JPH09264160A - Fuel injection device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively limit an angular speed change during the idle running of a diesel engine. SOLUTION: A fuel injection device includes an injection condition control means 9 for controls a fuel injection condition so as to pilot-injecting a small amount of fuel before main injector for injecting combustion to the combustion chamber of a diesel engine. In this case, the injection condition control means 9 includes an angular speed fluctuation detecting means 22 for detecting the angular speed fluctuation condition of the diesel engine and an injection condition correcting means 8 for correcting the pilot injection condition in a direction for limiting the angular speed fluctuation according to the output signal of this angular speed fluctuation detecting means 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a diesel engine configured to pilot-inject a small amount of fuel prior to main injection for injecting combustion into a combustion chamber of the diesel engine.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-153530, measures against noise of an internal combustion engine composed of a diesel engine and measures against harmful exhaust substances such as NOx have been proposed.
In a fuel injection control device for an internal combustion engine configured to achieve pilot injection prior to fuel injection, the operating state of the internal combustion engine is determined according to the time interval from the end of pilot injection to the start of main injection determined by the operating state. By correcting the main injection control time determined by the above, it is possible to compensate for the residual pressure in the fuel injection nozzle and the influence of the cavity in the fuel pressure feed passage on the main injection that occur at the end of pilot injection.

[0003]

By the way, the engine may have a large angular velocity fluctuation depending on various conditions during its idle operation, and if such a situation occurs, the driver feels uncomfortable. There is a problem that the driving feeling deteriorates. On the other hand, the conventional fuel injection control device has not taken any measures.

Further, since the fuel injection control device for the internal combustion engine described in the above publication is configured to correct the interval between the pilot injection and the main injection, that is, the pilot interval in units of time, the pilot injection timing can be adjusted. There is a problem that it cannot be controlled precisely. That is, when the pilot injection timing with respect to the main injection timing of fuel set based on the angular velocity of the internal combustion engine is set in time units as described above, precise pilot injection control that takes into account the change in the angular velocity of the internal combustion engine is executed. There was a problem that I could not do it.

In view of the above circumstances, the present invention provides a fuel injection device for a diesel engine, which can effectively suppress angular velocity fluctuations during idle operation of the diesel engine and can execute precise pilot injection control. It is provided.

[0006]

The invention according to claim 1 is
A fuel injection device for a diesel engine, comprising: an injection state control means for controlling an injection state of fuel so as to pilot-inject a small amount of fuel prior to main injection for injecting combustion into a combustion chamber of the engine. The angular velocity fluctuation detecting means for detecting the angular velocity fluctuation state and the injection state correcting means for correcting the pilot injection state in the direction of suppressing the angular velocity fluctuation of the engine according to the output signal of the angular velocity fluctuation detecting means are the injection state control means. It was installed in.

According to the above configuration, the fuel injection amount in the pilot injection is corrected or the interval between the pilot injection and the main injection is corrected according to the detected value of the angular velocity fluctuation state of the diesel engine detected by the angular velocity fluctuation detecting means. By doing so, the control for suppressing the fluctuation of the angular velocity is executed by the injection state correction means.

According to a second aspect of the present invention, in the fuel injection device for a diesel engine according to the first aspect, pilot interval correction means for suppressing the angular velocity fluctuation of the diesel engine by correcting the interval between the pilot injection and the main injection. Is provided in the injection state correcting means.

According to the above construction, the interval between the pilot injection and the main injection is corrected by the correction means in accordance with the detected value of the angular speed change state of the diesel engine detected by the angular speed change detection means, whereby the combustion of combustion is performed. The state is appropriately controlled, and the angular velocity fluctuation is suppressed.

According to a third aspect of the present invention, in the fuel injection device for a diesel engine according to the second aspect, during the idle operation of the diesel engine, the angular velocity fluctuation state of the diesel engine is previously determined according to the output signal of the angular velocity fluctuation detecting means. When it is confirmed that the value is larger than the set reference value, the pilot interval correcting means corrects the interval between the pilot injection and the main injection in the direction of increasing the interval.

According to the above construction, when it is confirmed that the angular velocity fluctuation state of the diesel engine is in a large fluctuation state above the reference value according to the output signal of the angular velocity fluctuation detection means during the idle operation of the diesel engine. In this case, a correction for increasing the interval between the pilot injection and the main injection is executed, so that the maximum combustion pressure of the fuel is reduced and the fluctuation of the angular velocity is suppressed.

According to a fourth aspect of the present invention, in the fuel injection device for a diesel engine according to any one of the first to third aspects, the output of the diesel engine is in a high output operation state larger than a preset reference value. An operating state determination means for determining whether or not there is is provided, and when the operating state determination means confirms that the diesel engine is in a high output operating state, the pilot injection is prohibited.

According to the above construction, when it is confirmed by the operation state determination means that the diesel engine is in the high output operation state, the pilot injection is prohibited so that the fuel is relatively injected in the main injection. The amount is increased to ensure sufficient engine output.

According to a fifth aspect of the present invention, in the fuel injection device for a diesel engine according to any one of the first to fourth aspects, a rotational speed detecting means for detecting a rotational speed of the diesel engine and an idle operation of the diesel engine are provided. At times, in accordance with the deviation between the rotation speed of the diesel engine detected by the rotation speed detection means and the target rotation speed in the idle operation state, in the direction of matching the rotation speed of the diesel engine with the target rotation speed, in the pilot injection The injection state correction means is provided with pilot injection amount correction means for correcting the fuel injection amount.

According to the above structure, the pilot injection is performed based on the correction coefficient set according to the deviation between the rotational speed of the diesel engine detected by the rotational speed detecting means and the target rotational speed in the idle operation state of the diesel engine. By correcting the fuel injection amount in, the control for matching the rotational speed of the diesel engine with the target rotational speed is executed.

According to a sixth aspect of the present invention, in the fuel injection device for a diesel engine according to any of the first to fifth aspects, the acceleration detecting means for detecting the acceleration of the vehicle and the output signal of the acceleration detecting means are used. Accordingly, when it is confirmed that the acceleration of the vehicle is in a high acceleration operation state equal to or higher than a preset reference value, pilot injection amount correction means for correcting the fuel injection amount in pilot injection in a direction to decrease, and pilot injection The injection state correcting means is provided with pilot interval correcting means for correcting the distance between the main injection and the main injection.

