JPH10103119A - Control device for diesel engine with exhaust gas recirculating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold good combustibility by suppressing sticking and depositing of carbon in an injection port of a fuel injection nozzle, even in the case of lasting of low load operation of idle operation or the like performing EGR further with a small fuel injection amount. SOLUTION: In a Diesel engine provided with an exhaust gas recirculating device, exhaust gas recirculation control device 51 so as to perform recirculation of exhaust gas at least in an engine low load region and a fuel injection amount control device 52, correction means 53 is provided, which performs up loading increase correction further increasing an increase of fuel injection amount when an external load is operated in the engine low load region by a prescribed amount temporarily more than an amount matched with a target torque increase component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a diesel engine having an exhaust gas recirculation device, which is provided with an exhaust gas recirculation device and operates the exhaust gas recirculation device at least in a low engine load region.

[0002]

2. Description of the Related Art In general, a diesel engine is provided with a fuel injection nozzle provided in a combustion chamber and a fuel injection pump for pumping fuel to the fuel injection nozzle. It is adjusted according to the state.

[0003] Further, as disclosed in Japanese Patent Publication No. 4-59458, for example, an electronically controlled fuel injection pump is provided,
There is also known an apparatus in which a fuel injection amount and an injection timing are controlled by a signal from a control unit.

[0004] As a technique for suppressing the generation of NOx, an exhaust gas recirculation system for recirculating exhaust gas (EGR) from an exhaust passage of an engine to an intake system is widely known.

[0005] In a diesel engine, NOx is easily generated even during low load operation such as idling operation, and at a low load, a relatively large amount of EGR gas is supplied to the combustion chamber because air is excessively supplied. Since the combustion is not hindered by the introduction, the exhaust gas is recirculated at a large EGR rate during idle operation or the like to reduce NOx.

[0006]

However, in the engine with the exhaust gas recirculation device described above, when the fuel injection amount is small and the idling operation in which a relatively large amount of EGR is performed continues for a long time. For example, the adhesion of carbon to the injection port of the fuel injection nozzle becomes a problem.

That is, in a diesel engine, a fuel injection nozzle is provided so as to face a combustion chamber (a pre-combustion chamber, a vortex chamber, etc. in the case of a sub-chamber type), regardless of whether it is a sub-chamber type or a direct injection type. When EGR is performed, carbon in the EGR gas adheres to the injection port of the fuel injection nozzle. Then, when the fuel injection amount is large and the load is high, there is no problem because the carbon attached to the injection port is blown off by the injected fuel,
For example, when the driver is napping in a stopped state and the idling operation state continues for a long time, carbon adheres to the injection port of the fuel injection nozzle by EGR, and the carbon is blown off because the fuel injection amount is small. It accumulates without being clogged and gradually blocks the injection port. This makes it difficult for fuel injection to be performed satisfactorily, making combustion unstable,
There are concerns about rough idols and stalling.

In view of the above circumstances, according to the present invention, even when EGR is performed and low load operation such as idle operation with a small fuel injection amount is continued, carbon adheres to the injection port of the fuel injection nozzle. An object of the present invention is to provide a control device for a diesel engine with an exhaust gas recirculation device, which can maintain good combustibility by suppressing the accumulation.

[0009]

In order to achieve the above object, the present invention provides an exhaust gas recirculation device for recirculating exhaust gas to an intake system of an engine, and an exhaust gas recirculation device for operating the exhaust gas recirculation device at least in a low engine load region. A fuel injection nozzle provided in the combustion chamber, and a fuel for increasing a fuel injection amount to match a target torque increase according to the load when an external load is operated in a low engine load region. In a diesel engine equipped with an exhaust gas recirculation device having an injection amount control means, the increase in the fuel injection amount when the external load is operated in the low engine load region is temporarily increased by a predetermined amount more than the amount corresponding to the target torque increase. A correction means for performing an additional increase correction is provided.

That is, it has been conventionally known to increase the fuel injection amount according to the load in order to compensate for the torque loss caused by the external load when the external load is operated, but the exhaust gas recirculation is performed in a low engine load region. In this case, when the fuel increase is further added to the fuel increase according to the load described above, the injection amount from the fuel injection nozzle increases, and the carbon attached to the injection port is blown off.

