amount. This predetermined retardation amount is set according to the amount of increase in the compression pressure. In Patent Document 1, it is disclosed as a preferred embodiment that fuel injection is started after switching to a high lift to prevent misfire, but in the present invention, the pilot injection timing is changed according to the compression pressure. Specifically, by controlling to the advance side at a low compression pressure and retarding at a high compression pressure, optimum combustibility can be obtained according to the compression pressure, which allows combustion to start at a low compression pressure Thus, torque shock can be avoided.

  When using a variable lift valve that has a configuration in which the lift amount is continuously variable or switched in three or more stages, the pilot injection timing is set according to the operation amount (lift amount) (described later). The same applies when setting the main injection timing).

  FIG. 18 shows a flow of the fourth embodiment in which the main injection timing is changed together with the pilot injection timing according to the compression pressure, and the pilot injection timing and the main injection timing are shown in FIG. 19 according to the compression pressure in step S407. Set by searching from a map with characteristics.

  Specifically, as with the pilot injection timing, the main injection timing is also set to an advanced side when the compression pressure is low, and is retarded as the compression pressure increases, but when the compression pressure is low The interval from the pilot injection timing is short, and the interval is set longer as the compression pressure becomes higher.

  In this way, the pilot injection timing and the main injection timing are both changed according to the compression pressure, and the interval between the pilot injection and the main injection timing is changed according to the compression pressure, so that the rapid increase in combustion pressure can be suppressed more effectively. The effect of suppressing torque shock can be enhanced.

  FIG. 20 shows an example of the in-cylinder pressure waveform diagram with respect to the crank angle when the injection timing control according to the present embodiment is performed, and shows the effect of improving the combustion stability as compared with the case where this control is not performed. . A thick line is an example of a combustion waveform when stable combustion is possible by fuel injection timing control, and a thin line is an example of a combustion waveform when there is variation in combustion. By performing the injection timing setting as shown in FIG. 19, the variation in combustion can be reduced, so that the effect of improving the stability of combustion can be obtained.

  FIG. 21 shows a timing chart in an embodiment in which the present invention is applied to the configuration provided with the compression pressure changing means described above.

  In a region where the rotational speed is relatively low, including the resonance point of the engine mount and drive system, the compression pressure is lowered to reduce engine torque fluctuation and vibration. Thereafter, when the compression pressure is gradually returned to become a rail pressure that can be injected and becomes a compression pressure that can be ignited, the fuel injection timing is determined according to the compression pressure, and fuel injection is started.

  FIG. 22 shows a comparison of the in-cylinder pressure waveform (indicated by a thick line) with respect to the crank angle when fuel injection is started at a low compression pressure according to the present invention as compared to the case when fuel injection is started at a high compression pressure (indicated by a thin line). It is shown. As in the present invention, by starting fuel injection at a low compression pressure in the middle of returning the compression pressure, compared to the case of starting fuel injection at a high compression pressure, the in-cylinder pressure peak generated by combustion is suppressed and at the time of the first explosion It is clear that the torque shock can be reduced.

  FIG. 23 shows an example of combustion characteristics when effective in improving the stability of combustion. Combustion stability can be further improved by controlling the injection timing so that the combustion pressure is greater than the compression pressure and the peak of the heat generation rate is near and after the top dead center.

  Next, a fifth embodiment in which the present invention is applied to an engine having no compression pressure changing means 35 as described above will be described.

  Since there is a relationship as shown in FIG. 24A between the atmospheric pressure and the compression pressure, the pilot injection timing and the main injection timing are set according to the atmospheric pressure as shown in FIG. .

  In this way, even when the compression pressure decreases with a decrease in atmospheric pressure, such as when traveling at high altitudes, the effect of improving the combustion stability by controlling the main injection timing can be obtained.

  FIG. 25 shows a flow of a sixth embodiment in which the operation amount of the compression pressure changing means is adjusted according to the atmospheric pressure in an engine provided with the compression pressure changing means.

  In step S502, in addition to the engine rotational speed NE and rail pressure PR, the atmospheric pressure PA detected by the atmospheric pressure sensor is read. In step S503, the operation amount of the compression pressure changing means is set in the same manner as in step S403 in FIG. After the setting, in step S504, the operation amount adjustment amount of the compression pressure changing means corresponding to the atmospheric pressure is added.

  As the operating amount adjustment amount, a value set by searching from a map having the characteristics shown in FIG. 26 according to atmospheric pressure is used. Specifically, the operation amount adjustment amount is set to be larger as the atmospheric pressure PA is lower than the standard atmospheric pressure (760 mmHg).