According to the above construction, when it is confirmed that the acceleration of the vehicle is in the high acceleration operation state above the reference value, the correction for reducing the fuel injection amount in the pilot injection is executed by the pilot injection amount correction means. In addition, the correction of reducing the interval between the pilot injection and the main injection is executed by the pilot interval correction means, so that the output of the diesel engine is secured and the desired acceleration state is obtained.

According to a seventh aspect of the present invention, in the fuel injection device for a diesel engine according to any one of the first to sixth aspects, the fuel temperature detecting means for detecting the fuel temperature and the diesel engine during idle operation are used. When it is confirmed that the fuel temperature is low according to the output signal of the fuel temperature detection means, the injection state correction means is provided with pilot injection amount correction means for correcting the fuel injection amount in the pilot injection in the direction of decreasing the fuel injection amount. It is a thing.

According to the above configuration, when it is confirmed that the fuel temperature is low in accordance with the output signal of the fuel temperature detecting means, the control for reducing the fuel injection amount in the pilot injection is executed, so that the fuel An increase in fuel injection pressure due to high viscosity is suppressed.

According to an eighth aspect of the present invention, in the fuel injection device for a diesel engine according to any one of the first to seventh aspects, there is provided operating state determining means for determining whether or not the diesel engine is in an idle operating state. When the diesel engine is confirmed to be in the idle operating state by the operating state determining means, the pilot injection state is feedback-controlled.

According to the above configuration, during the idle operation of the diesel engine, according to the detected value of the angular velocity fluctuation of the diesel engine detected by the angular velocity fluctuation detecting means,
The fuel injection amount in the pilot injection is feedback-controlled by the injection state correction means to be appropriately corrected, or the interval between the pilot injection and the main injection is appropriately corrected by the feedback control.

The invention according to claim 9 is provided with injection state control means for controlling the injection state of the fuel so as to pilot-inject a small amount of fuel prior to the main injection for injecting combustion into the combustion chamber of the diesel engine. A fuel injection device for a diesel engine, comprising: a required injection amount calculation means for calculating a required injection amount of fuel from a map in which the operating state of the diesel engine is set as a parameter; and an output signal of the required injection amount calculation means. Basic injection amount calculation means for calculating the basic injection amount of fuel in pilot injection, and the basic of pilot injection timing and main injection timing in units of crank angle of diesel engine according to the output signal of the required injection amount calculation means A basic interval calculating means for calculating an interval is provided in the injection state control means.

According to the above construction, the basic injection amount of fuel in the pilot injection is calculated by the basic injection amount calculation means in accordance with the required injection amount of fuel calculated by the required injection amount calculation means, and the required injection of fuel is made. The basic interval between the pilot injection timing and the main injection timing in units of the crank angle of the diesel engine is calculated by the basic interval calculation means based on the amount, and the pilot injection state is determined based on the calculated values of the basic injection amount and the basic interval. Will be controlled.

According to a tenth aspect of the present invention, in the fuel injection device for a diesel engine according to the ninth aspect, main injection timing calculating means for calculating a main injection timing corresponding to an operating state of the diesel engine, and the main injection timing. The injection state control means is provided with an injection state correction means for correcting the pilot injection state according to the output signal of the calculation means.

According to the above arrangement, the basic injection amount calculating means and the basic interval calculating means determine the basic fuel injection amount in the pilot injection and the basic interval between the pilot injection timing and the main injection timing by the main injection timing calculating means. The values are properly corrected based on the calculated calculated values of the main injection timing, and the pilot injection state is controlled based on the corrected fuel injection amount and pilot interval.

[0026]

1 shows an embodiment of a fuel injection device for a diesel engine according to the present invention. This fuel injection device includes a plunger pump 2 driven by a camshaft 1 of a diesel engine, a fuel supply passage 4 for supplying fuel discharged from the plunger pump 2 to a fuel injection nozzle 3, and a fuel supply passage 4 has a fuel supply means 5 for supplying combustion to the plunger pump 2 and a control valve 7 for discharging the fuel discharged from the plunger pump 2 to a drain passage 6. 2 and the control valve 7 are installed for each cylinder of the engine body 10.

The control valve 7 is a conventionally known control valve having a drive section composed of a piezoelectric element or the like that expands and contracts in response to the application of a voltage, and a needle valve driven by this drive section. It is configured to be controlled by the injection state control means 9 which operates in response to a control signal output from. That is, when a positive voltage is applied to the piezoelectric element and the piezoelectric element expands, the needle valve is brought into close contact with its valve seat and the fuel supply passage 4 and the drain passage 6 are shut off from each other. The fuel discharged from the jar pump 2 is the fuel injection nozzle 3 described above.
Is injected into the combustion chamber of the engine body 10. When a negative voltage is applied to the piezoelectric element and the piezoelectric element contracts, the needle valve separates from its valve seat and the fuel supply passage 4 and the drain passage 6 are brought into communication with each other. The fuel discharged from the plunger pump 2 is configured to be returned to the fuel supply section via the drain passage 6.

The injection state control means 9 detects various signals input via the engine control unit 8, for example, a crank angle sensor 11 for detecting a crank angle, an accelerator sensor 12 for detecting an accelerator opening, or a fuel temperature. By outputting the control signal generated according to the detection signal of the fuel temperature sensor 13 or the like to the control valve 7,
Control is performed to pilot-inject a small amount of fuel prior to the main injection that injects combustion into the combustion chamber of the engine body 10, and the operation state of the diesel engine and the running state of the vehicle equipped with the diesel engine are controlled. Accordingly, the pilot injection state is controlled accordingly.

As shown in FIG. 2, the injection state control means 9 calculates the required injection amount of fuel based on the value read from a map preset with the operating state of the diesel engine as a parameter. Output of the required injection amount calculation means 14, the basic injection amount calculation means 15 for calculating the basic injection amount of fuel in the pilot injection according to the output signal of the required injection amount calculation means 14, and the required injection amount calculation means 14 described above. A basic interval calculating means 16 for calculating a basic interval between the pilot injection timing and the main injection timing according to the signal is provided.

