JP4196742B2 - Fuel injection timing control method for in-cylinder direct injection CNG engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method during fuel injection of an in-cylinder direct injection CNG engine having a stratified combustion operation region by directly injecting compressed natural gas (CNG) into the cylinder, and more specifically, the fuel pressure has changed. Even when the fuel spray and the cavity collide, the distance between the fuel injection valve and the cavity can be kept substantially constant, and the fuel injection timing of the in-cylinder direct injection CNG engine that can achieve stratified combustion with poor robustness It relates to a control method.
[0002]
[Prior art]
In recent years, from the viewpoints of energy and environmental measures, compressed natural gas (CNG) has been used as a fuel for automobile internal combustion engines, and CNG fuel has been injected into the cylinder to improve fuel efficiency and output. In-cylinder direct injection CNG engines (hereinafter referred to as “CNG engines” where appropriate) that directly inject fuel are being actively developed, and various techniques have been proposed.
[0003]
Although not shown in the drawings, such an in-cylinder direct injection CNG engine is provided with a concave cavity for establishing stratified combustion at the intake side portion of the piston top surface. The CNG engine normally includes a CNG fuel cylinder that stores CNG fuel, a fuel injection valve that directly injects CNG fuel into each cylinder, a delivery pipe that accumulates CNG fuel and distributes the fuel to each fuel injection valve, and CNG A high-pressure regulator is provided in the middle of the fuel supply pipe connecting the fuel cylinder and the delivery pipe, and depressurizes the CNG fuel to a predetermined pressure, and is configured to be able to switch between stratified combustion and homogeneous combustion.
[0004]
CNG fuel is stored at a high pressure (for example, about 20 MPa at the maximum) in the CNG fuel cylinder, but when pumped from the CNG fuel cylinder, in-cylinder injection can be performed by the high pressure regulator before being supplied to the delivery pipe. The pressure is reduced to a certain constant pressure (for example, about 5 MPa).
[0005]
Therefore, conventionally, a combustion map corresponding to the constant pressure value is set in advance, and based on this map, control is performed to switch between stratified combustion and homogeneous combustion according to the engine speed and load conditions, etc. .
[0006]
That is, such an in-cylinder direct injection CNG engine is intended to increase the charging efficiency and the like by improving the performance by injecting fuel in the compression stroke, so that it is necessary to inject fuel into the combustion chamber at a high pressure. In addition, it is known that when the residual gas pressure in the CNG fuel cylinder is equal to or lower than the above-described constant pressure value, the CNG fuel cannot be regulated and supplied by the high pressure regulator, and thus the cruising distance cannot be increased.
[0007]
For this reason, when the fuel pressure is lower than the reference pressure, the fuel pressure is low by controlling the intake valve to advance in the in-cylinder injection in the first half of the intake stroke or the compression stroke (immediately after the intake dead center). However, a technology that enables fuel injection and extends the cruising distance is disclosed (see Patent Document 1).
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-328997
[Problems to be solved by the invention]
However, in the prior art as described above, if the fuel spray injected at a high pressure from the fuel injection valve has a different fuel pressure (injection pressure), the spray length has the same fuel injection amount and injection time. As a result, the collision position with the cavity is different at the same injection start timing. For this reason, during the stratified combustion in which the compression stroke injection is performed, if the collision position of the fuel spray with the cavity is different, there is a possibility that misfire or the like may occur even at the same fuel amount injection.
[0010]
Therefore, it is desirable to provide a fuel injection timing control method for a direct injection CNG engine that can keep the distance between the fuel injection valve and the cavity almost constant even when the fuel spray changes and the cavity collides. It was.
[0011]
In addition, it has been desired to provide a fuel injection timing control method for a direct injection CNG engine that can perform appropriate fuel injection even when there is an abnormal pressure adjustment such as when the high pressure regulator is abnormal or when the amount of remaining fuel is low.
[0012]
The present invention has been made in view of the above, and even when the fuel pressure changes, the distance between the fuel injection valve and the cavity at the time of the collision between the fuel spray and the cavity can be kept substantially constant, and the robustness is improved. It is an object of the present invention to provide a method for controlling the fuel injection timing of a direct injection CNG engine that can establish poor stratified combustion.