  Further, the setting of the pilot injection timing and the main injection timing in step S507 is set using the characteristics of FIG. 19 according to the operating amount of the compression pressure changing means, as in step S407 of FIG. Since an adjustment amount by the atmospheric pressure is added, when the atmospheric pressure is low, an appropriate injection timing is set according to the operation amount that is greatly adjusted.

  In this way, for example, when the compression pressure is changed by the compression pressure changing means such as the intake throttle valve, when the atmospheric pressure is low such as when traveling at a high altitude, the compression pressure at the same compression pressure changing means operating amount decreases. Therefore, it can be corrected to an appropriate compression pressure by adding an operation amount adjustment amount, and the pilot injection timing and the main injection timing are also appropriately set according to the operation amount of the compression pressure changing means adjusted appropriately. Is done. Therefore, even if the atmospheric pressure changes, the combustion stability can be improved, and a good restart can be performed while suppressing torque shock.

  FIG. 27 shows a flow of the seventh embodiment in consideration of the engine temperature at the time of engine restart.

  Steps S601 to 608 and 611 are the same as steps S401 to S408 in FIG. Note that the atmospheric pressure correction may be performed by adding an operation amount adjustment amount corresponding to the atmospheric pressure in step S504 of FIG.

  After the fuel injection is permitted and the pilot injection timing and the main injection timing are set in step S607, it is determined in step S608 whether a predetermined time has elapsed since the start of fuel injection was permitted.

  Here, as shown in FIG. 28 (A), the predetermined time is variably set according to the cooling water temperature at the time of starting (cooling water temperature detected from the start of cranking to the start of fuel injection), and is cooled at the time of starting. It is set longer as the water temperature is lower than the water temperature after warming up.

  When the predetermined time has not elapsed, the process proceeds to step S609, and the injection timing adjustment amounts of the pilot injection timing and the main injection timing are set. As shown in FIG. 28B, the injection timing adjustment amount is set to be larger as the start-up cooling water temperature is lower than the warm-up water temperature.

  In step S610, the advance angle adjustment amount is added to the pilot injection timing and the main injection timing set in step S607.

  That is, each injection timing is corrected to a larger advance side for a longer time as the coolant temperature at start-up is lower. It should be noted that the adjustment of the injection timing according to the start-up coolant temperature may be performed only for the pilot injection timing, and when adjusting at both injection timings, the adjustment amount may be set separately for each injection timing.

In the present embodiment, the cooling water temperature is used as the combustion room temperature parameter for setting the injection timing adjustment amount. Also good.
FIG. 29 shows changes in various state quantities after the start of cranking when the injection timing adjustment based on the starting coolant temperature is performed.

  In FIG. 29, the adjustment amount of each injection timing within the predetermined time is set to gradually decrease in the latter half so that it becomes 0 by the end of the predetermined time.

  In this way, since the ignitability decreases when the combustion room temperature is low, the pilot injection timing, or the pilot injection timing and the main injection timing are further advanced in accordance with the combustion room temperature within a predetermined time after the injection is permitted. By ensuring that the ignition delay period is secured and combustion is adjusted so that the heat generation rate reaches a peak near top dead center, combustion stability can be further improved, and combustion stability is ensured even during cold start. it can.