The required injection amount of the fuel is determined by an experiment or the like so as to be an optimum value in the entire operating range of the diesel engine according to the cooling water temperature, the fuel temperature, the supply air temperature, the EGR amount, the accelerator opening degree, etc. of the diesel engine. Is calculated in advance and stored as a map. Generally, the higher the engine speed, the more the required injection amount of the fuel tends to increase. Further, the basic injection amount of fuel in the pilot injection is
A value read from a pilot injection rate map set in advance by experiments or the like using the operating state of the diesel engine as a parameter is calculated by, for example, multiplying the calculated value of the required injection amount. Further, the basic interval between the pilot injection timing and the main injection timing is calculated based on a value read from a map preset with the required injection amount as a parameter, and the engine main body 1
It is configured so that the crank angle of 0 can be obtained as a unit.

The injection state control means 9 has a main injection timing calculation means 17 for calculating a main injection timing based on a preset map using the operating state of the diesel engine as a parameter, and the main injection timing calculation means. Injection state correction means 18 is provided for correcting the pilot injection state by correcting the basic injection amount of fuel in the pilot injection and the basic interval between the pilot injection timing and the main injection timing according to the output signal of 17. There is.

That is, the injection state correction means 18 uses the main injection timing as a parameter, and based on the correction coefficient read from the preset map, the fuel quantity in the pilot injection calculated by the basic injection amount calculation means 15 is calculated. The pilot injection amount correcting means 19 for correcting the basic injection amount, and the pilot injection timing and the main injection calculated by the basic interval calculating means 16 on the basis of the correction coefficient read from a map preset with the main injection timing as a parameter. Pilot interval correction means 20 for correcting the basic interval with respect to the time is provided.

The pilot injection amount correction means 19 is also provided.
Is a rotation speed detecting means 2 for detecting the rotation speed of the diesel engine according to the detection signal from the crank angle sensor 11 or the like.
Based on the output signal of No. 1, the fuel injection in the pilot injection is performed in the direction in which the rotation speed of the diesel engine matches the target rotation speed in accordance with the deviation between the rotation speed of the diesel engine and the target rotation speed in the idle operation state of the diesel engine. It has a function to correct the quantity.

Specifically, when it is confirmed that the actual engine rotation speed is higher than the target rotation speed in the idle operation state of the diesel engine, the fuel injection amount in the pilot injection is increased and the fuel injection amount is relatively increased. By reducing the fuel injection amount in the main injection, the engine rotation speed is reduced to match the target rotation speed. Further, in the idle operation state of the diesel engine, when it is confirmed that the actual engine speed is lower than the target speed, the fuel injection amount in the pilot injection is reduced to relatively perform the fuel injection in the main injection. By increasing the amount, feedback control is performed to increase the engine rotation speed to match the target rotation speed.

The pilot interval correction means 20 is also provided.
Has a function of correcting the pilot interval in a direction of suppressing the angular speed fluctuation based on the output signal of the angular speed fluctuation detecting means 22 which detects the angular speed fluctuation state of the diesel engine according to the output signal of the rotational speed detecting means 21. Have Specifically, in the idle operation state of the diesel engine, when it is confirmed that the angular velocity fluctuation state of the diesel engine is larger than a preset reference value in accordance with the output signal of the angular velocity fluctuation detection means 22, the pilot The feedback control for reducing the maximum combustion pressure of the fuel is executed by correcting the interval between the injection and the main injection to be larger.

The injection state control means 9 detects the acceleration of the vehicle according to the output signal of the accelerator sensor 12 and the fuel temperature according to the output signal of the fuel temperature sensor 13. The fuel temperature detecting means 24 and the operating state determining means 25 for determining whether or not the output of the diesel engine is in a high output operating state equal to or higher than a preset reference value are provided.

When it is confirmed that the vehicle is in an accelerating state equal to or higher than the preset reference value according to the output signal of the acceleration detecting means 23, the pilot injection amount correcting means 19 causes the fuel in the pilot injection to be increased. Control is performed so that the injection amount is reduced and the pilot interval correction means 20 corrects the interval between the pilot injection and the main injection. Further, when it is confirmed that the fuel temperature is low according to the output signal of the fuel temperature detection means 24 in the idle operation state of the diesel engine, the pilot injection quantity correction means 19 reduces the fuel injection quantity in the pilot injection. The control for correcting in the direction of making it executed is executed.

Further, when it is confirmed by the operating condition judging means 25 that the diesel engine is in the high output operating condition, for example, when the engine speed is in the over-rotation condition of a predetermined value or more, the vehicle speed is the predetermined value or more. When the vehicle is traveling at a high vehicle speed, or when it is confirmed that the engine is in an enriched state with a large amount of combustion injection, the fuel injection amount in the pilot injection is set to 0 and the pilot interval is set to 0. As a result, the pilot injection is prohibited. When it is confirmed by the driving state determination means 25 that the vehicle is in the fuel cut control execution state in the predetermined deceleration state, the pilot injection is also stopped.

The basic control operation by the injection state control means 9 having the above construction will be described with reference to the flow charts shown in FIGS. When the basic control operation starts, first, initial setting is performed in step S1, and then, in step S2, the detection signals output from the crank angle sensor 11, the accelerator sensor 12, the fuel temperature sensor 13 and the like are input. Next, in step S3, after the required injection amount QF of fuel required according to the above operating state is obtained by the required injection amount calculation means 14, step S4
At, the operating state of the diesel engine is determined by the operating state determining means 25.

Further, in step S5, it is determined whether or not it is in the pilot injection zone in which pilot injection is executed according to the determination result of the above operating state. If NO is determined, the process proceeds to steps S18 and S19. The pilot injection amount QP and the pilot interval AP to 0
To prohibit pilot injection.

If YES is determined in step S5, the required injection amount QF obtained by the required injection amount calculation means 14 is calculated in step S7 after the feedback determination control described later is executed in step S6.
Based on the basic injection amount Q of fuel in pilot injection
FB is calculated by the basic injection amount calculation means 15, and in step S8, the basic interval AP between the pilot injection and the main injection is calculated based on the required injection amount QF.
B is calculated by the basic interval calculation means 16 and is obtained.

