JP3334330B2 - Fuel injection valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel injection valve for supplying fuel to a cylinder of an internal combustion engine, for example.

[0002]

2. Description of the Related Art In general, a fuel injection valve for injecting fuel into each cylinder of an internal combustion engine typified by an automobile engine is provided by:
A casing, a nozzle body having an injection hole mounted on the distal end side of the casing, a valve body such as a needle valve provided in the nozzle body so as to be displaceable in the axial direction and opening and closing the injection hole, and the valve body A valve spring for urging the valve in the valve closing direction;
An electromagnetic actuator for opening the valve body against the spring force of the valve spring is provided, and the fuel is injected and supplied according to an injection signal from the control unit.

[0003] As a fuel injection valve, a suck hole type fuel injection valve having a suck hole type nozzle main body that guides fuel to an injection hole through a suck hole formed on the tip side is known. However, in this suck hole type fuel injection valve, fuel accumulated in the suck hole may flow into the combustion chamber due to thermal expansion after the valve is closed, and the emission amount of HC may increase. For this reason, a suckless fuel injection valve equipped with a suckless nozzle body that eliminates or minimizes the sac hole that becomes a fuel pool and directly opens and closes the inlet of the injection hole with a valve body is also known. More suggested.

Therefore, based on FIGS. 11 and 12, a fuel injection valve according to the prior art is disclosed in, for example, Japanese Utility Model Laid-Open No. 60-88.
This will be described by taking, for example, JP-A-0774.

FIG. 11 is an enlarged sectional view showing a main part of a suckless type fuel injection valve, and a fuel tank, a fuel pump and a pressure regulator (both are provided) are provided at the tip end of a casing containing an electromagnetic actuator and the like. A nozzle body 100 to which fuel is supplied via a not-shown) or the like is fixed. A needle valve 101 is provided in the nozzle body 100 so as to be slidable in the axial direction. The needle valve 101 allows a pair of injection holes 102 and 103 formed at the conical tip portion 100a of the nozzle body 100 to have the same diameter. Are opened and closed simultaneously.

Here, each of these injection holes 102, 103 is 2
As shown in the sectional view of FIG. 12, a total of four sets are provided at a distance of about 90 degrees. In addition, each of the injection holes 102 and 103 has the injection axis of the nozzle body 100.
The nozzle body 100 is formed obliquely from the radial direction at the distal end 1a of the nozzle body 100 so as to intersect at the radially outer peripheral end side.

The conventional suckless fuel injection valve is configured as described above. When the needle valve 101 is opened by an injection signal, approximately equal amounts of fuel are respectively obliquely downwardly directed from the injection holes 102 and 103. It is injected. Then, the injected fuels collide with each other outside the nozzle body 100 and are atomized, and then flow into the combustion chamber along the intake air flow.

[0008]

However, in the above-described fuel injection valve according to the prior art, atomization can be achieved by causing fuel to collide with each other, but the diameters of the injection holes 102 and 103 are simply set equal. Therefore, the resonance phenomenon at the time of collision cannot be effectively used, and the atomization performance has not been sufficiently exhibited.

The present invention has been made in view of the above-mentioned problems of the prior art, and a main object of the present invention is to enhance the atomization performance of fuel by utilizing a resonance phenomenon. Another object of the present invention is to further improve the atomization performance of the fuel by making the injection pressure uniform and making the particle diameter of the injected fuel substantially equal.

[0010]

Therefore, a fuel injection valve according to the present invention comprises a nozzle body having a conical portion formed on the tip end side with an injection hole provided in a radial direction, and a nozzle body having an axially extending inside thereof. Movably provided with a valve element for opening and closing the injection hole, and eliminating or eliminating a suck hole serving as a fuel pool.
And the inlet of the injection hole is directly opened and closed by the valve
In the fuel injection valve, a pair of large and small injection holes is provided on the tip side of the nozzle body with a large injection hole on the upstream side.
Spaced apart axially so as to be positioned, the respective injection holes
So that the square root ratio of the cross-sectional area is in the range of 1.25 to 3.5
And the injection axis of each of the injection holes intersects outside the nozzle body so that the fuel injected from each of the injection holes collides with each other.

