JPH01155054A - Fuel controller for diesel engine - Google Patents

Abstract

PURPOSE:To make the abatement of NOx or the like promotable by keeping off an injection lag of pilot injection attributable to supercharging. CONSTITUTION:In a Diesel engine which is provided with a supercharger 4 while constituted so as to perform pilot injection prior to the main injection of fuel, there is provided with a control means advancing injection timing of the pilot injection relatively to the main injection with the increase of supercharging pressure by the supercharger 34. In brief, an operating control value of a control rack in a fuel injection pump P in compensated at an electronic control unit 19 by the detected value of a pressure sensor 45 installed in a suction passage 41. With constitution like this, since the injection timing of the pilot injection is advance with the increase of the supercharging pressure, an ignition lag due to leanness of fuel in a combustion chamber is thus prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides fuel control for a daypil engine equipped with a supercharger and configured to perform pilot injection before main injection of fuel. It is related to the device.

(Prior Art) In general, in a diesel engine that uses compression ignition, an ignition delay may occur when the injected fuel is under conditions that make it relatively difficult to ignite, and this causes explosive combustion, causing combustion noise and NOx in the exhaust gas may increase.

As a means of suppressing such combustion noise and NOx, it is known to pilot inject a small amount of fuel prior to main injection and use this as a spark for combustion of the main injected fuel (for example, Japanese Patent Laid-Open No. 59 (Refer to Publication No.-165856).

By the way, such diesel engines are often equipped with a supercharger to send supercharging air into the combustion chamber, but conventionally, when such supercharging is performed, the pilot injection The fuel supplied into the cabin tends to be thinned out, which causes a delay in ignition relative to the main injection. As a result, the amount of premixed fuel injected before ignition increases, which causes the NOx
There was a problem in that the effect of reducing the amount of gas was weakened and the amount of unburned gas discharged also increased.

(Object of the Invention) In view of the above circumstances, the present invention prevents the ignition delay of pilot injection caused by supercharging in a supercharged diesel engine configured to perform pilot injection before main fuel injection. The object of the present invention is to provide a fuel control device capable of reducing NOx and the like.

(Structure of the Invention) The present invention provides a diesel engine equipped with a supercharger and configured to perform pilot injection before main injection of fuel, in which, as the supercharging pressure by the supercharger increases, The control means is provided for advancing the injection timing of the pilot injection relative to the main injection.

According to this configuration, the injection timing of the pilot injection is advanced as the supercharging pressure increases, thereby preventing an ignition delay due to thinning of the fuel in the combustion chamber.

(Embodiment) FIGS. 1(a) and 1(b) show a diesel engine according to an embodiment of the present invention, and this diesel engine includes a morning type fuel injection pump P as shown in FIG. It is established ().

In the figure, a camshaft 1 is rotationally driven by the driving force of a crankshaft of an engine, and a cam 3 for driving a plunger 2 is provided on the camshaft 1. On the other hand, the plunger 2 is supported in a housing 4 so as to be movable in the axial direction, and a tappet 1-roller 5 that slides on the cam 3 is attached below the plunger 2, and is urged downward by a spring 24. The situation is as follows. Therefore, the plunger 2 is reciprocated in the vertical direction by the rotation of the camshaft 1 and the cam 30.

A center hole 2a is provided at the center of the plunger 2 and extends in the axial direction to its upper end, and this center hole 2a communicates with a fuel pumping chamber 4a formed above. A fuel intake groove 6, a first lead 7, and a second lead 8, which communicate with the center hole 2a, are formed on the outer peripheral surface of the plunger 2. has a shape in which the upper edge thereof is inclined with respect to the outer circumferential surface of the plunger 2.

On the other hand, around this plunger 2, a control sleeve 9, a cam disk 101, a control sleeve 11, and a control sleeve 12 are fitted from the outside in order from below. 13 is fitted.Furthermore,
The control sleeve 12 is provided with a fuel boat 12a corresponding to the fuel intake portion 6 and the first glue portion 7, and the control sleeve 11 is provided with a cut-off boat 11a corresponding to the second glue portion 8. Fuel for injection is supplied from the fuel port 1-12a through the fuel intake groove 6 and the center hole 2a into the fuel pumping chamber 4a above the plunger 2.

The control sleeve 9 is movable only in the axial direction relative to the plunger 2 (actually, the plunger 2 moves), and has a gap-shaped disc 2 on its outer peripheral surface.
5 is fixed, and the upper end surface of this disk 25 is engaged with a control rack 14 provided within the housing 4. The horizontal movement of the control rack 14 causes the disk 25, control sleeve 9, and plunger 2 to rotate together.

