JP2002038997A - Fuel injection control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the dispersion of a fuel injection amount and a fuel injection timing of a fuel injection valve provided in each cylinder. SOLUTION: A reference injection amount Qm and a reference injection timing Itm are set depending on engine operated conditions (S2). If stable idling is discriminated (S3), an injection amount correction value ΔQi is calculated in accordance with an engine speed in each injection valve (S5), an injection timing correction value ΔIti is calculated in accordance with the correction value ΔQi (S6), a modifying correction value ΔQin is calculated in accordance with the correction value ΔIti (S7), and the reference injection amount Qm and the reference injection timing Itm are corrected in accordance with these corrected values ΔIti, ΔQin (S8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a diesel engine in which a fuel injection valve for injecting fuel into a combustion chamber is provided for each cylinder.

[0002]

2. Description of the Related Art As a fuel injection control device for a diesel engine, a common rail type fuel injection control device disclosed in Japanese Patent Application Laid-Open No. 62-258160 is known. In this device, high-pressure fuel pumped from a fuel pump is accumulated in a kind of surge tank (fuel accumulation chamber) called a common rail, and the pressure of the high-pressure fuel is fed back based on a signal from a pressure sensor attached to the common rail. The fuel is supplied to the fuel injection valve of each cylinder via an injection pipe. Each fuel injection valve is provided with an electromagnetic valve that adjusts the back pressure of the push rod that presses the needle valve, and fuel is injected by opening the needle valve in accordance with this back pressure. I have.

A fuel injection control device disclosed in Japanese Patent Application Laid-Open No. H11-132077 is known as a device for correcting and controlling the fuel injection timing. This supplies fuel directly to the combustion chamber with the spark plug,
The combustion state in the combustion chamber is determined by the ion detection circuit, and when it is determined that the combustion state has deteriorated, the fuel injection timing is corrected.

[0004]

In a common rail type fuel injection control device, for example, as shown in FIG. 2 of Japanese Patent Application Laid-Open No. 62-258160, a fuel injection valve is provided corresponding to the start and end timings of fuel injection. The energization time to the solenoid valve is adjusted. As described above, this solenoid valve is not configured to directly drive the needle valve. In other words, by opening the solenoid valve, the back pressure of the push rod that drives the needle valve is reduced, the resultant force of this back pressure and the set load of the spring, the fuel reservoir of the needle valve and the valve element of the needle valve. When the balance between the resultant force and the pressure applied to the upstream side of the seat portion is lost, the needle valve is opened and fuel is injected.

[0005] However, the diameter of the above-mentioned seat portion is
Variations are likely to occur due to dimensional tolerances of the needle valve and the nozzle body, and the diameter of the seat portion tends to increase with time due to wear of the seat due to prolonged operation. As described above, in the case where the diameter of the seat portion, that is, the pressure receiving area is different for each of the fuel injection valves of the plurality of cylinders, if the drive control of each fuel injection valve is attempted by the same control signal, the injection amount and the injection timing of each fuel injection valve Causes variation. Similarly, if there is variation in the friction of the needle valve of each fuel injection valve due to variation in the dimensional accuracy of the push rod that presses the needle valve, etc., when trying to control the injection timing and injection amount with the same control signal, Again, the injection amount and the injection timing for each fuel injection valve vary.

[0006] If the injection amount and the injection timing of such a plurality of fuel injection valves vary, the control accuracy is reduced, the combustion performance is reduced, and the engine torque and the mechanical speed between the cylinders are reduced. Since it is different, unpleasant vibration may occur particularly at the time of idling.

In normal single-stage injection in which fuel is injected only once during one cycle, the above-described vibration during idling is controlled by controlling idle speed, etc., although fuel consumption is slightly deteriorated. It can be suppressed to some extent. However, for example, when the fuel is injected in a plurality of times during one cycle, that is, when the so-called pilot injection for injecting the fuel before the injection of the main fuel is performed, the pilot injection timing and the pilot injection amount are also different from each fuel injection valve. It changes due to the variation for each. Since the pilot injection amount is very small, the error is likely to be large.As a result, the fuel by the pilot injection does not ignite or burns excessively, and the exhaust performance and the sound vibration performance are greatly deteriorated. May be invited.

