JPS599749B2 - Intake system for fuel-injected internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel-injected internal combustion engine, and more particularly to an intake system for a fuel-injected internal combustion engine that injects gasoline into an intake port.

In a fuel-injected internal combustion engine that injects gasoline into the intake port, the gasoline is injected into the intake port in the form of droplets, so gasoline is injected into the intake port in the form of droplets, especially during low-speed, low-load operation when the air flowing through the intake port is slow. There is a problem in that the atomization and mixing with air are not sufficiently promoted, and as a result, the air-fuel ratio of the air-fuel mixture supplied to each cylinder fluctuates greatly, making it impossible to obtain stable combustion.

The present invention is designed to atomize the injected liquid fuel temporarily stored in the fuel reservoir formed on the lower wall surface of the intake port during low-load operation using high-velocity jetted air, thereby promoting atomization and mixing of the fuel. The goal is to provide equipment.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is the engine body, 2a t 2 b
y2c and 2d are the 1st cylinder, 2nd cylinder, and 3rd cylinder, respectively.
No. 4 cylinder, 3 is the intake valve, 4 is the intake port, 5 is the exhaust valve,
6 indicates exhaust ports, respectively.

Referring to FIG. 2 which shows a side sectional view of FIG. 1, 7 is a cylinder block, 8 is a piston that reciprocates within the cylinder block 7, 9 is a cylinder head fixed on the cylinder block 7, and 10 is a piston 8 and a combustion chamber formed between the cylinder head 9 and the cylinder head 9, and 11 represents an ignition plug.

As shown in FIGS. 1 and 2, the cylinder head 9
An intake manifold 13 having four manifold branch pipes 12 is fixed, and within each of these manifold branch pipes 12 is a fuel injection valve 14 for injecting fuel into the intake port 4 as shown by the arrow. provided.

Air is supplied into the intake manifold 13 through an air introduction pipe 15, and within this air introduction pipe 15 are a throttle valve 16 connected to an accelerator pedal (not shown), and an air flow meter 17 for measuring the amount of intake air. is provided.

This air flow meter 17 is connected to an electronic control circuit for fuel injection control (not shown), and based on the output signal of the air flow meter 17, fuel is supplied to the fuel injection valve 1 in proportion to the amount of intake air.
It is injected from 4.

The fuel ejected from the fuel injection valve 14 directly collides with the fuel injector 14. A groove 18 forming a fuel reservoir is formed on the lower wall surface of the intake port 4.
covered by 0.

The groove 18 is connected to a common communication passage 21 via a communication branch 19, and the central part of the common communication passage 21 is connected to the air introduction pipe 15 between the throttle valve 16 and the air flow meter 17 via a sub-intake passage 22. Concatenated.

Note that a sub-throttle valve 23 is provided within the sub-intake passage 22 .

Figure 4 is a slot. It shows changes in the opening degrees of the torque valve 16 and the sub-throttle valve 23.

In Fig. 4, the vertical axis P shows the throttle opening, and the horizontal axis D
indicates the amount of depression of the accelerator pedal.

Note that in FIG. 4, a curve S indicates the sub-throttle valve 23, and a curve T indicates the throttle valve 16.

As shown in Fig. 4, when the accelerator pedal is depressed, the sub-throttle valve 23 gradually opens while the throttle valve 16 is kept fully closed, and then when the sub-throttle valve 23 is fully opened, the sub-throttle valve 23 is fully open. It can be seen that the throttle valve 16 gradually opens while being held at .

Therefore, the throttle valve 16 and the sub-throttle valve 23 are the fourth
They are connected to each other via a link mechanism (not shown) so as to have the opening relationship shown in the drawing.

During low-load engine operation, the throttle valve 16
is held in the fully closed state, so the air flow meter 17
The air sucked in through the sub-intake passage 22, the common communication passage 21, the communication branch passage 19, and the groove 18 passes through the perforated plate 20.
The air is blown out into the air intake port 4 during the intake stroke.

On the other hand, fuel is injected from the fuel injection valve 14 without particular synchronization with the opening operation of the intake valve 3, and a portion of this injected fuel is temporarily stored in the groove 18.

Then, as described above, during the intake stroke, air is ejected at high speed from within the groove 18 through the perforated plate 20, and at this time, the liquid fuel stored in the groove 18 also flows into the perforated plate 20 along with the air.
The air is ejected into the intake port 4 through the air.

Therefore, when the stored liquid fuel passes through the holes of the perforated plate 20 at high speed, it is torn off and atomized, and these fuel particles mix well with the air in the intake port 4.

In this way, during low-load operation, fuel atomization is promoted and mixing with air is promoted, so the air-fuel ratio of the mixture supplied into the combustion chamber 10 becomes uniform, thus achieving stable combustion. Obtainable.

On the other hand, during high-load operation, the throttle valve 16 opens and most of the air is supplied into the intake port 4 via the intake manifold 13, but a large negative pressure is generated within the intake port 4 during the intake stroke. Because of this negative pressure, the concave groove 18
The liquid fuel stored therein is sucked out into the intake port 4 through the perforated plate 20, and atomization of the liquid fuel is promoted at this time.

Another embodiment is shown in FIGS. 5 and 6.

