JP2001241345A - Fuel control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a fuel injection amount by an injector 5 to increase when a direct injecting diesel engine 1 becomes an accelerating operation state, and to make improving acceleration performance and reducing combustion noise and emission compatible at a high level when conducting auxiliary injection by the injector 5 in advance of main injection at least in an early accelerating operation stage. SOLUTION: When the engine 1 becomes an accelerating operation state (SA4), the auxiliary injection amount and the main injection amount of fuel by the injector 5 are respectively corrected to increase (SA7), and the engine 1 is estimated whether shifting to a set operating area in a high load side or not (SA8). When the engine 1 is estimated to shift to the set operating area, increasing correction of the auxiliary injection amount is limited so as to decrease an auxiliary injection ratio R which is a ratio of the auxiliary injection mount of fuel to the main injection amount (SA9, SA10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control apparatus for a direct injection diesel engine in which fuel is directly supplied to a combustion chamber in a cylinder of an engine by a fuel injection valve. It belongs to the technical field of auxiliary injection control.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection control device for this type of engine, for example, in a diesel engine equipped with a turbocharger as disclosed in Japanese Patent Application Laid-Open No. 9-228880, the fuel injection control device is used in the early stage of acceleration operation. There is a known configuration in which a pilot injection (sub-injection) is performed prior to a main injection until a supercharging pressure of intake air by a turbocharger rises. In this device, a sensor for detecting the amount of intake air to a combustion chamber in a cylinder of an engine is provided, and based on an output signal from the sensor, the smaller the amount of intake air, the more the fuel injection amount by pilot injection is increased. By raising the in-cylinder temperature when performing main injection by combustion of
Even in the low supercharging pressure state, the ignition delay time of the main injected fuel is shortened so that the combustion noise is appropriately reduced.

[0003] Such an effect of improving the ignitability by the pilot injection can be similarly obtained even in the case where the turbocharger is not provided. Generally, the temperature state of the combustion chamber is relatively low at the beginning of the acceleration operation. Nevertheless, since the fuel injection amount is increased in accordance with the increase in the required output, the pilot output is performed at this time to greatly improve the ignitability of the fuel spray of the main injection, thereby reducing the engine output. While raising
Combustion noise can be reduced and emissions can be reduced.

[0004]

In recent years, a fuel injection device employing a common rail system or the like has been put to practical use in a diesel engine, and the injection pressure of fuel (light oil) into a combustion chamber in a cylinder has been increased as compared with the conventional case. The ignition delay period tends to be significantly shorter because the atomization characteristics of the fuel mist are significantly improved.

[0005] If the pilot injection is performed corresponding to the acceleration operation of the engine as described above under the condition of such ultra-high pressure fuel injection, as described above, the output is improved, the combustion noise and the emission are reduced at the beginning of the acceleration operation. However, if the temperature of the combustion chamber rises late in the acceleration operation, the combustion of the fuel injected by the pilot becomes excessively violent, resulting in increased combustion noise and increased emissions. Sometimes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a direct injection type diesel engine which performs sub-injection of fuel in response to acceleration operation. By devising control of the injection amount, it is possible to achieve both higher acceleration performance and lower combustion noise and emission at a high level.

[0007]

In order to achieve the above object, according to a first solution of the present invention, when the engine is in an acceleration operation state, the acceleration operation causes the engine to operate in a predetermined high load operation state. , And when it is predicted that the vehicle will be in a high-load operation state, the increase in the sub-injection amount of the fuel is limited.

More specifically, as shown in FIG. 1A, a fuel injection valve 5 for directly injecting fuel into a combustion chamber 4 in a cylinder 2 of an engine 1 and an engine 1 comprising: A fuel increase correction means 40b for increasing and correcting the fuel injection amount by the fuel injection valve 5 when the vehicle is in an acceleration operation state; and a main injection of fuel by the fuel injection valve 5 and It is assumed that the fuel control device A of the diesel engine includes the fuel injection control means 40a for performing the preceding sub-injection. Then, when the engine 1 enters an acceleration operation state, a prediction unit 40 for predicting whether or not the engine 1 shifts to a set operation region on the high load side.
c, the sub-injection ratio R, which is the ratio of the sub-injection amount of the fuel to the main injection amount, is smaller than when the engine 1 is predicted to shift to the set operation region by the prediction means 40c. And an increase regulating means 40d for limiting the increase of the sub-injection amount.

With the above configuration, at least the engine 1
Is in the acceleration operation state, the fuel injection control means 4
By controlling the operation of the fuel injection valve 5 according to 0a, the main injection of fuel and the sub-injection preceding it are performed. That is, the sub-injected fuel is mixed with air and burns (premixed combustion). When the temperature and pressure of the combustion chamber 4 are increased by this combustion, the main injection is performed by the fuel injection valve 5. Therefore, the main injected fuel has an extremely short ignition delay time, so that the fuel is favorably diffused and burned. By increasing the sub-injection amount and the main injection amount of the fuel by the fuel increase correction means 40b, the engine output is improved, and the temperature and pressure state of the combustion chamber 4 can be controlled by the increase in the sub-injection amount. As soon as possible, even if the fuel injection amount is increased,
Combustion noise and emissions are reduced.

Further, when the predicting means 40c predicts that the engine 1 will shift to the set operation region on the high load side, the increase correction means 40d limits the increase correction of the sub-injection amount. Even if the engine 1 shifts to the set operation range in the latter half of the period and the combustion chamber 4 becomes overheated, the combustion of the sub-injected fuel is prevented from becoming excessively violent, and therefore, an increase in combustion noise and emission is suppressed. Can be avoided.

According to the second aspect of the present invention, the increase control means prohibits the increase in the sub-injection amount by the fuel increase correction means. By doing so, the sub-injection amount of the fuel by the fuel injection valve becomes the same as in the steady operation state even in the accelerated operation state of the engine, and it is possible to reliably prevent the combustion of the sub-injected fuel from becoming excessively violent.

According to the third aspect of the present invention, the increase control means decreases the increase correction amount of the sub-injection amount by the fuel increase correction means by a predetermined amount. By doing so, it is possible to increase the temperature and the pressure state of the combustion chamber 4 at the early stage of the acceleration operation of the engine, and to suppress excessively intense combustion of the fuel injected by the fuel injection valve by the fuel injection valve at the latter stage of the acceleration operation.

Next, according to a second solution of the present invention, when the engine is in an accelerating operation state and thereafter actually shifts to the set operation region on the high load side, the fuel sub-fuel ratio is compared with that before the shift. The increase in the injection amount is limited.