The cam disk 10 is rotatable relative to the plunger 2, and the control sleeve 11 is rotatable and axially movable relative to the plunger 2. A wavy cam 10a is formed on the upper surface of the cam disk 10,
The control sleeve 11 is placed on the upper surface of this cam 10a.
A part of the F surface of the cam disc 1o is in contact with the cam disc 1o.
and ] Con 1 to 1 call racks 15 and 16 are engaged with the outer circumferential surface of the conher roll sleeve 11, respectively.

Therefore, the horizontal movement of the controller 1 to the roll rack 16 rotates the controller 1 to the roll sleeve 11, and
The horizontal movement of the control rack 15 causes the cam disc 10 to rotate, which causes the control sleeve 1 to move axially (up and down).

The control sleeve 12 is supported from below by a spring 18 and is movable only in the axial direction relative to the plunger 2. The cam disk 13 has a cam 13a similar to the cam 10a described above formed on its lower surface, and a part of the upper surface of the i-roll sleeve 12 is in contact with this cam 13a. The outer peripheral surface of this cam disk 13 is engaged with a roller rack 17, and the horizontal movement of the roller rack 17 causes the cam disk 13 to rotate, thereby causing the roller rack 17 to rotate.
- The roll sleeve 12 is adapted to move in the axial direction relative to the plunger 2.

Further, above the plunger 2, a delivery valve 2 is provided.
6, a spring 27, a delivery valve holder 28, etc. are provided, and the delivery valve holder 28 is provided with a fuel delivery port 28a communicating with the fuel pressure delivery chamber 4a.

On the other hand, each of the control racks 14 to 17 is provided with a position sensor (not shown), and the output of this position sensor is input to one ECU (control means) shown in FIGS. 1(a) and 1(b). On the other hand, this E
Drive control of each of the control racks 14 to 17 is performed by control signals output from the CU 19.

Furthermore, as shown in FIG. 1(b), this engine has a supercharging system driven by the exhaust pressure in the exhaust passage 42.
fi 43 is provided, and this supercharging 1143 supplies supercharging air from the intake passage 41 into the combustion chamber. A pressure sensor 45 is provided in this intake passage 41, and in addition to this pressure sensor 45, the above-mentioned position sensor and accelerator sensor 2 are provided.
0 (Fig. 1(a)), the detected values of the engine coolant temperature sensor 21, the engine speed sensor 22, etc. are input to the ECU 19, and the ECU 19 receives these input values and controls each rack. 14 to 17 are controlled.

In such an fS construction, the plunger 2 is driven upward by the rotation of the camshaft 1.
When the intake valve 6 is lowered to match the fuel port 12a, fuel is sucked into the center hole 2a from the fuel port 12a. Then, this plunger 2 rises again from the bottom dead center, and the lower edge of the intake manifold 6 is brought into contact with the fuel port 1.
When the plunger 2 is located above the upper edge of the plunger 2a, the center hole 2a of the plunger 2 is blocked from the outside, and the fuel is forced to be fed from the fuel feeding chamber 4a to the engine cylinder through the delivery port 28a (pilot injection The start of the).

Furthermore, the plunger t2 continues to rise, and the second glue portion 8 is cut off from the control sleeve 11 through the cutoff holes 1 to 11a.
When reaching this point, the two become in communication, and the fuel escapes to the outside from the cup 1 to the off port 11a, thereby interrupting the pressure feeding of the fuel (end of pilot injection).

When the plunger 2 further rises and the position of the second lead 8 shifts from the cut-off port 11a, both are cut off.
Pressure feeding of fuel is started again (start of main injection). Then, the first lead 7 rises to the position of the fuel boat 12a and communicates with the fuel boat 12a, so that the fuel 1 is sent back from the fuel boat 12a, and the pressure feeding is stopped again (the main injection end). Therefore, each time the plunger 2 performs one upward movement, the steps shown in FIGS. 3(a) to (d)
Pilot injection and main injection as shown by solid line 30 are repeated.

Moreover, in this structure, the timing and injection amount of the pilot injection and main injection are changed by the operation of the control racks 14 to 17.

Specifically, when the disk 13, control sleeve 9, and plunger 2 are rotated by the control rack 14, the upper edges of both leads 7.8 are formed to be inclined with respect to the plunger 2. Therefore, by the rotation of this plunger 2, each boat 11a
, 12a, the opening area of the leads 7.8 will change. For example, if the plunger 2 is rotated so that this opening area becomes larger, the end timing of the pilot injection and the main propellant will be earlier, and as a result, the injection amount of both injections will decrease, as shown in Figure 3 ( (Refer to the two-dot chain line 31 in a)) On the other hand, if the plunge v2 is rotated so that the above-mentioned frontage area becomes smaller, the end timing of pilot injection and main injection will be delayed, and as a result, the injection amount of both injections will be (See the broken line 32 in FIG. 3(a)).

