JP3326750B2 - Electronic control fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection system for simultaneously injecting fuel into all cylinders of a two-cycle multi-cylinder engine.

[0002]

2. Description of the Related Art Conventionally, as an electronically controlled fuel injection device mounted on a two-cycle multi-cylinder engine, there is one that injects fuel into all cylinders simultaneously once per engine revolution. In such an apparatus, fuel is simultaneously injected into all cylinders in accordance with the combustion cycle of a specific cylinder, that is, each time the specific cylinder enters the suction / compression stroke.

[0003]

In the above-mentioned conventional electronically controlled fuel injection system, the fuel injection timing is adjusted to the combustion cycle of a specific cylinder. Therefore, the fuel injection timing is applied only to that specific cylinder. Is appropriate,
That is, fuel is injected in the state of the suction / compression stroke. That is, the fuel injection timing is always inappropriate for cylinders other than the specific cylinder. Therefore, in a particular cylinder, the amount of fuel adhering to the intake manifold inner wall is small, while in other cylinders, the amount of fuel adhering to the intake manifold inner wall is increased. For this reason, there is a problem that the air-fuel ratio varies between the cylinders, the combustion state becomes uneven, and irregular torque fluctuations are caused.

The present invention is capable of periodically changing cylinders at which fuel injection timing is appropriate, thereby suppressing variations in air-fuel ratio between cylinders and eliminating irregular torque fluctuations. It is an object to provide a control fuel injection device.

[0005]

SUMMARY OF THE INVENTION An electronically controlled fuel injection device according to the present invention is an electronically controlled fuel injection device mounted on a two-cycle multi-cylinder engine, and detects a fuel injection valve and an operating state of the engine. Detecting means, and control means for controlling the fuel injection valve based on the detection of the detecting means, and simultaneously injecting a required amount of fuel to all the cylinders of the engine at a predetermined periodic injection timing , control means, line fuel injection at a rate of once per engine N rotation represented by the following formula
Injection timing is appropriate for each cylinder periodically
Timing, and the injection timing is appropriate
It is characterized in that the fuel injection valve is controlled so as to periodically change the fuel injection valve. N = m / n (n is an engine is inputted during one rotation, the number of ignition signals corresponding to the number of cylinders; m pairs in n
And any disjoint integer )

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a schematic diagram showing a control system of a two-cycle two-cylinder engine (hereinafter simply referred to as an engine) to which an electronically controlled fuel injection device according to one embodiment of the present invention is applied. In this figure, an electronic control unit 10 (ECU) obtains an injection pulse width based on engine speed, throttle opening, engine cooling water temperature, and various other sensor information, and based on the injection pulse width, opens the fuel injection valve 11. The valve time is controlled, whereby a required amount of fuel is simultaneously injected into the intake manifold 13 of each cylinder 12. The fuel injected from the fuel injection valve 11 rises along with the air sucked through the air cleaner 15 through the intake hole 16 and the crankcase 17 due to the rise of the piston 14 during the compression stroke.
Inhaled into. And the piston 1 in the expansion stroke
By the lowering of 4, the air is sucked into the cylinder 12 from a scavenging hole (not shown) instead of the exhaust gas. After the combustion, the exhaust gas is discharged from the exhaust manifold 18 into the atmosphere through a catalytic converter (not shown), a muffler, and the like.

[0007] Fuel injection is performed once every N engine revolutions represented by the following equation. N = m / n (1)

Here, n is the number of ignition pulses P inputted every one revolution of the engine, and is 2 in the two-cylinder engine of this embodiment, for example, three in the three-cylinder engine.
m is a number other than an integral multiple of n and a number that satisfies the relationship represented by the following equation. 1 ≦ m ≦ 3n + 1 (2)

M is preferably slightly less than n,
Or a slightly larger number. In this embodiment, m = 3. Therefore, N = 3/2, and fuel injection is performed once every 3/2 revolutions of the engine. That is, 1
If the first fuel injection is performed when the first cylinder enters the suction / compression stroke, the second fuel injection is performed after the engine has rotated 3/2 times from the first fuel injection, that is, the second cylinder has the suction.・ It is performed when entering the compression stroke.

