JPH09170478A - Method for controlling fuel injection of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eject fuel to a combustion chamber in its appropriate injection amount at appropriate timing in the fuel injection pump of a diesel engine even though a fuel injection nozzle is deteriorated. SOLUTION: Injection starting timing in which a fuel injection nozzle is opened is detected, and also the injection starting timing in an idling condition is previously memorized as reference phase Tb. The memorized reference phase and injection starting timing Ts at the time of idling thereafter are compared to each other (step 103), and the lowering rate of opened valve pressure at the time of idling thereafter is calculated from the phase difference Terr. On the basis of the foregoing, the correction rate of a spill valve command value which is injection starting/finishing control commands, and the correction rate of an injection timing control command value which is a crank angle at which a fuel injection pump is operated, are calculated (steps 106, 107) so as to control fuel injection timing.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel injection control method for a diesel engine.

[0002]

2. Description of the Related Art In a fuel injection pump used in a diesel engine or the like, fuel is pressure-fed to a fuel injection nozzle at a pressure equal to or higher than a valve opening pressure at which the fuel injection nozzle opens to inject it into a combustion chamber. The injection period is changed according to the accelerator opening degree and the like. In JP-A-60-135631, an electromagnetic valve for releasing the hydraulic pressure of the fuel to be pumped to a fuel chamber of about 5 atm is provided to open and close the fuel injection nozzle, and the timing of pumping the fuel is changed. Disclosed is a distributed fuel injection pump in which the injection rate can be changed in addition to the fuel injection period. However, the above-mentioned JP-A-60
In the distributed type fuel injection pump described in Japanese Patent No. 135631, the opening and closing of the fuel injection nozzle for changing the fuel injection period is open loop control, and therefore the secular change of the spring that sets the valve opening pressure of the fuel injection nozzle, etc. Therefore, if the actual valve opening period changes, accurate control may not be possible. For example, in order to reduce the NOx emitted from the engine, it is known that split injection in which one injection stroke is performed in two stages of pre-injection with a small injection amount and main injection that continues at intervals is effective. However, when the valve opening pressure of the fuel injection nozzle has dropped, an appropriate injection amount cannot be injected at an appropriate time, or fuel is injected between the preceding injection and main injection, making split injection impossible. There is a risk that

Thus, the above-mentioned Japanese Patent Laid-Open No. 60-135631 is used.
The distributed fuel injection pump described in Japanese Patent Publication is not always sufficient to cope with the recent tightening of exhaust gas regulations. Therefore, a needle valve position sensor for detecting the lift amount of the needle valve of the fuel injection nozzle is provided as in the electronic control device for a self-ignition type internal combustion engine disclosed in Japanese Patent Publication No. 52570/1989 to detect the position and speed of the needle valve. There is a system in which the valve opening time and the valve closing time are known, and the valve opening period is feedback-controlled based on this. In addition, JP-A-7-127552
In the publication, a piezoelectric element that generates an electric signal in response to the opening / closing operation of the fuel injection nozzle is provided so that the actual valve opening timing and valve closing timing can be detected from the change in the waveform of the output signal. There is something.

[0004]

However, in the electronic control unit for the self-ignition type internal combustion engine described in Japanese Patent Publication No. 52570/1990, the mounting position of the needle valve position sensor is ensured in order to secure the detection accuracy of the needle valve position and speed. Strict adjustment and complicated signal processing circuit of needle valve position sensor are required. Further, in Japanese Patent Application Laid-Open No. 7-127552, the valve opening timing is simple because it is sufficient to detect the rising of the output signal of the piezoelectric element, but the valve closing timing corresponds to the valve closing from the output signal including noise after the valve opening. Since it is necessary to extract a true waveform change, a complicated signal processing circuit for that purpose is required, which is not necessarily practical.

Therefore, the present invention provides a fuel injection control method for a diesel engine, which is capable of injecting an appropriate amount of fuel at an appropriate time and has a simple detection of the valve opening period of the fuel injection nozzle. The purpose is to provide.

[0006]

According to the present invention, there is provided a fuel injection pump for pumping fuel at a pressure equal to or higher than a valve opening pressure of a fuel injection nozzle to open the fuel injection nozzle to inject fuel into a combustion chamber of a diesel engine, As shown in FIG. 1, the timing at which the fuel injection nozzle opens is detected (step 10
2) The operation phase of the fuel injection pump at the fuel injection nozzle opening timing in the idling state is stored in advance as a reference phase, and the reference phase and the fuel injection at the fuel injection nozzle opening timing at the time of idling thereafter are injected. The operation phase of the pump is compared (step 103), the decrease amount of the valve opening pressure at the time of idling thereafter is calculated from the phase difference (step 105), and the increase amount of the injected fuel according to the decrease amount is calculated. The fuel injection period is controlled so as to cancel each other (claim 1).