The exhaust gas recirculation control means operates the exhaust gas recirculation device during idle operation, and the fuel injection amount control means comprises:
In addition to performing feedback control of the fuel injection amount so that the engine speed becomes the target speed during idle operation,
When the external load is activated, the fuel injection amount is increased by open control.

With this arrangement, when an external load is applied during the idling operation, the feedback control is switched to the open control, and the increase according to the external load and the additional increase are performed. The effect of blowing off the removed carbon is obtained favorably.

The correction means may perform an additional increase correction when an external load is operated after the set time of the operation of the exhaust gas recirculation device during idling operation. In this case, carbon correction to the injection port is performed. Unnecessary increase in the amount of addition is not performed while the amount of the adhesion is small.

The above-mentioned correction means only needs to perform the additional increase correction for a predetermined time from the start of the operation of the external load. In this case, the additional increase is not performed unnecessarily long, and the fuel consumption is improved. It is advantageous for saving.

Further, in the apparatus of the present invention, a throttle type nozzle having a throttle section at a valve lift is provided as a fuel injection nozzle, and the additional increase correction by the correction means is such that the lift amount of the fuel injection nozzle becomes larger than the throttle section. By doing so, even if a throttle type nozzle which easily causes carbon adhesion is used, the carbon adhesion is effectively eliminated.

In addition to the above-described structure, when the operation of the exhaust gas recirculation device in the idle operation state continues for a predetermined allowable limit time or more, the exhaust gas recirculation by the exhaust gas recirculation device is restricted or stopped. By providing the recirculation restricting means, it is possible to more reliably prevent operability deterioration such as engine stall due to accumulation of carbon at the injection port of the fuel injection valve.

Alternatively, an angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of the engine when the exhaust gas recirculation device is operated at a low load is provided, and the angular velocity fluctuation detected by the angular velocity fluctuation detecting means is used as a reference. Even if an exhaust gas recirculation control means is provided to stop the operation of the exhaust gas recirculation device when the value exceeds the value, it is possible to effectively prevent deterioration in operability such as engine stall due to accumulation of carbon in the injection port of the fuel injection valve. Is done.

Alternatively, there is provided an angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of the engine when the exhaust gas recirculation device is operated at a low load, and the angular velocity fluctuation detected by the angular velocity fluctuation detecting means is detected by the angular velocity fluctuation detecting means. The correction means is configured to perform the additional increase correction of the fuel injection amount at the time of the external load operation when the external reference value becomes equal to or more than the first reference value, and the angular velocity fluctuation is equal to or more than the second reference value larger than the first reference value Even if an exhaust gas recirculation restricting means for stopping the operation of the exhaust gas recirculation device is provided, the accumulation of carbon in the injection port of the fuel injection valve and the deterioration in operability such as engine stall due to the exhaust gas recirculation can be effectively prevented. Is prevented.

Further, as another invention, an exhaust gas recirculation device for recirculating exhaust gas to an intake system of an engine, and exhaust gas recirculation control means for operating the exhaust gas recirculation device at least during idling operation are provided, and are provided adjacent to a combustion chamber. In a diesel engine equipped with an exhaust gas recirculation device having a fuel injection nozzle and fuel injection amount control means for controlling the fuel injection amount from the fuel injection nozzle, the fuel is increased so that the fuel injection amount is increased when an external load is operated. In addition to constituting the injection amount control means, when the operation of the exhaust gas recirculation device in the idle operation state continues for a preset allowable limit time or more, the exhaust gas recirculation device restricts the exhaust gas recirculation by the exhaust gas recirculation device, or the exhaust gas recirculation restriction device for stopping It is provided.

According to this configuration, the fuel attached to the injection port of the fuel injection nozzle may be blown off by an increase in the amount of fuel during the operation of the external load, and the operation of the exhaust gas recirculation device in the idle operation state continues for a long time. Occasionally, the restriction or stoppage of the recirculation of the exhaust gas is performed, so that the deterioration of operability such as engine stall is suppressed.