Further, even under the operating conditions other than the idling time, if the injection timing and the injection amount vary among the fuel injection valves of each cylinder as described above, the (0.5 order) vibration of the engine deteriorates, There is a possibility that the output performance in a high load region is reduced, smoke is deteriorated, or the like.

On the other hand, in a fuel injection control device as disclosed in Japanese Patent Application Laid-Open No. H11-132077, fuel supply timing is corrected by detecting deterioration of combustion in a combustion chamber. Corresponding to engines, especially diesel engines with pilot injection, is not very useful. This is because even if the pilot injection is not normal, an abnormality in the pilot injection cannot be detected as long as the main fuel is burning for the time being.

The present invention has been made in view of such conventional problems, and an object of the present invention is to eliminate variations in the injection amount and the injection timing for each fuel injection valve of each cylinder.

Another object of the present invention is to suppress engine vibration during idling.

[0012]

The fuel injection control device of the present invention is applied to a diesel engine provided with a fuel injection valve for injecting fuel into a combustion chamber for each cylinder.

According to a first aspect of the present invention, there is provided a fuel injection control device for setting a reference injection amount and a reference injection timing of fuel injected from the fuel injection valve according to an engine operating state, Means for determining a state, and means for detecting an engine speed for each cylinder, wherein when the idle stable state is determined, the reference injection amount is determined based on the engine speed for each cylinder. Is calculated for each fuel injection valve, and based on this injection amount correction value, the injection timing correction value of the reference injection timing is calculated for each fuel injection valve, and these injection amount correction values and The reference injection amount and the reference injection timing are corrected for each fuel injection valve based on the injection timing correction value.

As described above, when the idling state is stable, the injection amount correction value and the injection timing correction value of each fuel injection valve are calculated, and correction is performed based on these correction values. Even if it is not performed, it is possible to make a fine correction for each fuel injection valve.

For example, the fuel injection valve of one cylinder A has a delayed fuel injection timing as compared with the fuel injection valve of another cylinder due to deterioration over time, manufacturing errors, etc. The operation performed when the fuel injection control device according to the present invention is in the idling stable state when is relatively small will be described. In this case, since the torque of the cylinder A and the engine speed are relatively smaller than those of the other cylinders, first, the injection amount correction value is increased on the increasing side so as to compensate for the decrease in the engine speed. Is set to Next, a deviation of the fuel injection timing is estimated based on the injection amount correction value, and an injection timing correction value is set so as to cancel the deviation.

Preferably, when the injection amount correction value is on the increasing side as in the invention according to claim 3, the injection timing correction value is on the advance side and the injection amount correction value is on the decreasing side. In this case, the injection timing correction value is set to a value on the retard side. In the above case, since the injection amount correction value is a value on the increasing side, the injection timing correction value is set to a value on the advance side so as to offset the amount of retardation.

Although a detailed description is omitted, when the fuel injection timing of the fuel injection valve of a certain cylinder A is relatively advanced and the fuel injection amount is relatively large, the above case is reversed. Then, the injection amount correction amount is set to a value on the decrease side, and the injection timing correction amount is set to a value on the retard side.

The reference injection amount and the reference injection timing of the fuel injection valve of each cylinder are corrected based on the injection amount correction value and the injection timing correction value thus set. As a result, the difference between the injection timing and the injection amount of each fuel injection valve is accurately corrected, the injection characteristics are made uniform among the plurality of fuel injection valves, and the variation in torque and engine speed between cylinders is eliminated. As a result, engine vibration and the like during idling can be effectively suppressed.

Further, since the injection amount correction value and the injection timing correction value set in this way are corrections caused by variations in the injection characteristics of each fuel injection valve, the amount of change in the operation state changes. Is small.