By detecting the fuel injection nozzle opening timing in the idling state, the deviation amount of the fuel injection nozzle opening timing under the same condition can be known. The valve opening pressure of the fuel injection nozzle under the same conditions increases or decreases according to the deviation of the fuel injection nozzle opening timing, so the operation of the fuel injection pump at the fuel injection nozzle opening timing in the idling state By detecting the phase, the amount of decrease in the valve opening pressure of the fuel injection nozzle can be known. Then, by controlling so that the increase amount of the injected fuel corresponding to the decrease amount is offset, the fluctuation of the fuel injection amount is suppressed.

By narrowing the interval between the timing at which the injection start control command is issued and the timing at which the injection end control command is issued according to the amount of decrease, the length of the fuel injection period is shortened (claim 2). Even if the valve opening pressure decreases, the fuel injection amount is kept constant.

The fuel injection is divided into a pre-injection and a main injection that continues at intervals, and the timing at which the injection end control command for the pre-injection is issued is increased as the above-mentioned amount of decrease is increased. By changing to the advance side of
While suppressing the change of the fuel injection amount of the pre-injection in which the fuel injection amount is apt to change due to the decrease of the valve opening pressure, each time when the injection start control command and the injection end control command of the main injection are issued By changing the advance angle according to the advance amount of the timing at which the injection end control command is issued, it is possible to suppress the change in the interval between the preceding injection and the main injection (claim 3).

The advance amount at each timing when the injection start control command and the injection end control command for the main injection are issued is set as the advance amount at the time when the injection end control command for the preceding injection is issued (claim 4). ), So that the interval from the preceding injection can be maintained more appropriately.

When the fuel injection period is changed to the advance side or the retard side of the operation phase of the fuel injection pump, the crank angle at which the fuel injection pump operates is changed according to the advance amount or the retard amount. By retarding or advancing the engine (claim 5), it is possible to suppress the fluctuation of the crank angle at which the fuel is injected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 6 shows a fuel injection pump used in the practice of the present invention. A drive shaft 21 is connected to an engine (not shown) and is rotationally driven in synchronization with 1/2 of engine rotation. At the same time, a face cam 51 for driving a plunger 52 for fuel pressure feed and a vane feed pump 3 for fuel feed are connected. The face cam 51 is pressed against the roller 42 of the roller ring 41 by a spring 54 together with the plunger 52.

The face cam 51 is the drive shaft 21.
When it is driven to rotate, the convex portion rides on the roller 42, and the face cam 51 itself and the plunger 52 integrated with the face cam 51 reciprocate in the axial direction while accompanied by rotational movement. The plunger 52 is inserted into the cylinder bore 53a of the pump cylinder 53, and a pressure chamber 53b is formed at the tip of the plunger 52. The reciprocating motion of the plunger 52 expands and contracts the volume of the pressure chamber 53b.
By the rotational movement of 2, the port on the suction side and the port on the discharge side opening to the pressure chamber 53b are switched. Fuel of about 5 atm discharged from the discharge port 32 of the feed pump 3 is stored in the fuel chamber 1a, which is sucked into the pressure chamber 53b when the plunger 52 retracts and pressurized to a high pressure when advancing the fuel. It is pressure-fed to the nozzle 7.

As shown in FIG. 7, the fuel injection nozzle 7 has an injection hole 72 formed in the tip of a substantially cylindrical housing 71 toward the combustion chamber, and communicates with the injection hole 72 in the wall of the housing 71 to form a fuel passage 73a. , 73b are formed, and when the plunger 52 moves forward, fuel flows from the pressure chamber 53b to the injection hole 7b.
It reaches two. A nozzle needle (not shown) is provided inside the housing 71 of the injection hole 72,
The pressure receiving surface at the tip is urged downward by the spring 74 and closes the injection hole 72. When the hydraulic pressure of the fuel that reaches the injection hole 72 from the pressure chamber 51b of the plunger 52 exceeds the compression force of the spring 74 (hereinafter referred to as the nozzle opening pressure), the hydraulic pressure of the fuel resists the compression force of the spring 74 and the nozzle. Fuel is injected from the injection hole 72 into the combustion chamber by pushing up the needle. A piezoelectric element 75 is provided on the fixed end side of the spring 74, and an electric signal (hereinafter referred to as a nozzle lift signal) synchronized with the expansion and contraction of the spring 74 is output from a lead wire 76 to an electronic control unit (ECU) 9 described later. It is supposed to do.