Specifically, as shown in FIG. 1 (b), a fuel injection valve 5 for directly injecting and supplying fuel to a combustion chamber 4 in a cylinder 2 of an engine 1, A fuel increase correction means 40b for increasing and correcting the fuel injection amount by the fuel injection valve 5 when the vehicle is in an acceleration operation state; and a main injection of fuel by the fuel injection valve 5 and It is assumed that the fuel control device A of the diesel engine includes the fuel injection control means 40a for performing the preceding sub-injection. A determining means 40e for determining that the engine 1 has shifted to the set operating area on the high load side; and when the determining means 40e determines that the engine 1 has shifted to the set operating area, the fuel Sub injection ratio R, which is the ratio of the sub injection amount to the main injection amount
And an increase regulation means 40d for limiting the increase correction of the sub-injection amount so as to reduce the amount. Note that the determination unit 40e may determine that the engine 1 has shifted to the set operation range based on, for example, the load state of the engine 1 or the engine speed.

With the above configuration, when the engine 1 is in the acceleration operation state, the sub injection and the main injection of the fuel are performed by the fuel injection valve 5 as in the first aspect of the present invention, and the injected fuel is discharged. Good diffusion combustion occurs after a very short ignition delay. Further, by increasing the sub injection amount and the main injection amount of the fuel by the fuel increase correction means 40b, the engine output is improved. Further, the temperature and pressure of the combustion chamber 4 rise as quickly as possible due to the increase of the sub-injection amount of the fuel, and the combustion noise and the emission are reduced. On the other hand, when the engine 1 shifts to the set operation region on the high load side in the latter half of the acceleration operation, this is determined by the determination means 40e, and the fuel injection amount is increased so that the sub-injection ratio R of the fuel becomes smaller than before the determination. Regulating means 40d
Thus, the correction for increasing the sub-injection amount is limited. This allows
Even if the combustion chamber 4 of the engine 1 becomes overheated, the combustion of the sub-injected fuel is prevented from becoming excessively intense, and the increase in combustion noise and emission can be avoided.

That is, in the initial stage of the acceleration operation of the engine 1, the sub-injection amount of the fuel is sufficiently increased, and the combustion noise and the emission can be reduced by increasing the combustibility of the main injected fuel, while the combustion chamber 4 is overheated. In the late stage of the acceleration operation, which is rather unpleasant, combustion noise and emissions can be reduced by limiting the increase in the sub-injection amount.

According to a fifth aspect of the present invention, when the determination means determines that the engine has shifted to the set operating range, the fuel increase correction means forcibly increases the increase in the sub-injection amount. It shall be set to zero.
By doing so, in the latter half of the accelerated operation of the engine, the amount of sub-injection of fuel by the fuel injection valve becomes the same as in the steady operation state, thereby ensuring that the combustion of the sub-injected fuel becomes excessively intense. Can be avoided.

Next, according to a third solution of the present invention, when the engine is in an accelerating operation state, the ratio of the sub-injection amount of the fuel by the fuel injection valve to the main injection amount (sub-injection ratio) is determined by the load of the engine. As the condition increased, it was reduced.

Specifically, the invention according to claim 6 is a fuel injection valve for directly injecting fuel into a combustion chamber in a cylinder of an engine, and the fuel injection by the fuel injection valve when the engine is in an accelerating operation state. A fuel for a diesel engine comprising: a fuel increase correction means for increasing the amount of fuel; and a fuel injection control means for performing a main injection of fuel and a sub-injection preceding the fuel injection valve at least in an initial stage of the acceleration operation of the engine. Assuming a control device, in this device, when the engine is in an accelerating operation state, the fuel increase correction means adjusts the sub injection ratio, which is the ratio of the sub injection amount of the fuel to the main injection amount, to increase the load state of the engine. The increase correction amounts of the sub-injection amount and the main injection amount are changed so as to decrease accordingly.

With this configuration, the fuel injection valve performs the sub-injection and the main injection of the fuel while the engine is in the accelerating operation state, as in the first or fourth aspect of the invention.
The sub-injection amount and the main injection amount are each increased by the fuel increase correction means, so that the engine output is improved and the combustion noise and the emission are reduced. Then, when the engine shifts from the low load side to the high load side due to acceleration operation,
By the fuel increase correction means, the increase correction amount of the fuel sub-injection amount and the main injection amount is appropriately changed such that the sub-injection ratio gradually decreases in accordance with an increase in the load state of the engine.
Thus, the fuel sub-injection amount is sufficiently increased in the initial stage of the engine acceleration operation, and thereafter, the sub-injection ratio is optimized according to the change in the engine operation state. Accordingly, the improvement of the engine output during the acceleration operation and the reduction of the combustion noise and the emission can be achieved at an extremely high level.

According to the invention of claim 7, according to claim 1, 4, or 6
The fuel increase correction means in any one of the above-described embodiments is characterized in that, when the engine is in the accelerated operation state in the low load operation state, at least the sub injection in the initial stage of the acceleration operation is compared with when the engine is in the acceleration operation state in the medium load operation state. To increase the percentage,
It is assumed that the sub-injection and main injection amounts of the fuel are respectively increased.

As a result, the lower the load condition and the lower the temperature condition of the combustion chamber when the engine is in the accelerated operation state, the greater the fuel sub-injection amount, and the combustion of the combustion chamber by the combustion of the sub-injection fuel. Is quickly raised. Thus, even if the fuel injection amount by the fuel injection valve is considerably increased in response to the acceleration operation, the large amount of fuel can be satisfactorily burned.

[0023]

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

(Embodiment 1) FIG. 2 shows Embodiment 1 of the present invention.
1 shows an in-line four-cylinder diesel engine mounted on a vehicle. This engine 1 has four cylinders 2, 2, 2, 2
A piston (not shown) is fitted in each cylinder 2 so as to be able to reciprocate, and a combustion chamber 4 is defined in each cylinder 2 by the piston. At the approximate center of the upper surface of each of the combustion chambers 4, an injector (fuel injection valve) 5 is arranged to extend along the center line of the cylinder 2, which is shown in an exaggerated manner in the figure. An injection nozzle is provided integrally at the tip of the nozzle 5. Each of these injectors 5, 5,... Is connected to a common common rail 6 for storing fuel in a high pressure state equal to or higher than its injection pressure by branch pipes 6a, 6a,. By being opened and closed, the high-pressure fuel supplied from the common rail 6 is
Injection is directly supplied to the combustion chamber 4 from a plurality of injection holes at the tip of the injection nozzle. The common rail 6 is provided with a fuel pressure sensor 6b for detecting an internal fuel pressure (common rail pressure).