[0010] Of the engine operation information sent to the electronic control unit 10, the engine speed is determined by the ignition unit 1
9 is calculated from the ignition pulse P sent. The ignition unit 19 causes the spark plug 20 to generate an electric spark. The throttle opening is determined by the throttle valve 21
It is detected by a throttle position sensor 22 provided in the vicinity. The water temperature is detected by a water temperature sensor 24 provided near the cooling water passage 23.

The operation of the embodiment will be described. In the electronic control unit 10, the injection pulse width is determined based on the engine speed, the throttle opening, the water temperature, and other various sensor information. The opening time of the fuel injection valve 11 is controlled based on the injection pulse width, and a required amount of fuel is simultaneously injected into the intake manifold 13 of each cylinder 12.

As shown in FIG. 2, fuel injection is performed once every 3/2 revolutions of the engine. In the figure, the hatched portion indicates that the fuel is being injected, and the arrow indicates the input of the ignition pulse P. In the first rotation of the engine, when the first cylinder enters the suction / compression stroke, the first fuel injection is performed. The second fuel injection is performed after the engine has completed 3/2 rotation from the first fuel injection. At the second rotation of the engine, the first cylinder enters the suction / compression stroke and the crank angle becomes approximately 180.
° CA shift. Therefore, the second fuel injection substantially coincides with the timing at which the second cylinder enters the suction / compression stroke. The third fuel injection is performed after the engine has rotated 3/2 times from the second fuel injection. At the third rotation of the engine, the second cylinder enters the intake / compression stroke, and
The crank angle shifts about 180 ° CA. Therefore, the third fuel injection substantially coincides with the timing at which the first cylinder enters the suction / compression stroke again. Hereinafter, fuel injection is performed in the same manner.

In some cases, only one fuel injection is performed for two intake / compression strokes. In other words, no fuel injection is performed during the third rotation of the engine. Since the fuel is sucked into the cylinder 12 through the case 17, even if a combustion cycle in which fuel injection is not performed occurs periodically, the air-fuel ratio does not suddenly change due to the cushioning action of the crankcase 17.

FIG. 3 is a flowchart of the fuel injection timing control. The process up to the output of the fuel injection pulse will be described with reference to FIG. This program is interrupted every time the ignition pulse P is input. Before this program is executed for the first time, N calculated by the above-described equation (1) is set in the counter i.

In step S1, 1 is decremented from the counter i. In step S2, it is determined whether or not the counter i is 0. If the counter i is not 0, the process is returned.

On the other hand, if it is determined in step S2 that the counter i is 0, the process proceeds to step S3. Step S3
In the above, N calculated in advance by the above equation (1) is substituted for the counter i, and a fuel injection pulse is output in step S4.

As described above, according to the above embodiment, the cylinder 12 at which the fuel injection timing is appropriate, that is, the cylinder 12 which is in the suction / compression stroke at the time of fuel injection, is periodically changed by the first and second cylinders. Can be done. Thereby, the variation of the air-fuel ratio in each cylinder 12 can be eliminated, and the combustion state of each cylinder 12 becomes substantially uniform, thereby suppressing irregular torque fluctuation.

FIG. 4 is a diagram showing the fuel injection timing of the electronically controlled fuel injection device according to the second embodiment of the present invention.
This electronically controlled fuel injection device is mounted on a two-cycle three-cylinder engine, where n = 3. Also, m = 2
Is set to Therefore, N = ２, and the fuel injection timing is once every ２ rotation of the engine.

In the first rotation of the engine, when the first cylinder enters the suction / compression stroke, the first fuel injection is performed. The second fuel injection is performed after the engine has been rotated 2/3 of the time since the first fuel injection. At the second rotation of the engine, the first cylinder enters a suction / compression stroke.
The crank angle is shifted by about -120 ° CA. Therefore, the second fuel injection substantially coincides with the timing at which the second cylinder enters the suction / compression stroke. The third fuel injection is after the engine has been rotated 2/3 of the time since the second fuel injection,
At the second rotation of the engine, the timing at which the second cylinder enters the suction / compression stroke and the crank angle is approximately
Shift. Therefore, the third fuel injection substantially coincides with the timing at which the third cylinder enters the suction / compression stroke. 4
The second fuel injection is performed by the engine after the third fuel injection.
After the third rotation, the crank angle deviates by about -120 ° CA from the timing at which the third cylinder enters the suction / compression stroke at the third rotation of the engine. Therefore, the fourth fuel injection substantially coincides with the timing at which the first cylinder enters the suction / compression stroke again. Hereinafter, fuel injection is performed in the same manner.