An electromagnetic spill valve (hereinafter, simply referred to as a spill valve) is provided on the dishead 11 (FIG. 6) of the fuel injection pump.
6 is provided, and its opening and closing is controlled by a spill valve drive signal (denoted as SPV drive signal in the figure) from the ECU 9. When the spill valve 6 opens, the pressure chamber 53b
The pressure of is released. Therefore, when the spill valve 6 is open, even if the plunger 52 moves forward and the volume of the pressure chamber 53b is reduced, the hydraulic pressure of the fuel that has reached the injection hole 72 of the fuel injection nozzle 7 is the nozzle opening pressure. Fuel injection is regulated without exceeding the limit.

The cylindrical outer peripheral surface of the roller ring 41 can be rotated within a predetermined angle range about the axis of the drive shaft 21, and the roller 42 is rotated by the rotation.
The position of moves in the circumferential direction. As a result, the timing at which the convex portion of the face cam 51 rides on the roller 42 changes, and the crank angle at which the plunger 52 reciprocates is changed.

FIG. 8 shows the details around the roller ring 41. The signal rotor 22 is coaxially attached to the drive shaft 21 at the coaxial position of the roller ring 41, and convex teeth are provided on the outer periphery thereof. A plurality is formed. A rotation angle sensor 43 is provided on the roller ring 41 so as to face the outer periphery of the signal rotor 22, and a pulse signal (hereinafter referred to as NE signal) corresponding to the engine speed is generated by electromagnetic induction of the convex teeth to generate the ECU 9 It is designed to output to.

The signal rotor 22 has convex teeth on the outer periphery,
The tooth portion A has a small interval and is densely formed, and the tooth portion B has a large interval and is roughly formed. The tooth portions B are formed at equal intervals by the number of cylinders (90 ° for 4 cylinders, 60 ° for 6 cylinders), and the duty ratio of the NE signal is detected by the rotation angle sensor 43 at the tooth portions A. This is different from when the fuel injection pump is operating, and the starting point of the operating phase of the fuel injection pump can be known. That is, since the angular positions of the roller 42 provided on the roller ring 41 and the rotation angle sensor 43 around the drive shaft 21 do not change, the pulse of the NE signal from the starting point is counted to allow the plunger 5 to move.
The operation phase of the fuel injection pump when the fuel is sucked and pumped by the reciprocating motion of 2 is known. The spill valve 6 is set with an injection start control command, an injection end control command for opening and closing valve command values (hereinafter referred to as spill valve command values) with the starting point as a reference.

A timer cylinder 81 is formed in the housing 1 below the roller ring 41 in a direction orthogonal to the drive shaft 21, and a timer piston 82 is housed in the timer cylinder 81 so as to be movable left and right (see FIG. During,
The timer cylinder 81 and the timer piston 82 are drawn 90 ° for convenience of description. In the timer piston 82, the right end surface side of the timer piston 82 communicates with the fuel chamber 1a to form a high-pressure timer high pressure chamber 81a, and the left end surface side of the timer piston 82 communicates with the suction port 31 of the feed pump 3 so that the timer piston 82 is always connected. , Atmospheric pressure timer low pressure chamber 8
1b. The timer piston 82 is positioned at a position where these pressures and the resultant force of the spring 84 provided in the timer low pressure chamber 81b are balanced. A passage 85 connecting the timer high pressure chamber 81a and the timer low pressure chamber 81b
A hydraulic control valve 86 is provided in the middle of a, 85b, and the passage 8
The flow rate of fuel flowing through 5a and 85b is controlled to adjust the fuel pressure on the timer high pressure chamber 81a side, and the position of the timer piston 82 is changed. The roller ring 41 is
The slide pin 44 extending from this is the timer piston 82.
And a hydraulic control valve drive signal (referred to as TCV drive signal in the figure) is output to the hydraulic control valve 86 according to an injection timing control command value described later, and when the timer piston 82 moves in the left-right direction, It is designed to rotate in the reverse direction.