[0011]

[0012]

[0013]

[0014]

When the valve is opened, fuel is injected from a pair of injection holes having different injection hole diameters, and these fuels collide with each other outside the nozzle body and are atomized.

In particular, the square root ratio of the sectional area of each injection hole is set to 1.2.
If it is set in the range of 5 to 3.5, the resonance phenomenon at the time of the fuel collision can be utilized while securing the collision area of the fuel, so that the effective atomization can be performed.

Further, if a pair of large and small injection holes are provided apart from each other in the axial direction so that the larger diameter of the injection hole is located on the upstream side, the pressure difference applied to the inlet of each injection hole can be reduced. By making the particle diameters of the fuel injected from the injection holes substantially equal, a strong resonance phenomenon can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

First, FIGS. 1 to 4 relate to a first embodiment of the present invention, and FIG. 1 is an enlarged sectional view showing a main part of a fuel injection valve. It is fixed to the distal end side of the built-in casing by fixing means such as caulking, and is mounted facing a combustion chamber (both not shown).

The nozzle body 1 has a cylindrical portion 1a fixed to the distal end of the casing and a conical portion 1b integrally formed at the distal end of the cylindrical portion 1a. Fuel tank via supply pipe etc. (none shown)
Is formed.

In the conical portion 1b of the nozzle body 1,
A pair of large and small injection holes 2 so as to communicate with the fuel flow path 1c;
3 are formed radially apart from each other in the direction of the axis Ax.
More specifically, as shown in FIG. 2, the injection hole 2 having a larger cross-sectional area (hereinafter, referred to as “large injection hole 2”) is located on the upstream side and is obliquely located below the nozzle body 1 from the radial direction. Drilled towards. On the other hand, the injection hole 3 having a smaller cross-sectional area (hereinafter, referred to as “small injection hole 3”) is located on the downstream side of the large injection hole 2 and is formed in the nozzle body 1 obliquely downward from the radial direction. ing.

Here, the injection axis X ₁ of the large injection hole 2 is inclined by a predetermined angle θ _{1 in the} fuel inflow direction with respect to the axis Ax. On the other hand, the injection axis X ₂ of the small injection hole 3 is also inclined at a predetermined angle θ _{2 in the} fuel inflow direction with respect to the axis Ax.
The two axes X ₁ and X _{2 correspond} to a point P outside the nozzle body 1.
, The fuel injected from each of the injection holes 2 and 3 collides with each other. In addition, even if each injection axis X ₁ , X ₂ does not intersect at one point P on the same plane and there is a distance between the axes, the injection holes 2, 3 are provided so that the injected liquids collide with each other. Is also possible.

The ratio α (α = (S ₁ ) ^1/2 of the square root of the cross-sectional area S ₁ of the large injection hole 2 to the square root of the cross-sectional area S ₂ of the small injection hole 3.
/ (S ₂₎ ^1/2) is from 1.25 to 3 for the reasons described below.
The value is set in advance to be a value within the range of 5. Note that the square roots of these cross-sectional areas S ₁ and S ₂ are positive values because a negative sign is inappropriate.

In the nozzle body 1, a valve body 4 for opening and closing the injection holes 2 and 3 is provided so as to be movable in the direction of the axis Ax. The valve body 4 includes a long rod-shaped valve shaft 4a inserted into the nozzle body 1, a conical valve portion 4b integrally formed on the distal end side of the valve shaft 4a, and a valve portion 4b. And a sheet portion 4c that seals by contacting the conical portion 1b of the nozzle body 1. And
In each of the injection holes 2 and 3, the seat portion 4c of the valve body 4 is
Than position for sealing contact of the conical portion 1 b the inner surface is provided located downstream side, and thereby constitute a Sakkuresu fuel injection valve as a whole.