Then, in step S9, the injection timing correction coefficient QPT for correcting the basic injection amount and the injection for correcting the basic interval are performed based on the main injection timing obtained by the main injection timing calculating means 17. The timing correction coefficient APT is calculated by the pilot injection amount correction means 19 and the pilot interval correction means 20, respectively.

As shown in FIG. 5, the injection timing correction coefficient APT for correcting the basic interval APB is such that the main injection is at the top dead center (TDC) in the idle operation state or the like.
When it is performed within a range of 5 ° before and after, the setting of 1 is set so that the basic interval APB is not corrected.

Further, when the main injection is performed within a range of 5 ° or more in crank angle units from the top dead center in a high output operation state of the diesel engine, the injection is performed in order to improve the engine output. Timing correction coefficient A
By setting PT to a value smaller than 1, the pilot interval is corrected to be narrower, and in the normal operating region (partial load region), the main injection is 5 ° or more after the top dead center. In the case of the above range, the injection timing correction coefficient APT is corrected to be wider than the pilot interval set to a value larger than 1 in order to improve emission and fuel consumption.

Then, in step S10, as will be described later, the pilot injection amount F / for feedback controlling the pilot injection amount based on the engine rotation speed is used.
The B correction coefficient QPF is calculated by the pilot injection amount correction means 1 described above.
In step S11, the pilot interval correction means 20 calculates the pilot injection interval F / B correction coefficient APF for feedback controlling the pilot injection interval based on the angular velocity fluctuation of the diesel engine. Ask.

In step S12, an acceleration correction coefficient QPA for correcting the pilot injection amount and an acceleration correction coefficient APA for correcting the pilot injection interval are calculated based on the vehicle acceleration as described later. The pilot injection amount correction means 19 and the pilot interval correction means 20 calculate and obtain the value, and step S1
3, the fuel temperature correction coefficient QPC for correcting the pilot injection amount is calculated by the pilot injection amount correcting means 19 based on the fuel temperature.

Next, at step S14, the calculated value QPB of the basic injection amount and the correction coefficients QPT and QPT.
The final injection amount QP in the pilot injection is calculated based on PC, QPF and QPA. That is, the injection timing correction coefficient Q is added to the calculated value QPB of the basic injection amount.
Multiply PT and the fuel temperature correction coefficient QPC,
The F / B correction coefficient QPF and the acceleration correction coefficient QP
The final pilot injection amount QP is obtained by multiplying by the value (1 + QPF−QPA) obtained based on A.

Further, in step S15, the calculated value APB of the basic interval and the correction coefficients APT, AP
The final interval AP in pilot injection is calculated based on F and APA. That is, the calculated value A of the basic interval
A value (1 + APF-AP) obtained by multiplying PB by the injection timing correction coefficient APT, and by multiplying this by the F / B correction coefficient APF and the acceleration correction coefficient APA.
The final pilot interval AP is obtained by multiplying A).

Next, in step S16, the final main injection amount QM is obtained by subtracting the final calculated value QP of the pilot injection amount from the calculated value QF of the required injection amount.
After determining, in step S17, fuel injection control is executed by outputting a control signal corresponding to each of the final calculated values QP, AP, QM.

The operation state determination control operation executed in step S4 of the basic control operation will be described with reference to the flowcharts shown in FIGS. 6 and 7. When the control operation is started, first, initial setting is performed in step S21, and then in step S22, it is determined whether or not the engine speed NE is in an overspeed region equal to or higher than the first reference value KN1 set to about 45000 rpm. judge.

If YES is determined in the above step S22, the control operation is ended after the overspeed flag F1 indicating that the engine speed is in the overspeed region is set to 1 in step S23. When it is determined to be NO in step S22, it is determined in step S24 whether or not the vehicle speed SP is in a high vehicle speed operation state equal to or higher than the reference vehicle speed KS set to about 180 km.

If YES is determined in step S24, the control operation is ended after the high vehicle speed flag F2 indicating that the vehicle is in the high vehicle speed operation state is set to 1 in step S25. In addition, the above step S24
If NO is determined in step S29, it is determined in step S29 whether the idle switch is ON and Y
If determined as ES, in step S30,
It is determined whether the engine speed NE is greater than or equal to the second reference value KN2 set to about 2000 rpm.

If YES is determined in the above step S30, it is determined that the vehicle is in the predetermined deceleration state, the process proceeds to step S34, and the deceleration flag F4 indicating the fuel cut control state is set to 1. To do. If NO in step S30, step S3
1, the deceleration flag F4 in the previous control is 1
If it is determined to be NO, the process proceeds to step S32 to continue the non-execution state of the fuel cut control.

On the other hand, YES in step S31.
It is determined that the deceleration flag F4 in the previous control is 1
If it is confirmed that the engine speed NE is set to 1, the engine speed NE is 1500 rpm in step S33.
It is determined whether or not the third reference value KN3 set to the degree is equal to or more than the above, and if YES is determined, the above step S3 is performed.
If the routine shifts to step 2, the fuel cut control is stopped, and YES is determined in step S33, step S34 is performed.
And the fuel cut control is continued.

Next, in step S35, it is determined whether or not the engine speed NE is greater than or equal to the fourth reference value KN4 set to about 3500 rpm. If YES is determined, the combustion injection amount is determined in step S36. The enrichment flag F3, which indicates that there is a large amount, is set to 1.
Then, if NO in the step S35, in the step S37, the required amount calculating means 14
It is determined whether or not the fuel demand amount QF obtained by the above is greater than or equal to a predetermined reference value KQ1 set in advance, and if YES is determined, the process proceeds to step S36 to confirm that the combustion injection amount is large. The enrichment flag F3 shown is set to 1.

If NO at step S37, the idle switch is turned on at step S38.
If it is determined to be YES in the N state, it is determined in step S39 whether the engine speed NE is equal to or greater than a preset fifth reference value KN5, If YES is determined, it is further determined in step S40 whether or not the required fuel amount QF is equal to or greater than a preset reference value KQ2.