The common rail 6 is connected to a fuel supply pump 8 via a high-pressure fuel supply pipe 7, and the fuel supply pump 8 is connected to a fuel tank 10 via a fuel supply pipe 9. The fuel supply pump 8 is driven by receiving a rotation input from a crankshaft of the engine 1 to an input shaft 8a, and draws up fuel while filtering the fuel in a fuel tank 10 through a fuel supply pipe 9 by a fuel filter 11. The fuel is pumped to the common rail 6 by a jerk type pumping system. Further, a part of the fuel delivered by the pumping system to the fuel supply pump 8 is released to the fuel return pipe 12,
An electromagnetic valve for adjusting the discharge amount of the pump is provided, and the opening degree of the electromagnetic valve is controlled in accordance with the value detected by the fuel pressure sensor 6b, so that the pressure state of the fuel in the common rail 6 is controlled by the engine 1. Is maintained in a predetermined state corresponding to the operating state of

Reference numeral 13 in the figure denotes a pressure limiter for discharging fuel from the common rail 6 when the common rail pressure becomes equal to or higher than a predetermined value. The fuel discharged from the pressure limiter passes through a fuel return pipe 14. It circulates and is returned to the fuel tank 10. Reference numeral 15 denotes a fuel return pipe for returning a part of the fuel from the injector 5 to the fuel tank 10.

Although not shown in detail, the engine 1 has a crank angle sensor 16 for detecting a rotation angle of a crankshaft, a cam angle sensor 17 for detecting a rotation angle of a valve system camshaft, and a coolant temperature ( An engine water temperature sensor 18 for detecting an engine water temperature is provided. The crank angle sensor 16 is composed of a plate to be detected provided at the end of the crankshaft and an electromagnetic pickup arranged so as to face the outer periphery thereof, at equal intervals around the entire outer periphery of the plate to be detected. A pulse signal is output in response to the passage of the formed protrusion. The cam angle sensor 17 also includes a plurality of protrusions similarly provided at predetermined positions on the peripheral surface of the cam shaft, and an electromagnetic pickup that outputs a pulse signal when each of the protrusions passes. Reference numeral 19 denotes a vacuum pump driven by the cam shaft.

One side of the engine 1 (upper side in the figure)
Is connected to an intake passage 20 that supplies air filtered by an air cleaner (not shown) to the combustion chamber 4. A surge tank 21 is provided at a downstream end of the intake passage 20. Each passage branched from the surge tank 21 communicates with the combustion chamber 4 of each cylinder 2 through an intake port (not shown). Further, the surge tank 21 is provided with a supercharging pressure sensor 22 for detecting a pressure state of intake air pressure-fed by a turbocharger 31 described later. Further, the intake passage 2
0 in order from upstream to downstream.
A hot film type air flow sensor 23 for detecting the flow rate of intake air sucked into the blower; a blower 24 driven by a turbine 29 to compress the intake air; an intercooler 25 for cooling the intake air compressed by the blower 24; And an intake throttle valve 26 composed of Although not shown in detail, the intake throttle valve 26 is configured such that the valve shaft is rotated by a stepping motor and positioned in an arbitrary state from fully closed to fully open.
Further, a notch is provided so that air can flow even in a fully closed state.

On the other hand, the combustion gas (exhaust gas) from the combustion chamber 4 of each cylinder 2 is provided on the opposite side (the lower side in the figure) of the engine 1.
An exhaust manifold 27 for exhausting the exhaust gas is connected, and an exhaust passage 28 is connected to a downstream end gathering portion of the exhaust manifold 27. The exhaust passage 28 includes, in order from the upstream side to the downstream side, a turbine 29 rotated by the exhaust flow and a catalytic converter for removing harmful components (unburned HC, CO, NOx, smoke, etc.) in the exhaust gas. 30 are provided. Blower 24 of turbine 29 and intake passage 20
Although details are not shown, the turbocharger 31
VGT in which the cross-sectional area (nozzle cross-sectional area) of the exhaust flow path to the turbine 29 is changed by a movable flap
(Variable geometry turbo), wherein the flap is rotated by a negative pressure driven actuator 35 using a negative pressure from a vacuum pump 19.

Although not shown in detail, the catalytic converter 30 has a cordierite carrier having a honeycomb structure having a large number of through holes extending in parallel with each other in the direction in which exhaust gas flows. A catalyst layer of a so-called lean NOx catalyst is formed on each through hole wall surface. This lean NOx catalyst can reduce and purify NOx in exhaust gas even when the oxygen concentration in the exhaust gas is high, that is, in a lean state in which the average excess air ratio λ of the combustion chamber 4 is larger than 1. In the vicinity of the air-fuel ratio, it also functions as a three-way catalyst.

Further, the exhaust passage 28 is provided in the turbine 2
9 and is branched upstream of an exhaust gas recirculation passage (hereinafter referred to as an EGR passage) 33 that recirculates part of the exhaust gas to the intake side at a position upstream of the exhaust gas, and a downstream end of the EGR passage 33 is an intake throttle. It is connected to the intake passage 20 in the middle of the valve 26 and the surge tank 21 so that a part of the exhaust gas taken out from the exhaust passage 28 is returned to the intake passage 20. An exhaust gas recirculation amount control valve (hereinafter, referred to as an EGR valve) 34 whose opening can be adjusted is disposed near the downstream end of the EGR passage 33. The EGR valve 34 is connected to a flap of the turbocharger 31. Similarly, the opening / closing operation by the negative pressure drive type actuator 35 linearly changes the passage cross-sectional area of the EGR passage 33, and regulates the flow rate of the exhaust gas recirculated to the intake passage 20.

Each of the injectors 5, fuel supply pump 8, intake throttle valve 26, VGT 31, EGR valve 34, etc.
All control units (Electronic Control
The unit is operated by a control signal from a unit (hereinafter referred to as an ECU) 40. On the other hand, the ECU 40 receives an output signal from the fuel pressure sensor 6b, an output signal from the crank angle sensor 16 and the cam angle sensor 17, an output signal from the engine coolant temperature sensor 18, and a signal from the supercharging pressure sensor 22. At least an output signal, an output signal from the air flow sensor 23, and an output signal from an accelerator opening sensor 36 that detects an operation amount (accelerator opening) of an accelerator pedal (not shown) by a driver of the vehicle are input.

As the basic control by the ECU 40, the target fuel injection amount is determined mainly based on the accelerator opening, and the fuel injection supply amount and the injection timing are controlled by controlling the operation of the injector 5. The operation of the high-pressure supply pump 8 controls the common rail pressure, that is, the fuel injection pressure. The average excess air ratio of the combustion chamber 4 is controlled by adjusting the intake air amount by controlling the operation of the intake throttle valve 26 and the EGR valve 34. In addition, VGT3
The supercharging efficiency of the intake air is increased by the operation control of the flap (VGT control).