The fuel injection amount control means performs feedback control of the fuel injection amount so that the engine speed becomes the target speed during idling operation, and increases the fuel injection amount by open control when the external load is operated. It should just be.

When a throttle type nozzle having a throttle section at a valve lift is provided as a fuel injection nozzle, the drivability due to carbon adhesion is increased while using a throttle type nozzle which easily causes fuel adhesion when the lift amount of the fuel injection nozzle is small. Is prevented from deteriorating. .

In addition, a turbocharger is provided by connecting a turbine disposed in an exhaust passage with a compressor disposed in an intake passage, and a turbocharger is provided from an exhaust passage upstream of the turbine to an intake passage downstream of the compressor. If the exhaust gas recirculation device is configured to recirculate exhaust gas, a large amount of exhaust gas can be recirculated.

[0024]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an entire diesel engine with an exhaust gas recirculation device. In FIG. 1, reference numeral 1 denotes an engine body of a diesel engine. A fuel injection nozzle 3 is provided in a combustion chamber 2 of the engine. The fuel injection nozzle 3 is connected to an electronically controlled fuel injection pump 4 through a fuel passage 5. It is connected. An intake passage 6 and an exhaust passage 7 are connected to the engine body 1. An intake port downstream of the intake passage 6 and an exhaust port upstream of the exhaust passage 7 open to the combustion chamber 2, and an intake valve 8 and an exhaust valve 9 are provided. It is opened and closed by.

Reference numeral 11 denotes a turbocharger, which includes a turbine 12 disposed in the exhaust passage 7 and a compressor 13 disposed in the intake passage 8 and connected to the turbine 12. It is driven by energy to supercharge the intake air. In order to adjust the maximum supercharging pressure, a wastegate passage 14 bypassing the turbine 12 is provided to the turbocharger 11.
And a waste gate valve 15 that opens and closes this passage according to the supercharging pressure or the like.

In the intake passage 6, an air cleaner 16, the compressor 13, an intercooler 17 for cooling the supercharged air, and a shutter valve 18 are arranged in this order from the upstream side.
Is provided. The shutter valve 18 is operated by a negative pressure supplied from a vacuum pump 19 via a solenoid valve 20 and is opened during operation of the engine, and closed when the engine is stopped, thereby performing a shock prevention and fail-safe function. ing.

On the other hand, the turbine 12
A catalyst device 21 for purifying exhaust gas is provided downstream of.

The engine is provided with an exhaust gas recirculation device 25 for recirculating exhaust gas to an intake system. The exhaust gas recirculation device 25 includes an EGR passage 26 that connects the exhaust passage 7 and the intake passage 6, and an EGR valve 27 that opens and closes the EGR passage 26. EGR passage 26
Is that the EGR gas inflow side end 26a is
The EGR gas outlet side end 26 b is connected to the exhaust passage 7 upstream of the compressor 2 and the intake passage 6 downstream of the compressor 13.

The EGR valve 27 is connected to the EGR passage 26
It has a valve body 27a provided therein and a negative pressure responsive actuator 27b for operating the valve body 27a. The actuator 27b is connected to the vacuum pump 19 via an EGR solenoid valve 28.

Reference numeral 30 denotes an ECU (engine control unit), which comprises a microcomputer or the like. The ECU 30 includes a rotational speed sensor 31 for detecting the engine rotational speed, an accelerator sensor 32 for detecting the accelerator opening (the amount of depression of the accelerator pedal), and an idle for detecting an accelerator fully closed state (a state where the accelerator pedal is not depressed). Signals from a switch 33, a water temperature sensor 34 for detecting an engine cooling water temperature, an air conditioner switch 35 for detecting the operation of an air conditioner as an example of an external load, and the like are input. The ECU 30 controls the spill valve 46 and the timer control valve 47 provided in the fuel injection pump 4 to control the fuel injection amount and the fuel injection timing, and also controls the EGR solenoid valve 28. As a result, the EGR valve 27 is controlled.