[0013]
Another object of the present invention is to provide a method for controlling the fuel injection timing of a direct injection CNG engine that can perform appropriate fuel injection even when the fuel pressure changes due to abnormal pressure regulation.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a fuel injection timing control method for a direct injection CNG engine according to claim 1 of the present invention has a cavity in the piston top surface and stratified combustion and homogeneity according to engine operating conditions. A fuel injection timing control method for an in-cylinder direct injection CNG engine that switches between combustion, and when the fuel pressure is within the pressure-correctable level range and the injection timing correction required level range during stratified combustion, The fuel injection start timing is changed so that the collision position of the injected fuel spray with the cavity is the same as the collision position at the reference pressure.
[0015]
Therefore, according to the present invention, even when the fuel pressure changes, the distance between the fuel injection valve and the cavity at the time of collision between the fuel spray and the cavity can be kept substantially constant, so that stratified combustion with poor robustness is established. be able to.
[0016]
According to a second aspect of the present invention, there is provided a fuel injection timing control method for an in-cylinder direct injection CNG engine according to the first aspect, wherein the fuel pressure is within a pressure-correctable level range and a high pressure. The fuel supply system determines that the pressure regulation is abnormal due to an abnormality in the regulator, and switches to homogeneous combustion.Furthermore, the fuel injection start timing is fixed near the top dead center of the intake stroke, and fuel is injected in the injection period calculated from the sampling average fuel pressure. It is characterized by injecting.
[0017]
Therefore, according to the present invention, misfire due to the failure of stratified combustion or the like can be suppressed even when pressure regulation is abnormal, and uniform combustion can be handled.
[0018]
According to a third aspect of the present invention, there is provided a fuel injection timing control method for an in-cylinder direct injection CNG engine according to the first aspect of the present invention, wherein the fuel pressure is within a pressure correctable level range and a low pressure. When it is determined that the remaining amount of fuel is low, the combustion is switched to homogeneous combustion, and the injection end crank angle is calculated from the minimum interval map between injection and ignition, and the current pressure is calculated from the in-cylinder pressure map and fuel pressure defined in advance by the rotation speed and load. An injectable crank angle is calculated, the two calculated crank angles are compared, and the more advanced side is defined as the final injection end crank angle, and the injection start crank angle is determined based on the final injection end crank angle and the current fuel pressure. Is calculated and fuel is injected.
[0019]
Therefore, according to the present invention, when the remaining fuel amount decreases and the fuel pressure decreases, even if the control is immediately switched to the first half of the intake stroke injection or the compression stroke injection, the fuel can be injected in the compression stroke as much as possible. It is possible to suppress the homogeneous combustion region from being reduced at a stretch due to the shortage of quantity, and the homogeneous combustion region can be reduced stepwise. As a result, it is possible to minimize the time during which an inoperable region occurs.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a fuel injection timing control method for an in-cylinder direct injection CNG engine according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
[0021]
FIG. 1 is a flowchart showing a fuel injection timing control method for a direct injection CNG engine according to an embodiment of the present invention, FIG. 2 is a flowchart showing a control method when pressure regulation is abnormal, and FIG. It is a flowchart which shows the control method when there are few. FIG. 4 is a sectional view showing a schematic configuration of the CNG engine, and FIG. 5 is a schematic diagram showing a fuel supply system to the CNG engine.
[0022]
First, a schematic configuration of a CNG engine 10 and its fuel supply system to which the present invention is applied will be described with reference to FIGS. 4 and 5. As shown in FIGS. 4 and 5, the CNG engine 10 is a direct injection type in which CNG fuel is directly injected into the combustion chamber 10 a by the injector 23, and basically has the same configuration as a normal direct injection type gasoline engine. ing.
[0023]
That is, as shown in FIG. 4, the combustion chamber 10 a of the CNG engine 10 is configured by a cylinder bore 11, a cylinder head 13, and a piston 12 that is reciprocally disposed in the cylinder bore 11. A concave cavity 12a is formed in the intake side portion of the top surface of the piston 12 in order to establish stratified combustion.