Next, when the cam disc 10 is rotated by the control rack 15, this rotation causes the controllers 1 to 1 to
The roll sleeve 11 moves up and down, and its cut-off boat 1
1a moves up and down with respect to plunger 2. If this cut-off port t-11a is set above the plunger 2, the end timing of the pyrower 1 injection and the start timing of the main injection will be delayed, and this will cause the injection by the pyrower 1 injection to be delayed. As the amount increases, the amount of injection by the main injection decreases (the third
(See broken line 33 in figure (b)). Conversely, when the cutoff boat 11a is lowered relative to the plunger 2,
The end timing of the pilot injection and the start timing of the main injection become earlier, thereby reducing the amount of injection due to the pilot injection and increasing the amount of injection due to the main injection (see the two-dot chain line 34 in FIG. 3(b)).

Furthermore, when the control sleeve 11 is rotated by the control rack 6, the cutoff boat 11a and the plunger 2 rotate relative to each other, thereby causing the second lead 8 corresponding to the cutoff boat 11a to rotate. The frontage area will change. Therefore, when the control sleeve 11 is rotated so that this opening area becomes larger, the end timing of the pyrower 1 injection becomes earlier, and as a result, only the injection amount due to the pilot injection decreases, as shown in FIG. 3(C). On the other hand, if the control sleeve 11 is rotated so that the opening area becomes smaller, the end timing of the pilot injection will be delayed, and as a result, only the injection amount due to the pilot injection will increase (see the two-dot chain line 35). Broken line 36 in diagram (C)
.

Furthermore, the cam disc 1 is controlled by the control rack ] 7.
3 is rotated, the control sleeve 12 moves up and down due to this rotation, and its fuel boat 12a moves up and down with respect to both the fuel intake groove 6 of the plunger 2 and the first boat 7.

Therefore, when this fuel boat 12a is placed above the plunger 2, the start timing of pilot injection and the end timing of main injection are delayed, and as a result, the injection amount due to pilot injection is reduced and the injection amount due to main injection is delayed. increases (see broken line 37 in FIG. 3(d)).

Conversely, when the cutoff boat 11a is lowered relative to the plunger 2, the start timing of pilot injection and the end timing of main injection become earlier, thereby increasing the amount of injection by pilot injection and increasing the amount of injection by main injection. 1) 'J village decreases (same figure (
(See double-dot chain line 38 in d)).

That is, in this fuel injection pump P, the control sleeve 11.12 is rotated and axially moved relative to the plunger 2 by the operation of the control racks 14 to 17, and the combination of these movements causes pilot injection and The main injection timing and skewer can be changed as appropriate. For example, if you want to change only the injection timing of the pilot injection, you can change the injection timing of the pilot injection and the end timing of the main injection by operating the control rack 17 (FIG. 3(d)), and also change the end timing of the main injection. The control rack 14 is operated so that the amount of change in timing becomes O (see Fig. 3 (a>
), the control rack 16 may be operated to change the end timing of the pilot injection, thereby adjusting the injection amount of the pilot injection.

As shown in FIGS. 1(a) and 1(b), the operation control of these controller roll racks 14 to 17 is performed by the FCU 19, but here, as a feature of the present invention, the operation control by the pressure sensor 45 is performed by the FCU 19. The injection timings of the pyrower 1 injection and the main injection are controlled according to the operating state including the detected supercharging pressure.

The fuel control operation actually performed by this ECU 19 is as follows:
This will be explained based on the flowcharts of FIGS. 4 and 5.

In Fig. 4, first, the driving state detected by the accelerator sensor 20 etc. is read (Sftsub S1).
, After that, basic MAP III is started (Step 32 >. Here, first, based on the operating state read in step S1 above, the ignition is set to occur near the compression top dead center, taking into account the time from injection to ignition. The pilot injection timing is set to , and the main injection timing is set so that the main injection starts in time with ignition.

Then, based on the injection timing and injection amount of the pilot injection and main injection obtained in this way, the output to each of the racks 14 to 17 is calculated accordingly, that is, the output of the pump actuator 1-1 is calculated (step S3),
Furthermore, the control value calculated in step S3 above is corrected according to the boost pressure detected by the pressure sensor (
Step s4).

