JPH11264365A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize the injection amount and the spraying shape of fuel to be injected from a nozzle hole to respective directions. SOLUTION: This fuel injection valve has the relationship of 0.1<t/D<0.25 between the distance (t) in the axial direction of a needle valve 25 at the lifting time of the needle valve 25, between the tip surface 25b of the needle valve 25 and a facing surface 32b of a nozzle plate 32 and the pitch diameter D between the nozzle holes 32a, and the relationship of δ/L<=0.2 between the eccentric amount δ from an axis of the needle valve 25 and the lift amount L in lifting of the needle valve 25. Therefore, when a contact part 25a is separated from a valve seat 31a, the flow of fuel to be allowed to flow to the nozzle plate 32 through between the contact part 25a and the valve seat 31a is equalized in the circumferential direction. Moreover, fuels collide with each other without being allowed to directly flow to the nozzle hole 32a, and atomization is promoted. Therefore, even if the needle valve 2 is made eccentric, the injection amount and the spraying shape of fuel to be injected from the nozzle hole 32a to respective directions can be equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve for injecting fuel into, for example, an internal combustion engine for an automobile (hereinafter referred to as "internal combustion engine").

[0002]

2. Description of the Related Art As a fuel supply system for a multi-cylinder engine, a so-called single-position injector (SPI) is provided which collects an inlet side of an intake manifold connected to each cylinder and is provided with a throttle body having an intake throttle valve at the inlet side. A) -type fuel supply device is known. This SP
In the I-type fuel supply device, a part of the fuel injected from a single fuel injection valve is vaporized or atomized to be in a spray state and supplied as a mixture with air. It is supplied to the cylinder.

In general, a needle valve of a fuel injection valve is supported by a valve body so as to be able to reciprocate, and is separated from a valve seat formed on the downstream side of the needle valve or is seated on the valve seat so that the needle valve of the fuel injection valve can be moved. The nozzle is opened and closed. When the needle valve reciprocates, the needle valve and the valve body slide. A clearance is formed in the sliding portion between the needle valve and the valve body, and it is necessary to secure this clearance to some extent from the viewpoint of manufacturing.

[0004]

However, in the above-described conventional fuel injection valve, when the needle valve is eccentric due to the clearance between the needle valve and the valve body, the abutting portion of the needle valve and the valve seat of the valve body are not provided. The flow of the fuel passing through the opening may not be uniform in the circumferential direction, and the injection amount or the spray shape of the fuel injected from the injection hole in each direction may be uneven. When the fuel injection amount or the spray shape in each direction becomes uneven, the distribution of the fuel taken into the engine is disturbed, causing a difference in the air-fuel ratio for each cylinder, and the fuel consumption, exhaust emission, and engine stability There is a problem that the drivability and the like deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and is directed to a fuel injection valve capable of making the amount and shape of fuel injected in each direction from an injection hole uniform. The purpose is to provide.

[0006]

According to the fuel injection valve of the present invention, the spray particle diameter of the fuel injected from the injection hole is suppressed to a predetermined particle diameter, and the fuel is injected in each direction from the injection hole. Therefore, even if the valve member is eccentric due to the clearance between the valve member and the valve body, the spray particle diameter of the fuel injected from the injection hole is kept at a predetermined particle diameter. Up to this point, the fuel injection amount injected in each direction from the injection hole becomes uniform. Therefore, atomization of the fuel spray injected from the injection hole is promoted, and the fuel spray is easily mixed with the air over a wide range, and the combustion efficiency of the fuel is increased. Therefore, when the fuel injection valve of the present invention is mounted on the intake pipe,
The distribution of the fuel taken into the engine becomes uniform, and the fuel consumption, the exhaust emission, and the stable operability of the engine are improved.

According to the fuel injection valve of the second aspect of the present invention, the axial distance t of the valve member when the valve member is lifted between the distal end surface of the valve member and the opposing surface of the plate member, and the distance between the injection holes. There is a relationship of 0.1 <t / D <0.25 with the pitch diameter D. Therefore, when the contact portion of the valve member is separated from the valve seat, the interval between the opening portions between the contact portion and the valve seat becomes uniform in the circumferential direction, and the opening between the contact portion and the valve seat is increased. The flow of the fuel passing through the portion toward the plate member becomes uniform in the circumferential direction.