Therefore, even in an operating state other than the idling stable state, for example, the reference injection amount and the reference injection timing are set based on the injection amount correction value and the injection timing correction value. By performing correction for each injection valve, it is possible to effectively correct variations in injection characteristics for each injection valve.

In other words, these correction values can be reflected even in an operating state other than the idling state.
In the invention according to the first aspect, there is provided storage means for storing an injection amount correction value and an injection timing correction value for each fuel injection valve.

Further, since these correction values are values based on the individual differences of the fuel injection valves, when a plurality of fuel injections are performed during one cycle, these correction values are applied to each injection control. Can be applied.

For example, in the invention according to claim 6, pilot injection means for injecting pilot fuel separately from main fuel injection during one cycle, and a reference pilot injection amount and a reference pilot injection timing of the pilot injection amount are set. Pilot injection setting means, and when at least the idle stable state is determined, the reference pilot injection amount and the reference pilot injection timing are set for each fuel injection valve based on the injection amount correction value and the injection timing correction value. It is corrected every time.

The injection amount at the time of such pilot injection is:
Since the amount is very small compared to the injection amount of the main fuel, it is easy to cause variation in combustion due to variation in injection characteristics, and it is particularly effective to apply the present invention.

More preferably, when it is determined that the engine is in the idling stable state, the injection amount correction value is corrected to a corrected injection amount correction value based on the injection timing correction value. The reference injection amount and the reference injection timing are corrected based on the injection timing correction value and the corrected injection amount correction value.

That is, the correction value of the corrected injection amount is set so as to absorb the fluctuation of the engine torque and the engine speed accompanying the correction of the injection timing to the advance or retard side by the injection timing correction value. The reference injection amount can be corrected with higher accuracy based on the injection amount correction value.

According to a second aspect of the present invention, the fuel injection valve has a needle valve for opening and closing the fuel injection nozzle in accordance with the operating oil pressure, and an electromagnetic valve for adjusting the operating oil pressure to the needle valve. By controlling the operation of each solenoid valve,
The injection timing and the injection amount of each fuel injection valve are controlled.

As described above, in the fuel injection valve of the type in which the needle valve is driven to open and close in accordance with the operating oil pressure, the needle valve and the fuel injection nozzle suffer from dimensional tolerances, deterioration over time, variation in friction of the needle valve, and the like. Since individual differences easily occur in the injection characteristics of the fuel injection valves, the present invention is particularly suitable for the present invention which can eliminate variations in the injection characteristics of each fuel injection valve.

The invention according to claim 7 is characterized in that it has a fuel pressure accumulating chamber (common rail) for supplying a common high-pressure fuel to a plurality of fuel injection valves provided for each cylinder.

In the case where a common high-pressure fuel is supplied to a plurality of fuel injection valves, only the correction amount of the fuel injection amount and the injection timing of each fuel injection valve can be accurately determined by the above-described correction control according to the present invention. It is particularly suitable for the present invention because it allows extraction.

[0031]

As described above, according to the present invention, in the idling stable state, the injection amount correction value and the injection timing correction value are calculated for each fuel injection valve, and these correction values are used. Therefore, the variation of the injection characteristics of each fuel injection valve can be accurately corrected without being greatly affected by the combustion state or the like. As a result, the injection amount and injection timing of each fuel injection valve are made uniform,
Variations in engine torque and engine speed of each cylinder can be suppressed, and combustion performance and operating performance can be improved.

In particular, engine vibration during idling due to variations in engine torque and engine speed for each cylinder can be reliably suppressed.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a fuel injection control device according to the present invention is applied to an in-line four-cylinder diesel engine will be described below in detail with reference to the drawings.

FIG. 1 shows the overall configuration of a fuel injection control device according to this embodiment, and FIG. 2 shows a fuel injection valve 1 provided in a combustion chamber of each cylinder.