Next, in forming the present invention, the relationship between the ratio of the square root of the cross-sectional areas S ₁ and S ₂ of the injection holes 2 and 3 (hereinafter referred to as “aperture ratio α”) and the resonance, which were independently found. This will be described with reference to FIG.

That is, FIG. 3 is a characteristic diagram showing a correlation between the aperture ratio α and the resonance which is a nonlinear pull-in phenomenon.
It has been found that changing the aperture ratio α in the range of 1 to 5 causes a nonlinear change in the intensity of resonance generated at the time of collision.

Specifically, the intensity of the resonance due to the collision decreases when the aperture ratio α becomes larger than “1”, but when it reaches about “1.25”, it becomes the same as when α is “1”. of until the value M ₁ to recover, and aperture ratio α is about "1.5" takes a maximum value M _2. When the aperture ratio α is further increased, the intensity of the resonance gradually decreases, and when it reaches “3.5”, the intensity of the resonance becomes M ₁ again.

Therefore, the aperture ratio α is set to “1.25 to 3.5”.
, Resonance at least equivalent to that of the prior art can be obtained. On the other hand, the aperture ratio α is “4.4”
Even if the above, the intensity of resonance has been found that greater than M _1.

However, if the aperture ratio α is too large, the ratio of the collision area of the fuel decreases, and as a result, the amount of the atomized fuel decreases. That is, FIG. 4 is a characteristic diagram showing the relationship between the aperture ratio α uniquely found and the collision area of each fuel. As the aperture ratio α is increased from “1”, the fuel The ratio of the collision area is quadratic,
Declines exponentially.

Specifically, when the aperture ratio α is “1.25”, the ratio of the collision area is β ₁ , and when α is increased to “3.5”, the ratio of the collision area becomes a small value β ₂ . Take. further,
If the aperture ratio α is increased above this, the ratio of the collision area becomes extremely small, so the area ratio of the non-collision part increases, and one spray penetrates the other spray, causing substantial atomization. There is no state.

Therefore, even if the aperture ratio α is set to “3.5” or more, the ratio of the fuel collision area is greatly reduced.
Atomization performance cannot be improved. Therefore, in the present invention, the aperture ratio α is considered in consideration of both the resonance intensity and the ratio of the collision area.
Is limited to the range of “1.25 to 3.5”.

Next, the operation of the fuel injection valve according to this embodiment will be described.

First, when the valve body 4 moves upward in response to an injection signal from a control unit (not shown), the seat portion 4c separates from the conical portion 1b, and the fuel in the fuel flow path 1c is supplied to each of the injection holes 2 and 3. Inflow toward. Then, the fuel is injected into the combustion chamber from the injection holes 2 and 3 along the injection axes X ₁ and X ₂ , and collides obliquely at the intersection P to be atomized.

Here, in the present embodiment, the large injection hole 2 having a large sectional area S ₁ is vertically spaced apart from the small injection hole 3 having a small sectional area S _{2 in} the direction of the axis Ax. since placed, first after the big large injection hole 2 of the cross-sectional area S ₁ allowed to flow into the fuel, can be made to flow fuel into smaller sub-nozzle hole 3 of the sectional area S _2, thereby, the injection holes 2, 3 From each other, the particle diameters of the injected fuel can be made substantially equal, and a strong resonance effect can be obtained.

That is, by providing the large injection hole 2 upstream of the small injection hole 3, the pressure (injection pressure) P ₁ acting on the large injection hole 2 is increased.
Although better pressure P ₂ acting becomes slightly lower in small nozzle hole 3 than the small- nozzle hole 3 is smaller cross-sectional area S ₂ itself, the flow rate of the fuel injected from both injection holes 2, 3 substantially It is about the same.
Since the particle diameter of the injected fuel is a function of the flow velocity, if the flow velocity of the two injection holes 2 and 3 is substantially the same, the particle diameter of each injected fuel is also substantially equal. Therefore, fuels having substantially the same particle diameter can be caused to collide with each other, so that the above-described resonance phenomenon can be more effectively utilized and atomization can be achieved.