In addition to the nozzle lift signal output from the piezoelectric element 75 of the fuel injection nozzle 7 and the NE signal output from the rotation angle sensor 43, the ECU 9 reciprocates in the cylinder of the engine at the top dead center. At some time, a top dead center (TDC) signal output from the engine is input as a pilot signal of the crank angle of the engine, and the phase difference between the operating phase of the fuel injection pump and the crank angle of the engine becomes known. ing. Further, the ECU 9 is input with an accelerator opening signal indicating the magnitude of the engine load and a cooling water temperature (referred to as water temperature in the figure) signal.

The operation of the fuel injection pump and the fuel injection control in the fuel injection pump will be described with reference to FIGS. 1 and 8. FIG. 1 shows a control flow of the ECU 9,
First, the nozzle lift signal, the TDC signal, and the NE signal are read during idling (step 101). FIG.
These signals are read into the CU 9, and since the idling is in progress, the NE signal ((B) in the figure) is always in phase with the TDC signal ((A) in the figure). The operation phase of the fuel injection pump at the fuel injection nozzle opening timing in the idling state, which is the phase difference Ts from the start point to the timing when the fuel injection nozzle 7 opens and the nozzle lift signal rises (hereinafter referred to as the injection start timing). ) Is measured by counting the pulses of the NE signal (step 10
2). The timing at which the nozzle lift signal rises is detected by comparing the nozzle lift signal with a predetermined threshold value.
The injection start timing is pre-assembled (hereinafter referred to as the initial state)
Is also measured at the injection start timing T in the initial state, which is the reference phase.
It is stored in the memory of the ECU 9 as s. Then T
The above-mentioned Tb is subtracted from s to calculate the deviation amount Terr of the fuel injection start timing from the initial state which is a phase difference (step 10).
3). Next, the sign of Terr is determined (step 10
4) If Terr is positive, it is determined that the valve opening pressure of the fuel injection nozzle 7 has dropped, and the routine proceeds to step 105.

In step 105, Terr is multiplied by a coefficient k, and k · Terr is used as an estimated value of the decrease amount of the nozzle opening pressure. In the experiment, k is the injection start timing advance amount shown in FIG.
It is determined from the relationship of the amount of decrease in the nozzle opening pressure, and may be regarded as linear for practical purposes, and is constant. Then, the correction amount of the spill valve command value is determined. The preset correction coefficient is α
As the first opening timing of the spill valve 6 (hereinafter, OFF
Timing), the second valve closing timing (hereinafter referred to as ON timing), and the second OFF timing correction amount Δφ are determined by equations (step 106). Δφ = α ・ k ・ Terr ……

Next, the correction amount of the injection timing control command value is determined. The injection timing control command value is a target crank angle at which fuel is injected, and the hydraulic control valve 86 is controlled accordingly to rotate the roller ring 41 and the crank angle at which the plunger 52 reciprocates in the axial direction. It is set uniquely. The correction amount Δθ of the injection timing control command value is determined by an equation (step 107). Δθ = β ・ k ・ Terr ……

It should be noted that Δφ and Δθ are reference correction amounts, which are changed according to the engine speed as will be described later during normal operation. If Terr is negative in step 104, the nozzle opening pressure is determined to be normal, and no correction is performed. In this case, since the nozzle valve opening pressure is normal, even if the control is based only on the fuel injection start timing, the injection of an appropriate injection amount is performed at an appropriate time.

Next, the split injection control performed by correcting the spill valve command value and the injection timing control command value based on the above Δφ and Δθ will be described with reference to FIG. In the figure, the solid line shows the case of split injection performed with the spill valve command value before correction and the injection timing control command value (hereinafter referred to as before correction), and the broken line corrects the spill valve command value and injection timing control command value. The case of split injection (hereinafter referred to as “corrected”) is shown. In the fuel injection, the plunger 52 retracts at a crank angle corresponding to the injection control command value, which is a crank angle at which the fuel injection pump operates, and the fuel is injected into the pressure chamber 53b, and then the NE signal is counted for the first time. When the spill valve command value at the ON timing is reached, a spill valve drive signal is issued to the spill valve 6 ((B) in FIG. 4) and the spill valve 6 is closed. Then, in synchronization with the rotation of the drive shaft 21, the face cam 51 at the proximal end of the plunger 52 moves the roller ring 41.
Riding on the roller 42, the amount of displacement of the face cam 51 ((A) in FIG. 4, referred to as cam lift in the figure) rises.