As shown in FIG. 2, the fuel injection valve 1 is composed of an injection nozzle holder 2, an injection nozzle 3, and an injection valve driving unit 4. The injection nut holder 2 and the injection nozzle 3 are retained by a retaining nut 5. Are integrated. A needle valve sliding hole 6 and a fuel reservoir 7 are formed in the injection nozzle 3, and a fuel injection nozzle hole 8 communicating with the fuel reservoir 7 is formed at the tip. The large diameter portion 10 of the needle valve 9 is slidably fitted in the needle valve sliding hole 6.
The large diameter portion 10 of the needle valve 9 has a connecting portion 11 formed therein, and a small diameter portion 12 and a valve body portion 13 are integrally formed at a lower end portion. Then, the seat portion X is opened and closed by the valve body portion 13, and the injection from the nozzle hole 8 is turned on / off.

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

An injection valve driving section 4 for driving the needle valve 9 and the push rod 14 is disposed above the injection nozzle holder 2. An electromagnetic valve 22 is built in the injection valve driving section 4, and power is supplied through a connector section 23.
The solenoid valve 22 opens and closes a communication passage 39 that communicates the back pressure chamber 38 of the push rod 14 with the low pressure chamber (fuel tank), thereby adjusting the pressure (operating oil pressure) of the fuel in the back pressure chamber 38 of the push rod 14. Is done. The needle valve 9 is driven to open and close according to the fuel pressure in the back pressure chamber 38, and the fuel injection is controlled to be turned on and off. The injection valve control drive unit 4
Is connected to the injection nozzle holder 2 by a lock nut 25. The leaked fuel in the injection valve 1 is returned from the fuel outlet 24 into the fuel tank.

The fuel supply passage 1 is provided in the injection nozzle holder 2.
9 is formed, one end of which is exposed to the surface of the injection nozzle holder 2, and the other end of which is communicated with the fuel storage chamber 7. Further, an inlet 18 is mounted on the surface of the injection nozzle holder 2 and communicates with the fuel supply passage 19.

Then, the high-pressure fuel of the common rail 26 described later is supplied to the fuel storage chamber 7 through the inlet 18 and the fuel supply passage 19. Normally, the needle valve 9 is urged in the closing direction by the spring 16 via the push rod 14, but when the solenoid valve 22 is controlled to open from this state, the high-pressure fuel in the back pressure chamber 38 passes through the communication path 39. , The pressure in the back pressure chamber 38 decreases. As a result, the needle valve 9 and the push rod 14 are
The valve is opened by the fuel pressure applied to the fuel cell and fuel is injected.

Such a fuel injection valve 1 (1A to 1D)
Are the cylinders # 1, # 2, # 3, and # 4, as shown in FIG.
Each is provided for each. Each injection valve 1 is configured to directly inject fuel into a combustion chamber of a corresponding cylinder, and is connected to a common high-pressure fuel accumulator, a so-called common rail 26, via an injection pipe 27. The common rail 26 has a supply pipe 28 and a check valve 29.
Is connected to the high-pressure supply pump 30. The high-pressure supply pump 30 boosts the pressure of the fuel sucked from the fuel tank 31 through the fuel filter 32 and the fuel feed pump 33, and controls the fuel to a predetermined high pressure. That is, the drive shaft 34 having the cam lobe rotates in synchronization with the rotation of the engine, the piston in the high-pressure supply pump 30 reciprocates, and the fuel from the fuel feed pump 33 is pressurized and supplied to the common rail 26. Also,
The high-pressure supply pump 30 is provided with a discharge amount control solenoid valve 35 for always controlling the common rail pressure to a desired pressure.

The electronic control unit (ECU) 36 has a memory and a CPU for storing and executing various engine control processes. As will be described later, the electronic control unit (ECU) 36 is determined from signals from the engine rotation sensor 40 and the accelerator opening sensor 41 and the like. Engine speed (engine speed) Ne, accelerator opening Ac
c, etc., depending on the operating state of the engine such as c.
A control signal is output to the electromagnetic valve 22 (FIG. 1) so that the fuel injected from the fuel injection valve has an appropriate fuel injection amount and fuel injection timing. The electronic control unit 36 includes a pressure sensor 37
The feedback control of the discharge amount of the common rail 26 is performed based on the common rail pressure detected by the above.

