JPH06249108A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To improve performance of carburetion and atomization by injecting fuel from a gap formed by a shade of an intake valve and an intake port opening in an intake process while forming an injection port formed on an injector provided on the intake port in the vicinity of a combustion chamber, then injecting the fuel through both sides of a stem of the intake valve, and thereby avoiding adhesion to a wall surface which may be caused by increase of a fuel injection amount. CONSTITUTION:A shutter valve provided on an intake port 12 on which an injector 20 is not arranged is closed in an intake process where an intake valve 11 is opened under a low load and low rotational speed area. Intake air is supplied only from an intake port 12 on which the injector 20 is arranged to a combustion chamber 14 for generating satisfactory swirl inside a cylinder 2. At this time a timed control valve 27 is opened, and assist air is supplied from an upstream side of a throttle valve 7 through a passage 26 to the injector 20. Fuel is directly injected into the cylinder through both sides of a stem of the intake valve 11 from a gap formed by the intake valve 11 and the intake port 12. Atomized fuel is divided into two under a lean condition, so that adhesion to a wall surface is prevented even when the fuel injection amount is increased. Fuel consumption performance and emission are thus improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an engine, and more particularly to a fuel injection device for an engine that performs lean burn.

[0002]

2. Description of the Related Art Conventionally, there has been developed a fuel injection system for an engine which improves fuel efficiency by performing lean combustion. The lean combustion is performed by utilizing the in-cylinder flow of swirl, tumble, squish, etc. to make the air-fuel mixture uniform and achieve rapid and stable combustion.

When lean combustion is performed by utilizing such in-cylinder flow, the effect saturates when the air-fuel ratio (A / F) is around 22, so the fuel efficiency is improved even if the lean limit is further extended. The reality is that we cannot hope for it.

[0004]

Therefore, in order to extend the lean limit and improve the fuel economy, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 3-61716, an injector is provided in an intake port in the vicinity of a combustion chamber, and fuel is injected by the injector from a gap between an umbrella portion of an intake valve and an intake port opening during an intake stroke. What has been done is proposed.

In the one described in this publication, the fuel is directly injected into the cylinder having a low pressure during the intake stroke when the intake valve is lifted, whereby stratification of the air-fuel mixture is achieved and the air-fuel ratio is 30 to 30. It becomes possible to perform a lean burn of about 40. However, since the one described in this publication has only one fuel injection port of the injector, stratification of the air-fuel mixture is possible by optimally setting the injection angle, the injection direction, and the injection timing. Considering the contact of the spray with the valve, the injection direction, and the atomization, there is room for further improvement.

Therefore, the present invention has been made in order to further improve the conventional apparatus, and it is possible to perform fuel injection having excellent vaporization and atomization without causing wall adhesion even if the fuel injection amount increases. An object is to provide a possible fuel injection device for an engine.

[0007]

In order to achieve the above object, the present invention provides an injector in an intake port in the vicinity of a combustion chamber so that a gap between an umbrella portion of an intake valve and an intake port opening is provided during an intake stroke. In an engine fuel injection device for injecting fuel into a cylinder by the injector, two injectors are formed in the injector, and fuel is injected from the two injectors through both sides of a stem portion of an intake valve. It is characterized by having done.

In the present invention thus constructed,
The injector provided in the intake port near the combustion chamber injects fuel into the cylinder from the gap between the head portion of the intake valve and the opening of the intake port during the intake stroke. At the time of this fuel injection, the fuel is injected through both sides of the stem portion of the intake valve by the two injection ports formed in the injector.

Therefore, in the present invention, since the spray is dispersed by the two injection ports as compared with the one injection port, even if the fuel injection amount increases, adhesion of the wall surface of the umbrella portion or the stem portion does not occur. Further, the mixing of air and fuel is promoted, and the vaporization and atomization property is improved. Further, since the fuel can be directly injected into the cylinder without hitting the stem portion, vaporization and atomization is further promoted.

The present invention further has a swirl generating means, and one of the two injection ports of the injector is directed toward the spark plug and the other is directed toward the outer peripheral portion of the cylinder. For this reason, a swirl flow is formed, and the mixing of air and fuel is improved. further,
The present invention further has an assist air supply means for supplying the assist air to the injector, and the assist air supply means supplies the assist air having a flow velocity higher than that of the one injection port to the other injection port. To do.