On the other hand, if the small injection hole 3 is provided on the upstream side of the large injection hole 2, on the other hand, the pressure P ₁ applied to the large injection hole 2 having a large sectional area S ₁ decreases. The flow velocity of the fuel injected from the large injection hole 2 decreases, and the particle diameter of the injected fuel increases. On the other hand, the pressure P ₂ acting on the small small nozzle hole 3 side cross-sectional area S ₂ rises, increasing the flow rate, particle size of the injected fuel becomes small. Therefore, in this case, a relatively large difference occurs in the particle diameter (mass) of the fuel injected from each of the injection holes 2 and 3, and the spray having a large particle diameter penetrates the spray having a small particle diameter. The resonance phenomenon cannot be used sufficiently effectively.

According to the present embodiment configured as described above,
The following effects are obtained.

First, a pair of injection holes 2 and 3 having different injection hole diameters.
Are provided in the nozzle body 1 at a distance in the axial direction, and the injection axes X ₁ , X ₂ of these injection holes 2, 3 are set at points P outside the nozzle body 1.
In this case, the fuel injected from each of the injection holes 2 and 3 can collide with each other to obtain a resonance phenomenon, and the fuel injection can be atomized by utilizing this resonance phenomenon. As a result, it is possible to prevent the injected fuel from colliding and adhering to the wall surface of the combustion chamber, and it is possible to greatly reduce the amount of HC emission. Further, the temperature of the combustion chamber can be effectively lowered by vaporizing the atomized fuel.

Second, since the square root ratio α of the sectional areas S ₁ and S ₂ of the injection holes 2 and 3 is set in the range of 1.25 to 3.5,
As described above, the resonance phenomenon can be used while securing the collision area of the fuel, and the atomization can be effectively performed.

Third, since the large injection hole 2 having a large cross-sectional area S ₁ is positioned upstream of the small injection hole 3 having a small cross-sectional area S ₂ , the fuel injected from each of the injection holes 2 and 3 is The particle size can be made approximately the same, and a stronger resonance effect can be obtained, so that the atomization performance can be greatly improved.

Fourth, the present embodiment is applied to a suckless fuel injection valve in which each injection hole 2, 3 is opened and closed directly by the valve body 4 and fuel is injected without passing through a suck hole.
The volume that becomes the fuel pool is small. Accordingly, since the above-described reduction of HC by improving the atomization performance of fuel and the reduction of HC due to the suckless fuel injection valve exhibit a synergistic effect, it is possible to more effectively suppress the amount of HC emission. Can be.

Next, a second embodiment of the present invention will be described with reference to FIGS.
An example will be described. In the following embodiments, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The nozzle main body 11 according to the present embodiment has a cylindrical portion 11a, like the nozzle main body 1 described in the first embodiment.
The first embodiment has a conical portion 11b and a fuel flow path 11c, but is different from the first embodiment in that two pairs of injection holes, which will be described later, are provided to face two pairs in the radial direction. Is different from

That is, the conical portion 11b of the nozzle body 11 has a first injection hole set including a large injection hole 12a having a large cross-sectional area and a small injection hole 13a having a small cross-sectional area, and another large injection hole set having a large cross-sectional area. A second injection hole set including a large injection hole 12b and a small injection hole 13b having a small sectional area is provided to face the nozzle body 11 in the diametric direction. Here, as described in the first embodiment, one large injection hole 12a and small injection hole 13a and the other large injection hole 12b and small injection hole 13b have a square root ratio of each other of 1. Each is set so as to be in the range of 25 to 3.5.

In this embodiment, each large injection hole 12a, 1
2b and the cross-sectional area of each small injection hole 13a, 13b,
The cross-sectional area S ₁ of the large injection hole 2 described in the first embodiment,
Since the set equal to S _2, the value of the aperture ratio α in the injection holes sets are identical. However, the present invention is not limited to this, and one of the aperture ratios α and the other may be formed differently in consideration of, for example, the shape of the combustion chamber.