FIG. 3 is a flowchart showing a control flow according to this embodiment. The routine of FIG. 3 is repeatedly executed at least at a cycle of 180 ° CA or less so as to be applied to each of the injection valves 1A to 1D.

In S (step) 1, the engine speed N
Various engine operating conditions such as e and accelerator opening Acc are read.

At S2, the reference injection amount Qm, the reference injection timing ITm, the reference pilot injection amount Qpm, and the reference pilot injection timing ITp are set according to the operating conditions read at S1.
m and the reference common rail pressure Pm are calculated.

These values correspond to all the fuel injection valves 1A to 1A.
It is applied to D in common, and the definition of each value is shown in FIG.
Shown in In this embodiment, in a predetermined operating state, fuel injection is performed a plurality of times during one cycle. That is, in the predetermined operation state, pilot injection for injecting pilot fuel Fb is performed prior to injection of main fuel Fa.

The advance amount (crank angle) from the compression top dead center to the injection (start) timing of the main fuel Fa is defined as the reference injection timing ITm, and the injection period from the reference injection timing ITm is defined as the reference injection amount Qm. The advance amount (crank angle) from the reference injection timing ITm to the start of injection of the pilot fuel Fb is defined as a reference pilot injection timing ITpm, and the injection period from the reference pilot injection timing ITpm is defined as a reference pilot injection amount Qpm. ing.

These reference values are calculated by referring to a control map shown in FIG. 5, for example, based on the engine speed Ne and the accelerator opening Acc. The maps (a) to (e) shown in FIG.
6 is stored in the memory. For example, as shown in FIG. 5C, the reference pilot injection amount Qpm is set to 0 (zero) in a region where low-temperature premix combustion is performed, that is, in a low-speed low-load region (I) or a high-speed high-load region (IV). , In the other areas (II) and (III), predetermined values Qp1,
Qp2 is set.

Note that, if necessary, these reference values may be corrected based on the cooling water temperature or the like.

Referring again to FIG. 3, in subsequent S3, it is determined whether or not the engine is in the idling stable state. For example, if the ON state of the idle switch has continued for a certain time, it is determined that the idle switch is in the stable state, and the process proceeds to S4.

At S4, the engine speed Ne for each cylinder is determined.
i (i = 1, 2, 3, 4) is calculated. For example, as shown in FIG. 6, the average engine speed for a predetermined period (engine speed sampling period) ΔD is sequentially read for each cylinder based on the detection signal of the engine speed sensor 40, and the The engine speed Nei is sequentially calculated. This sampling period ΔD is preferably set during an expansion stroke in which variations in engine torque and engine speed for each cylinder are most likely to appear, as shown in FIG.

In S5, the fuel injection valve 1 of each cylinder is set so that the engine speed of each cylinder becomes a uniform value Nem.
An injection amount correction value ΔQi for the reference injection amount Qm is calculated. That is, the fuel injection amount is corrected for each individual fuel injection valve 1 so that the engine speed does not vary among the plurality of cylinders and becomes a constant value Nem. For example, the relationship shown in FIG. 7 is stored in advance in the memory of the electronic control unit 36, and the injection amount correction value ΔQi for each cylinder is calculated based on this relationship. That is, as shown in FIG.
As the value obtained by subtracting the engine speed Nei from the target value Nem increases, the injection amount correction value ΔQi increases, and as the value decreases, the injection amount correction value ΔQi decreases.

In S6, an injection timing correction value ΔITi with respect to the reference injection timing ITm is calculated based on the injection amount correction value ΔQi for each cylinder. Specifically, data as shown in FIG. 8 is stored in advance in the memory of the electronic control unit 36, and ΔITi is determined based on this data. That is, as shown in FIG. 8, the injection timing correction value ΔITi is increased toward the advance side as the injection amount correction value ΔQi increases, and the injection timing correction value ΔITi decreases as the injection amount correction value ΔQi decreases.
To the retard side.