Therefore, uniform multi-stratification can be realized in the rich cylinder outer peripheral portion near the plug. Further, the assist air makes it easier for the fuel to be atomized. Further, since the assist air is jetted toward the outer peripheral portion of the cylinder, the formation of swirl flow is promoted and the fuel is prevented from adhering to the wall surface of the cylinder, which is advantageous for fuel consumption and emission.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram showing an embodiment of an engine fuel injection device of the present invention. In FIG. 1, 1 is an engine body, and this engine body 1 is
It is composed of a cylinder 2 and a cylinder head 3.
The intake air is ignited via an air cleaner 4, an air flow chamber 6 accommodating an air flow sensor 5, a throttle valve body 8 accommodating a throttle valve 7, a surge tank 9, an intake manifold 10, and an intake port 12 opened and closed by an intake valve 11. It is supplied to the combustion chamber 14 in which the plug 13 is arranged. The path from the air cleaner 4 to the intake port 12 constitutes an intake passage 15.
The amount of intake air flowing through the intake passage 15 is controlled by an opening / closing operation by the throttle valve 7, while being measured by the air flow sensor 5. On the other hand, the exhaust gas from the combustion chamber 14 is exhausted by the exhaust port 1 which is opened and closed by the exhaust valve 16.
The gas is discharged to the atmosphere via the exhaust passage 18 connected to 7. Further, an injector 20 is provided in the intake port 12 near the combustion chamber 14.

FIG. 2 is a sectional view showing the vicinity of the injector,
FIG. 3 is a plan view showing the vicinity of the injector. As shown in FIGS. 2 and 3, specifically,
The injector 20 is provided near the combustion chamber 14 of the one intake port 12a. In addition, the injector 2
0 has two injection ports 21 and 22 as described later. The injector 20 directly injects fuel into the cylinder through the gap between the cap portion 11a of the intake valve 11 and the intake port opening 23 through both sides of the stem portion 11b of the intake valve 11. A shutter valve 25 is provided on the other intake port 12b. By closing the shutter valve 25, a srail flow is formed.

Further, as shown in FIG. 1, an assist air passage 26 is connected to the injector 20 via a timed air control valve 27. The upstream end of the assist air passage 26 opens to the upstream side of the throttle valve 7 in the intake passage 15. Therefore, by opening the timed air control valve 27 during the intake stroke, the negative pressure in the cylinder communicates with the atmosphere on the upstream side of the throttle valve 7, and the differential pressure thereof supplies the assist air into the cylinder. To be done. Further, 30 is a fuel tank from which fuel is supplied to the injector 20.

FIG. 4 is a sectional view showing the injector, and FIG. 5 is a bottom view showing the injector. As shown in FIGS. 4 and 5, the injector 20 is provided with the two injection ports 21 and 22 as described above. As shown in FIG. 3, the one injection port 21 is directed to the spark plug 13, and the other injection port 22 is directed to the cylinder outer peripheral portion 28 of the engine 1. Further, the injection port 21 of the ignition plug 13 is formed to have a larger diameter than the injection port 22 directed to the cylinder outer peripheral portion 28, and the injection ports 21 and 21 are provided.
2 are connected to the branch passages 26a and 26b of the assist air passage 26 branched near the injector 20, respectively. As a result, the flow velocity of the air jetted from the jet port 21 becomes smaller than the flow velocity of the air jetted from the jet port 22, and the flow velocity of the air jetted from the jet port 22 becomes smaller.
It becomes larger than the flow velocity of the air jetted from the No. 1.

Next, the operation will be described. First, as shown in FIG. 6, the shutter valve 25 is closed in the low load / low rotation range (A), and the shutter valve 25 is closed in the high load / high rotation range (B).
Is open. As described above, in the low load / low speed operation region, the shutter valve 25 is closed in the intake stroke in which the intake valve 11 is opened, so that intake air is supplied into the combustion chamber 14 from only one intake port 12a. As a result, a good swirl flow is formed in the cylinder.

Further, at this time, by opening the timed air control valve 27, assist air is injected from the injector 20 from the upstream side of the throttle valve 5 through the assist air passage 26 and the branch passages 26a and 26b thereof. It is supplied to the mouths 21 and 22. Further, this assist air causes the spray from the injector 20 to be injected into the injection port 2
Air is assisted at 1 and 22, and is directly injected into the cylinder through the gap between the cap portion 11a of the intake valve 11 and the intake port opening 23 through both sides of the stem portion 11b of the intake valve 11.