The block diagram which shows an example of the power train of the system which applied this invention to the idle stop vehicle. The figure which shows the input / output state of the engine controller of a powertrain same as the above. The block diagram which shows an example of the power train of the system which applied this invention to the hybrid vehicle. The figure which shows the input / output state of the hybrid controller of a powertrain same as the above. The figure which shows an example of the engine to which this invention is applied. The figure which shows the effect | action for every different compression pressure change means in an engine same as the above. The flowchart which shows the control which concerns on 1st Embodiment at the time of engine starting. The diagram which shows the operation amount setting characteristic of the compression pressure change means of embodiment same as the above. The diagram which shows the setting characteristic of the pilot injection timing of embodiment same as the above. The figure which shows the heat release rate at the time of performing pilot injection timing control by this invention compared with the heat release rate at the time of conventional control. The flowchart which shows the control which concerns on 2nd Embodiment at the time of engine starting. The time chart which shows the change of the various state quantity at the time of control which concerns on 2nd Embodiment. The diagram which shows an example of the setting characteristic of the pilot injection timing of 2nd Embodiment. The diagram which shows the relationship between intake pressure and compression pressure in 2nd Embodiment. The diagram which shows another example of the setting characteristic of the pilot injection timing of 2nd Embodiment. The flowchart which shows the control which concerns on 3rd Embodiment at the time of engine starting. The time chart which shows the change of the various state quantity at the time of control which concerns on 2nd Embodiment. The flowchart which shows the control which concerns on 4th Embodiment at the time of engine starting. The diagram which shows an example of the setting characteristic of the pilot injection time of 4th Embodiment, and the main injection time. The diagram which shows an example of the cylinder pressure waveform figure with respect to a crank angle in 4th Embodiment. The timing chart in embodiment which applied this invention to the structure provided with the compression pressure change means. The diagram which shows the cylinder pressure waveform when fuel injection is started with the low compression pressure of this invention compared with the time when fuel injection is started with the low compression pressure. The diagram which shows an example of the combustion characteristic in the case of being effective for the improvement of combustion stability. The figure which shows the relationship between atmospheric pressure and compression pressure in 5th Embodiment. The flowchart which shows the control which concerns on 6th Embodiment at the time of engine starting. The diagram which shows the characteristic of the operation amount adjustment amount according to atmospheric pressure in 6th Embodiment. The flowchart which shows the control which concerns on 7th Embodiment at the time of engine starting. The diagram which shows an example of the predetermined time setting and injection timing adjustment amount setting which perform injection timing adjustment in 7th Embodiment. The time chart which shows the change of the various state quantities after the cranking start when performing injection timing adjustment same as the above.

Explanation of symbols

1 engine,
2 starter motor 3 fuel injection valve 4 engine controller 6 first motor / generator 11 second motor / generator 13 engine controller 14 first motor controller 15 second motor controller 16 hybrid controller 31 atmospheric pressure sensor 32 water temperature sensor 33 fuel pressure sensor 34 rotation Speed sensor 35 Compression pressure changing means 36 Throttle valve 37 Intake shut-off valve 38 Intake valve characteristic varying means

Claims (14)

In an engine having fuel injection means for performing main injection and pilot injection,
An engine fuel injection control device comprising means for changing a pilot injection timing in accordance with a compression pressure in a cylinder.   The engine fuel injection control apparatus according to claim 1, wherein the pilot injection timing is set so that combustion by main injection is started in a combustion process by pilot injection.   The engine fuel injection control device according to claim 1 or 2, wherein the pilot injection timing is advanced as the compression pressure is lower.   The engine fuel injection control device according to any one of claims 1 to 3, wherein means for changing the main injection timing is provided, and the main injection timing is advanced as the compression pressure is lower.   The engine fuel injection control apparatus according to claim 4, wherein the lower the compression pressure, the closer the interval between the pilot injection timing and the main injection timing.   6. The pilot injection timing and the main injection timing are controlled so that the heat release rate peak is near and after the top dead center during combustion. Engine fuel injection control device.   The means for changing the compression pressure is provided, and the pilot injection timing, or the pilot injection timing and the main injection timing are adjusted in accordance with the operation amount thereof. Engine fuel injection control device.   The compression pressure changing means is provided with means for changing a valve characteristic of an intake valve, and the pilot injection timing, or the pilot injection timing and the main injection timing are adjusted according to the valve characteristic of the intake valve. 8. A fuel injection control device for an engine according to claim 7.   8. The engine according to claim 7, wherein means for changing the intake pressure is provided as the compression pressure changing means, and the pilot injection timing or the pilot injection timing and the main injection timing are adjusted according to the intake pressure change amount. Fuel injection control device.   The means for detecting atmospheric pressure is provided, and the pilot injection timing or the pilot injection timing and the main injection timing are adjusted according to the atmospheric pressure. Engine fuel injection control device.   The engine fuel injection control apparatus according to any one of claims 1 to 10, wherein the pilot injection timing is further advanced within a predetermined time from the start of injection.   The engine fuel injection control device according to any one of claims 1 to 11, wherein the main injection timing is further advanced within a predetermined time from the start of injection.   The engine fuel according to claim 11 or 12, wherein the predetermined time is set according to a temperature detection value representing a combustion room temperature detected between the start of cranking and the start of fuel injection. Injection control device.   The pilot injection timing or the additional advance amount of the pilot injection timing and the main injection timing is set according to a temperature detection value representing a combustion room temperature detected between the start of cranking and the start of fuel injection. The engine fuel injection control device according to any one of claims 11 to 13, wherein the engine fuel injection control device is any one of the above.

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