[0024]
A spark plug 14 for igniting the air-fuel mixture is disposed substantially at the center of the combustion chamber 10a. An intake valve 16 is disposed at the intake port 15 facing the combustion chamber 10a, and an exhaust valve 20 is disposed at the exhaust port 18 facing the combustion chamber 10a. An injector 23 that directly injects CNG fuel into the combustion chamber 10a is disposed near the intake valve 16 in the combustion chamber 10a.
[0025]
The injector 23 has its spray shape and spray angle set so that the fuel spray 23a is injected into the cavity 12a. The distance L1 indicates the distance between the injection hole of the injector 23 and the bottom wall of the cavity 12a when the fuel spray 23a collides with the piston 12.
[0026]
The fuel spray 23a injected from the injector 23 enters the cavity 12a, collides with the bottom wall of the cavity 12a, and then forms an air-fuel mixture while flowing in the direction of the spark plug 14 along the bottom wall. The air-fuel mixture is burned by being ignited by a spark plug 14.
[0027]
Next, the configuration of a fuel supply system for supplying CNG fuel to the CNG engine 10 will be described with reference to FIG. In FIG. 5, the exhaust system configuration is not shown.
[0028]
As shown in FIG. 5, the CNG fuel cylinder 32 is for storing the CNG fuel in a high pressure state (for example, about 20 MPa at the maximum). In addition, although illustration is abbreviate | omitted, the CNG fuel cylinder 32 is provided with the pressure sensor which detects the pressure in a cylinder, and the temperature sensor which detects temperature. The CNG fuel cylinder 32 and the delivery pipe 33 of the CNG engine 10 are connected by a fuel supply pipe (fuel supply system) 34.
[0029]
The delivery pipe 33 is for distributing the CNG fuel that has been pumped through the high pressure regulator 35 described later to the injectors 23. The delivery pipe 33 is a pressure sensor 33a that detects the pressure in the delivery pipe 33, and the temperature. A temperature sensor 33b for detection is provided.
[0030]
A fuel supply pipe 34 extending from the CNG fuel cylinder 32 to the injector 23 has a high pressure regulator 35 for reducing the pressure of the CNG fuel pumped from the CNG fuel cylinder 32 to a predetermined pressure (for example, about 5 MPa) that can be injected into the cylinder. Is provided.
[0031]
The CNG engine 10, the injector 23, the high pressure regulator 35 and the like described above are various sensors such as a pressure sensor 33 a and a temperature sensor 33 b of the delivery pipe 33, a pressure sensor and a temperature sensor (not shown) of the CNG fuel cylinder 32. It is controlled by an electronic control unit (ECU) (not shown) based on the information.
[0032]
Next, a fuel injection timing control method according to the present invention will be described with reference to FIGS. At that time, FIGS. 4 and 5 and FIGS. Here, FIG. 6 is a map showing an example of the injection start timing, showing the crank angle BTDC (before top dead center) for each rotation speed and fuel injection amount, and stored in advance in the electronic control unit (ECU). Yes. FIG. 7 is a schematic diagram showing how the spray length is measured in a constant volume container, and FIG. 8 is a map showing an example of the relationship between the injection time and the spray length measured in the constant volume container. Each fuel amount is prepared in advance and stored in the electronic control unit (ECU).
[0033]
FIG. 9 is a map showing an example of the distance between the injector and the cavity when the fuel spray collides with the piston at the reference pressure, and shows the distance for each rotational speed and injected fuel amount. (ECU) is stored in advance. FIG. 10 is an in-cylinder pressure map showing an example of the relationship between the in-cylinder pressure and the crank angle, and is a graph (1) and a map (2). The in-cylinder pressure map according to FIG. 10 is also stored in advance in the electronic control unit (ECU).
[0034]
As shown in FIG. 1, first, when the CNG engine 10 is started (step S10), the fuel pressure (the pressure in the delivery pipe 33 shown in FIG. 5 and the injection pressure) is within a level range in which pressure correction is possible. It is determined whether or not there is (step S11). For example, when the fuel pressure is 5 MPa and the level range in which pressure correction is possible is 4 to 6 MPa, it is determined that the fuel pressure is within the level range in which pressure correction is possible.
[0035]
If the fuel pressure is not within the level range in which pressure correction is possible (No in step S11), the control proceeds to pressure regulation abnormality control described later (step S20). If the fuel pressure is within the level range in which pressure correction is possible (Yes at Step S11), it is determined whether or not the operation region is stratified combustion (Step S12).