As a result, the plunger 52 is moved forward to compress the fuel in the pressure chamber 53b, and the injection pressure, which is the oil pressure of the fuel reaching the fuel injection nozzle 7, rises according to the displacement amount of the face cam 51 (FIG. 4). (C)). When the NE signal count reaches the spill valve command value at the first OFF timing, a spill valve drive signal is issued to the spill valve 6 and the spill valve 6 opens. Then, the hydraulic pressure of the pressure chamber 53b is released to the fuel chamber of about 5 atm, and the injection pressure is reduced. Thus, the injection pressure has a profile according to the displacement amount of the face cam 51 and the opening / closing of the spill valve 6.

When the injection pressure exceeds the nozzle opening pressure of the fuel injection nozzle 7, the fuel reaching the fuel injection nozzle 7 pushes up the nozzle needle and the fuel is injected from the fuel injection nozzle 7. FIG. 4D shows the fuel injection rate,
When the above correction is not performed, the fuel injection amount increases due to the decrease in the nozzle opening pressure of the fuel injection nozzle 7. Moreover, since the nozzle opening pressure of the fuel injection nozzle 7 is lower than the injection pressure in the period between the front injection and the main injection, the injection rate is not 0 in this period. That is, split injection is impossible.

In the present invention, the spill valve 6 is turned off for the first time.
From the correction amount Δφ determined during idling, the command value of the timing is φ1 for the first OFF timing of the spill valve 6 after correction, and φ0 for the first OFF timing of the spill valve 6 before correction.
, The maximum engine speed is Nmax and the current engine speed is N, and is corrected by the equation. The coefficient (Nmax
-N) / N is based on the fact that both the deviation amount of the fuel injection amount and the deviation amount of the injection start timing become smaller as the engine speed increases. φ1 = φ0-Δφ ・ (Nmax-N) / N ... By advancing the first OFF timing of the spill valve 6, the injection pressure during pre-injection starts to decrease earlier than before correction, and the nozzle Since the valve opening pressure is divided, the period in which the injection rate becomes 0 can be set between the pre-injection and the main injection, and split injection can be performed. In addition, the fuel injection amount in the pre-injection is the
Depending on the advance amount of the first OFF timing of
The advance amount of the OFF time for the second time depends on the correction coefficient α. The correction coefficient α is set so that the corrected fuel injection amount becomes the fuel injection amount when the nozzle opening pressure is normal. That is, as shown in FIG. 5, the relationship between the fuel injection start timing shift amount (indicated as an injection start timing change amount in the figure) Terr and the fuel injection amount is previously obtained by an experiment,
From now on, α is set. Here, there is an optimum value for the fuel injection amount that is highly effective in reducing NOx, and the spill valve command value is set so that the fuel injection amount becomes the above optimum value when the nozzle opening pressure is normal. Therefore, even if the nozzle valve opening pressure decreases, the fuel injection amount becomes the optimum value.

Then, the second ON time of the spill valve 6,
The command value of the OFF timing is corrected by the same amount as the first OFF timing. That is, the intervals A1 and B1 between the first OFF timing and the second ON timing before and after the correction are changed to be the same as the second valve opening times A2 and B2 before and after the correction. In the main injection, since the spill valve 6 is closed during the pressure feeding of the face cam 51 having a high cam lift speed, the rising speed of the injection pressure during the main injection is fast, and the higher the injection pressure is, the faster the opening speed of the spill valve 6 is. The falling speed of the injection pressure also becomes faster. Therefore, in the main injection, only the injection period advances, the profile of the injection pressure hardly changes, and the fuel injection amount is constant. As a result, the injection amount of the pre-injection and the main injection and the split interval between the pre-injection and the main injection can be kept substantially constant before the nozzle opening pressure decreases.

Next, the injection timing control command value is changed based on the correction amount .DELTA..theta. Determined during idling, with the fuel injection command value before correction being .theta.0 and the fuel injection command value after correction being .theta.1. θ1 = θ0 + Δθ. (Nmax-N) / N ... However, the operating phase of the fuel injection pump is retarded with respect to the crank angle of the engine. Since the period of pre-injection and main injection is changed to the advance side of the operating phase of the fuel injection pump, the retard amount of the operating phase of the fuel injection pump and the advance amount of the pre-injection and main injection cancel each other out, Pre-injection and main injection are performed at a substantially constant crank angle. As a result, the timing of split injection is kept substantially constant, and split injection is performed at a predetermined crank angle even if the nozzle opening pressure of the fuel injection nozzle 7 drops.

