JPS63105275A - Fuel feeding device for engine - Google Patents

Abstract

PURPOSE:To improve a lean limit which can feed a lean mixture in the circumferential direction of a combustion chamber by providing first and second fuel feeding means in an intake passage and a swirl generating means in said combustion chamber. CONSTITUTION:At the time of fuel injection by means of first and second fuel injection valves 21, 22, a good ignaitable fuel is fed by the lower course side fuel injection valve 21 while a fuel with good vaporizing and atomizing properties is fed by the upper course side fuel injection valve 22. Thereby, a rich mixture is fed to the periphery of an ignition plug on the upper part of a combustion chamber 7 while a lean mixture is fed to the lower part, to form the layer condition of fuel improving fuel consumption. Further, at the time of low load when the opening of a closing valve 20 is small, a mixture is introduced in the tangential direction of a cylinder bore by the primary passage 8 as a swirl generating means, generating a strong swirl, to securely feed a lean mixture with good vaporizing and atomizing properties in the circumferential direction of the combustion chamber 7. Thereby, a lean limit can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel supply system for an engine equipped with a fuel injection valve that supplies fuel in the second half of the intake stroke, for example.

(Prior Art) Conventionally, as a fuel supply system for the above-mentioned engine, there is, for example, a system described in Japanese Patent Laid-Open Publication No. 58-85319.

That is, this is a device that controls the fuel injection timing for each cylinder and sets the fuel injection timing immediately before the end of the intake stroke of that cylinder.In this conventional device, a rich air-fuel mixture is injected around the spark plug in the upper part of the combustion chamber. Due to the stratification of the fuel present,
This has the effect of ensuring efficient combustion with less fuel.

However, in the above method, fuel is supplied only just before the end of the intake stroke, so only air exists at the bottom of the combustion chamber, and during the combustion process, that is, during the flame propagation, the air causes combustion. is inhibited,
There is a problem that flammability deteriorates.

Therefore, in addition to the above conventional technology, by supplying thin fuel with good vaporization to the lower part of the combustion chamber at a predetermined timing,
One idea is to improve the flame propagation and ensure combustibility with as little fuel as possible.

However, even in such a case, there are the following problems.

In other words, since the above-mentioned conventional device does not have a swirl generating means, if the air-fuel mixture is not well supplied in the circumferential direction of the combustion chamber, the presence of air in the circumferential area will impede the transmission of flame propagation. combustion is inhibited by
This had the problem of deteriorating flammability.

(Object of the Invention) The present invention is capable of stratifying the air-fuel mixture to improve fuel efficiency, and in particular, by providing a swirl generating means, the swirl generating means reliably vaporizes the mixture in the circumferential direction of the combustion chamber. The purpose of the present invention is to provide an engine fuel supply device that can supply a lean mixture with good atomization and improve the lean limit of rotating the engine with as lean fuel as possible while ensuring combustibility. shall be.

(Structure of the Invention) The present invention provides a combustion chamber or an intake passage near the combustion chamber.
a first fuel supply means for supplying fuel in the latter half of the intake stroke;
A predetermined fuel is supplied to the F-flow intake passage from a location where the fuel is supplied by the first fuel supply means to make the mixture leaner than the mixture obtained by the fuel supplied by the first fuel supply means. A second fuel supply means for supplying, and the above-mentioned combustion! A fuel supply device for an engine is characterized in that it includes a swirl generating means for giving a circumferential swirl in a combustion chamber to an air-fuel mixture supplied to the combustion chamber.

(Effects of the Invention) According to the present invention, since the first fuel supply means described above can supply fuel with good ignitability, and the second fuel supply means can supply fuel with good vaporization and atomization, Rich air-fuel mixture is supplied to the upper part of the combustion chamber around the spark plug, and lean air-fuel mixture is supplied to the lower part of the combustion chamber to achieve stratification, thereby improving fuel efficiency.

Moreover, since the swirl generating means described above can reliably supply a lean mixture with good vaporization and atomization in the circumferential direction of the combustion chamber, the engine can be run with as lean a fuel as possible while ensuring combustibility. This has the effect of improving the limit.

(Example) An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows a fuel supply system for an engine, and in FIG. 1, an air flow meter 2 is installed at the purified air outlet of an air cleaner 1.
A throttle body 3 is connected to the rear of the air flow meter 2.

A throttle valve 5 is disposed in the throttle chamber 4 within the throttle body 3, and a throttle opening sensor 6 for detecting the opening of the throttle valve 5 is disposed outside the throttle body 3. .

Further, at the rear of the above-mentioned throttle body 3, there is a primary passage 8 as a swirl generating means for giving the air-fuel mixture supplied to the combustion chamber 7 a circumferential swirl in the combustion chamber 7;
Dual induction system D with next passage 9
The IS intake pipe 10 is connected.

The above-mentioned primary passage 8 for low loads and secondary passage 9 for high loads
The primary intake boat 11 and the secondary intake boat 12 (see Fig. 2) each have an intake valve 1 corresponding to the
3.13 is installed, while the exhaust valve 1 is installed on the steam boat 14.
5 is arranged in a cross-flow arrangement.