If YES is determined in the above step S40, the F / B flag F6 indicating that the feedback control described later is executed is set to 1 in step S41 because the diesel engine is in the idle operation state. Set to. In addition, the above steps S38, S
When it is determined to be NO in either 39 or S40,
In step S42, a map showing that the pilot injection state is open-loop controlled based on the map because the diesel engine is in a normal operating state that is neither a high output operating state, a fuel cut operating state, nor an idle operating state. The zone flag F7 is set to 1.

The operating state of the diesel engine is determined as described above, and based on each flag set in accordance with the result of this determination, for example, in step S5 of the basic operation described above, whether or not it is in the pilot injection zone. A decision will be made.

Next, the control operation of the feedback judgment executed in step S6 of the basic control operation will be described with reference to the flowchart shown in FIG. When the above control operation starts, first in step S51,
It is determined whether or not the F / B flag F6 set by the above operation state determination control is 1, that is, whether or not the feedback control state is in effect, and if YES is determined,
In step S52, the F / B at the time of the previous control
It is determined whether the flag F6 'is 1.

If it is determined NO in step S52 and it is confirmed that the F / B flag F6 has changed to 1 at this time, in step S53, the first counter for pilot injection amount control determination is counted. Value CNT1
Is set to a predetermined value, and the count value CNT2 of the second counter for pilot injection interval control determination is set to a predetermined value in step S54, and then step S54
At 55, the above-mentioned F / B flag F6 'is set to 1.

If it is determined YES in step S52, it is determined in step S56 whether the count value CNT1 of the first counter is 0. If NO is determined, In step S57, the pilot injection amount F / B flag F9 indicating that the feedback control of the injection amount is being performed is reset to 0, and in step S58, the count value CN is set.
Subtract T1. When it is determined YES in step S56 and it is confirmed that the count value CNT1 of the first counter is 0, the pilot injection amount F / B flag F9 is set to 1 in step S59.

Next, in step S60, it is determined whether or not the count value CNT2 of the second counter is 0. If NO is determined, in step S63, the pilot injection interval feedback control state is set. Pilot injection interval F / B flag F10 indicating that
Is reset to 0, and the count value CNT2 is subtracted in step S64. When it is determined YES in step S60 and it is confirmed that the count value CNT2 of the second counter is 0,
In step S62, the pilot injection interval F /
The B flag F10 is set to 1.

Until the counting by the first and second counters is completed as described above, the feedback injection determination process for the pilot injection amount and the pilot injection interval in the idle operation state of the engine is executed.

Next, step S10 of the above basic control operation.
The calculation control operation of the pilot F / B correction coefficient QPF used when the pilot injection amount is feedback-controlled in the above will be described with reference to the flowchart shown in FIG. When the above control operation starts, first, step S7
1, the F / set by the judgment control of the driving state
It is determined whether or not the B flag F6 is 1, that is, whether or not the feedback control is in the execution state, and if NO is determined, the above correction for feedback controlling the pilot injection amount is performed in step S72. Coefficient QPF
Set the value of to 0.

If YES is determined in step S71, it is determined in step S73 whether the engine speed NE is larger than the preset target speed NA in the idle operation state. When it is determined to be YES, it is determined in step S74 whether the engine speed NE 'during the previous control is greater than the target speed NA.

In step S74, it is determined to be NO, and at the time of this control, the engine speed NE is the target speed NA.
If it is confirmed that the proportional control correction coefficient QPFP for feedback controlling the pilot injection amount is set to a predetermined value KQ in step S75.
Along with setting P, the value of the integral control correction coefficient QPFI is set to 0. If YES is determined in the step S74, the proportional control correction coefficient QPFP is set to 0 in a step S76, and
The integral control correction coefficient QPFI is set to a predetermined value KQI.

If it is determined NO in step S73 and it is confirmed that the engine speed NE is less than or equal to the target speed NA, in step S77, the engine speed NE 'during the previous control is controlled. , Is determined to be greater than the target rotational speed NA.

It is determined YES in step S77,
At the time of this control, the engine speed NE is set at the target speed N.
If it is confirmed that the result is A or higher, step S
At 78, the proportional control correction coefficient QPFP for feedback controlling the pilot injection amount is set to a predetermined value-KQP.
And the value of the integral control correction coefficient QPFI is set to 0. If YES is determined in step S77, the value of the proportional control correction coefficient QPFP is set to 0 and the integral control correction coefficient QPFI is set to a predetermined value -KQI in step S79.

Then, the proportional control correction coefficient QPFP and the integral control correction coefficient QPFI obtained as described above are
In step S80, the correction coefficient QPF is obtained by adding the value to the previous correction coefficient QPF '. Then, by correcting the pilot injection amount QP based on the correction coefficient QPF, as shown in FIG.
Feedback control for matching the engine speed NE, that is, the engine speed to the target speed NA in the idle operation state, that is, the target speed is executed.

Next, step S11 of the basic control operation described above.
The calculation control operation of the pilot F / B correction coefficient APF used when the pilot injection interval is feedback-controlled in step 1 will be described with reference to the flowchart shown in FIG. When the above control operation starts, it is first determined in step S81 whether the F / B flag F6 set by the operation state determination control is 1, that is, whether the feedback control is in the execution state, and NO If it is determined that the value of the correction coefficient APF for feedback controlling the pilot injection amount is set to 0 in step S84.

If YES in step S81, the amount of change in the angular velocity N of the diesel engine is N.
Eθ is calculated. That is, the angular velocity change amount NEθ is obtained by obtaining the deviation between the engine speed NE ′ during the previous control and the engine speed NE during the present control, and then in step S83, the absolute value of the angular speed change amount is obtained. It is determined whether or not | NEθ | is greater than or equal to a preset reference value ND0.

It is determined YES in step S83,
The angular speed change NEθ of the diesel engine is the reference value ND
When it is confirmed that it is 0 or more, step S8
In step 5, the proportional control correction coefficient APFP for calculating the correction coefficient APF is set to a predetermined value KAP. When it is determined NO in step S83 and it is confirmed that the angular velocity change amount NEθ of the diesel engine is less than the reference value ND0, the proportional control correction coefficient APFP is set to 0 in step S86.

