JPH11153056A - Control unit for diesel engine - Google Patents

Abstract

(57) [Problem] To detect the actual fuel injection period and the ignition delay period and control the maximum lift amount of the fuel injection valve so that the ignition delay period is longer than the fuel injection period.
NOx and PM can be reduced at the same time. Kind Code: A1 A sensor for detecting fuel injection start and end timings from a fuel injection valve, a sensor for detecting combustion start timing of injected fuel, and detection values of fuel injection start timing and injection end timing. The fuel injection period is calculated from the fuel injection start timing and the combustion start timing, and the ignition delay period is calculated from the detected values.If the ignition delay period is shorter than the injection period, the fuel injection period is shortened. And adjusting means 22 for controlling the maximum lift amount of the fuel injection valve 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a diesel engine which reduces NOx (nitrogen oxide) and PM (particulate matter).

[0002]

2. Description of the Related Art NO emitted from a diesel engine
An exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air is effective in reducing the x amount, but on the other hand, when the exhaust gas recirculation rate is increased, the PM tends to increase accordingly. Therefore, the exhaust gas recirculation rate could not be made so large to suppress PM.

On the other hand, low-temperature premixed combustion of a diesel engine has attracted attention as a method for simultaneously reducing NOx and PM in a trade-off relationship.

[0004] This simultaneously realizes reduction of NOx by low-temperature combustion and reduction of PM by premix combustion.
By recirculating a part of the exhaust gas into the intake air, the maximum combustion temperature is suppressed and the generation of NOx is suppressed, while increasing the chance of contact between as much fuel spray and air (oxygen) as possible before ignition. In order to increase the contact time, the gas flow in the combustion chamber is increased, and the ignition delay period from fuel injection to ignition is made as long as possible.

In particular, in this low-temperature premixed combustion, as shown in FIG. 5, when the ignition delay period becomes longer than the fuel injection period, the amount of PM emitted for the same exhaust gas recirculation rate tends to sharply decrease. In this case, even in a region where the exhaust gas recirculation rate is large, the absolute value of the PM emission amount can be suppressed to a small value, and simultaneous reduction of NOx and PM can be achieved.

[0006]

However, the ignition delay period of a diesel engine is determined substantially depending on the fuel injection timing and the operating conditions of the engine at that time, and conventionally, the ignition delay period is specially controlled. That was not done.

[0007] As a fuel injection system for a diesel engine, there is a common rail type injection device capable of injecting a plurality of times during one cycle, and stores high-pressure fuel in a fuel storage chamber called a common rail. It supplies high-pressure fuel to the fuel injection valve of a cylinder, and has a feature that fuel injection can be freely controlled by adjusting the opening and closing timing and period of the fuel injection valve (see Japanese Patent Application Laid-Open No. 62-258160).

Even when such a common rail type fuel injection device is used, the ignition delay period described above is
At that time, the common rail pressure (fuel injection pressure), fuel temperature,
Due to fluctuations in the specific gravity of the fuel and precise variations in the fuel injection valve, the exhaust gas recirculation control valve, etc., the target ignition delay period is set with high accuracy, that is, the ignition delay period is always longer than the fuel injection period, and maintained It was very difficult to do.

For this reason, in low-temperature premixed combustion, attempts to reduce PM simultaneously with NOx by lengthening the ignition delay period are naturally limited, and satisfactory results have not always been obtained. .

The present invention has been proposed in order to solve such a problem. The fuel injection is performed so that the fuel injection period is shorter than the ignition delay period while detecting the actual fuel injection period and the ignition delay period. By controlling the maximum lift amount of the valve, the ignition delay period is set relatively long, so that NOx and PM having a trade-off relationship can be reduced at the same time.

[0011]

According to a first aspect of the present invention, there is provided a fuel accumulator for storing high-pressure fuel pumped from a fuel pump, and means for controlling a fuel pressure of the fuel accumulator to a target value corresponding to an operation state. A fuel injection valve connected to the fuel accumulator and injecting fuel into each cylinder, an injection control means for variably controlling the opening / closing timing and the lift amount of the fuel injection valve, and an injection amount and an injection timing according to an operation state. Start of fuel injection from the fuel injection valve in a diesel engine provided with control means for driving the injection control means so that exhaust gas recirculation control means for introducing a part of exhaust gas into intake air and suppressing combustion temperature. Means for detecting the timing and end time, means for detecting the combustion start time of the injected fuel, and a fuel injection period calculation means for calculating the fuel injection period from the detected values of the fuel injection start time and the injection end time. And an ignition delay period calculating means for calculating an ignition delay period from the detected values of the fuel injection start time and the combustion start time, and the same fuel injection amount when the fuel injection period is longer than the calculated ignition delay period. Adjusting means for increasing and correcting the maximum lift amount of the fuel injection valve so that the injection period of the fuel injection valve is shorter than the ignition delay period.