In S7, the injection timing correction value ΔIT for each cylinder
i, the injection amount correction value ΔQ for each cylinder calculated in S4
The corrected injection amount correction value ΔQin is calculated by correcting i. For example, data as shown in FIG. 9 is stored in the memory of the electronic control unit 36 in advance, and the corrected injection amount correction value ΔQin is determined based on this data. That is, as shown in FIG. 9, as the injection timing correction value ΔITi increases toward the advance side, the correction injection amount correction value ΔQin decreases, and as the injection timing correction value ΔITi increases toward the retard side, the correction injection amount increases. The correction value ΔQin is increased.

In S8, the final control command values are calculated and set by reflecting the correction values calculated in S5 to S7. That is, for each fuel injection valve 1, the corrected fuel injection amount correction value ΔQin is added to the reference fuel injection amount Qm to calculate and set the final fuel injection amount Qi, and the fuel injection timing correction value Δm is added to the reference fuel injection timing ITm.
The final injection timing ITi is calculated and set by adding ITi. The correction values ΔQin and ΔITi for the main fuel injection are also applied to the pilot injection. That is, for each fuel injector 1 of each cylinder, the corrected pilot injection amount correction value ΔQin is added to the reference pilot injection amount Qpm to set the final pilot injection amount Qpi, and the injection timing correction value is added to the reference pilot injection timing ITpm. The final pilot injection timing ITpi is set by adding ΔITi. Furthermore, S
The reference common rail pressure Pm calculated in 2 is set as the final common rail pressure P.

The reference common rail pressure is controlled based on such set values, and the fuel injection valve 1 of each cylinder is controlled.
Each time, the fuel injection amount and the fuel injection timing are independently controlled. Actually, the drive pulse signal of the solenoid valve 22 of each fuel injection valve 1 is controlled.

The processing of S5 to S8 is described with reference to FIG.
For further discussion. FIG. 10A shows the solenoid valve 22.
The timing a1 corresponds to the reference injection timing ITm, and the period a2 corresponds to the reference injection amount Qm. (B) to (d) show some examples of the lift characteristic of the needle valve 9 that follows the reference drive pulse characteristic of the solenoid valve 22 with a slight response delay.

As shown in (b) to (d), the lift characteristics of the needle valve 9 include factors such as variations in friction of the needle valve 9, dimensional variations of the needle valve 9 and the seat portion X, and deterioration with time. Therefore, there are some individual differences. In particular,
Compared to the standard needle valve lift characteristics (b), (c),
As shown in (d), the variation of the rising of the needle valve is
It tends to be relatively larger than the variation in the fall.

Therefore, when the needle valve 9 of a certain cylinder rises relatively early, as shown in FIG. 7 (f), the fuel injection timing is substantially advanced and the fuel injection amount is increased. Tends to be larger than those of other cylinders.

In such a case, in this embodiment, first,
The injection amount correction value ΔQi is set to a decreasing value (negative value) so as to reduce an unnecessary increase in (torque) of the engine speed (S5 in FIGS. 7 and 3 and (e) in FIG. 11). )
reference). Next, based on such a decrease in the injection amount correction value ΔQi, it is recognized that the needle valve rises too early,
In order to offset the leading angle of the rise, the injection timing correction value ΔITi is set to a value on the retard side (FIG. 8, S6).
(See (i) of FIG. 11). Further, in order to compensate for the decrease in the engine speed (torque) due to the retardation of the injection timing, a final corrected injection amount correction value ΔQin is obtained by slightly increasing the injection amount correction value ΔQi. (Fig. 9,
S7, see (i) of FIG. 11). Therefore, the lift characteristic (j) obtained based on the injection timing correction value ΔITi and the corrected injection amount correction value ΔQin is almost the same as the standard lift characteristic (b).

Conversely, as shown in FIG. 11 (h), when the rising of the needle valve 9 of a certain cylinder is later than that of the other injection valve 1, the fuel injection timing is relatively retarded. The fuel injection amount tends to decrease, and the torque of the cylinder and the engine speed relatively decrease.