Specifically, for example, as fuel injection control,
As will be described in detail later, in substantially the entire operation range of the engine 1, as shown in FIG. 3B, the injector 5 performs the main injection of the fuel near the compression top dead center (TDC) of the cylinder and the injection of the main fuel into the main injection. Each of the preceding sub-injections is performed. Further, the total injection amount of the fuel by the sub-injection and the main injection is increased or decreased mainly in accordance with the change in the load state of the engine 1, and a ratio (sub-injection ratio) R of the sub-injection amount of the fuel to the main injection amount. And the start timing of each injection operation, etc., can be finely changed according to changes in the load condition and rotation speed of the engine 1,
The formation of the fuel spray in the combustion chamber 4 of each cylinder 2 is optimized, so that the fuel consumption performance, output performance,
Various requirements that conflict with each other, such as heat resistance and emission, are satisfied at a high level.

The operation control of the EGR valve 34 (EG
As the R control, for example, a target excess air ratio common to all the cylinders 2 is determined according to the operating state of the engine 1, and the actual intake air amount into the combustion chamber 4 of each cylinder 2 based on the output of the airflow sensor. Is detected, and the exhaust gas recirculation amount is controlled based on the detected value and the fuel injection amount for each cylinder 2 so as to achieve the target excess air ratio. That is, by adjusting the exhaust gas recirculation amount for each cylinder 2, the intake amount of fresh air (outside air) into the combustion chamber 4 is changed, and the excess air ratio of the combustion chamber 4 in each cylinder 2 is changed to the target excess air ratio. It is controlled so that

Further, as for the operation control of the intake throttle valve 26, in order to recirculate a required amount of exhaust gas by the above-described EGR control, the intake throttle valve 26 is mainly closed during an idling operation of the engine 1, While a negative pressure is generated in the passage 20, the intake throttle valve 26 is set to be almost fully opened in other operation states.

In general, in a direct-injection diesel engine, the generation of NOx can be suppressed by increasing the amount of exhaust gas recirculation to make the rise of initial premixed combustion gentle, but the exhaust gas recirculation amount increases. For example, the intake air amount of fresh air decreases accordingly, the average excess air ratio in the combustion chamber decreases, and the amount of smoke generated in a locally rich mixture tends to increase. Therefore, in the control of the EGR valve 34 in this embodiment, the target value of the excess air ratio is set to a value as small as possible in a range where the smoke does not increase so much.

(Fuel Injection Control in Steady State) Next, the fuel injection control when the engine 1 is in the steady state will be described. In the memory of the ECU 40, an example is shown in FIGS. A plurality of injection control maps are stored electronically, and control data is read from these injection control maps in accordance with the operating state of the engine 1. For example, the map of the fuel injection amount shown in FIG.
The optimum value of the basic fuel injection amount Qb experimentally determined according to the load state of the engine 1 and the change in the engine speed is recorded, and the target torque (based on the output signal from the accelerator opening sensor 36) is obtained. The basic fuel injection amount Qb corresponding to the required output of the engine 1 from the fuel injection amount map, based on the engine 1 load state) and the engine speed obtained based on the output signal from the crank angle sensor 16.
Is read. The basic fuel injection amount Qb is set and recorded so as to increase as the target torque increases and as the engine speed increases, and the basic injection amount Qb read in this manner is changed to the engine water temperature and the intake pressure. Corrected accordingly, the final target fuel injection amount is determined.

In the map of the sub-injection ratio shown in FIG. 3B, the sub-injection ratio R is recorded in association with the load state of the engine 1 and the engine speed in the same manner as described above. According to the drawing, the sub-injection ratio R is set to R = 20 to 40% in the low load side operation region (a) except for the fuel cut region in which the fuel injection supply by the injector 5 is stopped. R = 10 to 20% in the load operation range (b)
In the operation region (c) on the high load side, R = 5 to
It is 10%. That is, the sub-injection ratio R is increased as the load state of the engine 1 is lower. It should be noted that the total fuel injection amount of the sub-injection and the main injection increases as the load state of the engine 1 increases, so that the fuel sub-injection amount increases on the high load side of the engine 1.

Further, although not shown, the memory of the ECU 40 stores the valve closing timing of the injector 5 in the sub-injection and the main injection (nozzle of the injector 5) in association with the load condition and the engine speed of the engine 1 in the same manner as described above. Is stored electronically, and a valve closing time of the injector 5 and a valve opening time interval of the injector 5 for injecting required fuel are read from the map. Based on the above, the crank angle position for opening the nozzle of the injector 5, that is, the injection start timing is set.

In the injection timing map, the valve closing timing of the injector 5 is recorded in association with, for example, the load state of the engine 1, the engine speed, the engine water temperature, and the common rail pressure. The injection timing is advanced as the water temperature is lower and the common rail pressure is lower. This corresponds to the fact that the ignition delay time of the fuel changes depending on the engine water temperature, etc.
This is for always making the combustion state optimal. Further, in this embodiment, as the engine 1 is on the higher load or higher rotation side, the timings of the sub-injection and the main injection are advanced, and the injection stop interval between them is made longer. Even if the fuel injection timing is advanced or retarded in this way, the main injection end timing is set to the cylinder 2 in order to prevent the deterioration of the combustion state.
After compression top dead center (ATDC) of 35 ° CA.

(Fuel Injection Control in Accelerated Operating State) Next, the fuel injection control when the engine 1 is in the accelerated operating state will be described. This is a so-called transient state, in which a transient fuel increase correction is performed. That is, in addition to the control of the operating state of the engine 1 as described above, that is, the control of the steady operating state performed based on the load state and the engine speed, the target fuel injection amount is increased and the increased correction amount is determined as the sub-injection. The timing of the sub-injection and the timing of the main injection are respectively corrected to the advanced side.

The correction amount for increasing the fuel injection amount is increased in accordance with the state of change of the accelerator opening so as to increase as the state of rapid acceleration increases. In this embodiment, the manner in which the fuel increase correction amount is distributed to the sub-injection and the main injection is determined mainly based on the load state and the engine speed of the engine 1 when the engine 1 is in the acceleration operation state. In particular, the sub-injection amount or sub-injection ratio is changed according to the load state of the engine 1 and the engine speed in the latter half of the acceleration operation.

Hereinafter, the processing procedure of the fuel injection amount control when the engine 1 is in the acceleration operation state will be specifically described with reference to the flowchart shown in FIG. This control procedure is executed independently for each cylinder 2 at a predetermined crank angle according to a control program stored electronically on the memory of the ECU 40.

First, in step SA1 after the start, data such as a crank angle signal, an air flow sensor output, an accelerator opening, a supercharging pressure, and an engine water temperature are input. In a succeeding step SA2, a target torque calculated from the accelerator opening is input. 4A, the basic fuel injection amount Qb is read from the fuel injection amount map shown in FIG. 4A, and the basic fuel injection amount Qb is used as an engine water temperature, intake pressure, and the like. Then, the target fuel injection amount Q is set. Subsequently, in step SA3,
The sub-injection ratio R is read from the sub-injection ratio map of FIG. 4 (b), and the target fuel injection amount Q obtained in step SA2 is distributed based on the sub-injection ratio R. The quantity Qp and the main injection quantity Qm are calculated.