As a result, compared with the one injection port, the spray is dispersed by the two injection ports 21 and 22. Therefore, even if the fuel injection amount is increased, adhesion of the wall surface of the umbrella portion 11a and the stem portion 11b is caused. In addition, since the mixing property of the air and the fuel is further improved, the vaporization atomization property is improved. Furthermore, since the fuel can be directly injected into the cylinder without hitting the stem portion 11b, vaporization and atomization is further promoted.

Further, a spray having a high flow velocity is ejected from the injection port 22 directed to the cylinder outer peripheral part 28 toward the cylinder outer peripheral part and the injection port 21 directed to the ignition plug 13 is also formed.
Since the spray having a small flow velocity is ejected from the vicinity of the spark plug 13, uniform multi-stratification can be realized in the peripheral portion of the rich cylinder in the vicinity of the plug. Further, the assist air makes it easier for the fuel to be atomized. Further, the cylinder outer peripheral portion 28
Since the assist air is jetted toward, the formation of the swirl flow is promoted and the fuel is prevented from adhering to the cylinder wall surface, which is advantageous for fuel consumption and emission.

Next, another embodiment of the present invention will be described with reference to FIGS. This embodiment is characterized in that the injection port 31 of the injector 30 has a flat shape. Also in this injector 30, as in the above embodiment, the fuel is directly injected into the cylinder through the gap between the cap portion 11a of the intake valve 11 and the intake port opening 23 through both sides of the stem portion 11b of the intake valve 11. I have to. In the present embodiment, the injection port 31 has a flat shape so as to follow the shapes of the umbrella portion 11a of the intake valve 11 and the intake port opening 23.

As a result, the spray sprayed from the spray port 31 has a flat shape as shown by reference numerals 32 and 33 in FIG. Here, 32 shows the outer shape of the spray in the cross section taken along the line AA in FIG. 7, and 33 shows the outer shape of the spray in the cross section taken along the BB line in FIG. 7. By thus forming the injection port 32 in a flat shape, the contact area between the intake air and the fuel in the cylinder is greatly expanded, and mixing is further promoted.

[0022]

As described above, according to the fuel injection system for an engine of the present invention, even if the fuel injection amount increases, the mixing of air and fuel is further promoted without causing the adhesion of the wall surface of the umbrella portion or the stem portion. This improves vaporization and atomization. Further, it is possible to realize uniform multi-stratification in the peripheral portion of the rich cylinder near the plug. Further, the assist air makes it easier for the fuel to be atomized. Further, since the assist air is ejected toward the outer peripheral portion of the cylinder, the formation of swirl flow is promoted and at the same time fuel adhesion on the cylinder wall surface is prevented,
It is advantageous for fuel efficiency and emission.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a fuel injection device for an engine of the present invention.

FIG. 2 is a sectional view showing the vicinity of the injector.

FIG. 3 is a plan view showing the vicinity of the injector.

FIG. 4 is a sectional view showing an injector.

FIG. 5 is a bottom view showing the injector.

FIG. 6 is a diagram for setting the opening / closing of a shutter valve from the relationship between load and rotation speed.

FIG. 7 is a plan view showing the vicinity of an injector according to another embodiment of the present invention.

FIG. 8 is a view showing the outer shape of the spray ejected from the injector.

FIG. 9 is a bottom view showing the injection port of the injector.

[Explanation of symbols]

 1 Engine Main Body 2 Cylinder 3 Cylinder Head 10 Intake Manifold 11 Intake Valve 11a Intake Valve Head 11b Intake Valve Stem 12 Intake Port 13 Spark Plug 14 Combustion Chamber 20 Injector 21 Injector 22 Injector 25 Shutter Valve 26 Assist Air Passage 27 Timed air control valve 28 Cylinder outer periphery 30 Injector 31 Injection port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area F02M 69/04 P 7825-3G

Claims (3)

[Claims] 1. A fuel injection system for an engine, wherein an injector is provided in an intake port in the vicinity of a combustion chamber, and the injector injects fuel into a cylinder from a gap between an umbrella portion of the intake valve and an opening of the intake port during an intake stroke. A fuel injection device for an engine, wherein two injectors are formed in the injector, and fuel is injected from the two injectors through both sides of a stem portion of an intake valve. 2. A swirl generating means, wherein the two injection ports of the injector are formed so that one of them is directed to the spark plug and the other is directed to the outer peripheral portion of the cylinder. Engine fuel injectors. 3. An assist air supply means for supplying assist air to the two injection ports of the injector, the assist air supply means having a flow velocity higher than that of the one injection port at the other injection port. The fuel injection device for the engine according to claim 2, wherein the assist air is supplied.