JPS61116026A - Intake-air device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To enhance the performance of combustion of an internal-combustion engine provided with an intake-air device in which a shut-off valve that is opened and closed in accordance with the operating condition of the engine is disposed in one of two intake-air ports, by providing a fuel injection valve which is directed to the entire periphery of inner wall of the other intake-port incorporating no shut-of valve, upstream of an air-intake valve. CONSTITUTION:In an engine in which there are provided two intake-air ports 12 and two intake-air valves for opening and closing these intake-air ports for every engine cylinder, and in which a shut-off valve that is opened and closed in accordance with the operating condition of the engine is disposed in one of the intake-air ports 12, a fuel injection valve 15 is disposed in the other intake-air port 12 in which no shut-off valve is disposed. The fuel injection valve 15 is so arranged that the center axis A of the injection valve nozzle passes through the center section of a valve seat 16. Further, the injection angle theta of the fuel injection valve 15 is set to be larger than that of the conventional one so that injected fuel from the fuel injection valve impinges upon over the entire periphery of the inner wall of the intake-air port 12. With this arrangement the evaporating characteristic of fuel may be enhanced, thereby it is possible to enhance the performance of combustion.

Description

[Detailed description of the invention] Industrial application fields> The present invention relates to an intake system for an internal combustion engine.

<Prior Art> As a conventional example of this type of intake system for an internal combustion engine, there is one shown in FIGS. 8 and 9 (Japanese Patent Application No. 58-2253
(See No. 56).

That is, two first and second intake valves IA for each cylinder.
, the first and second intake ports 2 of 2-) with IB interposed
person, 2B, one of them (e.g. second intake hole) 2
A butterfly type on-off valve 3 is installed in B.

When the engine is in a low-speed operating region, the on-off valve 3 is closed and intake air is supplied to the combustion chamber 4 from only the two first intake ports, allowing combustion to occur with the intake air flowing against the inner peripheral wall of the combustion chamber 4. A swirl is formed in chamber 4 to improve combustion at low speeds. In addition, in the medium speed to high speed operation range, the on-off valve 3 is opened for both intake ports, 2B to #5. Intake air is supplied to the combustion chamber 4 to increase the intake air charging efficiency and improve the engine output.

Here, since the on-off valve 3 does not open frequently in the normal operating range, the fuel injection valve 5
is provided in the first intake port 2All11 which is always open, and the fuel is injected in a concentrated manner near the center of the valve shaft of the umbrella portion of the first intake valve 1A as shown in FIG.

Incidentally, exhaust valves 6A, 6B, one exhaust port, and two exhaust ports TB are also provided, and an ignition plug 8 is provided near the center of the combustion chamber 4.

<Study points to be solved by the invention> However, in such a conventional intake device, fuel is injected from the fuel injection valve 5 in a concentrated manner at the center of the valve shaft of the umbrella portion of the first intake valve 1A. Therefore, the large particle diameter fuel injected from the fuel injection valve 5 flows into the combustion chamber 4 without being mixed well with the air in the intake port, and the fuel adheres to and accumulates on the head of the first intake valve and the valve shaft. was flowing into the combustion chamber 4 at once when the valve was opened. For this reason, even in the combustion chamber 4, fuel with large particle diameters has poor mixing properties with air, and the fuel is difficult to be transported by the air flow, resulting in poor mixing properties with air (HC (hydrocarbon) emissions). There was a problem in that the number increased.

In addition, in the operating range where the on-off valve 3 is open, two people at both intake ports and two
Approximately the same amount of air is supplied to the combustion chamber 4 through B, while fuel is supplied to the combustion chamber 4 from the two first intake ports, so even if it returns, it will be formed on the combustion chamber 4 wall. The quench layer tends to float in the vicinity of the first intake valve 1A, which has the drawback of reducing combustion performance and aggravating the above problem.

The present invention was made in view of the above-mentioned circumstances.
An object of the present invention is to provide an intake device that reduces C emissions.

Means for Solving Distance Point> Therefore, in the present invention, a fuel injection valve that injects fuel is provided all around the inner wall of the intake port upstream of the intake valve on the side where the on-off valve is not installed.

゛Thus, most of the soot injected from the fuel injection valve adheres to the intake port wall and is then supplied to the combustion engine to improve the vaporization characteristics of the fuel, thereby improving combustion performance. KyoJ) Efforts were made to reduce HC emissions.

Legend> An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In the figure, a cylinder head 11 is formed with a first intake port 12 and a second intake port (not shown) arranged side by side as in the conventional example, and the second intake port is provided with an on-off valve. ing. A first intake valve (not shown) is installed in the first intake port 12, and a second intake valve is installed in the second intake port. A water jacket 13 is formed in the cylinder head 11 so as to surround the first intake port 12 .

In addition, an intake manifold 1 is provided on the outer wall of the cylinder head 11.
4 is attached to the intake manifold 14, and an outward-opening type fuel injection valve 15 is attached to the intake manifold 14. Fuel injection valve 15
The fuel squirting center axis is located at the valve seat 16 of the first intake valve.
It is set to pass through the center of Furthermore, the injection angle θ of the fuel injection valve 15 is set larger than before, so that the injected fuel of the fuel injection valve 15 collides with the entire circumference of the inner wall of the first intake port 12, as shown in FIG. .

A specific example of a set of fuel injection valves 15 is as shown in FIG.
is the divergence angle θ' of the tip of the 15m needle shown in Figure 3.
This can be achieved by setting the value larger than before. At this time, the spread angle θ' is set to be slightly larger than the injection angle θ. In addition, to prevent the injection angle θ line injected fuel from colliding with the protector 15b at the front end of the fuel injection valve 15,
It becomes 85°.

