JP2007297993A - Fuel injection valve for direct injection spark ignition type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the directivity of a spray directed toward an ignition plug when forming at least one spray directed toward the ignition plug and a plurality of sprays directed toward the lower side from the ignition plug by injecting fuel from a plurality of nozzle holes on a tip face of a fuel injection valve to inside of a combustion chamber. <P>SOLUTION: A nozzle hole A1 of spray directed toward the ignition plug is arranged in the central part on the tip face of the fuel injection valve. Nozzle holes A2 to A4 of sprays directed toward the lower side from the ignition plug are arranged so as to be offset from the central part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection valve (multi-hole injector) of a direct-injection spark-ignition internal combustion engine that is disposed at a side portion of a combustion chamber and injects fuel into the combustion chamber from a plurality of injection holes on the front end surface.

The fuel injection valve described in Patent Document 1 injects fuel into the combustion chamber from a plurality of nozzle holes on the front end surface, thereby causing one spray directed to the spark plug and a plurality of sprays directed to the lower side of the spark plug. And so on.
JP 2005-098117 A

However, in the fuel injection valve described in Patent Document 1, since the spray hole directed to the ignition plug is formed offset from the center of the front end surface of the fuel injection valve, sufficient directivity to the ignition plug is provided. There was a problem that could not be secured.
That is, when the fuel injection valve is mounted, rotational variation with respect to the axial center of the fuel injection valve occurs, which affects the directivity of the nozzle hole. At this time, the axis and the nozzle hole are offset and arranged. In this case, in addition to the rotational variation, a variation in offset from the center is also added, and the variation becomes extremely large, so that sufficient directivity cannot be secured.

  In view of the actual situation and the fact that the directivity of the spray directed to the spark plug has the most influence on the combustion performance, the present invention improves the directivity of the spray directed to the spark plug in the multi-hole injector. The purpose is to be able to.

  For this reason, in this invention, it is set as the structure which arrange | positions the spray hole directed to the ignition plug at the front end surface center portion of the fuel injection valve.

  According to the present invention, when the fuel injection valve is mounted, even if there is a rotational variation with respect to the axial center of the fuel injection valve, the spray nozzle directed to the spark plug is connected to the center portion of the front end surface (axial center) of the fuel injection valve. ), The variation in offset from the center can be avoided, and the effect of minimizing the variation and securing the directivity to the spark plug having the greatest influence on the combustion performance can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a front view of a combustion chamber showing a first embodiment of the present invention, and FIG. 2 is a plan view of the same combustion chamber, showing spraying by a fuel injection valve (multi-hole injector). FIG. 3 is an arrangement diagram of nozzle holes on the front end face of the fuel injection valve in the first embodiment, and FIG. 4 is an explanatory view of the injection direction.
A spark plug 2 is arranged at the center of the upper surface of the pent roof type combustion chamber 1 of the internal combustion engine. A fuel injection valve (injector) 3 that directly injects fuel into the combustion chamber 1 is disposed obliquely downward on the side portion of the combustion chamber 1 (side portion on the intake side).

As shown in FIG. 3, a plurality of injection holes are formed in the front end surface (planar or hemispherical surface) of the fuel injection valve 3, and fuel is injected into the combustion chamber 1 from the plurality of injection holes. Form a spray.
The plurality of sprays are divided into four groups (rows). That is, from the upper side, a first group of sprays F1 composed of one spray, a second group of sprays F2 composed of two sprays, a third group of sprays F3 composed of two sprays, and a second group of sprays composed of two sprays. It is divided into four groups of sprays F4.

The first group of sprays F1 (spray center line C1) is directed to the spark plug 2, as shown in FIGS.
The second group spray F2 (spray center line C2) has an angle θa (FIG. 1) with respect to the first group spray F1 and is directed below the spark plug 2 and below the first group spray F1. ing.

The third group of sprays F3 (spray center line C3) has an angle θb (FIG. 1) with respect to the second group of sprays F2 and is directed below the spark plug 2 and below the second group of sprays F2. ing.
The fourth group spray F4 (spray center line C4) has an angle θc (FIG. 1) with respect to the third group spray F3 and is directed to a position below the spark plug 2 and below the third group spray F3. ing.

Here, the angle θa formed between the first group of sprays F1 (spray center line C1) and the second group of sprays F2 (spray center line C2) is such that the first group of sprays F1 interferes with the second group of sprays F2. (Intervals that do not change the shape and characteristics of the spray during the single injection of the first group of sprays F1).
On the other hand, the angle θb formed between the second group spray F2 (spray center line C2) and the third group spray F3 (spray center line C3), and the third group spray F3 (spray center line C3) and the third group spray F3 (spray center line C3). The angle θc formed by the four groups of sprays F4 (spray center line C4) is sufficiently smaller than the above θa (θb <θa, θc <θa), and the sprays of adjacent groups in the second to fourth groups interfere with each other. It is set as the space | interval which turns into one spray lump. Note that θb = θc or θb≈θc.