[0036]
When the operation region is not stratified combustion (No at Step S12), normal homogeneous combustion control is performed (Step S50). That is, the fuel is injected while correcting only the injection period with the fuel pressure. This is because homogeneous combustion has extremely good robustness, so that it is not necessary to change the injection timing, and it is sufficient to correct only the injection period. In addition, after this normal homogeneous combustion control is performed, it returns to step S11.
[0037]
On the other hand, when the operation region is stratified combustion (Yes at Step S12), it is determined whether or not the fuel pressure is within a level range where the injection timing needs to be corrected (Step S13). That is, it is determined whether or not the pressure fluctuation is within a normal range and does not need to be corrected. For example, if the current fuel pressure is 5 MPa and the preset unnecessary correction range is 4.8 to 5.2 MPa, the current fuel pressure is within the correction unnecessary range. Judged as unnecessary.
[0038]
When it is not necessary to correct the injection timing as described above (No at Step S13), normal stratified combustion control is performed (Step S60). In this case, only the injection period is corrected with the current fuel pressure. In addition, after this normal stratified combustion control is performed, it returns to step S11.
[0039]
On the other hand, when the injection timing needs to be corrected (Yes at Step S13), the injection parameter is corrected by the following procedure.
(1) First, from the map shown in FIG. 9, between the injector 23 and the cavity 12a at the time of a collision between the fuel spray 23a and the cavity 12a at a standard conforming value (uncorrected value) at the reference pressure (for example, at 5 MPa). The distance L is calculated (step S14).
[0040]
FIG. 9 shows a spray length L2 for each crank angle from a map (see FIG. 6) showing the injection start timing and a map (see FIG. 8) showing the spray length measured in the constant volume container 25 (see FIG. 7). Next, the distance L1 between the injector 23 and the piston cavity 12a for each crank angle is calculated from the rotational speed, and the distance when these distances are the same (L1 = L2) is defined as L. Is stored in advance in the electronic control unit (ECU) as a map.
[0041]
(2) Next, the time at the distance L2 is calculated from FIG. 8 at the current fuel pressure (step S15).
[0042]
(3) Then, the difference between the time calculated in the above (2) and the time at the reference pressure and the same distance as (2) is calculated (step S16). This time difference is a time difference until a collision when the same injection is started, and has a positive / negative sign.
[0043]
(4) Next, the time difference calculated in the above (3) is converted from the rotational speed into a crank angle, and this is used as a corrected crank angle to correct the injection start timing at the reference pressure shown in FIG. Calculate (step S17).
[0044]
(5) Next, the injection period is corrected from the current fuel pressure and the reference pressure, and redefined (step S18).
[0045]
(6) Then, an injection end crank angle is calculated from the injection start crank angle calculated in (4) above and the injection period redefined in (5) above (step S18), and based on this injection end crank angle. Fuel is injected (step S19). In addition, after this fuel injection is performed, it returns to step S11.
[0046]
By controlling the fuel injection timing as described above, even when the fuel pressure changes, the distance between the injector 23 and the cavity 12a at the time of the collision between the fuel spray 23a and the cavity 12a can be kept substantially constant. Combustion can be established.
[0047]
Next, the control method (step S20) at the time of abnormal pressure adjustment, which is executed when the above step S11 is negative (see FIG. 1), will be specifically described based on FIG.
[0048]
In step S11 in FIG. 1 described above, it is determined that the fuel pressure is not within the level range where pressure correction is possible. Therefore, in step S21 shown in FIG. 2, this fuel pressure is further below the lower limit of the level where pressure correction is possible. Determine whether.
[0049]
When the fuel pressure is not more than the lower limit of the level at which pressure correction is possible (Yes at Step S21), the process proceeds to the control (see FIG. 3) when the fuel remaining amount is small, which will be described later (Step S40).
[0050]
On the other hand, if the fuel pressure exceeds the lower limit of the level at which pressure correction is possible (No in step S21), it can be determined that the pressure is high and the high pressure regulator 35 is abnormal (step S30). A warning to that effect is displayed on the hand with an indicator or the like (step S31), and it is determined whether or not the operation region is stratified combustion (step S32). The warning may be generated by sound generation means such as voice, or a combination of the sound generation means and display means such as the indicator.