In such a case, in this embodiment, first, the injection amount correction value ΔQi of the cylinder is set to a value on the increase side (plus value) so as to compensate for the decrease in the engine speed (torque) ( (See S5 in FIGS. 7 and 3 and (g) in FIG. 11).
Next, based on such an increase correction of the injection amount correction value ΔQi, it is recognized that the rising of the needle valve is too slow, and the injection timing correction value ΔITi is set to a value on the advance side so as to offset this delay amount. (FIG. 8, S6, (k) of FIG. 11)
reference). Further, in order to reduce the increase in the engine speed (torque) due to such advance of the injection timing, the corrected injection amount correction value ΔQi obtained by slightly reducing the injection amount correction value ΔQi.
n is calculated (see FIGS. 9, S7, and (k) of FIG. 11). Lift characteristics (l) obtained based on these injection timing correction value ΔITi and corrected injection amount correction value ΔQin
Is almost the same as the standard lift characteristic (b).

Referring again to FIG. 3, in S9, the current operating conditions, the injection timing correction value ΔITi, and the corrected injection amount correction value ΔQin are learned. That is, the correction values ΔITi and ΔQin for each of the fuel injection valves 1A to 1D of each cylinder are stored in the memory of the electronic control unit 36 as the latest learning amounts ΔITip and ΔQinp. This stored content is retained even after the engine is stopped, and is reflected at the next start, in addition to S10 described later. Accordingly, high-precision fuel injection control that does not vary from cylinder to cylinder can be performed from the start of the engine, and the control accuracy is significantly improved.

If it is determined in S3 that the vehicle is not in the idling stable state, the process proceeds to S10, and the latest learning values ΔITip and ΔQinp are reflected on each control command value. That is, even in an operation state other than the idling stable state, the reference injection amount Qm, the reference injection timing ITm, the reference pilot injection amount Qpm, and the reference pilot are based on the latest ΔITip and ΔQinp for each of the fuel injection valves 1A to 1D. The injection timing ITpm is corrected, and the final control command values Qi, ITi, Qpi, ITpi and P are calculated and set.

As described above, in this embodiment, when the engine is in the idling stable state, the corrected injection amount correction value ΔQ of each of the fuel injection valves 1A to 1D is determined based on the engine speed Nei of each cylinder.
In and the injection timing correction value ΔITi are calculated, and the fuel injection amount and the fuel injection timing are corrected based on these correction values. Therefore, variations in the fuel injection amount and the injection timing for each of the fuel injection valves 1A to 1D are reduced. It can be eliminated with high accuracy. As a result, it is possible to reliably suppress engine vibration during idling due to individual differences between the fuel injection valves 1A to 1D and the like.

The corrected injection quantity correction value ΔQin and the injection timing correction value ΔITi obtained as described above are calculated for each of the fuel injection valves 1A to 1D due to variations in the dimensions of the injection valve, friction, and aging. This is the correction amount for the variation in the injection characteristics, and since the change amount is small with respect to the change in the operation state, other correction control can be performed even when applied to the operation state other than the idle operation or to the pilot injection other than the main fuel injection. The variation in the injection characteristics of each injection valve can be accurately absorbed without adversely affecting the injection characteristics.

In particular, if the injection amount or the injection timing of the pilot injection with a small injection amount varies, the exhaust performance and the sound-vibration performance may be greatly deteriorated. The injection amount and the injection timing during the injection can be easily and accurately corrected by using the same correction values ΔQin and ΔITi as those of the main fuel injection.

More specifically, these corrected injection amount correction values Δ
Since the Qin and the injection timing correction value ΔITi are stored and stored as learning values, the learning values can be used not only during the operation other than the idling time as described above, but also when the engine is started.

The present invention is not limited to the above-described embodiments, but includes various changes and improvements without departing from the spirit of the present invention. For example, the present invention can be similarly applied to a six-cylinder engine.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing the fuel injection valve of FIG. 1 alone;

FIG. 3 is a flowchart illustrating a control flow according to the embodiment.

