JPH11182353A - Fuel supply structure of fuel injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction of mixture efficiency of fuel with suctioned air in a structure in which a fuel injection valve is attached so as to prevent the adhesion of fuel on a wall face in the vicinity of an intake port. SOLUTION: This is a fuel supply structure of a fuel injection type internal combustion engine constituted in such a way that gaseous fuel is supplied to the vicinity of an intake port 2 of the internal combustion engine through a fuel injection valve 4. The fuel injection valve 4 is arranged at a position where gaseous fuel can be injected so as to collide against a wall face opposing to the fuel injection valve in the vicinity of the intake port 2 in such a way that gaseous fuel crosses substantially orthogonally an air stream flowing in the vicinity of the intake port 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply structure for an internal combustion engine mounted on an automobile or the like for supplying fuel by injecting fuel near an intake port by a fuel injection valve.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine mounted on an automobile or the like, fuel is injected from a fuel injection valve attached to an intake manifold to an intake port near the intake valve as disclosed in Japanese Patent Laid-Open No. 3-194166. There is known a fuel injection system which supplies the fuel in a supply manner. Usually, the fuel injector is
The injection port is mounted downstream of the intake port, that is, toward the intake valve so that the injected fuel is supplied toward the intake valve along the flow of the intake air. Such a mounting structure of the fuel injection valve is for preventing the injected fuel from adhering to the inner wall surface of the intake manifold and delaying the fuel supply.

[0003]

However, in the above structure, the injected fuel is carried from the intake manifold along the flow of the intake air to the combustion chamber via the intake port and the intake valve. Although the adhesion of fuel to the inside wall of the manifold can be prevented, mixing with intake air is not so good. In other words, the fuel injected along the direction of intake of the intake air flows toward the intake valve, but is in a state where the fuel is pushed away by the air flow, so that the mixing with the air is poor unless the fuel is in a good atomized state. became.
Such poor mixing of air and fuel has an adverse effect on the combustion surface, leading to a reduction in fuel consumption and exhaust gas emissions. In the case of liquid fuel such as gasoline, no significant adverse effect was observed even with the above configuration, but in the case of gaseous fuel such as natural gas, the effect was particularly large.

An object of the present invention is to solve such a problem.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the fuel supply structure of the fuel injection type internal combustion engine according to the present invention injects the fuel injection valve for injecting the gaseous fuel near the intake port so that the gaseous fuel is substantially orthogonal to the intake airflow near the intake port. And is arranged at a position where it can collide with a wall surface facing the fuel injection valve near the intake port.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply structure for a fuel injection type internal combustion engine which is configured to be able to supply gaseous fuel to the vicinity of an intake port of the internal combustion engine via a fuel injection valve. The fuel injection valve is disposed at a position where the fuel injection valve can be injected so as to be substantially orthogonal to the airflow flowing near the intake port and to collide with the wall surface facing the fuel injection valve near the intake port. 1 is a fuel supply structure of a fuel injection type internal combustion engine.

[0007] According to such a configuration, since the gaseous fuel is substantially orthogonal to the inflow direction of the intake air near the intake port, the injected gaseous fuel faces the fuel injection valve near the intake port. , And a vortex flow, that is, a vortex flow is generated near the intake port in the inflow direction of the intake air, so that the diffusion of the gaseous fuel is promoted. Then, since the intake air flows into the diffused gaseous fuel, mixing of the gaseous fuel and the intake air is promoted, and a uniform air-fuel mixture can be obtained. This results in better combustion,
Fuel economy can be improved and exhaust gas emissions can be improved.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. The engine EG shown in FIG. 1 has a plurality of cylinders and uses CNG (compressed natural gas) as a gaseous fuel. FIG. 1 shows a configuration of one thin cylinder 1 in a multi-cylinder engine. In this engine EG, one end 3a of an intake manifold 3 is connected to an intake port 2 of each cylinder constituting an intake system, and a fuel injection valve 4 is provided near each intake port 2.
Is arranged. An intake valve 6 is provided in the cylinder head 5 near the intake port 2 so as to be openable and closable. When the intake valve 6 is opened, the intake manifold 3 and the combustion chamber 7 communicate with each other. A spark plug 8 is attached to an upper wall of the combustion chamber 7, and an exhaust manifold 10 is connected to an exhaust port 9. In the figure, 11 is a piston,
Reference numeral 12 denotes an exhaust valve.