A cylinder block 17 is attached to the lower part of the cylinder head 16 forming each of the above-mentioned boats 11, 12, 14, and a piston 18 is disposed within this cylinder block 17.

Further, in the secondary passage 9 of the above-mentioned intake pipe 10, an on-off valve 20 is disposed which is operated by an actuator 19 to open during high load and to open during light load. are connected.

By the way, in the secondary passage 9 of the intake pipe 10 as an intake passage in the vicinity of the combustion chamber 7 described above, a two-injection type first fuel injection valve 21 for supplying fuel in the latter half of the intake stroke is provided.

Further, a throttle valve 5 serving as an intake passage upstream of the location where fuel is supplied by the first fuel injection valve 21 described above is also provided.
The throttle chamber 3 at the front of the arrangement position has the above-mentioned first
A second fuel injection valve 22 is provided to supply a predetermined fuel to make the air-fuel mixture leaner than the air-fuel mixture obtained by the fuel supplied by the fuel injection valve 21.

In this way, the first and second fuel injection valves 21 and 22 are arranged, and the first fuel injection valve 21 injects fuel with good ignitability, and the second fuel injection valve 22 injects fuel with good vaporization and atomization. By supplying each of these, a mixture with a high fuel concentration is supplied to the vicinity of the spark plug (not shown) at the top of the combustion chamber, and a mixture with a lean fuel concentration is supplied to the bottom of the combustion chamber, thereby achieving stratification. .

By the way, the CPU 30 receives the intake air good signal shown in FIG.
The first fuel injection valve 21 and the second fuel injection valve
The actuator 19 for the fuel injection valve 22 and the on-off valve 20 is driven and controlled, and the RAM 25 stores necessary data such as fuel injection start crank angle data and fuel injection end crank angle data according to load conditions.

The operation of the engine fuel supply system configured as described above will be explained with reference to the flowchart shown in FIG.

In a first step 31, the CPU 30 reads various signals such as an engine speed signal, an intake air a signal, a crank angle signal, and a cylinder discrimination signal.

Next, in a second step 32, the CPIJ 30 calculates the injection pulse width for fuel injection based on the engine speed and intake air amount.

Next, in a third step 33, the CPU 30 controls each fuel injection valve 2.
The injection end crank angle of 1.22 is calculated.

Next, in a fourth step 34, the CPU 30 determines whether the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21, that is, the crank angle corresponding to the latter half of the intake stroke. The process moves to the next fifth step 35.

In this fifth step 35, the CPU 30 drives the first fuel injection valve 21 to inject fuel.

Next, in a sixth step 36, the CPU 30 determines whether the current crank angle has reached the injection start crank angle of the second fuel injection valve 22, and if the above-mentioned crank angle has not yet been reached, the The process moves to the seventh step 37.

In this seventh step 37, the CPU 30 determines whether or not the current crank angle has reached the injection end crank angle of the first fuel injector 21, and if it has, it moves to the next eighth step 38. do.

At this eighth step 38, the CPU 30 terminates the fuel injection by the first fuel injection valve 21.

Next, in a ninth step 39, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22. , the CPU 30 drives the second fuel injection valve 22 to inject fuel with good vaporization and atomization.

Next, in an 11th step 41, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22. , the CPU 30 ends the fuel injection by the second fuel injection valve 22.

Through the processing of each step 35 to 42 above, immobilized injection is performed as shown in FIG. 4a.

Note that in FIG. 4, X indicates fuel injection by the first fuel injection valve 21, and Y indicates fuel injection by the second fuel injection valve 22.

On the other hand, when the CP and U 30 determine in the aforementioned sixth step 36 that the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22, the process moves to the next thirteenth step 43. do.

In this thirteenth step 43, the CPU 30 drives the second fuel injection valve 22 to inject fuel.

Next, in the fourteenth step 44, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22, and when it has reached the fuel injection end crank angle, the CPU 30 proceeds to the next fifteenth step 45. , the CPU 30 terminates the fuel injection by the second fuel injection valve 22.

Next, in the 16th step 46, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and when the current crank angle has reached the fuel injection end crank angle, the CPU 30 proceeds to the next 17th step 47. , the CPU 30 terminates the fuel injection by the first fuel injection valve 21.

By performing the above steps 35, 36, and 43 to 47, simultaneous injection as shown in FIG. 4 is performed.

On the other hand, when the CPU 30 determines in the aforementioned fourteenth step 44 that the current crank angle has not reached the crank angle at which the fuel injection of the second fuel injection valve 22 ends, the next first crank angle is determined.
The process moves to step 48.

In this 18th step 48, the CPLJ 30 determines whether the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and when it has reached it, in the next 19th step 49, The CPU 30 ends the fuel injection by the first fuel injection valve 21 and skips it.

Next, in a 20th step 50, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22.
At step 51, the CPU 30 terminates the fuel injection by the second fuel injection valve 22.