FIG. 4 is an explanatory diagram showing the definition of each reference value.

FIG. 5 is a map for setting each reference value.

FIG. 6 is an explanatory diagram showing an engine speed sampling period.

FIG. 7 is data for setting an injection amount correction value ΔQi.

FIG. 8 is data for setting an injection timing correction value ΔITi.

FIG. 9 is data for setting a corrected injection amount correction value ΔQin.

FIG. 10 is an operation explanatory view of the embodiment.

[Explanation of symbols]

 1A to 1D: Fuel injection valve 8: Nozzle hole 9: Needle valve 22: Solenoid valve 26: Common rail 36: Electronic control unit 40: Engine rotation sensor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02M 47/00 F02M 47/00 A EF 47/02 47/02 F term (Reference) 3G066 AA07 AB02 AC09 AD12 BA22 CC06T CC08T CC14 CC64T CC66 CC67 CC68U CC70 CD26 CE22 DA01 DA04 DA09 DB01 DB07 DC04 DC09 DC18 3G301 HA02 HA06 JA04 JA05 JA24 JA37 KA07 LB06 LB11 MA11 MA18 MA23 NC01 ND01 NE01 NE06 NE11 NE12 PB08A PB08Z PE01Z PF03Z

Claims (8)

[Claims] In a diesel engine provided with a fuel injection valve for injecting fuel into a combustion chamber for each cylinder, a reference injection amount and a reference amount of fuel injected from the fuel injection valve according to an engine operating state. Means for setting an injection timing, means for determining an idling stable state, and means for detecting an engine speed for each cylinder. When the idling stable state is determined, the engine for each cylinder is determined. An injection amount correction value of the reference injection amount is calculated for each fuel injection valve based on the rotation speed, and an injection timing correction value of the reference injection timing is calculated for each fuel injection valve based on the injection amount correction value. Wherein the reference injection amount and the reference injection timing are corrected for each fuel injection valve based on the injection amount correction value and the injection timing correction value. 2. The fuel injection valve has a needle valve that opens and closes a fuel injection nozzle in accordance with an operating oil pressure, and an electromagnetic valve that adjusts the operating oil pressure to the needle valve, and controls the operation of each electromagnetic valve. 2. The fuel injection control device for a diesel engine according to claim 1, wherein the injection timing and the injection amount of each fuel injection valve are controlled. 3. When the injection amount correction value is a value on the increasing side,
When the injection timing correction value is a value on the advance side, and when the injection amount correction value is a value on the decrease side, the injection timing correction value is set to be a value on the retard side. The fuel injection control device for a diesel engine according to claim 1 or 2. 4. The fuel injection control device for a diesel engine according to claim 1, further comprising storage means for storing an injection amount correction value and an injection timing correction value for each fuel injection valve. . 5. Even in an operation state other than the idle stable state, based on the injection amount correction value and the injection timing correction value,
5. The fuel injection control device for a diesel engine according to claim 1, wherein the reference injection amount and the reference injection timing are corrected for each fuel injection valve. 6. A pilot injection means for injecting pilot fuel separately from main fuel injection during one cycle, and pilot injection setting means for setting a reference pilot injection amount and a reference pilot injection timing of the pilot injection amount. Wherein the reference pilot injection amount and the reference pilot injection timing are corrected for each fuel injection valve based on the injection amount correction value and the injection timing correction value at least when the idle stable state is determined. The fuel injection control device for a diesel engine according to claim 1. 7. A fuel injection system for a diesel engine according to claim 1, further comprising a fuel pressure accumulating chamber for supplying a common high-pressure fuel to a plurality of fuel injection valves provided for each cylinder. Control device. 8. When the idling state is determined, the injection amount correction value is corrected to a corrected injection amount correction value based on the injection timing correction value, and the injection timing correction value and the corrected injection amount correction value are corrected. The fuel injection control device for a diesel engine according to any one of claims 1 to 7, wherein the reference injection amount and the reference injection timing are corrected based on the following.