The intake manifold 3 is supported substantially horizontally, and has one end 3a connected to the intake port 2 of the cylinder head 5, and the other end for suppressing pulsation of intake air. It communicates with a surge tank (not shown). The intake air indicated by the arrow A1 flows into the intake manifold 3 via an air cleaner and a throttle valve (both not shown). One end 3 of the intake manifold 3 is structured to be cooled by the cooling water W so that the intake air is not heated by the heat transmitted from the engine EG. Further, as shown in FIG. 2, the internal longitudinal sectional shape of the intake manifold 3 is preferably an elliptical shape.
That is, the upper wall 3b to which the fuel injection valve 4 is attached and the lower wall 3c facing the upper wall 3b form a plane, and the left and right side walls 3d, 3 which are continuous with the upper wall 3b and the lower wall 3c.
e is formed in an arc shape bulging outward. this is,
This is because a vortex (indicated by an arrow A3) of the injected gaseous fuel (indicated by an arrow A2), which will be described later, is easily generated, and the mixing of the gaseous fuel and the intake air is smoothly performed.

The fuel injection valve 4 is detachably fixed to the upper wall 3b of the intake manifold 3 with the fuel injection hole directed downward. That is, the fuel injection valve 4 is mounted toward the lower wall 3c of the intake manifold 3 so that the injected gaseous fuel is substantially perpendicular to the intake air flow. The gaseous fuel injected from the fuel injection valve 4 is injected at a constant pressure by a fuel pump (not shown). In this case, the injection pressure is set to a value sufficient for the injected gaseous fuel to directly collide with the lower wall 3c against the intake air flow. The fuel injection valve 4 may be controlled so as to inject gaseous fuel independently in synchronization with the suction stroke, or may be controlled to rotate once per revolution.
It may be controlled to inject all cylinders simultaneously only once.

In such a configuration, when gaseous fuel is injected from the fuel injection valve 4, the injected gaseous fuel directly collides with the lower wall 3c of the intake manifold 3 near the intake port 2. This is because gaseous fuel does not adhere to the wall surface unlike liquid fuel even if it collides with the lower wall 3c. When the gaseous fuel collides with the lower wall 3c, the gaseous fuel is reflected by the lower wall 3c and rises. Further, the gaseous fuel that has risen to reach the vicinity of the upper wall 3b is turned downward by the subsequently injected gaseous fuel so as to be entrained in a downward flow, and then again toward the lower wall 3c. Descend.

At this time, such behavior of the gaseous fuel occurs in a direction parallel to the intake air flow, that is, in the upstream and downstream directions of the intake manifold 3, and in a direction perpendicular to the intake air flow, that is, in the central axis of the intake manifold. It also occurs in the vertical direction. That is, the gaseous fuel injected from the fuel injection valve 4 collides with the lower wall 3c, then diffuses in all directions near the intake port 2, that is, immediately below the fuel injection valve 4, rises once, and is subsequently injected. The gaseous fuel moves downward again and flows in a vortex shape.