[0012] In a second aspect based on the first aspect, the adjusting means sets the fuel injection period to a predetermined value and a maximum lift amount for the same fuel injection amount by the first fuel injection period. A minimum injection period is set, and when the ignition delay period is longer than the first minimum injection period, the maximum lift amount of the fuel injector is corrected to increase within a range of its maximum value.

In a third aspect based on the second aspect, the adjusting means is configured to calculate a correction value of a maximum lift amount according to a difference between the ignition delay period and a first minimum injection period. You.

[0014] In a fourth aspect based on the second or third aspect, the adjusting means includes a fuel injection period when the fuel injection pressure is the maximum value and the lift amount is the maximum value for the same fuel injection amount. Is set to a second minimum injection period, and when the ignition delay period is shorter than the first minimum injection period and longer than the second minimum injection period, the fuel injection pressure is set within a range of its maximum value. Is configured to perform the increase correction.

In a fifth aspect based on the fourth aspect, the adjusting means is configured to calculate a correction value of the injection pressure according to a difference between the ignition delay period and a second minimum injection period. .

In a sixth aspect based on the first aspect, the means for detecting the fuel injection start time and the end time comprises a lift sensor for detecting a lift of the fuel injection valve, and means for detecting the combustion start time. Is composed of an in-cylinder pressure sensor.

[0017]

In the first invention, the injection period is obtained from the actual fuel injection start timing and the actual fuel injection start timing, and the ignition delay period from the fuel injection to the ignition is determined from the fuel injection start timing and the ignition start timing. Is calculated. The actual ignition delay period calculated in this way is compared with the fuel injection period,
When the ignition delay period is shorter than the fuel injection period, the maximum lift amount of the fuel injector is increased, whereby the fuel injection period is shorter than the ignition delay period, that is, the ignition delay period is relatively longer. Is controlled as follows.

Therefore, even if the fuel injection pressure, the fuel temperature, the fuel specific gravity and the like fluctuate, and the fuel injection valve and the exhaust gas recirculation control valve and the like vary with accuracy, the ignition delay period is always the fuel injection period. Is controlled to be larger than that, so that good low-temperature premixed combustion can always be maintained,
It is possible to reduce PM simultaneously with reduction of NOx.

In the second invention, when the ignition delay period is longer than the first minimum injection period, the injection period is shortened by increasing and correcting the maximum lift amount of the fuel injection valve. The fuel injection period can be controlled to be longer than the fuel injection period, so that the fuel injection pressure does not need to be increased more than necessary, the driving torque of the fuel injection pump and the like can be reduced, and the fuel efficiency can be improved.

In the third aspect of the invention, the correction of the maximum lift amount of the fuel injection valve is performed in accordance with the deviation from the ignition delay period, so that the fuel injection period can always be controlled appropriately and responsively.

In the fourth invention, in the range where the ignition delay period is shorter than the first minimum injection period and longer than the second minimum injection period, the injection period is shortened by increasing and correcting the fuel injection pressure. I have. Therefore, the fuel injection period can be shortened responsively when necessary, and good low-temperature premixed combustion can be maintained under all operating conditions.

In the fifth aspect, the fuel injection pressure is corrected by
Since the adjustment is performed in accordance with the deviation from the ignition delay period, the fuel injection period can be shortened and controlled responsively without excessively increasing the fuel pressure.

According to the sixth aspect, detection of the fuel injection start timing, end timing, ignition timing, and the like can be reliably and easily performed.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure, in which 51 is a diesel engine main body, 52 is an exhaust passage, 53 is an intake passage, and an exhaust recirculation passage 54 for recirculating a part of the exhaust to the intake passage 53. Is provided, and an exhaust gas recirculation control valve 55 for controlling the amount of exhaust gas recirculation is interposed in the middle of this.
In addition, 57 is a supercharger that pressurizes intake air.

