JPH05240095A - Fuel injection controller of engine - Google Patents

Abstract

PURPOSE:To increase the effective pressure in a combustion stroke in a constant load driving state by installing a control means which controls the injection frequency of a fuel injection valve per one cycle of an engine and the number of injection cylinders so as to be thinned out according to a load driving state of the engine. CONSTITUTION:A fuel injection valve 6 sprays fuel to be fed out of a fuel tank into a cylinder 4 directly. A control means 10 consists of an arithmetic processing part 12 and an injection valve control part 14. This arithmetic processing part 12 inputs an intake vacuum signal and an engine speed signal or the like as a driving state signal of an engine 2 from a sensor group including a pressure sensor 16 and an engine speed sensor 18 or the like, judging a load driving state from these signals. Then it calculates a trigger signal driving the fuel injection valve 6 according to the load driving state judged, outputting it to the injection valve control part 14 which drives the fuel injection valve 6 in accordance with the trigger signal being inputted out of the arithmetic processing part 12, controlling it so as to be thinned out according to the load driving state of the engine, thus effective pressure in a low load driving state is increased.

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 an engine, and more particularly, it can simplify the structure and reduce the cost, and increase the indicated mean effective pressure in the combustion stroke under a low load operation condition. The present invention relates to a fuel injection control device for an engine capable of reducing combustion fluctuations and securing a sufficient scavenging time to improve combustibility.

[0002]

2. Description of the Related Art Some engines mounted on vehicles and the like are equipped with an electronic fuel injection control device as a countermeasure for improving the harmful components of exhaust gas and improving the fuel consumption rate. There is a fuel injection control device in which a fuel injection valve is attached so as to face a cylinder of an engine that completes one cycle in two strokes, and the fuel is directly injected into the cylinder by the fuel injection valve.

As such a fuel injection control device for an engine, Japanese Patent Application Laid-Open Nos. 1-247731 and 3-3 are available.
There is one disclosed in Japanese Patent No. 3449.

The one disclosed in Japanese Patent Laid-Open No. 1-247731 discloses an engine equipped with a fuel injection valve for injecting fuel directly into the cylinder of the engine which completes one cycle in two strokes. By controlling so that the number of injections of the fuel injection valve is thinned out at some times, scavenging during idle operation is improved and combustion is stabilized.

The one disclosed in Japanese Patent Laid-Open No. 3-33449 is provided with a fuel injection valve for injecting fuel toward a gap of a spark plug in a cylinder of an Otto cycle engine. By controlling the fuel injection by the fuel injection end timing set according to the gap arrival time and the fuel injection start timing set according to the fuel injection amount with respect to this fuel injection end timing, the combustibility is improved. It is intended.

[0006]

[Problems to be Solved by the Invention] By the way, 1 in 2 strokes
In the engine that completes the cycle, intake and compression are performed while the piston is rising, and combustion gas is discharged while the piston is descending and scavenging that discharges combustion gas by the intake introduced. In the case where such an engine is provided with a fuel injection valve that directly injects fuel into the cylinder, a device that controls so as to change the injection pressure according to the load state of the engine is generally required. To do.

However, such an apparatus for controlling the injection pressure has a disadvantage that the structure is complicated and the cost is increased. Further, in the engine that completes one cycle in the two strokes, combustion gas remains in the cylinder in a low load operation state such as idle operation, and it is difficult to perform good scavenging. If the fuel is controlled to be injected into the fuel cell, the combustibility is deteriorated.

[0008]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention relates to an engine equipped with a fuel injection valve for directly injecting fuel into a cylinder of the engine which completes one cycle in two strokes. In the fuel injection control device,
A control means is provided for controlling the number of injections and / or the number of injection cylinders of the fuel injection valve per one cycle of the engine so as to be thinned according to a load operating state of the engine.

[0009]

According to the structure of the present invention, the control means causes
Conventional injection pressure is controlled by controlling the number of injections and / or the number of injection cylinders of a fuel injection valve per cycle of an engine that completes one cycle in two strokes so as to be thinned according to the load operating state of the engine. In that case, the structure is not complicated, and the indicated mean effective pressure in the combustion stroke in the low load operation state can be increased and a sufficient scavenging time can be secured.

[0010]

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

1 to 5 show an embodiment of the present invention. In FIG. 1, 2 is an engine, 4 is a cylinder, 6 is a fuel injection valve, 8 is a fuel injection control device, and 10 is a control means.

The engine 2 is a so-called two-stroke engine (two-stroke engine) that completes one cycle in two strokes.
Is. The engine 2 includes a fuel injection valve 6 that faces the inside of the cylinder 4. The fuel injection valve 6 directly injects fuel fed from a fuel tank (not shown) into the cylinder 4. The fuel injection control device 8 for controlling the fuel injection valve 6 is provided with a control means 10.