The injection axis X ₁ of each of the large injection holes 12a, 12b is inclined at the same predetermined angle θ ₁ with respect to the axis Ax, while the injection axis X _{2 of} each of the small injection holes 13a, 13b is also the axis Ax. because they are both inclined at the same predetermined angle theta ₂ with respect to each intersection Pa of the fuel impinges, Pb are positioned on the same plane.

In this embodiment constructed as described above, when fuel is injected from each of the injection holes 12a, 12b, 13a and 13b, these injected fuels are mutually separated at intersections Pa and Pb outside the nozzle body 11. They collide and are atomized by the resonance phenomenon. Therefore, also in the present embodiment, the same effect as in the first embodiment can be obtained.

Although the above description has been made assuming that each injection hole set is diametrically opposed, the invention is not limited to this. For example, as shown in a first modified example shown in FIG. 7, the first injection hole set 12a, 13a and the 2
And the nozzle hole sets 12b and 13b may be shifted by 90 degrees in the circumferential direction. The separation angle θh between the injection hole sets can take various values according to the shape of the combustion chamber and the like.

Also, as in the second modification shown in FIG.
Three or more injection hole sets may be provided. That is, FIG.
Are the first set of injection holes 12a, 13a and the second set of injection holes 12a.
This shows a case in which a total of four injection hole sets b, 13b, third injection hole sets 12c, 13c, and fourth injection hole sets 12d, 13d are arranged 90 degrees apart from each other in the circumferential direction. In addition, the aperture ratio α in each of the nozzle hole sets is in the range of 1.25 to 3.5 as in the above-described embodiments, and the aperture ratio α of all the nozzle hole sets is the same. However, the aperture ratio α may be individually set for each injection hole set.

Next, a third embodiment of the present invention will be described with reference to FIGS. The feature of the present embodiment is that an injection hole set including a large injection hole and a small injection hole is
The point is that they are arranged in two stages in the x direction.

The nozzle body 21 according to the present embodiment is also
1a, a conical portion 21b, and a fuel flow path 21c, which are different from the nozzle body 1 described in the first embodiment in the arrangement of injection holes described later.

That is, in this embodiment, the downstream injection hole group and the upstream injection hole group are provided on the conical portion 21b of the nozzle body 21 so as to be separated in the direction of the axis Ax. Each of these injection hole groups is constituted by four sets of injection holes arranged at 90 degrees apart in the circumferential direction of the nozzle body 21.

More specifically, as shown in FIG. 10, the downstream injection hole group includes a first injection hole set including a large injection hole 22a and a small injection hole 23a, and a large injection hole 22b and a small injection hole 23b. A second injection hole set, a large injection hole 22c and a small injection hole 23c, and a fourth injection hole set including a large injection hole 22d and a small injection hole 23d. I have.

Similarly, the upstream injection hole group includes the large injection holes 3.
A first injection hole set including a second injection hole 2a and a small injection hole 33b;
A second injection hole set including a second injection hole 2b and a small injection hole 33b;
A third set of injection holes consisting of 2c and small injection holes 33c;
2d and a fourth injection hole set composed of small injection holes 33d. Each injection hole set of each upstream injection hole group corresponds to the upstream side of each injection hole set of the downstream injection hole group. It is provided.
In addition, the position of each of the injection hole sets of the upstream injection hole group may be rotated from the state shown in FIG. 10 to give a circumferential displacement to each of the injection hole sets of the downstream injection hole group. Further, the separation angle θh between the injection hole sets is not limited to 90 degrees, and various values can be adopted.

Then, the aperture ratio α in each nozzle hole set is:
It is set in the range of 1.25 to 3.5. In the present embodiment, the injection axis X ₁ , X ₂ of each injection hole set of the downstream injection hole group is set.
Intersects with a plane on which a lower intersection P _L is located,
The plane on which the upper intersection point P _H formed by the intersection of the injection axis X ₃ , X ₄ of each injection hole group of the upstream injection hole group is defined by the axis Ax
So that the injection axes X ₁ , X ₂ , X ₃ , X ₄
Are set with respect to the axis Ax. As a result, concentric spraying can be performed in the combustion chamber. Note that these intersections P _L, the injection axis X ₁ so that P _H are positioned on the same plane, X _2,
The angles of X ₃ and X ₄ with respect to the axis Ax may be set.