The fuel injection pump 4 has a structure as shown in FIG. 2, for example. That is, the fuel injection pump 4 includes a drive shaft 41 driven by the engine, and a pump plunger 4 that operates with the rotation of the drive shaft 41 to feed fuel to the fuel injection nozzle 3.
2, a feed pump 45 that draws fuel from the fuel tank 43 through the filter 44, a spill valve 46 that controls the fuel injection amount by adjusting the amount of fuel released from the spill port, and a timer that controls the fuel injection timing. A control valve 47 and a rotation speed sensor 31 are provided. The above spill valve 4
6 and the timer control valve 47 can be electronically controlled.

The fuel injection nozzle 3 is, for example, a throttle type nozzle, and is configured to inject and supply fuel into a sub chamber 2b connected to the main combustion chamber 2a as shown in FIG. As shown in FIG. 4, the fuel injection nozzle 3 composed of the throttle type nozzle has a fixed section (a so-called throttle section) in which the opening area between the needle valve 3a and the peripheral wall 3b is small during the valve lift. In terms of valve opening characteristics, as shown in FIG. 5, the opening amount and its change are small up to a predetermined lift amount L1, and the opening amount sharply increases when exceeding the predetermined lift amount L1. The reason for this is to enhance controllability in a region where the fuel injection amount is small.

FIG. 6 shows the configuration of the control system. In this figure, the ECU 30 includes an exhaust gas recirculation control unit 51, a fuel injection amount control unit 52, a correction unit 53, and an exhaust gas recirculation control unit 54.

The exhaust gas recirculation control means 51 opens the EGR valve 27 at least in the low engine load region to perform the EGR. For example, as shown in FIG. The EGR solenoid valve 28 is controlled so that EGR is performed in a load region (including an idle operation region). When the engine is cold with a low coolant temperature, the EGR is stopped to ensure combustion stability.

The fuel injection amount control means 52 controls the fuel injection amount basically by controlling the spill valve 46 in accordance with the operating state such as the engine load and the number of revolutions. In particular, in the idle operation range, the engine speed detected by the speed sensor 31 is compared with the target idle speed, and the fuel injection amount is feedback-controlled so as to reach the target idle speed. However, when the air conditioner switch 35 is ON, that is, when the air conditioner, which is an external load, is operating, an increase corresponding to the target torque increase with respect to the basic injection amount is performed by the open control. In FIG. 7, the area below the line NS is an area where the amount of fuel injection is small (nozzle throttle area) such that the lift amount of the fuel injection nozzle 3 is within the throttle section.

The correction means 53 performs an additional increase correction in which the increase in the fuel injection amount during the external load operation in the low engine load region is temporarily increased by a predetermined amount more than the amount corresponding to the target torque increase. Specifically, when the air conditioner switch 35 is turned on during the idling operation and the open control is switched to increase the amount according to the external load, when the air conditioner switch is turned on (the operation of the external load is started) The additional increase correction is performed only for a predetermined time from (time point).

When the operation of the exhaust gas recirculation device 25 in the idle operation state continues for a predetermined allowable limit time (for example, about one hour) or more, the exhaust gas recirculation device 25 recirculates the exhaust gas. Is limited (reduced EGR amount) or stopped.

The fuel injection amount control means 52 and the correction means 5
3 and the control by the exhaust gas recirculation restricting means 54 will be described with reference to the flowcharts of FIGS. The basic EGR control by the exhaust gas recirculation control means 51 is performed in another routine, and is not shown.

In FIG. 8, when the process of this flowchart is started, first, in step S1, various sensor output values such as an engine speed Ne, an accelerator opening AO, a coolant temperature TW, an air conditioner switch signal, and an idle switch signal are read. Next, in step S2, it is determined whether or not the engine is warmed up based on whether or not the cooling water temperature TH is equal to or higher than a predetermined temperature THO.

When the engine is in the cold state (NO in step S2), EGR is not performed, and it is not necessary to increase the injection amount to prevent carbon from adhering to the injection port of the fuel injection nozzle. Then, the correction coefficient B for the additional increase correction is set to "0" (step S3), and the flag F is set to "1" (step S4). And
The process proceeds to Step S12 described below.