The control means 10 comprises an arithmetic processing unit 12 and an injection valve control unit 14. The arithmetic processing unit 12 receives, for example, an intake negative pressure signal, a rotation speed signal, or the like as an operation status signal of the engine 2 from sensors such as the pressure sensor 16 and the rotation speed sensor 18, and determines the load operation status from these operation status signals. It is determined and a trigger signal for driving the fuel injection valve 6 is calculated according to the determined load operating state, and the injection valve control unit 14
Output to. The injection valve control unit 14 outputs a drive signal to the fuel injection valve 6 according to the trigger signal input from the arithmetic processing unit 12 to drive the fuel injection valve 6.

The control means 10 controls the number of injections and / or the number of injection cylinders of the fuel injection valve 6 per cycle of the engine 2 so as to thin out the number of injections according to the load operating state of the engine 2.

For example, as shown in the current example of Table 1, the control means 10 is controlled to change the injection pressure bar from 30 to 100 bar in the conventional case. Is the operating cylinder and the injection pressure bar is a constant 100 bar, and the number of injections Pa1 per one cycle (two strokes) of the engine 2 that completes one cycle in two strokes is determined according to the load operating conditions <1> to <4>. "1"
Control is performed so as to thin out to "0.25".

[0016]

[Table 1]

In Example A of Table 1, Nsel /
Ncyl is the number of operating cylinders Nse that operate by injecting fuel
It is the ratio of l to the total number of cylinders Ncyl. Therefore, in the case of "1", all the cylinders 4 are operating. In addition, <1> is a fully open to low load operating state, <2> is a low load (shaft average effective pressure 2 bar or less) operating state, <3> is an idle operating state, <4> is a no-load operating state (idle speed). The above is high rotation).

In the fuel injection control device 8, all the operating cylinders are used and the injection pressure bar is kept constant, and as shown in FIG. 4> The trigger signal according to 4> is output. The injection valve control unit 16 determines the number of injections Pal of the fuel injection valve 6 per one cycle (two strokes) of the engine 2 in accordance with the input trigger signals <1> to <4> to determine the load operation state <1> to Depending on <4>, 1palse / 1cycle-1pals
Control to thin out e / 4 cycles.

That is, the number of injections is 1 pulse / 1 cycle in the fully open to low load operating state <1>, and 1 pulse / cycle in the low load (shaft average effective pressure 2 bar or less) operating state <2>.
2 cycles, 1 pulse in idle operation <3>
4 cycles, 0 palse under no-load operation (high speed above idle speed) <4>.

In this way, the control means 10 sets all of the working cylinders and the injection pressure bar to a constant value as shown in Example A of Table 1 in contrast to the current example of controlling the injection pressure of Table 1. By controlling the number of injections Pal per cycle (two strokes) of the engine 2 to be thinned out to "1" to "0.25" in accordance with the load operating states <1> to <4>, the conventional injection pressure is reduced. The structure does not become complicated as in the case of control, and the indicated mean effective pressure in the combustion stroke in the low load operation state can be increased and sufficient scavenging time can be secured.

Therefore, the structure can be simplified and the cost can be reduced, and the indicated mean effective pressure in the combustion stroke under the low load operation condition can be increased to reduce the combustion fluctuation. Combustibility can be improved by ensuring a sufficient scavenging time.

The present invention is not limited to the above-mentioned embodiment A, and various application modifications are possible.

For example, in Example B of Table 2, all the working cylinders are used, and the injection pressure bar is 100 bar in the fully opened to low load operation state <1> and the low load (axial average effective pressure 2
bar or less) Operating state <2> and idle operating state <3>
The control is performed so that the injection number Pal per cycle (two strokes) of the engine 2 is fully opened to a low load operation state <1> and a low load (shaft average effective pressure 2 bar or less) operation. "1" in state <2> and "0.5" in idle operation state <3>
It is controlled so as to be thinned out in accordance with the load operating state of.

[0024]

[Table 2]

As described above, all the operating cylinders are used, the injection pressure bar is controlled so as to be changed according to the load operating state, and the injection number Pa1 is controlled so as to be thinned according to the load operating state. The indicated mean effective pressure in the combustion stroke can be further increased to reduce the combustion fluctuation, and a more sufficient scavenging time can be secured to improve the combustibility.