Thus, the present embodiment having the above-described structure can provide the same effects as those of the first embodiment. In addition to this, in the present embodiment, two injection hole groups each including a plurality of injection hole sets are arranged vertically apart from each other in the axis Ax direction, so that an optimum spray pattern according to the shape of the combustion chamber and the like can be easily formed. Can be formed.

In this embodiment, the case where each injection hole group is composed of four injection hole sets is exemplified. However, the present invention is not limited to this, and each injection hole group may be formed of one to three injection hole sets. Or a set of five or more injection holes. Further, the configurations of the two injection hole groups may be different, such that the downstream injection hole group is formed of four injection hole sets and the upstream injection hole group is formed of three injection hole sets.

[0057]

[0058]

As described above in detail, according to the fuel injection valve of the present invention, a pair of injection holes having different injection hole diameters are provided apart from each other in the axial direction, and the injection axis of each injection hole is set outside the nozzle body. The fuel can be atomized by utilizing the resonance phenomenon at the time of fuel collision. As a result, the emission amount of HC can be suppressed, and the temperature of the combustion chamber can be effectively reduced.

Further, the square root ratio of the sectional area of each injection hole is set to 1.2.
Since it is set so as to be in the range of 5 to 3.5, a strong resonance effect can be obtained while securing the collision area of the fuel, and the atomization of the fuel can be performed more effectively.

Further, a pair of large and small injection holes are provided spaced apart in the axial direction such that the injection hole having the larger cross-sectional area is located on the upstream side, so that the particle diameter of the fuel injected from each injection hole is provided. Can be made substantially equal, and the fuel can be effectively atomized by utilizing the stronger resonance effect.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a fuel injection valve according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1 in a state where a valve body is removed.

FIG. 3 is a characteristic diagram showing the relationship between the aperture ratio and the strength of resonance.

FIG. 4 is a characteristic diagram showing a relationship between an aperture ratio and a ratio of a fuel collision area.

FIG. 5 is a sectional view showing a main part of a fuel injection valve according to a second embodiment of the present invention.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5 in a state where a valve body is removed.

FIG. 7 shows a first modification of the second embodiment.
Sectional drawing similar to.

FIG. 8 shows a second modification of the second embodiment.
Sectional drawing similar to.

FIG. 9 is a sectional view showing a main part of a fuel injection valve according to a third embodiment of the present invention.

FIG. 10 is a sectional view taken along line XX in FIG. 9 in a state where a valve body is removed.

FIG. 11 is a cross-sectional view showing a main part of a suckless fuel injection valve according to a conventional technique.

FIG. 12 is a sectional view taken along the line AA in FIG. 12;

[Explanation of symbols]

 1,11,21 ... Nozzle body 2,12a-d, 22a-d, 32a-d ... Large injection hole 3,13a-d, 23a-d, 33a-d ... Small injection hole 4 ... Valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 61/18 320 F02M 63/00

Claims (1)

(57) [Claims] 1. A nozzle body in which an injection hole is provided in a conical portion formed on a distal end side in a radial direction, and a valve body which is provided in the nozzle body so as to be movable in an axial direction and opens and closes the injection hole. To eliminate or minimize the sack hole that becomes a fuel pool
And the inlet of the injection hole is opened directly by the valve body.
In the closed fuel injection valve, a pair of large and small injection holes is provided at the tip side of the nozzle body.
Are arranged in the axial direction so as to be located on the upstream side, and the square root ratio of the cross-sectional area of each of the injection holes is 1.25 to 3.5.
A fuel injection valve , wherein the injection axes of the injection holes intersect outside the nozzle body so that the fuel injected from the injection holes collide with each other.