Then, in step S80, the proportional control correction coefficient AFP 'thus obtained is added to the value of the previous correction coefficient APF' to obtain the final proportional control correction coefficient APF. Correction coefficient A
By correcting the pilot injection interval AP based on PF, the feedback control for suppressing the angular velocity fluctuation of the diesel engine is executed. In addition,
In the above embodiment, the angular velocity fluctuation state is directly detected based on the detected value of the angular velocity change amount NEθ of the diesel engine, but the present invention is not limited to this, and the angular velocity fluctuation state may be detected by another method. May be.

Next, step S12 of the basic control operation described above.
The calculation control operation of the acceleration correction coefficients QPA and APA executed in step 1 will be described with reference to the flowchart shown in FIG. When the above control operation is started, first in step S91, the accelerator opening AC'in the previous control
Then, after obtaining the deviation ACD from the accelerator opening AC at the time of this control, it is determined at step S92 whether or not the deviation ACD of the accelerator opening is equal to or greater than a preset reference value KC.

If YES is determined in the above step S92,
If it is confirmed that the vehicle is in the predetermined acceleration state, in step S93, the acceleration correction coefficient QP
After setting A and APA to predetermined values KQA and KAA, in step S95, the accelerator opening AC during the current control is set.
Is input as the previous value AC ′ to update the accelerator opening AC. If it is determined NO in step S92 and it is confirmed that the accelerator opening deviation ACD is less than the reference value KC, the correction coefficients QPA and APA are set to 0.

When it is confirmed that the vehicle acceleration is in the high acceleration operation state above the reference value as described above,
The pilot injection amount correction means 19 performs a correction for reducing the fuel injection amount QP in the pilot injection, and the pilot interval correction means 30 performs a correction for reducing the distance AP between the pilot injection and the main injection, whereby the diesel injection is performed. The engine output is secured and the desired acceleration state is obtained.

Next, step S12 of the basic control operation described above.
The operation for controlling the calculation of the fuel temperature correction coefficient QPC executed in step S1 will be described with reference to the flowchart shown in FIG. When the above control operation starts, first, step S9
6, it is determined whether or not the diesel engine is in the idle operation state by determining whether or not the F / B flag F6 set by the above operation state determination control is 1, and it is determined to be YES. If yes, step S
At 97, the fuel temperature correction coefficient QPC is set to a value KQC corresponding to the fuel temperature.

That is, when the diesel engine is in idle operation, the required fuel injection amount QF is relatively small, and when the fuel temperature is low in such an operating state, the fuel injection pressure tends to increase because the fuel viscosity is high. Therefore, in order to correct this, the above fuel temperature correction coefficient QPC
Is set to a value smaller than 1 to reduce the fuel injection pressure. If NO is determined in step S96, the value of the fuel temperature correction coefficient QPC is set to 1, and the correction of the idle injection amount corresponding to the fuel temperature is prohibited.

As described above, the angular velocity fluctuation detecting means 22 for detecting the angular velocity fluctuation state of the diesel engine, and the pilot injection state for suppressing the angular velocity fluctuation of the diesel engine in accordance with the output signal of the angular velocity fluctuation detecting means 22. The injection state correction means 18 for correction is provided in the injection state control means 9, and the basic injection amount calculation means 15 is provided according to the correction coefficient set in the injection state correction means 18.
Since the basic injection amount QPB in the pilot injection and the basic interval APB between the pilot injection and the main injection, which are obtained by the basic interval calculation means 16, are corrected, the angular velocity fluctuation that occurs during idle operation of the diesel engine is effective. Therefore, the driving feeling can be maintained in a good state.

That is, in the above embodiment, the injection state control means 19 is provided with the pilot interval correction means 20 for suppressing the variation in the angular velocity of the diesel engine by correcting the interval between the pilot injection and the main injection, and during the idle operation or the like. In the case where a large angular velocity fluctuation occurs, the correction for widening the pilot interval can be executed to lower the maximum fuel combustion pressure and effectively suppress the angular velocity fluctuation.

In particular, in the above-described embodiment, the correction by the pilot interval correction means 20 is performed only when the angular velocity change amount NEθ detected by the angular velocity fluctuation detection means 22 is larger than a predetermined reference value NE0 set in advance. Since it is configured to be executed, the correction by the pilot interval correction means 20 and the pilot injection amount correction means 21 are performed.
It is possible to effectively suppress the divergence of control due to the simultaneous correction of the pilot injection amount by.

Further, in the above-mentioned embodiment, the operating condition judging means 25 for judging whether or not the output of the diesel engine is in a high output operating condition larger than a preset reference value.
Since the pilot injection is prohibited when the diesel engine is confirmed to be in the high output operating state by the operating state determining means 25, the diesel engine is configured to prohibit the pilot injection. Is in an over-rotation state above a predetermined value, or when the vehicle speed is running at a high speed above a predetermined value, by prohibiting pilot injection and increasing the fuel injection amount in the main injection relatively, A sufficient output can be secured.

Further, in the above embodiment, the rotational speed detecting means 21 for detecting the rotational speed of the diesel engine and the rotational speed (rotational speed of the diesel engine detected by the rotational speed detecting means 21 during the idle operation of the diesel engine). NE) and the target rotation speed (target rotation speed NA) of the diesel engine in the idle operation state, the fuel injection amount in the pilot injection is corrected in a direction to match the rotation speed of the diesel engine with the target rotation speed. Pilot injection amount correcting means 20
Since the injection state correction means 18 is provided with the injection speed correction means 18, the correction coefficient Q is set according to the deviation between the rotation speed of the diesel engine detected by the rotation speed detection means 21 and the target rotation speed in the idle operation state of the diesel engine.
Fuel injection amount QP in pilot injection based on PF
By correcting the above, it is possible to execute the control for matching the rotation speed of the diesel engine with the target rotation speed.