Further, in the second group, the two sprays F2 and F2 (spray center lines C2 and C2) allow the fuel injection valve 3 in a plan view (FIG. 2) so that the spray can be evenly distributed in the combustion chamber. Are arranged symmetrically with respect to a line connecting the spark plug 2 and the spark plug 2. Here, the angle formed by the two sprays F2, F2 (spray center lines C2, C2) is θ2.
Similarly, in the third group, the two sprays F3 and F3 (spray center lines C3 and C3) are arranged symmetrically with respect to a line connecting the fuel injection valve 3 and the spark plug 2 in plan view. Here, an angle formed by the two sprays F3 and F3 (spray center lines C3 and C3) is θ3, which is larger than θ2 (θ3> θ2).

Similarly, in the fourth group, the two sprays F4 and F4 (spray center lines C4 and C4) are arranged symmetrically with respect to a line connecting the fuel injection valve 3 and the spark plug 2 in plan view. Here, the angle formed by the two sprays F4, F4 (spray center lines C4, C4) is θ4, which is larger than θ3 (θ4> θ3).
Therefore, in the second to fourth groups, the angle formed by the two sprays (spray center lines) of each group is increased as the group is directed to a lower position. That is, θ2 <θ3 <θ4.

The θ2 is reduced when the fuel is injected during the intake stroke to prevent interference with the intake valve and the flame of the spray F1 of the first group is spread to the sprays F2, F3, and F4 of the second group and later. This is to ensure a smooth flame connection.
The reason why θ4 (θ3) is increased is to form a wide and uniform air-fuel mixture in the entire combustion chamber and spread the flame over the entire combustion chamber (wide range).

Next, the arrangement of the nozzle holes on the tip surface of the fuel injection valve in the present embodiment will be described with reference to FIG.
The nozzle hole A1 that forms the first group of sprays F1 is disposed at the center (axial center) of the front end face of the fuel injection valve. This is because the first group of sprays F1 is directed to the spark plug, and its directivity is directly related to the driving performance. That is, when the fuel injection valve is installed, there is a rotational variation with respect to the axial center of the fuel injection valve, but if the injection hole is not at the axial center, in addition to the rotational variation, a variation in offset from the center is also added. , The directivity worsens. Therefore, by arranging the injection hole A1 of the spray F1 directed to the spark plug at the center of the shaft, the spray F1 directed to the spark plug can avoid the variation in the offset and ensure directivity to the spark plug. It is.

The nozzle holes A2 and A2 forming the second group of sprays F2 and F2 are disposed at an appropriate interval below the nozzle hole A1 of the first group of sprays F1 on the tip surface of the fuel injection valve.
The nozzle holes A3, A3 forming the third group sprays F3, F3 are slightly larger than the interval between the nozzle holes A2, A2 below the nozzle holes A2, A2 of the second group sprays F2, F2. Place them at intervals.

The nozzle holes A4, A4 forming the fourth group sprays F4, F4 are slightly larger than the interval between the nozzle holes A3, A3 below the nozzle holes A3, A3 of the third group sprays F3, F3. Place them at intervals.
Next, the operation will be described.
According to the present embodiment, by performing fuel injection in the vicinity of the compression top dead center, the first group of sprays F1 directed to the spark plug 2 does not receive interference from the other sprays, and is stable. A rich air-fuel mixture for ignition can be formed in a narrow space around 2. On the other hand, the other sprays diffuse in a wide space while interfering with each other to some extent, and as a combined spray mass, a mixture gas mass leaner than the rich gas mixture mass surrounding the rich gas mixture mass can be formed. it can.

Therefore, at the time of cold start, during the period until the temperature of the exhaust purification catalyst reaches the activation temperature, fuel injection is performed near the compression top dead center to form a rich mixture around the spark plug, and further In addition, by forming an air-fuel mixture that is leaner than the rich air-fuel mixture mass and burning (over-ignition ignition combustion), it is possible to promote afterburning, increase exhaust temperature, and reduce HC.
Further, when the fuel injection valve 3 is mounted, rotational variation occurs with respect to the axial center of the fuel injection valve 3, but the spray hole of the spray F <b> 1 directed to the spark plug 2 is formed at the center of the front end surface of the fuel injection valve 3. By disposing at the center), variations in offset from the center can be avoided, and variations can be minimized and directivity to the spark plug 2 having the greatest influence on the combustion performance can be ensured.