When the engine is in the warm-up state (the determination in step S2 is YES), it is determined in step S5 whether the operation state determined by the engine speed Ne and the accelerator opening AO is in the EGR ON region shown in FIG. Judge
If it is not in the EGR ON area, the routine returns as it is.

If it is in the EGR ON area, step S6
To set the flag F to "2", and furthermore, to step S7
It is determined whether the operation state is in the nozzle throttle region in FIG. If it is not in the nozzle throttle region, the value of the timer Ti for checking the permissible limit time required for the processing of the exhaust gas recirculation restricting means 54 is reset to "0" (step S8), and the process returns.

If it is in the nozzle throttle area, it is determined in step S9 whether or not the timer Ti is counting. If the determination is NO (immediately after the nozzle throttle area is reached), the timer Ti starts counting (step S9). S1
5).

In step S11 following step S9 or step S10, it is determined whether or not the value of the timer Ti is equal to or longer than a predetermined allowable limit time TiO. If the timer Ti is less than the allowable limit time TiO, the process proceeds to step S12.

In step S12, the idle switch 3
It is determined whether or not the operating state is in the idle region by setting an area where the engine speed 3 is ON and the engine rotational speed is equal to or lower than the predetermined idle determination rotational speed as an idle region. If it is in the idle region, subsequently, in step S13, it is determined whether or not the air conditioner switch 35 has been switched from off to on.

When the air conditioner switch 35 is switched from off to on while in the idle range, it is further determined in step S14 whether or not the EGR is being performed by checking whether or not the flag is "2". If the determination is YES, the additional increase correction coefficient B is set to B = 0.1 (step S15), and the count of the timer Tj for measuring the time of the additional increase correction is started (step S16). ) And the timer T
The value of i is reset to "0" (step S17). Then, control goes to a step S18.

In step S18, the fuel injection amount Qy is calculated. In this case, the correction coefficient A that matches the basic injection amount Qi and the target torque increase according to the load of the air conditioner.
The fuel injection amount Qy is determined by adding the increase (Qi · A) due to the above and the increase (Qi · B) due to the additional increase correction coefficient B.

If it is determined at step S13 that the air conditioner switch 35 has not been switched from OFF to ON, then at step S19 the air conditioner switch 35 is turned off.
Is turned on. If the air conditioner switch 35 is not on, normal ISC control is performed in step S20, that is, feedback control of the fuel injection amount is performed so that the engine speed becomes the target idle speed.

If the determination in step S19 is YES, it means that the air conditioner switch 35 is kept on. In this case, it is checked in step S21 whether or not the timer Tj is counting. If there is, in step S22, it is checked whether or not the timer Tj has reached a predetermined time TjO. If the timer Tj has not reached the predetermined time TjO, the state set in steps S15 to S17 is continued, and the process proceeds to step S18 to increase the amount (Qi · A) according to the load of the air conditioner. The fuel injection amount Qy is calculated in consideration of the increase (Qi · B).

At step S22, the timer Tj is set to the predetermined time T.
When it is determined that the value has reached jO, the value of the timer Tj is reset to “0”. In this case, or when the determination in step S21 is NO, the additional coefficient is stopped by setting the correction coefficient B to “0” in step S24 and then proceeding to step S18.

When it is determined in step S11 that the value of the timer Ti has become equal to or longer than a predetermined allowable limit time TiO, the EGR is stopped in step S25.

FIG. 10 is a timing chart showing the above control.

That is, when in the idle area, E
Since the engine is in the GR-on range, the EGR valve 27 is opened and the exhaust gas is recirculated as long as the engine is warmed up. In particular, in a diesel engine equipped with a turbocharger 11, the exhaust pressure in the exhaust passage 7 upstream of the turbine 12 increases due to the flow resistance in the turbine 12, while the exhaust pressure in the downstream intake passage 6 increases due to the flow resistance in the compressor 13. Is low at low load, and the EGR
If the passage 26 is connected, a large amount of EGR is possible, and the exhaust gas is recirculated at an EGR rate of, for example, 30% or more.