In the embodiment C of Table 2, the injection pressure bar is kept constant and the total number of operating cylinders Nsel is Ncyl.
Ratio of Nsel / Ncyl to full open-low load operating state <1> and low load (shaft average effective pressure 2 bar or less) "1" in operating state <2> and "2" in idle operating state <3> In addition, the number of injections Pal per cycle (two strokes) of the engine 2 is set to "1" in the full open to low load operating state <1> and low load (axial average effective pressure 2 bar or less) operating state <"0.5" in 2> and idle operation state <3>
It is controlled so as to be thinned out in accordance with the load operating state of.

In this case, the indicated mean effective pressure IME focusing on the combustion pressure in the operating cylinder where fuel is injected.
Preal is derived by the following equation: IMEPreal = (IMEPapparent / Pal) × (Ncyl / Nsel) ...

In equation 1, IMEPapparent
Is the requested indicated mean effective pressure IMEP (mean value).

IMEPreal is an injection period (mmsec.)
The relationship shown in FIG. Therefore, the injection period (mmsec.) Can be obtained from the required output by the number of injections Pal per cycle (two strokes) of the engine 2. Also, by thinning out the operating cylinder,
It can also contribute to the improvement of the fuel consumption rate.

Further, Example D in Table 2 shows an application example of Example C. In Example D of Table 2, the injection pressure ba
Controlling that the r is constant and the number of injections Pal per cycle (two strokes) of the engine 2 and the ratio Nsel / Ncyl of the number of operating cylinders Nsel to the total number of cylinders Ncyl are varied and thinned according to the load operating condition. Is.

In Example D of Table 2, Pal × (Nsel / Ncyl) was set to “1” in the full open to low load operation state <1>.
And Then, the minimum indicated mean effective pressure IMEP required to secure stable combustion is set to Imin, and under low load (shaft mean effective pressure 2 bar or less) operating state <2> and idle operating state <3>, Pal is set. × (Nsel / Ncy
l) is controlled to be fixed at Imin. That is, IME
Let Preal = Imin.

Low load in this case (shaft average effective pressure 2 bar
Below) the decimation operation in the operating state <2> and the idle operating state <3> is derived from the equation 1 by (Pal * Nsel) / Ncyl = IMEPapparent / Imin.

For example, when Imin = 2 bar, the total number of cylinders N
If cyl = 4 cylinders, 1 <IMEPapparent
<2 and the number of operating cylinders Nsel = 4, Pal = IM
It becomes EPapparent / 2. Also, 0 <IMEPapparent
If <1 and the number of operating cylinders Nsel = 2, then Pal = IM
Become EPapparent.

By controlling in this way, the indicated mean effective pressure IMEP in the low load operation range is set to a constant IM.
You can be satisfied with EPreal.

According to the embodiment D of Table 2, as shown in FIG. 3, as compared with the conventional example shown by the solid line, the thinned portion (IMEPreal = 2bar is constant at 2 bar or less because of constant COP changes as shown by the broken line. No)), and the scavenging improvement by thinning out indicated by the one-dot chain line due to the effect of hatching (improvement of scavenging by thinning operation)
Is obtained.

That is, in contrast to IMEPapparent = 2 (every time combustion) in FIG. 4, IMEPapparent = 1.33 in FIG.
By (combustion twice in three times), improvement by thinning can be obtained, and scavenging improvement by this thinning can be obtained. Note that C
OV is a coefficient of variation of Coefficient of variation: IMEPreal.

[0037]

As described above, according to the present invention, the structure is not complicated as in the case of controlling the injection pressure in the related art, and the indicated mean effective pressure in the combustion stroke in the low load operation state is obtained. Can be increased and sufficient scavenging time can be secured.

Therefore, the structure can be simplified to reduce the cost, and the indicated mean effective pressure in the combustion stroke in the low load operation state can be increased to reduce the combustion fluctuation and to sufficiently scaveng the gas. By ensuring the time, the combustibility can be improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between IMEPreal and an injection period.

FIG. 3 Combustion fluctuation COV and indicated mean effective pressure IMEPap
It is a figure which shows the relationship with parent.

FIG. 4 is a diagram showing a pressure change when the indicated mean effective pressure IMEPapparent = 2.

[FIG. 5] Illustrated average effective pressure IMEPapparent = 1.33
It is a figure which shows the pressure change at the time.

[Explanation of symbols]

 2 engine 4 cylinder 6 fuel injection valve 8 fuel injection control device 10 control means 12 arithmetic processing unit 14 injection valve control unit 16 pressure sensor 18 rotation speed sensor

Claims (1)

[Claims] 1. A fuel injection control device for an engine, comprising a fuel injection valve for directly injecting fuel into a cylinder of an engine that completes one cycle in two strokes, wherein the fuel injection valve per one cycle of the engine 2. A fuel injection control device for an engine, comprising control means for controlling the number of injections and / or the number of injection cylinders to be thinned according to the load operating state of the engine.