In this embodiment, a dish-shaped simple groove 24 is formed on the bottom wall surface of the intake port 4, and the common communication path 21 is formed in the communication branch path 1.
It is connected only within the concave groove 24 via 8.

In addition, a second throttle valve 25 is provided in each manifold branch pipe 12.
are inserted, and each of these second throttle valves 25 is fixed to a common throttle shaft 26.

As shown in FIG. 6, this common throttle shaft 26 is disposed within a wedge-shaped recess 27 formed on the bottom wall surface of the manifold branch pipe 12. As shown in FIG.

Note that the throttle valve 16 and the second throttle valve 25 change as the throttle valve 16 opens.
5 are connected to each other via a link mechanism (not shown) so as to open the valve.

When the ignition order is, for example, 1-2-4-3 in a four-cylinder internal combustion engine as shown in FIG. 5, if the first cylinder 2a is in the intake stroke, the second cylinder 2b is in the exhaust stroke.

Normally, at the end of the exhaust stroke, there is a valve polymerization period when both the intake valve 3 and the exhaust valve 5 open, but during this valve polymerization period at the end of the exhaust stroke, relatively high pressure burnt gas flows into the combustion chamber of the No. 2 cylinder. 10
The air is blown back from the inside into the intake port 4 of the second cylinder, thereby temporarily creating a positive pressure inside the intake port 4 of the second cylinder 2b.

On the other hand, when the second cylinder 2b is at the end of the exhaust stroke, the first cylinder 2b
A large negative pressure is generated in the intake port 4 of the second cylinder 2b. Therefore, at this time, the burned gas or air in the intake port 4 of the second cylinder 2b is connected to a communication branch that opens to the intake port 4 of the second cylinder 2b. 19 into the common communication passage 21, and then this forced burned gas or air is transferred to the intake port of the first cylinder 2a through the communication branch 19 which opens into the intake port 4 of the first cylinder 2a. It will eject at high speed within 4 hours.

Similarly, in the remaining cylinders, during the intake stroke, the burnt gas or air sent into the common communication passage 21 from other cylinders is ejected from the communication branch passage 19 into the intake port 4.

Therefore, the liquid fuel stored in the groove 24 is transferred to the communication branch 18.
The air is pushed into the common communication passage 21 through the common communication passage 21, and after flowing through the common communication passage 21, it is ejected into the intake port 4 of another air via the communication branch passage 19.

Therefore, in this embodiment, vaporization of the liquid fuel is promoted while the fuel flows in the common communication path 21, and on the other hand, atomization of the fuel is promoted when it is ejected from the communication branch path 19 at a high velocity.

The ejection action of fuel from the communication branch 18 as described above is caused by the second
This can be done even if the throttle valve 25 is not provided, but if a second throttle valve 25 is provided as shown in FIG. 6 to narrow down the flow passage cross-sectional area during low-load operation, the problem occurs in the intake port 4 at the end of the exhaust stroke. Since the positive pressure can be maintained for a while without attenuation, burnt gas or air can be ejected from the communication branch 19 for a long time.

In addition, by arranging the second throttle valve 25 as shown in FIG. 6, the second throttle valve 25 is
Since the air circulation gap F is formed only between the upper edge of the manifold branch pipe 12 and the earth wall surface of the manifold branch pipe 12, the air passing through the air circulation gap F flows along the earth wall surface of the intake port 4 as shown by arrow K. The fuel moves forward and then flows into the combustion chamber 10 to generate a circulating flow as shown by the arrow W in FIG.

As a result, the combustion speed is greatly increased, making it possible to ensure stable combustion.

As described above, according to the present invention, the atomization of the fuel and the mixing action with air can be promoted especially during low load operation, so that stable combustion can be ensured during low load operation.

[Brief explanation of drawings]

FIG. 1 is a plan view of an internal combustion engine according to the present invention, and FIG.
Figure 3 is a cross-sectional view taken along line 1 and 2 in Figure 2, Figure 4 is a graph showing the opening relationship between the throttle valve and sub-throttle valve in Figure 3, and Figure 5 The figure is a plan view of another embodiment, and FIG. 6 is a side sectional view of FIG. 5. 3...Intake valve, 4...Intake port, 1
3... Intake manifold, 14... Fuel injection valve, 16... Throttle valve, 18, 24...
... Concave groove, 19 ... Communication branch, 20 ...
... Perforated plate, 21 ... Common communication path, 22.
... Sub-intake passage, 23... Sub-throttle valve, 25... Second throttle valve.

Claims (1)

[Scope of Claims] 1. In an internal combustion engine equipped with a fuel injection valve for injecting fuel into an engine intake port, a fuel reservoir is formed on the bottom wall surface of each intake port, and a branch passage communicating with each fuel reservoir is provided. An intake system for a fuel-injected internal combustion engine that is connected to a common communication passage through a fuel injection type internal combustion engine. 2. In an internal combustion engine equipped with a fuel injection valve for injecting fuel into the engine intake port, a fuel reservoir is formed on the bottom wall surface of each intake port, and each fuel reservoir is connected to a common communication passage through a communication branch. An intake system for a fuel injection internal combustion engine, in which the common communication passage is connected to the atmosphere through an air supply control device for supplying air into the common communication passage when the engine load is equal to or higher than a predetermined load.