When the air conditioner is in the idle range and the air conditioner is not operating, the fuel injection amount is controlled by feedback control so as to reach the target idle speed, but the fuel injection amount for maintaining the target idle speed is controlled. When the fuel injection nozzle 3 is a throttle type nozzle, the lift amount is within the throttle section.

In a state where a large amount of EGR is performed and the fuel injection amount is small, carbon in the EGR gas easily adheres to the injection port of the fuel injection nozzle 3. In addition, although the fuel injection amount is small in the nozzle throttle region other than the idle region, the nozzle throttle region other than the idle region is in the deceleration region on the lower load side than the fixed running line,
It does not matter much because it only passes temporarily when decelerating. On the other hand, when the vehicle is napping while stopped, the idle state may continue for a long time. In such a case, carbon adhesion is a problem.

However, when the air conditioner is operated and the air conditioner switch 35 is turned on, the basic injection amount Qi is increased (Qi · A) according to the load of the air conditioner by open control.
Is added, and an additional increase (Qi · B) is also added for a predetermined time (until Tj ≧ TjO) from the air-conditioner operation start time t ₀ . As a result, the fuel injection amount of the fuel injection nozzle 3 is increased, the carbon attached to the injection port is blown off, and the accumulation of carbon is prevented. For this reason, rough idle and engine stall due to the accumulation of carbon in the injection port are prevented.

In this case, since the increase according to the load during the operation of the air conditioner is generally performed, the additional increase is performed in addition to the above. There is no.

In this increase correction, if the lift amount of the fuel injection nozzle 3 exceeds the throttle section, a sufficient fuel injection amount to blow off carbon can be obtained.

If the operation in the nozzle throttle region such as the idle region lasts for a long time and the air conditioner is not operated during that time, as shown by the two-dot chain line in FIG. EGR is stopped when (Ti ≧ TiO). This stops the accumulation of carbon on the injection port before the engine stalls. However, if the driving state is out of the nozzle throttle area due to the vehicle starting or running within the allowable limit time, or if the air conditioner is activated, the increase in fuel injection amount will eliminate carbon adhesion, Since the timer Ti is reset, the EGR is rarely actually stopped.

The specific example of the control by the control device of the present invention is not limited to the above embodiment, but can be variously changed, and several examples thereof will be described with reference to FIGS.

In the example shown in the flowchart of FIG. 11, steps S1 to S10 are almost the same as the example of FIG. 8 (however, step S6 is eliminated).
Subsequent to the determination of 10 or NO in step S9, in step S31, the value of the timer Ti is set to a predetermined reference time TiO ′.
It is determined whether or not the above has been achieved. Here, the reference time Ti
O ′ is shorter than the allowable limit time TiO, for example, about 30 minutes. If this determination is YES, the flag F is set to "2" in step S32, and then the process proceeds to step S11. Also, the determination in step S31 is N
In the case of O, the process proceeds to step S12. The processing after step S11 is the same as in the examples of FIGS.

According to this example, only when a certain reference time TiO ′ has elapsed since the nozzle throttle area was entered, the air conditioner is temporarily increased when the air conditioner is operated in the idle area. Since the additional increase is not performed before the time TiO ′ elapses, the additional increase is not performed as long as the amount of carbon deposited on the injection port of the fuel injection nozzle 3 is small, which is advantageous in reducing fuel consumption.

In the example shown in the flowchart of FIG. 12, steps S1 to S7 are the same as the example of FIG. 8, and if the determination in step S7 is NO, the process returns. If the determination in step S7 is YES, it is further determined in step S41 whether or not the engine is in an idle range. If the determination is in the idle range, the angular velocity (ω) and the angular speed variation (dω) of the engine are calculated (steps S42 and S42).
43).

Subsequently, at step S44, the angular velocity variation (d
ω) is larger than the reference value (dωO).
If this determination is NO, step S
13, but if this determination is YES, the process proceeds to step S
With the EGR stopped at 45, the process moves to step S13. The processing after step S13 is substantially the same as the example of FIG. However, step S17 is eliminated.