Each of the above steps 35.36.43.44.48-51
Through this process, fuel injection as shown in FIG. 4C is performed.

On the other hand, when the CPLI 30 determines in the fourth step 34 that the current crank angle has not reached the fuel injection start crank angle of the first fuel injection valve 21, the process proceeds to the next 22nd step 52.

In this 22nd step 52, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22. , CPtJ30 drives the second fuel injection valve 22 to inject fuel.

Next, in a twenty-fourth step 54, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21. , the CPU 30 drives the first fuel injection valve 21 to inject fuel.

Next, in the twenty-sixth step 56, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and when it has reached the fuel injection end crank angle, the CPU 30 proceeds to the next twenty-seventh step 57. , the CPU 30 ends the fuel injection by the first fuel injection valve 21.

Next, in the 28th step 58, the CPLJ 30 determines whether the current crank angle has reached the fuel injection end crank angle of the second fuel injector 22, and when the current crank angle has reached the fuel injection end crank angle, the CPLJ 30 executes the next 29th step 59. , the CPU 30 ends the fuel injection by the second fuel injection valve 22.

The simultaneous injection as shown in FIG. 4d is performed by the above steps 53 to 5 processing.

On the other hand, if the CPLJ 30 determines in the 26th step 56 of the previous water that the current crank angle has not reached the fuel injection end crank angle of the first fuel injection valve 21, the process moves to the next 30th step 60. Zuru.

At this 30th step 60, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22. stops the fuel injection by the second fuel injection valve 22.

Next, in step 62, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21. In step 63, the CPU 30 controls the first fuel injection valve 21.
Terminates fuel injection.

Through the processes of steps 53 to 56 and 60 to 63 described above, fuel injection as shown in FIG. 4e is performed.

On the other hand, when the CPU 30 determines in the above-mentioned 24th step 54 that the current crank angle has not reached the fuel injection start crank angle of the first fuel injection valve 21, the process moves to the next 34th step 64. .

In this 34th step 64, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22, and if it has reached it, in the next 35th step 65, The CPU 30 ends the fuel injection by the second fuel injection valve 22.

Next, in the 36th step 66, the CPU 30 determines whether the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21, and when it has reached the fuel injection start crank angle, the CPU 30 starts the next 37th step. At 67, the CPU 30 drives the first fuel injection valve 21 to perform fuel injection.

Next, in the above-mentioned 32nd step 62, the CPU 30 determines whether the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21. At 63, the CPU 30 ends the fuel injection by the first fuel injection valve 21, as described above.

Each of the above steps 53.54.64 to 67.62.63
Through the process, timed injection as shown in FIG. 4f is performed.

When the fuel is injected by the first and second fuel injection valves 21 and 22, the first fuel injection valve 21 on the downstream side injects fuel with good ignitability, and the second fuel injection valve 22 on the upstream side vaporizes the fuel. Since each type of fuel is supplied with good atomization, a rich mixture is supplied to the area around the spark plug at the top of the combustion chamber, and a lean mixture is supplied to the bottom of the combustion chamber, creating stratification, which improves fuel efficiency. There is an effect that can be done.

Furthermore, during light loads with a small opening/closing valve angle of 20 degrees, the primary passage 8 as the swirl generating means described above induces the air-fuel mixture in the tangential direction of the cylinder bore to generate a strong swirl S (see Figure 2). Therefore, a lean mixture with good vaporization and atomization can be reliably supplied to the circumferential direction of the combustion chamber 7. As a result, misfires can be prevented and the engine can be run with as lean fuel as possible while ensuring combustibility. This has the effect of improving the lean limit of rotation.

In the correspondence between the structure of the present invention and the above-described embodiment, the first fuel supply means of the present invention corresponds to the first fuel injection valve 21 of the embodiment, and the intake passage in which the first fuel supply means is arranged is , the second fuel supply means corresponds to the second fuel injection valve 22, the intake passage in which the second fuel supply means is arranged corresponds to the throttle chamber 4, and the swirl generation means corresponds to the primary passage 8, but the present invention is not limited to the configuration of the above-described embodiment.

For example, it goes without saying that a carburetor may be used instead of the second fuel injection valve 22.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a system diagram showing an engine fuel supply system, FIG. 2 is a schematic plan view of main parts, FIG. 3 is a flowchart showing fuel injection processing, and FIG. 4 FIG. 2 is an explanatory diagram showing a mode of fuel injection. 4... Throttle chamber 7... Combustion chamber 8... Primary passage 9...
Secondary passage 21...First fuel injection valve 22...Second fuel injection valve

Claims (1)

[Scope of Claims] 1. A first fuel supply means for supplying fuel to the combustion chamber or the intake passage near the combustion chamber in the latter half of the intake stroke; and upstream from the point where fuel is supplied by the first fuel supply means. a second fuel supply means for supplying a predetermined fuel to the intake passage of the combustion chamber to make the mixture leaner than the mixture obtained by the fuel supplied by the first fuel supply means; A fuel supply device for an engine, comprising a swirl generating means for giving a circumferential swirl in a combustion chamber to an air-fuel mixture.