A fuel injection valve 1 for directly injecting fuel into the engine combustion chamber 56 is provided.
As described later, a common rail (high-pressure fuel accumulator) 26
And high pressure fuel is supplied.

In order to realize low-temperature premixed combustion while recirculating a part of the exhaust gas into the intake air, although not shown, a swirl is generated in the combustion chamber 56 to generate a gas flow for promoting the mixing of fuel and air. Control means and the like are provided.

In order to control the ignition delay period in the low-temperature premixed combustion to be longer (longer) than the fuel injection period, the actual ignition delay period and the fuel injection period are calculated, and the ignition delay period is shorter. At times, the controller 60 controls the maximum lift amount of the fuel injection valve 1 so as to shorten the fuel injection period. The fuel injection period required to inject the same amount of fuel becomes shorter as the maximum lift becomes larger.Therefore, by variably controlling the maximum lift amount, the fuel injection period with respect to the ignition delay period becomes relatively small. It is possible to do.

For this reason, the controller 60 includes a signal from the lift sensor 61 as a means for detecting the fuel injection start timing and the injection end time of the fuel injection valve 1 and an in-cylinder pressure as a means for detecting the combustion start timing. A signal from the sensor 62 is input, a fuel injection period and an ignition delay period are calculated based on these signals, and the maximum lift amount of the fuel injection valve 1 is variably controlled as described later.

The controller 60 also controls the fuel injection timing and the injection amount of the fuel injection valve 1 to optimal values according to the operating condition. For this reason, the accelerator opening, the engine speed signal, and the cooling water temperature are controlled. Signals etc. are input. Further, the opening degree of the exhaust gas recirculation control valve 55 is controlled in accordance with the operation state, so that the exhaust gas recirculation amount is increased in a partial load region or the like, and the exhaust gas recirculation amount is reduced or stopped in a high load region.

Next, FIG. 2 shows details of the fuel injection valve 1 and FIG. 3 shows details of the fuel injection system.

In FIG. 2, the fuel injection valve 1 includes an injection nozzle holder 2, an injection nozzle 3, and an injection valve driving unit 4. The injection nozzle holder 2 and the injection nozzle 3 are integrated by a retaining nut 5. Have been. A needle valve sliding hole 6 and a fuel reservoir 7 are formed in the injection nozzle 3, and a nozzle hole 8 communicating with the fuel reservoir 7 is formed at the tip.

The large diameter portion 10 of the needle valve 9 is slidably fitted in the needle valve sliding hole 6. The large diameter portion 10 of the needle valve 9 has a connecting portion 11 formed therein, and a small diameter portion 12 and a valve body portion 13 are integrally formed at a lower end portion. The valve portion 13 opens and closes the seat portion X, and turns on / off the fuel injection from the nozzle hole 8.

A push rod 14 is in contact with the distal end of the connecting portion 11 of the needle valve 9 and is urged by a spring 16 in the valve closing direction. The pins 17 position the injection nozzle 3 and the injection nozzle holder 2. The push rod 14 is slidably fitted in a cylinder 15 formed in the injection nozzle holder 2.

An injection valve driving unit 4 for driving the needle valve 9 and the push rod 14 is disposed above the injection nozzle holder 2, and a piezoelectric element 22 is laminated in the injection valve driving unit 4. Power is supplied through the unit 23.

The piezoelectric element 22 expands and contracts in accordance with the energizing voltage value. A pusher 20 abuts on the piezoelectric element 22, and the pusher 20 presses the push rod 14, and when the piezoelectric element 22 contracts due to a decrease in the energizing voltage. Is raised by the return spring 21.

The injection valve control drive unit 4 is coupled to the injection nozzle holder 2 by a lock nut 25. In addition,
Leaked fuel in the fuel injection valve 1 is returned to the fuel tank from the fuel outlet 24.

A fuel supply passage 19 for high-pressure fuel is formed in the injection nozzle holder 2, one end of which is provided at the injection nozzle holder 2.
, And the other end is connected to the fuel storage chamber 7.
Communicate with The high-pressure fuel of the common rail 26 is supplied to the fuel storage chamber 7 through the inlet 18 and the fuel supply passage 19.