[0051]
In the case of stratified combustion (Yes at step S32), the robustness is poor and this may not be established, so switching to homogeneous combustion is performed (step S33).
[0052]
Although the fuel pressure is basically high, fluctuations in the fuel pressure may be large when pressure regulation is abnormal. For this reason, the injection start timing is set in the vicinity of the top dead center of the intake stroke so that injection can always be performed (step S34). On the other hand, if the combustion is homogeneous (No at Step S32), the injection start timing is set near the top dead center of the intake stroke (Step S34).
[0053]
Since the injection period varies depending on the fuel pressure, it is difficult to calculate the injection period if the fuel pressure varies greatly. Therefore, the fuel pressure measurement time is increased as much as possible, and the injection period is calculated as the sampling average fuel pressure (step S35). Then, fuel injection is performed in the calculated injection period without changing other compatible values (step S36).
[0054]
The control (step S30 to step S36) when the regulator 35 is abnormal as described above is repeatedly executed until the ignition (IG) is turned off (No at step S37), and when the ignition (IG) is turned off (step S37). (Yes), the control is terminated (step S38). By controlling in this way, it is possible to suppress the shift to normal control when the fuel pressure decreases due to fluctuations, even though the pressure regulation abnormality has not been corrected.
[0055]
By controlling as described above, misfire due to the failure of stratified combustion or the like can be suppressed even when pressure regulation is abnormal, and uniform combustion can be handled. In addition, since the injection start time is set near the top dead center of the intake stroke, it can only be expected to achieve the same performance as in the case of so-called intake port injection, but the effect of prompting the driver to recognize abnormal pressure regulation and prompting the vehicle to stop Can be expected.
[0056]
Next, FIG. 3 shows a control method (step S40) in the case where the remaining amount of fuel is low when step S21 in FIG. 2 is affirmative, that is, when the fuel pressure is below the lower limit of the pressure correctable level. A specific description will be given based on this.
[0057]
When the remaining amount of fuel is small, the fuel pressure is gradually reduced, and a preset normal control value cannot be used. In particular, during stratified combustion, since the injection period and the penetration force of the fuel spray change, problems such as misfire are likely to occur.
[0058]
Therefore, as shown in FIG. 3, when the remaining amount of fuel is small (step S40), the occurrence of problems such as misfire is suppressed by switching all combustion regions to homogeneous combustion (steps S41 and S42). ).
[0059]
Next, the following control is performed so that fuel can be injected in the compression stroke as much as possible even in a state where the combustion is switched to homogeneous combustion as described above.
[0060]
The ignition timing is determined by the rotational speed and load (intake pipe pressure and fuel amount) of the CNG engine 10, and is not affected by the fuel pressure. Further, the injected fuel and air are not sufficiently mixed unless there is a certain interval between the injection end timing and the ignition timing. Again, this has nothing to do with fuel pressure.
[0061]
Since CNG fuel is a gas, no vaporization time is required. Therefore, the injection end-ignition minimum interval is adapted by an injection start timing map (see FIG. 6) defined by the number of revolutions and the amount of fuel, and an electronic (not shown) It is stored in a control unit (ECU).
[0062]
Then, a possible injection end crank angle A is calculated from the injection end-ignition minimum interval map and the injection-ignition interval determined from the ignition timing (step S43).
[0063]
Next, the current injection end crank angle B (injectable crank angle) is calculated based on the in-cylinder pressure map during motoring (see FIG. 10) and the fuel pressure, which are defined in advance by the rotational speed and the intake pipe pressure (step S1). S44).
[0064]
Next, the injection end crank angle A and the injection end crank angle B are compared, and the more advanced angle is defined as the injection end crank angle (final injection end crank angle) (step S45).
[0065]
Then, an injection start crank angle is calculated from the injection end crank angle and the current fuel pressure, and fuel injection is performed based on the injection start crank angle (step S46).