As a result, the injected fuel forms a conical ring shape as shown in FIG. 4 and impinges on the entire circumference of the inner wall of the first intake port 12.

In addition, IT in FIG. 1 is a combustion chamber.

Next, the operation of this intake device will be explained.

Fuel is injected from the fuel injection valve 15 toward the inner circumferential wall of the first intake port 12, a part of which remains in the inner space of the intake port 12, and the remainder is widely distributed and adheres to the inner circumferential wall of the intake port 12.

At this time, since the water jacket 13 is formed to surround the first intake port 12, the temperature of the inner wall of the first intake port 12 rises to about the cooling water temperature. The vaporization of the fuel widely distributed and attached to the inner wall of the intake port 12 is promoted. In addition, since the injection angle θ is set to be large, the fuel particle size injected from the fuel injection valve 15 changes the direction of fuel movement at the needle portion, and the injected fuel is spread over a wide range.
Becomes

Then, as the first intake valve opens, the fuel vaporized from the inner peripheral wall of the first intake port 12 and the first intake port 1
A small amount of fuel accumulated in the internal space of the combustion chamber 2 is conveyed to the combustion chamber 17 by the intake air flow. Further, the fuel adhering to the inner circumferential wall of the first intake port 12 is combusted on the high-speed airflow flowing into the combustion chamber 1T through the narrow gap between the intake valve and the valve seat 16 at the initial stage of opening of the first intake valve. Since the fuel flows into the chamber 17, atomization of the fuel is promoted.

Therefore, since the mixing of fuel and air is promoted in the combustion chamber 17, combustion performance is improved and HC emissions can be reduced. Also, when the on-off valve installed in the second intake port opens and air flows into the combustion thtr from the second intake port, the fuel flowing from the intake port 12 of Kumo@i is vaporized and atomized. Since the mixing of fuel and air in the combustion chamber 17 is promoted, uneven distribution of fuel can be reduced, and the amount of HC emissions can be reduced.

Here, FIG. 5 shows experimental data when the injection angle θ of the fuel injection valve 15 was changed. According to this data, as the injection angle θ increases, the average particle diameter of the injected fuel decreases, and the weight of the fuel particles decreases accordingly. Also, H
The C emission concentration decreases rapidly until the injection angle is around 30°, and then remains at a substantially constant value. This is because fuel adheres to the inner circumferential wall of the first intake port 12 at an injection angle of 30° or more.

It should be noted that if the injection angle θ is set sharply so that the fuel adheres to the inner wall of the first intake port 12, it is expected that the responsiveness of the fuel air-fuel ratio control will decrease. The change in the input control control period was investigated in response to the change in the control period, and as shown in FIG. 5, the change in the control period was small, and the influence on the HC emission concentration 9 and the reduction in the conversion efficiency of the three-way catalyst were extremely small.

In addition, in order to increase the vaporization rate of the fuel in the first intake port 12, the fuel injection timing is set so that the fuel reaches the inner peripheral wall of the first intake port 12 immediately after the first intake valve is closed. It is preferable that the fuel stays in the intake port 12 for as long as possible and is heated by the cooling water.

Further, since the injected fuel from the fuel injection valve 15 adheres to the inner circumferential wall of the first intake port 12, there is an example shown in FIG. 6 as a method of setting the injection angle θ of the fuel injection valve 15 and its arrangement.

That is, the injection hole portion of the fuel injection valve 15 and the valve seat 1γ
When the distance between the fuel injector 15 and the fuel injection valve 15 is set to L, the injection angle of the fuel injector 15 is set to θ, and the aperture of the valve seat (valve seat) 17 is set to D, the fuel injection The fuel injected from the valve 15 comes to adhere to the inner peripheral wall of the first intake port 12. As a result, as shown in FIG. 7, the amount of fil and HC emissions decreases rapidly as Lθ/D approaches 1 from the small side, and then remains at a low value.

<Effects of the Invention> As explained above, the present invention is configured so that fuel is injected from one fuel injection valve to the entire circumference of the inner wall of the intake port upstream of the intake valve on the side where the on-off valve is not installed. Since the vaporization of the fuel is promoted in the combustion chamber, the mixing of the fuel and air in the combustion chamber is promoted, the combustion performance is improved, and ICC emissions can be reduced. In addition, even in the operating range where the on-off valve is open, where only air flows into the combustion chamber from the other intake port, the vaporization of fuel at one intake port is promoted, and the mixing of air and fuel in the combustion chamber is improved. HC emissions can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main part showing one embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part showing a specific example of a fuel injection valve, FIG. 3 is an enlarged view of the main part of FIG. Figure 5 shows the fuel injection shape of the fuel injection valve, Figure 5 shows the fuel average particle diameter 1 weight ratio, HC emission concentration, and input control control period with respect to the injection angle θ, Figure 6 shows the fuel injection shape of the fuel injection valve. A diagram to explain how to set it up,
Fig. 7 is a diagram showing the relationship between La/D in Fig. 6, HC emission amount, and fuel particle size, Fig. 8 is a plan view showing a conventional example of an intake system, and Fig. 9 is a cross section of the part shown in Fig. 8. Illustrated. 12...First intake port 13...Water jacket 15...Fuel injection valve 17...Combustion chamber patent Applicant Nissan Motor Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Le/D

Claims (1)

[Claims] For each cylinder, two intake ports, two intake valves installed in each of these intake ports, and an on-off valve installed in one of the intake ports that opens and closes according to engine operating conditions;
An intake system for an internal combustion engine, characterized in that the intake system for an internal combustion engine is provided with a fuel injection valve that injects fuel toward the entire circumference of the inner wall of the intake port upstream of the intake valve on the side where the on-off valve is not installed. .