Normally, the needle valve 9 is urged in the closing direction by the push rod 14 and the pusher 20. From this state, by controlling the energization to the piezoelectric element 22, the lift amount is controlled. That is, when the energizing voltage to the piezoelectric element 22 is reduced, the piezoelectric element 22 contracts, and the pusher 2
0 is returned by the return spring 21, and the pushing force of the push rod 14 from the back is reduced.
The needle valve 9 is lifted and opened by the fuel pressure applied to the valve, and fuel is injected.

At this time, the maximum lift amount of the needle valve 9 changes depending on the voltage applied to the piezoelectric element 22, and the smaller the voltage value, the larger the lift amount.

When the voltage applied to the piezoelectric element 22 is increased, the amount of expansion of the piezoelectric element 22 is increased, and the pusher 2
0, the needle valve 9 pressed via the push rod 14 closes, and fuel injection stops.

Next, in FIG. 3, the fuel injection valve 1 for each cylinder is connected via an injection pipe 27 to a high-pressure accumulator pipe common to each cylinder, a so-called common rail 26. A high-pressure supply pump 30 is connected to the common rail 26 via a supply pipe 28 and a check valve 29. This high pressure supply pump 3
Numeral 0 controls the pressure of the fuel sucked through the fuel feed pump 33 from the fuel tank 31 via the fuel filter 32 to a predetermined high pressure. In this case, the drive shaft 34 having the cam rotates in synchronization with the engine rotation, the piston in the high-pressure supply pump 30 reciprocates, and the fuel from the fuel feed pump 33 is pressurized.
Supplied to Further, the high-pressure supply pump 30 is provided with a discharge amount control solenoid valve 35 for always controlling the common rail pressure to a desired pressure.

Further, a pressure sensor 37 for detecting the fuel pressure (common rail pressure) in the common rail is provided on the common rail 26. The controller 60 determines that the detected pressure is an optimum value set in advance according to the load and the engine speed. In such a manner, the discharge amount is feedback-controlled via the electromagnetic valve 35.

The above-described control executed by the controller 60 will be described in detail with reference to the flowchart shown in FIG.

This flowchart is repeated in synchronization with the engine speed. In step S1, the engine speed Ne, the engine load Q, and the cooling water temperature Tw are read.

In step S2, a basic fuel injection amount, a basic injection timing (advance value), a basic exhaust gas recirculation rate (EGR rate), a basic maximum needle valve lift amount, a basic common rail pressure according to the operating state determined based on the above. For example, from FIG.
It is calculated based on the characteristic as shown in (E).

In step S3, in order to obtain the basic injection amount obtained in this manner, the injection period when the maximum needle valve lift is set to the maximum value while maintaining the basic common rail pressure at the above-mentioned read engine speed. For example, a certain minimum injection period (1) and a minimum injection period (2) obtained when the maximum needle valve lift is set to the maximum value and the common rail pressure is set to the allowable maximum value in order to obtain the same basic injection amount, for example, The calculation is performed based on the characteristics as shown in FIGS.

The common rail pressure corresponds to the fuel injection pressure. To obtain the same injection amount, the fuel injection period becomes shorter as the maximum needle valve lift is increased. Is increased, the injection period is further shortened. In this case, the injection period cannot be shorter than the minimum injection period (2).

In step S4, the outputs of the in-cylinder pressure sensor and the needle valve lift sensor of the fuel injection valve are read, and in step S5, the ignition delay period and the fuel injection period are calculated.

The ignition delay period is a period from the start of fuel injection to the start of combustion. As shown in FIG. 8, the combustion start timing, that is, the ignition timing, is the output of the in-cylinder pressure sensor. It can be determined from the differential value, and the injection start timing can be determined from the rise of the output of the lift sensor. The fuel injection period is a period from the start to the end of fuel injection, and can be determined from the output of the lift sensor.

Next, in step S5, the magnitudes of the ignition delay period and the fuel injection period are determined, and if the ignition delay period is longer, the control is terminated.

On the other hand, if the ignition delay period is shorter, the process proceeds to step S7, where the ignition delay period is compared with the minimum injection period (1) obtained as described above.

This minimum injection period (1) is the minimum injection period obtained when the maximum needle valve lift is set to the maximum value at the basic common rail pressure, and if the ignition delay period is shorter than the minimum injection period (1). If it is longer than
Since the fuel injection period can be shortened by increasing the maximum needle valve lift amount from the current state, the process proceeds to step S8, and in accordance with the difference, as shown in FIG. Is calculated.