Qp = R × Q, Qm = (1−R) × Q Further, the timings of the sub-injection and the main injection by the injector 5 are respectively set.

Subsequently, in step SA4, it is determined whether or not the engine 1 is in an accelerating operation state. This determination is made based on the accelerator opening, its change speed, and the degree of change in the engine speed. If the determination result is NO and the vehicle is not in the accelerating operation state, the process proceeds to step SA14. Is larger than the reference value and the change in the increase in the engine speed is larger than the predetermined reference value, it is determined to be YES in the acceleration operation state, and the routine proceeds to step SA5. In this step SA5, it is determined whether or not the value of an acceleration determination flag F indicating that the engine 1 is in the acceleration operation state is 0. If F = 1, the engine 1 continues from the previous control cycle in the acceleration operation state. If it is determined that there is, and the process proceeds to step SA13, if F = 0, it is determined that the engine 1 has changed from the steady operation state to the accelerated operation state, and the process proceeds to step SA6 to perform step S6.
In A6, the value of the acceleration determination flag F is set to 1 (F =
1).

Subsequently, in step SA7, the fuel injection amount is increased and corrected so as to correspond to the acceleration operation of the engine 1. That is, first, according to the change amount of the accelerator opening and the change speed thereof, the increase correction amount is calculated so that the larger the driver's accelerator operation amount and the steeper this operation, the larger the fuel injection amount. I do. Subsequently, for example, a distribution coefficient of the increase correction amount to the sub-injection is read from a control map as shown in FIG. 6, and the increase correction amount is distributed based on this coefficient, so that the auxiliary injection increase value ΔQp and the main injection increase Value ΔQ
m are respectively set (ΔQp> ΔQm).

Here, according to the control map of FIG.
The distribution coefficient is set so as to increase as the load state and the engine speed of the engine 1 at the time of the acceleration operation state decrease. For example, if the engine 1 is in the low rotation and low load operation state, the sub-injection is performed. The ratio R is about 100%, and when the engine 1 is in the middle rotation and low-medium load operation state, the sub-injection ratio is about 80%. The sub-injection ratio R becomes about 60%. That is, when the engine 1 enters the accelerated operation state, basically, the increase in the fuel injection amount is distributed to the sub-injection and the main injection at the distribution ratio corresponding to the operation state of the engine 1 at that time. I have to.

Subsequently, in step SA8, the engine 1 is set to a high level based on the amount of change in the accelerator opening and the rate of change thereof, as well as the load state and the engine speed when the engine 1 is in the acceleration operation state. Predict whether to shift to the set operation area on the load side. This set operation region is, for example, as shown by hatching in FIG.
The combustion chamber 4 in each of the cylinders 2 is slightly overheated because the fuel injection amount is large and the engine speed is high originally. It is an operation area where

Subsequently, when it is predicted in step SA8 that the operation mode shifts to the set operation range (the determination is YE).
S), in a subsequent step SA9, the sub-injection decrease value Qpt
In the subsequent step SA10, the sub-injection decrease value Qpt is subtracted from the sub-injection increase value ΔQp obtained in step SA7, and the value after this subtraction is set as the sub-injection increase value ΔQp, and the routine proceeds to step SA11. . on the other hand,
If it is predicted in step SA8 that the operation will not shift to the set operation range (the determination is NO), the auxiliary injection increase value ΔQ
The process proceeds to Step SA11 without changing p. In step SA11, the sub injection amount Qp calculated in step SA3 is added with the sub injection increase value ΔQp to calculate the final sub injection amount Qp. Subsequently, in step SA12, a control signal corresponding to the sub-injection amount Qp and the main injection amount ΔQm is output to the injector 5, and the injector 5
To execute the sub-injection and main injection of the fuel respectively, and then return.

That is, if it is predicted that the engine 1 will shift to the set operation region by the acceleration operation, the combustion of the sub-injected fuel will be excessive in consideration of the fact that the combustion chamber 4 becomes overheated in this set operation region. In order to prevent the fuel injection from becoming violent, an increase in the sub-injection amount of the fuel is suppressed in advance. In step SA9, the ECU 4 sets a predetermined value as the sub-injection decrease value Qpt.
0 may be read from the memory, or the value may be corrected according to the accelerator opening, the engine speed, or the like.

On the other hand, in step SA13, where it is determined that the engine 1 is in the accelerating operation state from the previous control cycle and NO has been reached in step SA5, the sub-injection increase value ΔQp is set to the value ( The previous time ΔQp), and the above step SA11 and step S
The process proceeds to A12, in which the injector 5 executes the sub injection and the main injection of the fuel, and then returns. That is, the sub-injection increase value ΔQp and the main injection increase value ΔQm set at the beginning of the acceleration operation of the engine 1 as described above are maintained until the acceleration operation of the engine 1 ends.

If it is determined in step SA4 that the engine 1 is not in the accelerating operation state, that is, if the engine 1 is in the steady operation state, it is determined in step SA4.
The routine proceeds to step 14, where the flag F is cleared (F = 0), and then to step SA12, where the injector 5 performs the sub-injection and main injection of the fuel, and thereafter returns. That is, in the steady operation state, the above-described increase correction of the fuel injection amount is not performed.

By each step of the flow shown in FIG. 5, the fuel injection control means 40a for performing the main fuel injection and the preceding sub-injection by the injector 5 as a whole in almost all operating regions of the engine 1 is constituted. Have been. Further, a fuel increase correction means 40b for increasing and correcting the fuel injection amount by the injector 5 when the engine 1 enters the acceleration operation state in step SA7. The fuel increase correction means 40b determines the operating state of the engine 1 when the engine 1 is in the accelerated operating state,
That is, the sub-injection and the main injection amount of the fuel are respectively increased based on the load state and the engine speed. When the engine 1 enters the acceleration operation state with a low load, the engine 1 enters the acceleration operation state with a medium load. The sub-injection ratio R is set to be larger than usual.

Further, in step SA8 of the flow, when the engine 1 is in the acceleration operation state, the prediction means 40c for predicting whether or not the engine 1 will shift to the set load operation region on the high load side is constituted. ,
In each step of SA10, when it is predicted that the engine 1 will shift to the set operation range, the sub-injection ratio R
Decrease the sub-injection increase value ΔQp so that
That is, an increase regulating means 40d for limiting the increase correction of the sub-injection amount by the fuel increase correcting means 40b is provided.

In the first embodiment, since the increase correction of the sub-injection amount by the fuel increase amount correction means 40b is restricted by the increase amount restriction means 40d as described above, the auxiliary injection increase value Δ
The constant sub-injection decrease value Qpt is subtracted from Qp. However, the present invention is not limited to this. For example, the sub-injection increase value ΔQp = 0 is forcibly set and the increase in the sub-injection amount by the fuel increase correction means 40b is prohibited. It is also possible to do so.