According to the present embodiment, the EGR is stopped when the allowable limit time has elapsed in the examples of FIGS. 7 and 8. Is stopped, but also in this case, the accumulation of carbon in the injection port is stopped before the engine stalls. In this case, in the processing of step S13 and subsequent steps, the processing of adding the additional amount for a predetermined time (steps S15, S16, steps S21 to S2)
3) may be eliminated, and only the increase according to the load may be performed at the time of operating the air conditioner.

The example shown in the flowchart of FIG.
2 corresponds to a modified example of the one shown in FIG.
If the determination at 44 is NO, it is further determined at step S46 whether or not the angular velocity variation (dω) is greater than a second reference value (dωL). Here, the second reference value (dωL) is a value smaller than the reference value (dωO).

If the determination in step S46 is NO, the flag F is set to "1" (step S47), and step S4 is performed.
If the determination of No. 6 is NO, the flag F is set to "2" (step S48). Then, the process proceeds to step S13. The other processing is substantially the same as that shown in FIG. 12 (however, step S6 is eliminated), so that illustration and description are omitted.

According to this example, when the angular velocity fluctuation becomes large to some extent, the additional increase correction is performed when the air conditioner is operated, which is advantageous for reducing fuel consumption.

Although the air conditioner is shown as an external load in the above embodiment, the same control may be performed when other external loads are operated.

In the above embodiment, the throttle type nozzle is used as the fuel injection nozzle. However, the present invention can be applied to other types of nozzles such as a hole nozzle used in a direct injection engine. Can be.

[0071]

According to the present invention, in a diesel engine in which exhaust gas is recirculated in a low engine load region, an increase in fuel injection amount when an external load is operated in a low engine load region is provided.
Since the additional increase correction that temporarily increases the predetermined amount more than the amount corresponding to the target torque increase is performed,
In addition to compensating for the torque loss caused by the external load operation, the carbon adhering to the injection port can be blown off by increasing the fuel injection amount more than that. Therefore, rough idle due to carbon deposition on the injection port,
Deterioration of drivability such as engine stall can be prevented. In addition, when the amount of load is increased according to the load during the operation of the external load, the additional correction is performed, so that the driver does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an engine with an exhaust gas recirculation device to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a specific structure of an electronically controlled fuel injection pump.

FIG. 3 is a sectional view of a portion where a fuel injection nozzle is provided.

FIG. 4 is an enlarged sectional view of a distal end portion of a throttle nozzle.

FIG. 5 is a characteristic diagram of a throttle type nozzle.

FIG. 6 is a block diagram of a control system.

FIG. 7 is a diagram showing an EGR region and the like.

FIG. 8 is a flowchart illustrating an example of control.

FIG. 9 is a flowchart following the flowchart of FIG. 8;

FIG. 10 is a time chart showing changes in various signals due to control.

FIG. 11 is a flowchart showing another embodiment.

FIG. 12 is a flowchart showing still another embodiment.

FIG. 13 is a flowchart showing a modified example of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Combustion chamber 3 Fuel injection nozzle 4 Fuel injection pump 6 Intake passage 7 Exhaust passage 11 Turbocharger 25 Exhaust recirculation device 27 EGR valve 30 ECU 31 Exhaust recirculation control means 32 Fuel injection quantity control means 33 Correction means 34 Exhaust Reflux control means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/16 F02D 41/16 G 45/00 362 45/00 362J F02M 25/07 570 F02M 25/07 570J 570G 570P 61/10 61/10 D

Claims (12)