In step S9, a correction amount is added to the basic maximum needle valve lift amount as the maximum needle valve lift amount.
The control ends.

In this case, the greater the maximum needle valve lift, the shorter the fuel injection period for achieving the same injection amount, which is equivalent to a relatively long ignition delay period.

If it is determined in step S7 that the ignition delay period is shorter than the minimum injection period (1), the process proceeds to step S1.
Move to 0, and fix the maximum needle valve lift to the maximum value.

Even if the maximum needle valve lift is increased by correction, the ignition delay period is shorter, that is, the minimum injection period (1).
If it is shorter than this, the reduction of the injection period by increasing the needle valve lift becomes a limit, so the maximum needle valve lift is fixed to a predetermined maximum value.

In step S11, the ignition delay period is compared with the minimum injection period (2). If the ignition delay period is shorter, the control is terminated.

The minimum injection period (2) is an injection period when the common rail pressure is increased to the maximum value with the maximum needle valve lift at the maximum value in order to obtain the same injection amount. The injection period cannot be shortened.

Therefore, when the ignition delay period is shorter than the minimum injection period (2), no further correction is possible, so that state is maintained and the control is terminated.

On the other hand, if it is determined that the ignition delay period is longer, the process proceeds to step S12, and the increase correction amount of the common rail pressure is calculated as shown in FIG. Then, the common rail pressure is added to the basic common rail pressure and the correction pressure is added to end the control.

In this case, the higher the common rail pressure, the shorter the fuel injection period for obtaining the same fuel injection amount.

As described above, when the ignition delay period is shorter than the fuel injection period, basically, by increasing the maximum needle valve lift of the fuel injection valve, the fuel injection period is shortened than the ignition delay period. , Maintain good low-temperature premixed combustion.

The configuration is as described above. Next, the overall operation will be described.

The degree of opening of the exhaust gas recirculation control valve 55 is controlled in accordance with the operation state of the diesel engine, and exhaust gas recirculation is performed. As a result, the maximum combustion temperature decreases. Decrease.

On the other hand, the PM in the exhaust gas increases as the exhaust gas recirculation rate increases. As shown in FIG. 5, this PM decreases as the ignition delay period becomes shorter than the fuel injection period at the same exhaust gas recirculation rate.

During the ignition delay period, the fuel particles are premixed with air, and as the degree of premixing increases, in other words, as the ignition delay period increases, the amount of PM generated during combustion decreases.

Accordingly, the fuel injection start timing and the fuel end timing of the fuel injection valve 1 are detected, the injection period is calculated from the difference between them, and the combustion start (ignition) timing is detected. Then, an ignition delay period corresponding to a period from the actual injection of fuel to the start of ignition is calculated. When the ignition delay period is shorter than the fuel injection period, the maximum needle valve lift is increased so that the fuel injection period becomes shorter.

By increasing the maximum needle valve lift, the injection period required to inject the same amount of fuel is shortened. Thus, the ignition delay period can be relatively longer than the fuel injection period, and the longer the ignition delay period, the more the amount of PM emission can be reduced.

When the fuel injection period is longer than the ignition delay period even though the maximum needle valve lift reaches the predetermined maximum value, the common rail pressure, that is, the fuel Increase injection pressure. This allows
The fuel injection period is further shortened, so that the ignition delay period can be relatively lengthened.

As described above, according to the present invention, the fuel injection period is controlled so that the ignition delay period is longer than the fuel injection period while detecting the actual ignition delay period and the fuel injection period. By making the ignition delay period longer than the fuel injection period, good low-temperature premixed combustion is realized, and NO
The trade-off between x and PM can be improved.

In this case, even if there are fluctuations in the fuel injection pressure, the fuel temperature, the fuel specific gravity, etc., and even if the fuel injection valve, the exhaust gas recirculation control valve, the supercharger, etc., have a precise variation, the actual The ignition delay period can be made longer than the fuel injection period, so that good low-temperature premixed combustion is reliably maintained.
Ox and PM can be reduced simultaneously.