(Effects of Embodiment 1) Therefore, according to the engine fuel control apparatus A according to Embodiment 1, first, in almost all operating regions of the engine 1,
As shown in FIG. 3 (b), fuel is supplied and injected into the sub-injection and the main injection by the injector 5 of each cylinder 2 of the engine 1. At this time, when the sub-injection of the fuel is performed in the compression stroke of the cylinder 2, the fuel is mixed with the air and burns (premixed combustion), and the temperature and the pressure state of the combustion chamber 4 are increased by the combustion. For example, the solid line in FIG. 3A shows a change in the pressure state (in-cylinder pressure) of the combustion chamber 4 when the sub-injection is performed, and the phantom line shows when the sub-injection is not performed. is there. According to the figure, it can be seen that the pressure state of the combustion chamber 4 is increased by the combustion of the fuel injected by the sub-injection, and together with the rise of the piston, the in-cylinder pressure becomes extremely high near TDC.

Subsequently, when the main injection is performed by the injector 5 in the vicinity of the TDC, since the temperature and the pressure state of the combustion chamber 4 are extremely high as described above, the ignition delay time of the main injected fuel is reduced. It becomes extremely short, and most of them become well diffused and burned. That is, FIG.
As shown by the solid line in (a), when the sub-injection is performed, the pressure rise at the start of combustion becomes gentle and the pressure peak becomes considerably higher than when the sub-injection is not performed. As a result, the output of the engine 1 can be improved while reducing the combustion noise and the emission at the beginning of combustion.

When the engine 1 is in the accelerated operation state, the fuel injection amount is increased and corrected by the fuel increase correction means 40b in accordance with changes in the accelerator opening, the engine speed, etc., and the engine output is increased. . That is, in the acceleration operation state in which the change is relatively steep, the fuel increase correction amount is increased, while in the acceleration operation state in which the change is relatively slow, the fuel increase correction amount is reduced.

At this time, the increase correction amount is distributed to the sub-injection and the main injection based on the load state of the engine 1 and the engine speed at the time of the acceleration operation state. That is, the lower the temperature of the combustion chamber 4 is, the lower the engine 1 is on the relatively low load or low rotation side at the start of the acceleration operation.
The sub-injection ratio R is increased, and the temperature of the combustion chamber 4 can be quickly increased by the combustion of the sub-injection fuel. Therefore, even if the fuel injection amount is considerably increased by the acceleration increase, the large amount of fuel is removed. As described above, it is possible to sufficiently obtain the operational effects such as the reduction of the combustion noise and the emission while sufficiently burning the engine to sufficiently increase the engine output.

As described above, if the sub-injection of the fuel is performed at the beginning of the acceleration operation of the engine 1, the ignition delay time of the main injection fuel is extremely shortened, and the combustion noise accompanying the premixed combustion of the main injection fuel is reduced. Although it is possible to reduce the emission and emission, and also to increase the engine output by improving the flammability, on the other hand, when the engine 1 shifts to the set operation region shown in FIG. This time, the combustion chamber 4 becomes overheated, so that the fuel of the sub-injected fuel becomes excessively vigorous, in combination with the correction of the increase in the fuel injection amount and the super-high pressure injection by the common rail method. At times, there is a concern that combustion noise and emission may increase.

Therefore, in this embodiment, when the engine 1 is in the accelerated operation state, whether to shift to the set operation area in the latter half of the accelerated operation based on the degree of change in the load state of the engine 1 at that time. Whether it is predicted (see step SA8 in FIG. 5), and when it is predicted to shift, the correction for increasing the sub-injection amount is limited. As a result, even if the engine 1 shifts to the set operation region in the later stage of the acceleration operation, the combustion of the sub-injected fuel does not become excessively intense. It is possible to avoid occurrence of problems such as combustion noise and increased emissions.

On the other hand, as shown by the arrow in FIG. 3B, if the change in the load state of the engine 1 in the initial stage of the acceleration operation is not so large, it is predicted that the engine 1 will not shift to the set operation region at this time. The sub-injection increase value ΔQp is not decreased. That is, unless the engine 1 shifts to the set operation range in the latter half of the acceleration operation, the combustion chamber 4 does not become overheated, so that a problem does not occur even if the increase in the sub-injection amount of fuel is not limited. Therefore, by increasing the correction amount of the sub-injected fuel sufficiently to correspond to the operating state of the engine 1 at the initial stage of acceleration, it is possible to improve the engine output at the initial stage of the acceleration operation, reduce the combustion noise and reduce the emission. The operation and effect can be sufficiently obtained.

(Embodiment 2) Next, FIG. 9 shows a control procedure in the acceleration operation state of the engine 1 in the fuel control apparatus A according to Embodiment 2 of the present invention. When the vehicle enters the acceleration operation state, similarly to the first embodiment, the sub-injection amount and the main injection amount of the fuel by the injector 5 are increased and corrected, and in the latter half of the acceleration operation, the increase correction amount of the sub-injection is decreased. Thus, an increase in combustion noise and emission due to the correction of the increase in the sub-injection is prevented. Since the overall configuration of the fuel control device A according to the second embodiment is the same as that of the first embodiment (see FIG. 2), the same reference numerals are given to the same components as those in the first embodiment, and the description thereof will be omitted. Omitted.

Specifically, in steps SB1 to SB7 of the flow shown in FIG.
The same control procedure as that of SA7 is executed, and the sub-injection amount and the main injection amount of the fuel by the injector 5 are increased and corrected in accordance with the acceleration operation of the engine 1. Subsequently, in step SB8, it is determined whether or not the latter half of the acceleration operation has been performed, more specifically, whether or not the engine 1 has shifted to the set operation region on the high load side (see FIG. 7). If the determination is YES and the latter half of the acceleration operation is performed, the process proceeds to step SB13. If the determination is NO, the process proceeds to step SA9 to set the injection ratio correction coefficient Rq1.

The value of the injection ratio correction coefficient Rq1 (0 <Rq1
<1) is a constant value larger than Rq2 described later (for example, Rq2).
(q1 = 0.5) may be set in advance. Further, the injection ratio correction coefficient Rq1 (0 <Rq1 <1) is associated with the operating state of the engine 1 when the engine 1 is out of the set operation range, that is, the load state of the engine 1 and the engine speed. For example, the value may be set to be smaller as the load becomes higher or the rotation speed becomes higher.