Further, in the above embodiment, the acceleration detecting means 23 for detecting the acceleration of the vehicle, and the acceleration detecting means 2
Pilot injection amount correction means for correcting the pilot basic injection amount QPB in a direction to reduce the pilot basic injection amount QPB when it is confirmed that the acceleration of the vehicle is in a high acceleration operation state equal to or higher than a preset reference value according to the output signal The injection state correcting means 18 is provided with 19 and a pilot interval correcting means 20 for correcting the basic distance APB between the pilot injection and the main injection so as to be decreased.

According to the above construction, when it is confirmed that the acceleration of the vehicle is in the high acceleration operation state above the reference value, the pilot injection amount correcting means 19 corrects the fuel injection amount QP in the pilot injection. In addition to the above, the pilot interval correction means 20 performs the correction for reducing the interval AP between the pilot injection and the main injection, whereby the output of the diesel engine can be secured and a desired acceleration state can be obtained. Moreover, since the correction of the pilot injection amount QP is configured to be executed only when the acceleration of the vehicle is equal to or higher than the reference value, a rapid change in the pilot injection state is prevented and the output of the diesel engine is effectively increased. Can be controlled.

Further, in the above embodiment, it was confirmed that the fuel temperature detecting means 24 for detecting the fuel temperature and the fuel temperature is low according to the output signal of the fuel temperature detecting means 24 during the idle operation of the diesel engine. In this case, the pilot injection amount correcting means 19 for correcting the pilot basic injection amount QPB is changed to the injection state correcting means 1 described above.
Since it is provided in No. 8, it is possible to prevent the fuel injection pressure from becoming high and to effectively stabilize the combustion state during the idle operation of the diesel engine during cold when the fuel viscosity is high.

Further, in the above-described embodiment, when the operating state determining means 25 confirms that the diesel engine is in the idle operating state, the pilot injection state is feedback-controlled, so that the angular velocity fluctuation detecting means 22 is used. According to the detected detected value of the angular velocity fluctuation state of the diesel engine, the pilot interval correction means 20 of the injection state correction means 18 feedback-controls the interval AP between the pilot injection and the main injection to effectively control the angular speed fluctuation. Can be suppressed.

Further, the pilot F / which is set in accordance with the deviation between the engine speed (rotation speed NE) detected by the rotation speed detecting means 21 and the target rotation speed (target rotation speed NA) in the idle operation state. B correction factor Q
Fuel injection amount PQ in pilot injection based on PF
By performing feedback control for correction, the rotational speed of the diesel engine can be effectively matched with a predetermined constant target rotational speed.

Further, in the above embodiment, the required injection amount calculating means 14 for calculating the required injection amount QF of fuel from the map set with the operating state of the diesel engine as a parameter, and the output of the required injection amount calculating means 14 A basic injection amount calculation means 15 for calculating a basic injection amount QPB of fuel in pilot injection according to a signal, and a pilot injection timing in units of crank angle of a diesel engine according to an output signal of the required injection amount calculation means 14. Basic interval calculation means 1 for calculating the basic interval APB with the main injection timing
6 is provided in the injection state control means 9, the basic injection amount QPB of fuel in the pilot injection is calculated based on the calculated value of the required injection amount QF of fuel calculated by the required injection amount calculation means 14. The basic interval calculation means 16 calculates the basic interval APB between the pilot injection timing and the main injection timing in units of crank angle of the diesel engine based on the fuel injection amount QF. The pilot injection state can be appropriately controlled based on the calculated values of QPB and basic interval APB.

In particular, as described above, the pilot injection interval A
When P is configured to be calculated based on the basic interval APB set with the crank angle of the diesel engine as a unit, even if the angular velocity change occurs in the diesel engine, the angular velocity change is handled in correspondence with this angular velocity change. Since the pilot injection interval AP can be set appropriately, there is an advantage that precise pilot injection control can be executed.

Further, in the above embodiment, the main injection timing calculating means 17 for calculating the main injection timing corresponding to the operating state of the diesel engine, and the pilot injection state is corrected according to the output signal of the main injection timing calculating means 17. Since the injection state correcting means 18 is provided, the basic fuel injection amount QPB in the pilot injection obtained by the basic injection amount calculating means 15 and the pilot injection timing and the main injection timing obtained by the basic interval calculating means 15 The basic interval APB can be appropriately corrected based on the calculated value of the main injection timing, and the pilot injection state can be appropriately controlled based on the corrected fuel injection amount and pilot interval.

In the above embodiment, the plunger pump 2 for discharging fuel to the combustion chamber of the engine main body 10 and the control valve 7 are installed in each cylinder of the engine main body 10, respectively. The example to which the present invention is applied has been described above, but the present invention is not limited to this, and is also applicable to a distribution type fuel injection device that discharges fuel to each cylinder by a single fuel pump. Further, in the fuel injection device configured to store the fuel discharged from the fuel pump in the pressure accumulator and inject the fuel derived from the pressure accumulator into the combustion chamber of each cylinder by the injection nozzle, The pilot injection state may be controlled by controlling the opening / closing.

[0093]

As described above, according to the present invention, the angular velocity fluctuation detecting means for detecting the angular velocity fluctuation state of the diesel engine, and the direction for suppressing the angular velocity fluctuation of the diesel engine according to the output signal of the angular velocity fluctuation detecting means. Further, since the injection state correction means for correcting the pilot injection state is provided in the injection state control means, it is determined by the basic injection amount calculation means and the basic interval calculation means according to the correction coefficient set in the injection state correction means. By correcting the basic injection amount in pilot injection and the basic interval between pilot injection and main injection, etc., while effectively preventing the generation of noise and NOx of the diesel engine, it is generated during idle operation of the diesel engine. It is possible to effectively suppress fluctuations in angular velocity and maintain a good driving feeling. Can.