This correction routine is shown at 70-diaert in FIG. In the figure, first, the operating condition is the supercharging pressure (P
, A) is read (step 351), and it is determined whether this supercharging pressure is above a certain value (step 55).
2). If it is above a certain value, a correction value is calculated according to the boost pressure (step $53).

This correction value is set based on the graph in FIG. 6(a). That is, as the boost pressure increases, the injection timing of the pilot injection is advanced (broken line 61 a), and the injection timing of the main injection is kept constant (solid line 62).
a). Accordingly, the relationship between the actual injection timing of pilot ll1l injection and main injection and supercharging pressure is as shown by the broken line 61b and the solid line 62b in FIG. 6(b), respectively.

After converting the correction value thus set into an output value to each rack (step 554), the process returns to the main routine shown in FIG. On the other hand, the above step S5
If the boost pressure is not above a certain value in step 2, no correction is made using the boost pressure.

After returning to the main routine, the control values set and corrected as described above are transferred to each control rack 14~
At the same time, each rack position is read (step S6), and the output of the control value is continued until a predetermined rack position is reached (step S7).
).

As described above, in this device, in the correction routine S4, the injection timing of the pilot injection is advanced with respect to the main injection according to the boost pressure, so that the injection amount in the combustion chamber is increased due to the increase in the boost pressure. When It is converted to gas and oil, it is possible to prevent the ignition caused by the pilot injection from being delayed with respect to the main injection, thereby reducing NO
It is possible to reduce x.

In the present invention, the injection timing of the pilot injection can be advanced relative to the injection timing of the main injection, so for example, as shown by the broken line 71 in FIG. Alternatively, the injection timing of the main injection may be delayed as the supercharging pressure increases, as shown by a solid line 72 in the figure.

In this case, the ignition timing is slightly delayed compared to the above embodiment,
Combustion occurs after the compression top dead center, and increases in pressure and combustion temperature are suppressed, making it even more advantageous to reduce NOx and the like. Furthermore, when the timing of the pilot injection is kept constant in this way, if the injection amount to the pylon 1 is increased as the boost pressure increases, as shown by the broken line 81 in FIG. It is possible to more actively improve the conversion of gas to oil.

Note that in the above embodiment, a single fuel injection pump P performs pilot injection and main injection, but
The present invention is not limited to this, but can also be applied to a device that separately performs pilot injection and main injection using two systems of fuel injection means.

(Effects of the Invention) As described above, the present invention provides a
3. With the increase in supercharging pressure from the supercharger, the injection timing of the pilot injection is advanced relative to the main injection, so the increase in supercharging pressure causes the injected fuel in the combustion chamber to ignition delay of the pilot injection due to this can be prevented, thereby reducing the N
This has the effect of reducing Ox, etc.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) show diagrams in one embodiment of the present invention.
tt engine and a structural diagram showing the input and output of the ECU in the same engine. Figure 2 is a cross-sectional view of the fuel vent 1 installed in the engine. Figures 3 (a) to (d) are the operations of each sleeve. Figures 4 and 5 are graphs showing the timing and amount of main injection and pilot injection adjusted by FCIJ.
Flowcharts 1 to 6 (a) are graphs showing the relationship between boost pressure and injection timing correction amount, and (b) is a graph showing the relationship between boost pressure and injection timing correction amount.
) is a graph showing the relationship between boost pressure and injection timing, FIG. 7 is a graph showing the relationship between boost pressure and injection timing in another embodiment, and FIG. 8 is a graph showing the relationship between boost pressure and injection seal. This is a graph showing. P...Fuel injection pump, 19...ECU (control means), 43...Supercharger, 45...Pressure sensor. Patent applicant Mazda Co., Ltd. Representative Patent attorney Etsushi Kogane
Patent Attorney Chief 1) Masamukai Patent Attorney
Sheet Metal Genjin No. 7 Ash Supply No. 8 Weekly Wages

Claims (3)

[Claims] 1. In a diesel engine equipped with a supercharger and configured to perform pilot injection before main injection of fuel, the injection timing of the pilot injection is changed to main injection as the supercharging pressure by the supercharger increases. 1. A fuel control device for a diesel engine, comprising a control means for advancing the fuel relative to the fuel. 2. The fuel control device for a diesel engine according to claim 1, further comprising control means for keeping the injection timing of the main injection constant and advancing the injection timing of the pilot injection as the boost pressure increases. . 3. 2. The fuel control device for a diesel engine according to claim 1, further comprising control means for delaying the injection timing of main injection as boost pressure increases.