Subsequently, in step SB10, the sub injection amount Qp and the main injection amount Qm are respectively corrected based on the injection ratio correction coefficient Rq1 set in step SB9.
Thereafter, the process proceeds to step SB11, in which the injector 5 performs the sub-injection and the main injection similarly to the first embodiment, and thereafter returns. If the injection ratio correction coefficient Rq1 is changed in association with the operating state of the engine 1, the sub-injection ratio R gradually changes with the change in the engine operating state due to the acceleration operation.
On the other hand, if the injection ratio correction coefficient Rq1 = 0.5, the sub injection ratio R does not change until the engine 1 shifts to the set operation region.

On the other hand, in step SB8, it is determined in the late stage of the acceleration operation that the answer is YES, and the process proceeds to step S8.
In B13, the injection ratio correction coefficient Rq2 is set in the same manner as in step SB9 (0 <Rq2 <Rq1 <1). The injection ratio correction coefficient Rq2 may be a value smaller than the correction coefficient Rq1, for example, Rq2 = 0.4. Then, in a succeeding step SB14, the injection ratio correction coefficient Rq2
Based on the sub injection amount Q in the same manner as in step SB10.
p and the main injection amount Qm, respectively, to correct the sub injection ratio R
Then, the routine proceeds to step SB11 where the injector 5 executes the sub-injection and the main injection, and thereafter returns.

That is, when the engine 1 is in the accelerating operation state, first, as in the first embodiment, based on the operation state of the engine 1 and the accelerator opening at that time, the fuel injection amount increase correction amount and The distribution ratio between the sub injection and the main injection is determined. On the other hand, when the engine 1 actually shifts to the set operation range in the latter half of the acceleration operation, the sub-injection ratio R is reduced as compared to before the shift.

Here, NO in step SB5
In step SB12, which has been determined, the sub-injection increase value ΔQp and the main injection amount ΔQm are set as values (previous values) in the previous control cycle, and the above-described steps SB8 to SB14 are performed.
Therefore, the values of the sub-injection increment value ΔQp and the main injection increment value ΔQm set when the engine 1 enters the acceleration operation state are not changed. Further, in the steady operation state of the engine 1 determined as NO in the step SB4, after the flag F is cleared in the step SB15 (F = 0), the process proceeds to the step SB11, and the fuel injection and the main injection by the injector 5 are performed. Let the injection run,
Return after a while. That is, in the steady operation state, the fuel increase correction is not performed.

The steps of the flow shown in FIG. 9 constitute the fuel injection control means 40a having the same functions as the first embodiment as a whole, and the step SB7 similarly constitutes the fuel increase correction means 40b. I have.
Further, the determination means 40e for determining that the engine 1 has shifted to the set operation region on the high load side is configured by step SAB8 of the flow, and steps SB13 and SB13 are performed.
In each of the fourteenth steps, when the determination means 40e determines that the engine 1 has shifted to the set operation range, the sub-injection amount and the main injection amount are corrected so that the sub-injection ratio R becomes smaller than before the determination. By doing so, an increase regulating unit 40d that limits the increase in the sub-injection amount of the fuel is configured.

In the second embodiment, the value of the injection ratio correction coefficient is changed by the increase control means 40d according to the operating state of the engine 1 (Rq1 → Rq2), and the sub injection ratio R However, the present invention is not limited to this. For example, when the engine 1 shifts to the set operation region, the sub-injection increase value ΔQp (the increase correction amount of the sub-injection amount of fuel) is forcibly set to zero. You may do so.

Therefore, according to the engine fuel control apparatus A of the second embodiment, as shown in FIG. 10, when the engine 1 is in the acceleration operation state (t = t
0), in the initial stage of the acceleration operation, the fuel injection amount by the injector 5 is increased and corrected in the same manner as in the first embodiment, and particularly, the fuel sub-injection amount is sufficiently increased (t).
1) There are obtained effects such as improvement of engine output, reduction of combustion noise and reduction of emission.

Then, as shown in FIG. 11 (a), the operating state of the engine 1 is changed from the point P1 → P2 →
P3, and when the engine 1 shifts to the set operation region on the high load side in the latter period of the acceleration operation (point P4) (t
2), the injection rate correction coefficient is changed by the increase control means 40d (Rq1 → Rq2), and the sub-injection rate R is reduced. As a result, even if the combustion chamber 4 of the engine 1 becomes overheated,
Excessive combustion of the sub-injected fuel can be suppressed, and problems such as an increase in combustion noise and an increase in emission can be prevented.

That is, in the second embodiment, the engine 1
By changing the sub-injection ratio R of the fuel by the injector 5 between the initial stage and the late stage of the acceleration operation, it is possible to sufficiently obtain the effects such as improvement of the acceleration performance of the engine 1 and reduction of the combustion noise and emission. it can.

Note that step SB of the flow shown in FIG.
9, at SB13, the injection ratio correction coefficients Rq1, Rq2
Are set to be smaller at higher loads or higher rotations according to the operating state of the engine 1, the engine 1 is brought into an accelerated operating state by the steps SB7 to SB10 and steps SB13 and SB14. During this time, the fuel increase correction is performed by changing the increase correction amount of the sub-injection amount and the main injection amount of the fuel by the injector 5 so that the auxiliary injection ratio R decreases in accordance with the load state of the engine 1 or the increase in the engine speed. The means 40b is configured.

In such a case, the engine 1 is in an acceleration operation state, and the operation state is as shown in FIG.
As shown in FIG. 1 (b), as the point P1 → P2 → P3 → P4 changes from the low load side to the high load or high rotation side, the injection ratio correction coefficient is gradually reduced. Is increased so that the sub-injection ratio R decreases as the operating state of the engine 1 changes.

Thus, during acceleration operation of the engine 1,
The sub-injection ratio R of the fuel is optimally changed so as to respond to changes in the load state and the engine speed of the engine 1 to improve the acceleration performance of the engine 1 and reduce combustion noise and emissions in a very high level. Can be compatible.

[0080]

As described above, according to the fuel control system for a diesel engine according to the first aspect of the present invention, when the engine is in an accelerating operation state, the fuel is injected by the fuel injection valve into the sub-injection and the main injection. At the same time, while increasing the injection amount, while improving the engine output,
Combustion noise in the initial stage of the acceleration operation can be reduced and emission can be reduced. Moreover, when the prediction means predicts that the engine will shift to the set operation region on the high load side, the increase correction means restricts the increase correction of the sub-injection amount, so that combustion noise and emission in the latter half of the acceleration operation are reduced. An increase can be avoided.

According to the second aspect of the present invention, when it is predicted that the engine will move to the set operation region on the high load side due to the acceleration operation, the increase in the sub injection amount by the fuel increase correction means is prohibited. It is possible to reliably prevent an increase in combustion noise and emission caused by the combustion of the injected fuel.

According to the third aspect of the invention, when the engine is predicted to shift to the set operation region on the high load side by the acceleration operation, the increase correction amount of the sub injection amount by the fuel increase correction means is reduced by a predetermined amount. Thus, the effect of the first aspect can be sufficiently obtained.