On the other hand, the other sprays F2 to F4 that are not directed to the spark plug 2 have an offset, so that the directivity cannot be obtained so much, but diffusion into the combustion chamber is required, and the directivity requirement is not severe. So it will not be a problem.
Further, according to the present embodiment, the injection holes A2 to A4 of the sprays F2 to F4 in the second group and subsequent groups are sprayed of the spray F1 directed to the spark plug at the tip surface of the fuel injection valve for each spray group. By disposing the lower side of the hole toward the lower side of the hole, the nozzle hole is not well balanced at the tip of the fuel injection valve. However, as shown in FIG. There is an advantage of not crossing.

In the present embodiment, the number of spray groups is four, but may be three, or may be five or more.
Next, a second embodiment of the present invention will be described.
FIG. 5 is a layout of nozzle holes on the front end face of the fuel injection valve showing the second embodiment of the present invention.
In the second embodiment, there are two first group sprays directed to the spark plug, and the spray holes A2 and A2 are arranged symmetrically in the center of the front end surface of the fuel injection valve. That is, it arrange | positions so that the shaft center may be enclosed in the shaft center vicinity of a fuel injection valve.

By doing so, even when there are two spray holes directed to the spark plug, the directivity to the spark plug can be ensured by minimizing the offset from the center.
In the present embodiment, the number of sprays (injection holes) after the second group is two, but one may be added to the center of each group (row) to obtain three.
Next, a third embodiment of the present invention will be described.

FIG. 6 is an arrangement diagram of nozzle holes on the front end face of the fuel injection valve showing the third embodiment of the present invention, and FIG. 7 is an explanatory view of the injection direction in the third embodiment.
In the present embodiment, the injection hole A1 of the first group of sprays F1 directed to the spark plug is disposed at the center of the front end surface of the fuel injection valve, and the injection holes A2 of the second group of sprays F2 and F2 are disposed below the injection holes A2. , A2 are arranged, and the nozzle holes A3, A3 of the third group of sprays F3, F3 are arranged on the lower side thereof. The injection holes A4, A4 of the fourth group of sprays F4, F4 directed to the lowermost side are the injection holes A1 of the first group of sprays F1, directed to the ignition plug at the center of the fuel injection valve front end surface. Place on the upper side.

  That is, among the spray holes of the second and subsequent groups, the spray holes A4 and A4 of the group that are directed to the lowest position are the first group of sprays that are directed to the spark plug at the tip surface of the fuel injection valve. It arrange | positions above the nozzle hole A1. In other words, the spray holes A4, A4 of the fourth group that do not overlap with the spray directed to the spark plug are arranged above the spray holes A1 directed to the spark plug.

In the case of the first embodiment, the injection holes are all disposed below the axial center of the fuel injection valve. In the case of the third embodiment, the injection holes are distributed above and below the axial center of the fuel injection valve. Therefore, the balance of the nozzle hole arrangement is improved.
Further, by arranging the spray holes A4 and A4 of the fourth group having the largest opening angle (θ4) of the two sprays on the upper side of the spray holes A1 directed to the spark plug, the spray directed to the spark plug Interference with other sprays can be avoided, so that the spray directed to the spark plug can avoid the spray variation caused by the interference.

Next, a fourth embodiment of the present invention will be described.
FIG. 8 is a layout diagram of nozzle holes on the front end face of the fuel injection valve showing the fourth embodiment of the present invention, and FIG. 9 is an explanatory view of the injection direction in the fourth embodiment.
In the present embodiment, the injection hole A1 of the first group of sprays F1 directed to the spark plug is disposed at the center of the front end surface of the fuel injection valve, and the injection holes A2 of the second group of sprays F2 and F2 are disposed below the injection holes A2. , A2 is arranged. The nozzle holes A3, A3 of the third group sprays F3, F3 are arranged above the nozzle holes A1 of the first group spray F1, which is directed to the spark plug at the center of the front end face of the fuel injection valve. The injection holes A4, A4 of the fourth group of sprays F4, F4 directed to the lowermost side are the injection holes A1 of the first group of sprays F1, directed to the ignition plug at the center of the fuel injection valve front end surface. Place it on either side of it.

  That is, among the spray holes of the second and subsequent groups, the spray holes A4 and A4 of the group that are directed to the lowest position are the first group of sprays that are directed to the spark plug at the tip surface of the fuel injection valve. Are arranged on the left and right sides of the nozzle hole A1. In other words, the spray holes A4 and A4 of the fourth group in which the interval between the two nozzle holes is taken are arranged on both sides of the spray hole A1 directed to the spark plug.