After the fuel has passed through the opening between the contact portion and the valve seat, the direction of the fuel is changed by the facing surface of the plate member without directly flowing into the injection hole, and a U-turn is made to make each injection hole. Head for. The fuel flow that makes a U-turn from the center of the plate member collides with the flow flowing from the outer periphery of the plate member to the injection hole at the center of the injection hole inlet. Since the strength of the flow flowing into the injection hole after making a U-turn at the center of the plate member is almost the same as the flow flowing into the injection hole from the outer periphery of the plate member, it is necessary to obtain a uniform collision without vortices around the injection hole And more efficient atomization can be obtained. At the same time, the fuel collides at the center of the injection hole, and a uniform collision is obtained. Therefore, the directionality of the atomized fuel is well controlled by the injection hole.

Therefore, even if the valve member is eccentric due to the clearance between the valve member and the valve body, the injection amount and the spray shape of the fuel injected in each direction from the injection hole can be made uniform. According to the fuel injection valve according to the third aspect of the present invention, δ / L ≦ 0,0 between the eccentric amount δ of the injection hole of the valve member from the pitch center and the lift amount L when the valve member is lifted.
There are two relationships. Therefore, by making the eccentric amount δ relatively small or the lift amount L relatively large, when the contact portion of the valve member separates from the valve seat, the opening between the contact portion and the valve seat is increased. The intervals between the portions are made uniform in the circumferential direction, and the flow of fuel that advances toward the plate member through the opening between the contact portion and the valve seat becomes uniform in the circumferential direction. Therefore, even if the valve member is eccentric due to the clearance between the valve member and the valve body,
The flow of the fuel passing through the opening between the contact portion and the valve seat can be made uniform in the circumferential direction, and the injection amount and the spray shape of the fuel injected from the injection hole in each direction can be made uniform. it can.

According to a fourth aspect of the present invention, there is provided a fuel supply system, comprising: a fuel injection valve according to the first, second, or third aspect of the present invention, which is connected to a downstream side of a throttle valve and to each cylinder. By being mounted upstream, a single fuel injection valve can supply a uniform and uniform fuel spray to each cylinder. Therefore, the fuel injection valve of the present invention is particularly suitable when mounted on a small engine.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. An embodiment in which the present invention is applied to a fuel injection valve of a fuel supply device for a gasoline engine is shown in FIG. 1, FIG. 2 and FIG. As shown in FIG. 2, the fixed core 21 made of a ferromagnetic material is housed inside a resin housing mold 11 of the fuel injection valve 10.

The movable core 22 made of a magnetic material is formed in a cylindrical shape, and has a non-magnetic pipe 23 and a magnetic pipe 24.
It is arranged in the internal space. The outer diameter of the movable core 22 is set slightly smaller than the inner diameter of the nonmagnetic pipe 23, and the movable core 22 is slidably supported by the nonmagnetic pipe 23. The movable core 22 faces the fixed core 21 in the axial direction,
It is arranged so as to form a predetermined gap with the lower end surface of the fixed core 21.

The non-magnetic pipe 23 is fitted around the outer periphery of the movable core side end of the fixed core 21 and fixed by laser welding or the like. A magnetic pipe 24 made of a magnetic material and formed in a stepped pipe shape is connected to an end of the non-magnetic pipe 23 opposite to the fixed core. The non-fixed core side of the non-magnetic pipe 23 forms a guide for the movable core 22. The contact portion 25a at the tip of the needle valve 25 as a valve member on the fuel injection side can be annularly seated on a valve seat 31a provided on an inner wall surface 31 of a valve body 30 as a valve body. At the other end of the needle valve 25, a joint 25b is formed. Then, the joint 25d and the movable core 22 are laser-welded, and the needle valve 25 and the movable core 22 are integrally connected. A double chamfer as a fuel passage is provided on the outer periphery of the joint 25d.

The valve body 30 is inserted into the magnetic pipe 24 via a spacer 28, and is fixed to the magnetic pipe 24 by laser welding or the like. The thickness of the spacer 28 is adjusted so that the air gap between the fixed core 21 and the movable core 22 has a predetermined value. A nozzle plate 32 as a stainless steel plate member is provided on the fuel downstream side of the needle valve 25 and on the side opposite to the spacer of the valve body 30. The nozzle plate 32 is joined to the distal end of the valve body 30 by welding, for example, by full circumference welding. Fuel injected from the injection holes 32a formed in the nozzle plate 32 is injected into each cylinder of the engine (not shown).

One end of the compression coil spring 26 is in contact with a spring seat 22 a provided on the movable core 22, and the other end of the compression coil spring 26 is in contact with the bottom of the adjusting pipe 27. The compression coil spring 26 urges the movable core 22 and the needle valve 25 downward in FIG. 2, that is, in a direction in which the contact portion 25a is seated on the valve seat 31a.