As described above, according to the second embodiment, the cylinder 12 at which the fuel injection timing is appropriate can be periodically changed in the order of the first cylinder, the second cylinder, and the third cylinder. Thereby, the variation of the air-fuel ratio in each cylinder 12 can be eliminated, and the combustion state of each cylinder 12 becomes substantially uniform, thereby suppressing irregular torque fluctuation.

FIG. 5 is a diagram showing the fuel injection timing of the electronic control fuel injection device according to the third embodiment of the present invention.
This electronic control fuel injection device is also mounted on a two-cycle three-cylinder engine similarly to the device of the second embodiment.
= 3. Also, m = 4 is set. Therefore N
= 4/3, and the fuel injection timing is the engine 4/3
Once per rotation.

In the first rotation of the engine, when the first cylinder enters the suction / compression stroke, the first fuel injection is performed. The second fuel injection is performed after the engine has rotated 4/3 from the first fuel injection. At the second rotation of the engine, the first cylinder enters a suction / compression stroke;
The crank angle shifts by about 120 ° CA. Therefore, the second fuel injection substantially coincides with the timing at which the third cylinder enters the suction / compression stroke. The third fuel injection is performed after the engine has rotated 4/3 from the second fuel injection. At the third rotation of the engine, the timing at which the third cylinder enters the suction / compression stroke is shifted by about 120 ° CA in crank angle. . Therefore, the third fuel injection substantially coincides with the timing at which the second cylinder enters the suction / compression stroke. In the fourth fuel injection, the engine starts 4/3 from the third fuel injection.
After the rotation, the crank angle deviates by about 120 ° CA from the timing at which the second cylinder enters the suction / compression stroke at the fourth rotation of the engine. Therefore, the fourth fuel injection coincides with the timing at which the first cylinder enters the suction / compression stroke again. Hereinafter, fuel injection is performed in the same manner.

As described above, according to the third embodiment, the cylinder 12 at which the fuel injection timing is appropriate can be periodically changed in the order of the first cylinder, the third cylinder, and the second cylinder. Thereby, the variation of the air-fuel ratio in each cylinder 12 can be eliminated, and the combustion state of each cylinder 12 becomes substantially uniform, thereby suppressing irregular torque fluctuation.

[0024]

As described above, according to the present invention, it is possible to periodically change the cylinders at which the fuel injection timing is appropriate, thereby suppressing variations in the air-fuel ratio among the cylinders and making the cylinders irregular. Torque fluctuation can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a control system of a two-cycle engine to which an electronically controlled fuel injection device according to one embodiment of the present invention is applied.

FIG. 2 is a diagram showing fuel injection timing of the electronic control fuel injection device according to the first embodiment of the present invention.

FIG. 3 is a flowchart of fuel injection timing control.

FIG. 4 is a diagram showing fuel injection timing of an electronic control fuel injection device according to a second embodiment of the present invention.

FIG. 5 is a view showing a fuel injection timing of an electronic control fuel injection device according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 electronic control unit (control means) 11 fuel injection valve 12 cylinder P ignition pulse

Claims (2)

(57) [Claims] An electronically controlled fuel injection device mounted on a two-cycle multi-cylinder engine, comprising: a fuel injection valve; detection means for detecting an operation state of the engine; and a fuel injection valve based on the detection of the detection means. Control and periodically injects the required amount of fuel
Control means for simultaneously injecting fuel at the injection timing , wherein the control means performs fuel injection at a rate of once every N engine revolutions represented by the following equation, and the injection timing
The proper injection timing is obtained periodically with the
Periodically change the cylinder at which the firing timing is appropriate
An electronically controlled fuel injection device characterized by controlling a fuel injection valve as described above . N = m / n (n is an engine is inputted during one rotation, the number of ignition signals corresponding to the number of cylinders; m pairs in n
And any disjoint integer ) 2. The electronically controlled fuel injection device according to claim 1, wherein said m is a value represented by the following equation. 1 ≦ m ≦ 3n + 1