Further, the required injection amount calculating means for calculating the required injection amount of fuel from the map set with the operating state of the diesel engine as a parameter, and the fuel in the pilot injection according to the output signal of the required injection amount calculating means. And a basic injection amount calculation means for calculating the basic injection amount, and a basic calculation for calculating the basic interval between the pilot injection timing and the main injection timing in units of the crank angle of the diesel engine according to the output signal of the required injection amount calculation means. When the interval calculation means is provided in the injection state control means, the basic injection amount of fuel in the pilot injection is set to the basic injection amount based on the calculated value of the required injection amount of fuel calculated by the required injection amount calculation means. A pilot in which the crank angle of the diesel engine is calculated as a unit based on the fuel injection amount calculated by the calculation means. Determined by the basic interval computing means the basic distance between the timing and main injection timing morphism, there is an advantage that the pilot injection state based on the calculated value of the basic injection amount and the basic interval can be precisely controlled.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram showing an overall configuration of a fuel injection device for a diesel engine according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of an injection state control unit.

FIG. 3 is a flowchart showing the first half of the basic control operation by the injection state control means.

FIG. 4 is a flowchart showing the latter half of the basic control operation by the injection state control means.

FIG. 5 is a graph showing an example of the relationship between the main injection timing and the injection timing correction coefficient.

FIG. 6 is a flowchart showing the first half of the operation state determination control operation.

FIG. 7 is a flowchart showing a second half of the operation state determination control operation.

FIG. 8 is a flowchart showing a control operation for feedback determination.

FIG. 9 is a flowchart showing a calculation control operation of a correction coefficient for feedback controlling the pilot injection amount.

FIG. 10 is a time chart showing a control state of engine speed.

FIG. 11 is a flowchart showing a calculation control operation of a correction coefficient for feedback controlling the pilot injection interval.

FIG. 12 is a flowchart showing a calculation control operation of a correction coefficient during acceleration.

FIG. 13 is a flowchart showing a calculation control operation of a fuel temperature correction coefficient.

[Description of Reference Signs] 9 injection state control means 14 required injection amount margin remaining means 15 basic injection amount calculation means 16 basic interval calculation means 17 main injection timing calculation means 18 injection state correction means 19 pilot injection amount correction means 20 pilot interval correction means 21 rotational speed detecting means 22 angular velocity detecting means 23 acceleration detecting means 24 fuel temperature detecting means 25 operating state determining means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 41/40 9523-3G F02D 41/40 F 45/00 330 45/00 330 330 362 362J 362Q

Claims (10)

[Claims] 1. A fuel injection device for a diesel engine, comprising injection state control means for controlling an injection state of fuel so as to pilot-inject a small amount of fuel prior to main injection for injecting combustion into a combustion chamber of the diesel engine. The angular velocity fluctuation detecting means for detecting the angular velocity fluctuation state of the diesel engine, and the injection state correction for correcting the pilot injection state in the direction of suppressing the angular velocity fluctuation of the diesel engine according to the output signal of the angular velocity fluctuation detecting means A fuel injection device for a diesel engine, characterized in that: 2. The diesel engine according to claim 1, wherein the injection state correcting means is provided with pilot interval correcting means for suppressing the angular velocity fluctuation of the diesel engine by correcting the interval between the pilot injection and the main injection. Fuel injector. 3. The pilot interval correction means when it is confirmed that the angular velocity fluctuation state of the diesel engine is larger than a preset reference value in accordance with the output signal of the angular velocity fluctuation detection means during idle operation of the diesel engine. 3. The fuel injection device for a diesel engine according to claim 2, wherein the fuel injection device is configured to correct the distance between the pilot injection and the main injection in a direction to increase the distance. 4. A driving state judging means for judging whether or not the output of the diesel engine is in a high output driving state larger than a preset reference value is provided, and the driving state judging means makes the diesel engine operate in a high output state. The fuel injection device for a diesel engine according to any one of claims 1 to 3, wherein the pilot injection is prohibited when the state is confirmed. 5. A rotation speed detecting means for detecting a rotation speed of the diesel engine, a rotation speed of the diesel engine detected by the rotation speed detecting means during idle operation of the diesel engine, and a target rotation speed in an idle operation state. 7. The injection state correction means is provided with pilot injection amount correction means for correcting the fuel injection amount in the pilot injection in the direction in which the rotation speed of the diesel engine is made to match the target rotation speed in accordance with the deviation of. The fuel injection device for a diesel engine according to any one of 1 to 4. 6. An acceleration detecting means for detecting an acceleration of the vehicle, and a case where it is confirmed that the acceleration of the vehicle is in a high acceleration driving state which is equal to or more than a preset reference value in accordance with an output signal of the acceleration detecting means. Further, the injection state correcting means is provided with a pilot injection amount correcting means for correcting the fuel injection amount in the pilot injection and a pilot interval correcting means for correcting the distance between the pilot injection and the main injection. The fuel injection device for a diesel engine according to any one of claims 1 to 5, wherein 7. Fuel temperature detection means for detecting a fuel temperature, and fuel for pilot injection when it is confirmed that the fuel temperature is low according to an output signal of the fuel temperature detection means during idle operation of a diesel engine. 2. The injection state correcting means is provided with pilot injection amount correcting means for correcting the injection amount so as to reduce the injection amount.
7. The fuel injection device for a diesel engine according to any one of items 1 to 6. 8. Pilot injection is provided when an operating state determining means for determining whether or not the diesel engine is in an idle operating state is provided, and when it is confirmed by the operating state determining means that the diesel engine is in an idle operating state. The fuel injection device for a diesel engine according to claim 1, wherein the fuel injection device is configured to perform feedback control of the state. 9. A fuel injection device for a diesel engine, comprising injection state control means for controlling an injection state of fuel so as to pilot-inject a small amount of fuel prior to main injection for injecting combustion into a combustion chamber of the diesel engine. The required injection amount calculation means for calculating the required injection amount of fuel based on the operating state of the diesel engine and the basic injection amount of fuel in the pilot injection according to the output signal of the required injection amount calculation means. The basic injection amount calculating means and the basic interval calculating means for calculating the basic interval between the pilot injection timing and the main injection timing in units of the crank angle of the diesel engine according to the output signal of the required injection amount calculating means. A fuel injection device for a diesel engine, characterized by being provided in an injection state control means. 10. A main injection timing calculating means for calculating a main injection timing corresponding to an operating state of a diesel engine, and an injection state correcting means for correcting a pilot injection state according to an output signal of the main injection timing calculating means. The fuel injection device for a diesel engine according to claim 9, wherein the fuel injection device is provided in the injection state control means.