Further, regarding the shortening of the fuel injection period,
Mainly maintaining the common rail pressure at the basic value and responding by increasing the maximum needle valve lift of the fuel injection valve, the common rail pressure is not increased unnecessarily, and the driving torque of the fuel injection pump is suppressed. Deterioration of fuel efficiency of the diesel engine can be avoided.

On the other hand, even if the maximum needle valve lift of the fuel injection valve is set to the maximum value, if the fuel injection period is required to be further reduced, the common rail pressure is increased within the allowable maximum value. Therefore, when necessary, the fuel injection period can be promptly converged within the ignition delay period.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a fuel supply system.

FIG. 3 is a sectional view of the fuel injection valve.

FIG. 4 is a flowchart showing a control operation.

FIG. 5 is an explanatory diagram showing a relationship between an ignition delay period and a PM emission amount.

FIG. 6 is an explanatory diagram showing characteristics in an operating state, where A is a fuel injection amount characteristic, B is a fuel injection timing characteristic, C is an exhaust gas recirculation characteristic, D is a common rail pressure characteristic, and E is a maximum needle valve lift amount characteristic. Show.

FIG. 7 is an explanatory diagram showing characteristics during a minimum injection period. A shows the characteristics when the maximum needle valve lift is changed, and B shows the characteristics when the common rail pressure is changed.

FIG. 8 is an explanatory diagram showing a relationship between in-cylinder pressure and an output of a needle valve lift sensor.

FIG. 9 is an explanatory diagram showing a correction characteristic of a maximum needle valve lift amount.

FIG. 10 is an explanatory diagram showing a correction characteristic of a common rail pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 22 Piezoelectric element 26 Common rail 51 Diesel engine 55 Exhaust recirculation control valve 60 Controller 61 Lift sensor 62 In-cylinder pressure sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/40 F02D 41/40 R 45/00 364 45/00 364N 368 368S

Claims (6)

[Claims] 1. A fuel storage chamber for storing high-pressure fuel pumped from a fuel pump, means for controlling a fuel pressure of the fuel storage chamber to a target value corresponding to an operating state, and each cylinder connected to the fuel storage chamber A fuel injection valve for injecting fuel into the fuel injection valve; an injection control means for variably controlling an opening / closing timing and a lift amount of the fuel injection valve; Control means, and exhaust gas recirculation control means for introducing a part of the exhaust gas into the intake air to suppress the combustion temperature, wherein a means for detecting fuel injection start timing and end timing from the fuel injection valve, Means for detecting the combustion start time of the injected fuel; fuel injection period calculation means for calculating the fuel injection period from the detected values of the fuel injection start time and the injection end time; and fuel injection start time An ignition delay period calculating means for calculating an ignition delay period from each detected value of the combustion start timing; and when the fuel injection period is longer than the calculated ignition delay period, the injection period at the same fuel injection amount is longer than the ignition delay period. Control means for increasing the maximum lift amount of the fuel injection valve so as to reduce the maximum lift amount. 2. The fuel injection control apparatus according to claim 1, wherein the adjusting means sets a fuel injection period when a fuel injection pressure is a predetermined value and a lift amount is a maximum value for a same fuel injection amount to a first minimum injection period, 2. The control system for a diesel engine according to claim 1, wherein when the period is longer than the first minimum injection period, the maximum lift amount of the fuel injector is corrected to increase within a range of the maximum value. 3. The method according to claim 1, wherein the adjusting means is configured to determine the ignition delay period and a first time.
3. The control device for a diesel engine according to claim 2, wherein a correction value of the maximum lift amount is calculated according to a difference from the minimum injection period. 4. The adjusting means sets a fuel injection period when a fuel injection pressure is a maximum value and a lift amount is a maximum value for a same fuel injection amount as a second minimum injection period,
3. The fuel injection pressure is increased and corrected within its maximum value when the ignition delay period is shorter than the first minimum injection period and longer than the second minimum injection period.
Or a control device for a diesel engine according to item 3. 5. The method according to claim 1, wherein the adjusting means is configured to determine the ignition delay period and a second time.
The control device for a diesel engine according to claim 4, wherein a correction value of the injection pressure is calculated according to a difference from the minimum injection period. 6. The means for detecting the fuel injection start and end times comprises a lift sensor for detecting a lift of the fuel injection valve, and the means for detecting the combustion start time comprises a cylinder pressure sensor. The control device for a diesel engine according to claim 1.