As described above, when the intake valve 6 is opened while the gas fuel swirl A3 is generated in the intake manifold 3 and the diffusion of the gas fuel is promoted, the intake air flow is generated by the negative pressure. The intake air flows from the upstream of the intake manifold 3 toward the combustion chamber 7, collides with the gaseous fuel that has been injected and forms the vortex A3, and becomes an air-fuel mixture. In this case, since the gaseous fuel is in the form of the vortex A3, the gaseous fuel is diffused in the cross-sectional direction inside the intake manifold 3 and is in a state of being very easily mixed with the intake airflow. Therefore, the gaseous fuel and the intake air are efficiently mixed, and a mixture in which the two are evenly mixed flows into the combustion chamber 7 from the intake port 2. As a result, the combustion efficiency is improved, the fuel efficiency is improved, and the emission of HC, CO, and the like in the exhaust gas is reduced. As shown in FIG. 3, when the air-fuel ratio is used as a parameter, these emissions can be reduced on average compared to the conventional one.

The present invention is not limited to the embodiment described above. For example, as shown in FIG. 4, the fuel injection valve 104 may be attached to the inclined intake manifold 103 so as to be inclined, and the gas fuel may be injected substantially orthogonally to the intake air flow. That is, in this embodiment, the intake manifold 103 is
It is a shape that curves upward from. When the fuel injection valve 104 is attached substantially vertically to the intake manifold 103 having such a shape as in the above-described embodiment, the height of the entire engine EG2 including the fuel injection valve 104 increases. Therefore, in order to lower the overall height of the engine EG2,
The fuel injection valve 104 can be mounted at an angle to the intake manifold 103 so that the height can be reduced at the position of the fuel injection valve 104.

When the fuel injection valve 104 is mounted as described above, if a fuel injection hole is provided at the tip of the fuel injection valve 104, gaseous fuel cannot be injected substantially orthogonally to the intake air flow. . Therefore, the fuel injection valve 104 in this embodiment has a fuel injection hole 104b on the side surface of the tip portion 104a. In particular,
The fuel injection holes 104b are connected to the intake ports 102 when the fuel injection valves 104 are attached to the intake manifold 103.
And at a position facing downward, that is, at a position facing the other end of the intake manifold 103 and facing downward.

By forming the fuel injection holes 104b in this way, the injected gaseous fuel is injected in a direction substantially perpendicular to the intake air flow, and the gaseous fuel is injected into the intake manifold 103 near the opposed intake port 102. It collides with the lower wall 103c. As a result, a vortex is generated in the vicinity of the intake port 102 as in the above-described embodiment, and the diffusion of the gaseous fuel is promoted. Therefore, the mixing with the intake air proceeds efficiently, and good combustion can be achieved. As a result, fuel efficiency can be improved and exhaust gas emissions can be reduced.

In the above embodiment, the gaseous fuel is C
Although NG has been described, other fuel gas can provide the same effect. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0018]

As described above, according to the present invention, since the gaseous fuel is substantially orthogonal to the inflow direction of the intake air near the intake port, the injected gaseous fuel is injected near the intake port. Since it collides with the wall surface facing the valve and generates a vortex flow, that is, a vortex flow in the inflow direction of the intake air near the intake port, the diffusion of the gaseous fuel can be promoted. Since the diffused gaseous fuel joins the intake air flow, the mixing of the gaseous fuel and the intake air can be promoted, and a uniform air-fuel mixture can be obtained.
As a result, combustion is improved, fuel efficiency can be improved, and exhaust gas emissions can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the intake manifold of the embodiment.

FIG. 3 is a graph showing comparative data of pollutants in exhaust gas of the same example as before.

FIG. 4 is a diagram corresponding to FIG. 1 of another embodiment of the present invention.

[Explanation of symbols]

 2 ... intake port 3 ... intake manifold 4 ... fuel injection valve 3 c ... lower wall

Claims (1)

[Claims] 1. A fuel supply structure for a fuel injection type internal combustion engine configured to be able to supply gaseous fuel to a vicinity of an intake port of the internal combustion engine via a fuel injection valve, wherein the gaseous fuel flows near the intake port. So as to be substantially perpendicular to the airflow,
A fuel supply structure for a fuel injection type internal combustion engine, wherein the fuel injection valve is disposed at a position where the fuel injection valve can be injected so as to collide with a wall facing the fuel injection valve near the intake port.