[Claims] An exhaust gas recirculation device for recirculating exhaust gas to an intake system of an engine, and an exhaust gas recirculation control means for operating the exhaust gas recirculation device at least in a low engine load region, and a fuel injection nozzle provided in a combustion chamber. And an exhaust recirculation device-equipped diesel engine comprising: a fuel injection amount control means for increasing a fuel injection amount to match a target torque increase according to the load when an external load is operated in an engine low load region. Correction means for performing an additional increase correction for temporarily increasing the increase in the fuel injection amount at the time of external load operation in the low engine load region by a predetermined amount more than the amount corresponding to the target torque increase is provided. Control device for diesel engine with exhaust gas recirculation device 2. The exhaust gas recirculation control means operates the exhaust gas recirculation device during idling operation, and the fuel injection amount control means performs feedback control of the fuel injection amount such that the engine speed becomes the target rotation speed during idling operation. 2. The control device for a diesel engine with an exhaust gas recirculation device according to claim 1, wherein the fuel injection amount is increased by open control when the external load is operated. 3. The exhaust gas recirculation according to claim 2, wherein the correction means performs the additional increase correction when the operation of the exhaust gas recirculation device at the time of the idling operation is performed after the set time has elapsed and the external load is operated. Control device for engine with equipment. 4. The diesel engine with an exhaust gas recirculation device according to claim 1, wherein the correction means performs the additional increase correction for a predetermined time from the start of the operation of the external load. Engine control device. 5. A throttle type nozzle having a throttle section at a valve lift as a fuel injection nozzle, and the additional increase correction by the correction means is performed so that the lift amount of the fuel injection nozzle becomes larger than the throttle section. The control device for a diesel engine with an exhaust gas recirculation device according to any one of claims 1 to 4. 6. When the operation of the exhaust gas recirculation device in the idling operation state continues for a predetermined allowable limit time or more,
The control device for a diesel engine with an exhaust gas recirculation device according to any one of claims 1 to 5, further comprising exhaust gas recirculation control means for restricting or stopping the recirculation of exhaust gas by the exhaust gas recirculation device. 7. An engine according to claim 1, further comprising an angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of the engine when the exhaust gas recirculation device is operated at a low load, and wherein the angular velocity fluctuation detected by the angular velocity fluctuation detecting means is used as a reference. The control device for a diesel engine with an exhaust gas recirculation device according to any one of claims 1 to 5, further comprising exhaust gas recirculation control means for stopping the operation of the exhaust gas recirculation device when the value becomes equal to or more than the value. 8. An angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of the engine when the exhaust gas recirculation device is operated at a low load, wherein the angular velocity fluctuation detected by the angular velocity fluctuation detecting means is a first angular velocity fluctuation. The correction means is configured to perform the additional increase correction of the fuel injection amount at the time of the external load operation when the reference value is equal to or more than the second reference value, and the angular velocity variation is equal to or more than the second reference value larger than the first reference value. The control device for a diesel engine with an exhaust gas recirculation device according to any one of claims 1 to 5, further comprising an exhaust gas recirculation restricting means for stopping the operation of the exhaust gas recirculation device when the exhaust gas recirculation device is turned on. 9. An exhaust gas recirculation device for recirculating exhaust gas to an intake system of an engine, and an exhaust gas recirculation control means for operating the exhaust gas recirculation device at least during idling operation, and a fuel injection nozzle provided to face a combustion chamber; In a diesel engine with an exhaust gas recirculation device having a fuel injection amount control means for controlling the fuel injection amount from the fuel injection nozzle, the fuel injection amount control means is configured to increase the fuel injection amount when an external load is operated. And an exhaust gas recirculation restricting means for restricting or stopping the recirculation of the exhaust gas by the exhaust gas recirculation device when the operation of the exhaust gas recirculation device in the idle operation state continues for a preset allowable limit time or more. Control device for diesel engine with exhaust recirculation system 10. The fuel injection amount control means performs feedback control of the fuel injection amount so that the engine speed becomes the target speed during idling operation, and increases the fuel injection amount by open control when the external load is activated. The control device for a diesel engine with an exhaust gas recirculation device according to claim 9, wherein the control is performed. 11. The control device for a diesel engine with an exhaust gas recirculation device according to claim 9, wherein a throttle type nozzle having a throttle section at a valve lift is provided as a fuel injection nozzle. 12. A turbocharger comprising a turbine arranged in an exhaust passage and a compressor arranged in an intake passage, and a turbocharger connected from an exhaust passage upstream of the turbine to an intake passage downstream of the compressor. The control device for a diesel engine with an exhaust gas recirculation device according to any one of claims 1 to 11, wherein the exhaust gas recirculation device is configured to recirculate exhaust gas.