Although the fuel injection pump of the above embodiment is a face cam pressure feed type fuel injection pump, it may be an inner cam pressure feed type fuel injection pump.

Further, by multiplying Terr by a coefficient k, k · Terr
Is the estimated value of the nozzle opening pressure, but the estimated value of the nozzle opening pressure may be expressed by a function that more closely matches the relationship between the actual nozzle opening pressure and Terr, or by using the map with Terr as the input. It may be estimated. Further, the correction amounts of the spill valve command value and the fuel injection command value may be obtained by a map instead of the above correction formula.

Although the correction amounts of the spill valve command value and the injection timing control command value are changed according to the engine speed, they may be constant depending on the degree of controllability required, and in that case. It is preferable to optimize the strictest controllability in the required engine speed range or average engine speed.

Although the injection timing control command value is retarded by the correction, when the injection is changed to the retard side by the correction of the spill valve command value, the injection timing control command value is advanced according to the retard amount. Also in this case, the crank angle at which the injection is performed is kept constant as in the above embodiment.

The present invention can also be applied to normal injection other than split injection.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a fuel injection control method for a diesel engine of the present invention.

FIG. 2 is a time chart illustrating a fuel injection control method for a diesel engine of the present invention.

FIG. 3 is a graph illustrating a fuel injection control method for a diesel engine of the present invention.

FIG. 4 is another time chart for explaining the fuel injection control method for the diesel engine of the present invention.

FIG. 5 is a graph explaining a fuel injection control method for a diesel engine of the present invention.

FIG. 6 is a vertical cross-sectional view of a fuel injection pump used for implementing the fuel injection control method for a diesel engine of the present invention.

FIG. 7 is a partial vertical cross-sectional view of a fuel injection pump used to carry out the fuel injection control method for a diesel engine of the present invention.

FIG. 8 is a partial cross-sectional view of a fuel injection pump used to carry out the fuel injection control method for a diesel engine of the present invention.

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Claims (5)

[Claims] 1. A fuel injection pump for pumping fuel at a pressure equal to or higher than a valve opening pressure of a fuel injection nozzle to open the fuel injection nozzle to inject fuel into a combustion chamber of a diesel engine, wherein the fuel injection nozzle is opened. Is a fuel injection control method for a diesel engine that controls the fuel injection timing by detecting the fuel injection timing, the operation phase of the fuel injection pump at the fuel injection nozzle opening timing in the idling state is stored in advance as a reference phase. , The stored reference phase is compared with the operating phase of the fuel injection pump at the fuel injection nozzle opening timing at the time of idling thereafter, and from the phase difference, the decrease amount of the valve opening pressure at the time of idling thereafter. Is calculated, and the fuel injection period is controlled so as to cancel out the increase amount of the injected fuel according to the decrease amount. Charge injection control method. 2. The fuel injection control method for a diesel engine according to claim 1, wherein an interval between a timing at which an injection start control command is issued and a timing at which an injection end control command is issued is narrowed according to the decrease amount. A fuel injection control method for a diesel engine that shortens the length of the injection period. 3. The fuel injection control method for a diesel engine according to claim 2, wherein the fuel injection is divided into a pre-injection with a small injection amount and a main injection continuing at intervals, and the pre-injection is performed. As the above-mentioned decrease amount increases the timing at which the end control command is issued, the timing at which the injection start control command and the injection end control command for the main injection are issued is changed while changing the advance phase of the operating phase of the fuel injection pump. A method for controlling fuel injection in a diesel engine, which advances the angle according to the amount of advance at the time when the injection end control command for the preceding injection is issued. 4. The fuel injection control method for a diesel engine according to claim 3, wherein the advance amount of each timing at which the injection start control command and the injection end control command of the main injection are issued is the injection end of the preceding injection. A fuel injection control method for a diesel engine, which uses an advance amount at the time when a control command is issued. 5. The method for controlling fuel injection of a diesel engine according to claim 2, wherein the crank angle at which the fuel injection pump operates is changed such that the fuel injection period is advanced to the operating phase of the fuel injection pump. Fuel injection control of a diesel engine that retards the fuel injection period according to the advance amount, and advances the fuel injection period according to the retard amount when the fuel injection period is changed to the retard side of the operating phase of the fuel injection pump. Method.