  Further, the third group spray nozzles A3, A3 are arranged above the first group spray nozzle A1 directed to the spark plug at the front end face of the fuel injection valve. In other words, the spray holes A3 and A3 of the third group that do not overlap the spray directed to the spark plug are arranged above the spray holes A1 directed to the spark plug. On the other hand, the spray holes A2 and A2 of the second group that overlap the spray directed to the spark plug are arranged below the spray holes A1 directed to the spark plug. In addition, although the spray of 2 groups and the spray of the 3rd group will overlap, since the influence by the overlap of spray is less than the spray of the 1st group directed to a spark plug, there is no problem.

  According to the fourth embodiment, the balance of the nozzle hole arrangement can be further improved with respect to the third embodiment.

The front view of the combustion chamber which shows 1st Embodiment of this invention Top view of the combustion chamber Arrangement of nozzle holes on the tip surface of the fuel injection valve in the first embodiment Explanatory drawing of the injection direction in 1st Embodiment Arrangement of nozzle holes on the end face of the fuel injection valve showing the second embodiment of the present invention Arrangement of nozzle holes on the end face of the fuel injection valve showing the third embodiment of the present invention Explanatory drawing of the injection direction in 3rd Embodiment Arrangement of nozzle holes on the end face of the fuel injection valve showing the fourth embodiment of the present invention Explanatory drawing of the injection direction in 4th Embodiment

Explanation of symbols

1 Combustion chamber 2 Spark plug 3 Fuel injection valve (multi-hole injector)
F1 to F4 First to fourth group sprays C1 to C4 First to fourth group spray centerlines A1 to A4 First to fourth group spray nozzles

Claims (8)

At least one spray directed to the ignition plug and a plurality of sprays directed to the lower side of the ignition plug by injecting fuel into the combustion chamber from the plurality of injection holes on the front end surface, disposed on the side of the combustion chamber A fuel injection valve for a direct-injection spark ignition internal combustion engine to be formed,
A fuel injection valve for a direct-injection spark-ignition internal combustion engine, characterized in that a spray hole directed to the spark plug is disposed at the center of the front end surface of the fuel injection valve. A first group of sprays, which are arranged on the side of the combustion chamber and inject fuel into the combustion chamber from a plurality of nozzle holes on the front end surface and are directed to the spark plug; and at least the first group A second group of sprays composed of at least one spray directed at a position lower than the spray of the second group, and a third group of sprays composed of at least one spray directed at a position lower than the spray of the second group, A fuel injection valve of a direct-injection spark ignition type internal combustion engine that forms a plurality of groups of sprays after the second group consisting of at least one spray for each group directed to a lower position sequentially,
A fuel injection valve for a direct-injection spark-ignition internal combustion engine, characterized in that a spray hole for a first group of sprays directed to the spark plug is disposed at the center of the tip surface of the fuel injection valve.   3. The direct injection spark ignition type according to claim 2, wherein there are two sprays of the first group directed to the spark plug, and the spray holes of these sprays are arranged symmetrically at the center of the front end surface of the fuel injection valve. A fuel injection valve for an internal combustion engine.   There are two sprays in each group of the second group, and the two sprays are symmetrical with respect to the line connecting the fuel injection valve and the spark plug in plan view, and the angle formed by the spray center line is 4. The fuel injection valve for a direct injection spark ignition type internal combustion engine according to claim 2, wherein the larger the group is directed to a lower position, the larger the group is.   The spray holes for the second and subsequent groups are more grouped at the front end surface of the fuel injection valve at the tip side of the fuel injection valve and below the spray holes for the ignition plug. 5. The fuel injection valve for a direct injection spark ignition type internal combustion engine according to claim 4, wherein the fuel injection valve is disposed on the lower side.   Among the spray holes of the second and subsequent groups, the spray hole of the group that is directed to the lowest position is more than the spray hole of the first group that is directed to the spark plug at the tip surface of the fuel injection valve. 5. The fuel injection valve for a direct injection spark ignition internal combustion engine according to claim 4, wherein the fuel injection valve is disposed on an upper side.   Among the spray holes of the second and subsequent groups, the spray holes of the group that is directed to the lowest position are the spray holes of the first group that are directed to the spark plug at the tip surface of the fuel injection valve. The fuel injection valve for a direct-injection spark-ignition internal combustion engine according to claim 4, wherein the fuel injection valve is disposed on both sides of the fuel injection valve.   After the second group, the sprays of the plurality of groups are constituted by the sprays of the second group to the fourth group, and the spray holes of the third group are directed to the spark plug at the tip end surface of the fuel injection valve. 8. The fuel injection valve for a direct-injection spark-ignition internal combustion engine according to claim 7, wherein the fuel injection valve is disposed above an injection hole for one group of sprays.

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