The adjusting pipe 27 is a fixed core 2
1 is pressed into the inner circumference. By adjusting the press-fitting position of the adjusting pipe 27 at the time of assembly, the urging force of the compression coil spring 26 can be adjusted. The electromagnetic coil 50 is wound around the outer periphery of a spool 51 made of resin, and the spool 51 is fixed core 21, non-magnetic pipe 23,
It is arranged on the outer circumference of the magnetic pipe 24. Electromagnetic coil 5
0 and a housing mold 11 on the outer periphery of the spool 51.
Are molded with resin, and the electromagnetic coil 50 is surrounded by the housing mold 11. When an exciting current flows from the terminal 52 to the electromagnetic coil 50 via a lead wire by an electronic control unit (not shown), the needle valve 25 and the movable core 22 are attracted toward the fixed core 21 against the urging force of the compression coil spring 26. And the contact portion 25a is
1a.

The terminal 52 is a housing mold 11
And is electrically connected to the electromagnetic coil 50. The terminal 52 is connected to the electronic control unit via a wire harness (not shown). The two metal plates 61 and 62 are provided such that one upper end is in contact with the outer periphery of the fixed core 21 and the other lower end is in contact with the outer periphery of the magnetic pipe 24. It is a member that forms a road. These two metal plates 6
The electromagnetic coil 50 is protected by 1 and 62.

The filter 63 is disposed above the fixed core 21 and is pumped from a fuel tank by a fuel pump or the like to remove foreign matter such as dust in the fuel flowing into the injector 10. The fuel flowing into the fixed core 21 through the filter 63 flows from the adjusting pipe 27 to the gap between the two chamfers formed at the joint 25 d of the needle valve 25, and further to the valve body 30 and the needle valve 25.
Through the gap with the four chamfers formed in the sliding part with
The valve portion includes the contact portion 25a of the needle valve 25 and the valve seat 31a.

Hereinafter, the needle valve 25 and the valve body 3
0, the structure of the nozzle plate 32 will be sequentially described in detail. (1) Needle valve 25 As shown in FIG.
5a, tip surface 25b, contact portion 25a and tip surface 25
and b. Tip surface 25
b is formed on the inner peripheral side of the contact portion 25a. The center axis of the needle valve 25 is a distance δ from the pitch center of the injection hole 32a.
Only eccentric. The lift amount L and the eccentric amount δ of the needle valve 25 when the needle is opened are set so as to satisfy the following expression (1).

Δ / L ≦ 0.2 (1) The ratio between the eccentric amount δ and the lift amount L is set so as to satisfy the expression (1) by making the eccentric amount δ relatively small or Alternatively, by increasing the lift amount L relatively, the needle valve 2
This is because when the contact portion 25a of 5 is separated from the valve seat 31a, the interval between the openings between the contact portion 25a and the valve seat 31a is made uniform in the circumferential direction. By making the interval between the openings between the contact portion 25a and the valve seat 31a uniform in the circumferential direction, the nozzle plate 32 passes through the opening between the contact portion 25a and the valve seat 31a. The flowing fuel flow becomes uniform in the circumferential direction.

That is, the amount of eccentricity δ and the amount of lift L are expressed by the following equation.
(1) is set so as to satisfy
The flow of the fuel passing through the opening between the valve and the valve seat 31a can be made uniform in the circumferential direction, and the injection amount and the spray shape of the fuel injected in each direction from the injection hole 32a can be made uniform. . (2) Valve Body 30 The inner diameter of the valve body 30 is reduced from the vicinity of the tip toward the nozzle plate 32, and the nozzle plate 32 of the inner wall surface 31 forming a fuel passage as a fluid passage is formed.
A conical slope 31b is formed on the side. Needle valve 25
The contact part 25a of the valve seat 31 formed on the conical slope 31b
a.

(3) Nozzle plate 32 The nozzle plate 32 for controlling the flow direction of the spray is shown in FIG.
As shown in FIG. 7, eight nozzle holes 32a having the same diameter are formed through the nozzle plate 32 in the plate thickness direction. As shown in FIG. 1, the injection holes 32 a are inclined so as to move away from the central axis toward the fuel downstream side of the nozzle plate 32.