[0066]
Thus, even when the control is switched to the first half of the intake stroke injection or the compression stroke injection immediately when the remaining amount of fuel decreases and the fuel pressure decreases, the fuel can be injected in the compression stroke as much as possible. It is possible to suppress the combustion region from being reduced at a stretch, and the homogeneous combustion region can be reduced stepwise. As a result, it is possible to minimize the time during which an inoperable region occurs.
[0067]
【The invention's effect】
As described above, according to the fuel injection timing control method for a direct injection CNG engine according to the present invention (Claim 1), even when the fuel pressure changes, the fuel injection valve at the time of collision between the fuel spray and the cavity Since the distance between the cavities can be kept substantially constant, stratified combustion with poor robustness can be established.
[0068]
Further, according to the fuel injection timing control method for a direct injection CNG engine according to the present invention (Claim 2), misfiring due to the failure of stratified combustion can be suppressed even when the pressure regulation is abnormal, and uniform combustion is supported. it can.
[0069]
Further, according to the fuel injection timing control method for a direct injection CNG engine according to the present invention (Claim 3), when the fuel remaining amount decreases and the fuel pressure decreases, the intake stroke injection or the compression stroke injection is immediately performed in the first half. Even if the control is switched, the fuel can be injected in the compression stroke as much as possible. Therefore, it is possible to suppress the homogeneous combustion region from being reduced at a stretch due to insufficient intake air amount, and the homogeneous combustion region can be reduced stepwise. As a result, it is possible to minimize the time during which an inoperable region occurs.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a fuel injection timing control method for an in-cylinder direct injection CNG engine according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control method when pressure regulation is abnormal.
FIG. 3 is a flowchart showing a control method when the remaining amount of fuel is low.
FIG. 4 is a cross-sectional view showing a schematic configuration of a CNG engine.
FIG. 5 is a schematic diagram showing a fuel supply system to a CNG engine.
FIG. 6 is a map showing an example of injection start timing.
FIG. 7 is a schematic diagram showing how the spray length is measured with a constant volume container.
FIG. 8 is a map showing an example of a relationship between an injection time and a spray length measured in a constant volume container.
FIG. 9 is a map showing an example of a distance between an injector and a cavity when fuel spray collides with a piston at a reference pressure.
FIG. 10 is an in-cylinder pressure map showing an example of a relationship between in-cylinder pressure and crank angle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 CNG engine 10a Combustion chamber 12 Piston 12a Cavity 14 Spark plug 15 Intake port 16 Intake valve 18 Exhaust port 20 Exhaust valve 23 Injector (fuel injection valve)
23a Fuel spray 32 CNG fuel cylinder 33 Delivery pipe 34 Fuel supply pipe (fuel supply system)
35 High pressure regulator
L1, L2 distance

Claims (3)

A fuel injection timing control method for an in-cylinder direct injection CNG engine having a cavity on a piston top surface and switching between stratified combustion and homogeneous combustion according to engine operating conditions,
When the fuel pressure is within the pressure correctable level range and the injection timing correction required level range during stratified combustion, the collision position of the fuel spray injected from the fuel injection valve with the cavity corresponds to the collision position at the reference pressure. A fuel injection timing control method for an in-cylinder direct injection CNG engine, wherein the fuel injection start timing is changed so as to be the same. If the fuel pressure is within the pressure-correctable level range and is high, it is determined that there is a pressure regulation abnormality due to an abnormality in the regulator provided in the fuel supply system, and the combustion is switched to homogeneous combustion, and the fuel injection start timing is set in the intake stroke. The fuel injection timing control method for an in-cylinder direct injection CNG engine according to claim 1, wherein the fuel injection is performed in an injection period that is fixed near a dead center and calculated from a sampling average fuel pressure. When the fuel pressure is within the pressure-correctable level range and low pressure, it is determined that the remaining amount of fuel is low, and the combustion is switched to homogeneous combustion,
Calculate the injection end crank angle from the minimum interval map of injection and ignition,
From the in-cylinder pressure map defined in advance by the rotational speed and load and the fuel pressure, the crank angle that can be injected at the present time is calculated,
Comparing the calculated crank angles, the more advanced side is the final injection end crank angle,
2. The fuel injection timing control method for an in-cylinder direct injection CNG engine according to claim 1, wherein an injection start crank angle is calculated based on the final injection end crank angle and the current fuel pressure, and fuel injection is performed.

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