According to the fuel control system for a diesel engine according to the fourth aspect of the present invention, the sub injection amount of fuel by the fuel injection valve is sufficiently increased at the beginning of the engine acceleration operation. While improving engine output in the same way as above, combustion noise can be reduced and emissions can be reduced, but in the latter half of accelerated operation when the combustion chamber tends to overheat,
Combustion noise and emissions can be reduced by limiting the increase in the sub-injection amount.

According to the fifth aspect of the invention, when the engine actually shifts to the set operation range in the latter half of the acceleration operation, the increase correction amount of the sub injection amount by the fuel increase correction means is forcibly set to zero. Thus, it is possible to reliably prevent an increase in combustion noise and emission caused by the combustion of the sub-injection fuel.

Further, according to the fuel control apparatus for a diesel engine according to the present invention, the auxiliary injection amount of the fuel by the fuel injection valve is sufficiently increased at the beginning of the engine acceleration operation, and thereafter, the operation of the engine is started. By appropriately reducing the sub-injection ratio according to the state change,
The improvement of the engine output during the acceleration operation and the reduction of the combustion noise and the emission can be achieved at an extremely high level.

According to the seventh aspect of the present invention, when the engine is in the accelerated operation state, the sub-injection ratio is increased as the temperature state of the combustion chamber is lower according to the load state of the engine at that time. By appropriately raising the temperature state of the combustion chamber, the combustibility of the fuel can be appropriately increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of the present invention.

FIG. 2 is an overall configuration diagram of a control device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an opening / closing operation state of an injector.

FIG. 4 is a diagram showing an example of a control map of (a) a fuel injection amount and (b) a sub-injection ratio.

FIG. 5 is a flowchart illustrating a procedure of fuel injection control.

FIG. 6 is a diagram illustrating an example of a control map in which a distribution coefficient of a sub-injection increase value in an acceleration increase correction is set.

FIG. 7 is a diagram showing an example of a set operation region in which the fuel increase correction is limited in the acceleration increase correction.

FIGS. 8A and 8B are explanatory diagrams showing changes in the operating state of the engine when (a) the engine shifts to the set operating region with acceleration operation and (b) when the engine does not shift.

FIG. 9 is a diagram corresponding to FIG. 5 according to the second embodiment of the present invention.

FIG. 10 is a time chart showing a state in which the sub-injection ratio decreases in the latter half of the acceleration operation of the engine.

FIG. 11 is a diagram (a) corresponding to FIG. 8 according to the second embodiment and a diagram (b) according to a modified example thereof.

[Explanation of symbols]

 A Fuel control device for engine 1 Diesel engine 2 Cylinder 4 Combustion chamber 5 Injector (fuel injection valve) 40 Control unit 40a Fuel injection control means 40b Fuel increase correction means 40c Prediction means 40d Increase control means 40e Judgment means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/38 F02D 41/38 B 45/00 314 45/00 314K (72) Inventor Keiji Araki Hiroki Aki No.3-1 Shinchi, Gunfu-cho Mazda Co., Ltd. F-term (reference) 3G084 AA01 BA13 BA15 CA04 DA01 DA07 DA10 EB02 EB08 EB12 FA07 FA12 FA20 FA33 FA34 FA38 3G301 HA02 HA11 JA01 JA24 JA37 KA09 KA12 LB11 MA11 MA19 MA23 NC01 NC02 ND01 PA01Z PA16Z PB03A PB05A PE01Z PE02Z PE03Z PE08Z PF03Z PF04Z

Claims (7)

[Claims] A fuel is directly injected into a combustion chamber in a cylinder of an engine.
A fuel injection valve for injecting and supplying; a fuel increase correction means for increasing and correcting a fuel injection amount by the fuel injection valve when the engine is in an acceleration operation state; and a fuel injection valve at least at an initial stage of the acceleration operation of the engine. A fuel control device for a diesel engine comprising a fuel injection control means for performing a main injection and a sub-injection prior to the main injection, wherein when the engine is in an acceleration operation state, the engine is in a set operation region on a high load side. Prediction means for predicting whether or not to shift to the set operation range, when the prediction means predicts that the engine will shift to the set operation region, the ratio of the sub-injection amount of the fuel to the main injection amount as compared to when it is not. A diesel engine characterized by comprising an increase regulating means for limiting an increase correction of the sub-injection amount so as to reduce the sub-injection ratio. Gin's fuel control device. 2. The fuel control device for a diesel engine according to claim 1, wherein the increase control means is configured to prohibit an increase in the sub-injection amount by the fuel increase correction means. 3. The fuel control device for a diesel engine according to claim 1, wherein the increase control means is configured to reduce the increase correction amount of the sub-injection amount by the fuel increase correction means by a predetermined amount. 4. The fuel is directly supplied to an in-cylinder combustion chamber of an engine.
A fuel injection valve for injecting and supplying; a fuel increase correction means for increasing and correcting a fuel injection amount by the fuel injection valve when the engine is in an acceleration operation state; and a fuel injection valve at least at an initial stage of the acceleration operation of the engine. A fuel injection control means for performing a main injection and a sub-injection preceding the main injection, wherein a determination means for determining that the engine has shifted to a set load operation region on the high load side; When it is determined by the determining means that the operation has shifted to the set operation range, the sub-injection amount of the fuel is set so that the sub-injection ratio, which is the ratio of the sub-injection amount of the fuel to the main injection amount, becomes smaller than before the determination. A fuel control device for a diesel engine, comprising: an increase control means for limiting an increase correction. 5. The fuel supply control device according to claim 4, wherein when the determination means determines that the engine has shifted to the set operation range, the fuel increase correction means forcibly sets the increase correction amount of the sub-injection amount to zero. A fuel control device for a diesel engine, wherein 6. The fuel is directly supplied to an in-cylinder combustion chamber of an engine.
A fuel injection valve for injecting and supplying; a fuel increase correction means for increasing and correcting a fuel injection amount by the fuel injection valve when the engine is in an acceleration operation state; and a fuel injection valve at least at an initial stage of the acceleration operation of the engine. A fuel injection control means for performing a main injection and a sub-injection preceding the main injection, wherein the fuel increase correction means comprises: The sub injection amount, which is a ratio of the sub injection amount to the main injection amount, decreases with an increase in the load state of the engine, and the increase correction amount of the sub injection amount and the main injection amount is changed. Diesel engine fuel control device. 7. The fuel increase correction means according to any one of claims 1, 4 and 6, wherein when the engine is in an acceleration operation state in a low load operation state, the fuel increase correction means is in an acceleration operation state in a medium load operation state. A fuel control device for a diesel engine, characterized in that the sub-injection and the main injection amount of the fuel are each increased so that the sub-injection ratio at least in the initial stage of the acceleration operation is increased as compared with the case of the above.