As shown in FIG. 3, assuming that the pitch diameter between the injection holes 32a is D, the shaft of the needle valve 25 at the time of needle opening between the front end surface 25b and the facing surface 32b of the nozzle plate 32 shown in FIG. The distance t in the direction and the pitch diameter D are set so as to satisfy the following equation (2). 0.1 <t / D <0.25 (2) The ratio between the distance t and the pitch diameter D is set so as to satisfy the expression (2) because the contact portion 25a of the needle valve 25 is a valve. Seat 31a
When separated from the nozzle plate 32 side through the opening between the contact portion 25a and the valve seat 31a, the interval between the openings between the contact portion 25a and the valve seat 31a becomes uniform in the circumferential direction. This is to make the flow of the fuel proceeding in the circumferential direction uniform in the circumferential direction. After flowing along the conical slope 31b, the fuel
After the direction is changed by the facing surface 32b of the nozzle plate 32 without directly flowing into the nozzle plate 2a, the nozzle plate 32 advances a predetermined distance between the facing surface 32b and the flat surface 25b. Therefore, the fuel can be atomized efficiently without the main flow of the fuel directly flowing into the injection holes 32a.

By satisfying the expression (2), the injection holes 32a can be arranged in a range not too close to the center of the nozzle plate 32 and not too wide on the outer peripheral side of the nozzle plate 32. Therefore, the strength of the fuel flow flowing into each injection hole 32a can be made substantially uniform regardless of the flow direction. As a result, the internal energy of the fuel can be efficiently used in the form of turbulence due to collision between flows, and extremely ideal atomization can be realized.

Furthermore, since a uniform collision can be obtained at the center of the entrance of the injection hole 32a, a spray having a highly directivity can be obtained along the inclination of the entire periphery of the side wall forming the injection hole 32a. FIGS. 4 and 5 show a state in which the fuel injection valve 10 is attached to the intake pipe. The engine shown in FIGS. 4 and 5 is a four-cylinder engine. As shown in FIG. 4, the fuel injection valve 10 includes intake manifold pipes 1a, 1b, 1c, and 1d of the intake manifold 1 connected to the cylinders on the downstream side of the intake flow.
Is mounted on an intake pipe (not shown) upstream of the collecting portion and downstream of a throttle valve (not shown). Each intake distribution pipe 1a, 1b, 1c, and 1d has a rib 2 inside the intake manifold 1 such that its axial sectional area divides the axial sectional area of the intake manifold 1 into four equal parts.
Is divided by Also, as shown in FIG.
The fuel injection valve 10 is attached to the intake pipe by the fuel injection valve attachment portion 3. 4 and 5 indicate the spray range of the fuel injection valve 10. Here, the fuel injection valve 1
The injection amounts of the fuel injected from the 0 injection hole 32a into the respective intake distribution pipes 1a, 1b, 1c and 1d are represented by Qa and Q, respectively.
b, Qc and Qd, and Qa, Qb, Qc and Qd
Is the maximum value of Qmax, and the minimum value of Qa, Qb, Qc and Qd is Qmin, the distribution variation ΔQ of the fuel injected into each intake pipe 1a, 1b, 1c and 1d is given by the following equation. Defined in (3).

[0026] Next, the spray particle diameter of the fuel injected from the injection hole 32a of the fuel injection valve 10 is d, the ratio between the distance t and the pitch diameter D is the horizontal axis, and the distribution variation ΔQ and the spray particle diameter d are vertical. FIG. 6 shows a graph on the axis. FIG. 6 shows the SMD (Sau
ter Mean Diameter (Sauter average particle size) represents the spray particle size d.

As can be seen from FIG. 6, when the equation (2) is satisfied, the spray particle diameter d is reduced to about 120 with the distribution variation ΔQ ≦ 1%.
μm. Fuel injection valve 10 of the present embodiment
Can inject the atomized fuel over a wide range as shown in FIGS. 4 and 5, so that a single fuel injection valve can uniformly and uniformly supply fuel to each cylinder. it can. Therefore, the number of parts is small and the control of the fuel injection valve is simplified as compared with the case where the fuel injection valve is attached to each cylinder, so that the manufacturing cost is reduced. In particular, it is effective to mount the fuel injection valve 10 of this embodiment on a small engine.

Next, the operation of the fuel injection valve 10 will be described. (1) When the power to the electromagnetic coil 50 is turned off, the movable core 22 and the needle valve 25 are urged downward in FIG. 2 by the urging force of the compression coil spring 26, and the contact portion 25a of the needle valve 25 is moved to the valve seat 31a. To sit down. Thereby, the injection hole 32
The fuel injection from a is cut off.

(2) When energization of the electromagnetic coil 50 is turned on, the movable core 22 is attracted to the fixed core 21 against the urging force of the compression coil spring 26.
The fifth contact portion 25a is separated from the valve seat 31a. As a result, fuel is injected from the injection hole 32a through the opening between the contact portion 25a and the valve seat 31a. In the present embodiment described above, the axial distance t of the needle valve 25 when the needle valve 25 is lifted between the distal end surface 25b of the needle valve 25 and the facing surface 32b of the nozzle plate 32, and the pitch between the injection holes 32a. Between the diameter D and 0.
1 <t / D <0.25, and the relationship of δ / L ≦ 0.2 between the amount of eccentricity δ of the needle valve 25 from the axis and the lift amount L when the needle valve 25 is lifted. is there. For this reason, when the contact part 25a of the valve member 25 is separated from the valve seat 31a, the interval between the openings between the contact part 25a and the valve seat 31a becomes uniform in the circumferential direction, and the contact part 25a The fuel flowing to the nozzle plate 32 through the opening between the valve seat 31a and the nozzle seat 32a becomes uniform in the circumferential direction.

After the fuel passes through the opening between the contact portion 25a and the valve seat 31a, the direction is changed by the facing surface 32b of the nozzle plate 32 without directly flowing into the injection hole 32a, and the U-turn is formed. And heads toward each injection hole 32a. The fuel flow that makes a U-turn from the center of the nozzle plate 32 collides with the flow flowing from the outer periphery of the nozzle plate 32 to the injection hole 32a at the center of the inlet of the injection hole 32a. After the U-turn at the center of the nozzle plate 32, the flow flowing into the injection holes 32a is almost the same as the flow flowing into the injection holes 32a from the outer periphery of the nozzle plate 32.
A uniform collision without vortex around 2a can be obtained, and more efficient atomization can be obtained. At the same time injection hole 32a
The fuel collides at the center of the inlet and uniform collision is obtained, so that the direction of the atomized fuel is well controlled by the injection holes 32a.

As described above, since the atomization of the fuel spray injected from the injection hole 32a is promoted, the fuel spray is easily mixed with air over a wide range, and the fuel combustion efficiency is increased. In this embodiment, even if the needle valve 25 is eccentric due to the clearance between the needle valve 25 and the valve body 30, the injection amount and the spray shape of the fuel injected in each direction from the injection hole 32a can be made uniform. Therefore,
When the fuel injection valve 10 is mounted on the intake pipe, the fuel consumption,
Exhaust emission and stable operability of the engine are improved.

In the present embodiment, the number of the injection holes 32a is set to eight. However, in the present invention, the number of the injection holes may be two or more.

[Brief description of the drawings]

FIG. 1 shows a fuel injection valve according to an embodiment of the present invention, and is an enlarged view of a main part of FIG.

FIG. 2 is a longitudinal sectional view showing a fuel injection valve according to one embodiment of the present invention.

FIG. 3 is a plan view showing a nozzle plate according to one embodiment of the present invention.

FIG. 4 is a plan view showing a state in which a fuel injection valve according to one embodiment of the present invention is mounted on an intake pipe.

FIG. 5 is a view in the direction of arrow V in FIG. 4;

FIG. 6 is a characteristic diagram showing a relationship between a ratio t / D of a distance t and a pitch diameter D, a distribution variation ΔQ, and a spray particle diameter d.

[Explanation of symbols]

 Reference Signs List 10 fuel injection valve 21 fixed core 22 movable core 25 needle valve (valve member) 25a contact portion 30 valve body (valve body) 31 inner wall surface 31a valve seat 32 nozzle plate (plate member) 32a injection hole

Claims (4)

[Claims] 1. A plate member having a plurality of injection holes, a valve body having a valve seat provided upstream of the injection holes, and an abutment supported on the valve body so as to be reciprocally movable and seated on the valve seat. And a valve member that opens and closes the injection hole when the contact portion is separated from the valve seat and seated on the valve seat, and is injected from the injection hole. A fuel injection valve characterized in that the spray particle diameter of the fuel is suppressed to a predetermined particle diameter, and variation in the amount of fuel injected in each direction from the injection hole is suppressed. 2. An axial distance of the valve member between the tip surface of the valve member and an opposing surface of the plate member when the valve member is lifted is t, and a pitch diameter between the injection holes is D. 2. The fuel injection valve according to claim 1, wherein 0.1 <t / D <0.25. 3. When the eccentric amount of the valve member from the pitch center of the injection hole is δ and the lift amount of the valve member at the time of lift is L, δ / L ≦ 0.2. The fuel injection valve according to claim 1. 4. A fuel supply device comprising the fuel injection valve according to claim 1, 2 or 3, mounted on a downstream side of the throttle valve and upstream of a collection portion of an intake distribution pipe connected to each cylinder. .