JP2000097129A - Solenoid type fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the atomization in the fuel injection time by suppressing the reduction of the fuel pressure while stabilizing the injection angle in the fuel injection time by improving the fuel diffusion in a diffusion chamber, in a solenoid type fuel injection valve. SOLUTION: In a solenoid type fuel injection valve in which a flat fuel diffusion chamber 23 to communicate the valve seat 2a of a valve housing, and plural fuel nozzle holes 171 and 172 of an injector plate 17 each other, is provided between both members, the crossing area S1 of the valve seat hole 2b is set in the same level as, or larger than the total crossing area S2 of the fuel nozzle holes 171 and 172, and a preliminary diffusion chamber 16 having a conical bottom surface with the taper angle θ2 larger than the taper angle θ1 of the valve seat 2a is provided between the valve seat 2a and the valve seat hole 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic fuel injection valve mounted on an internal combustion engine, and more particularly, to a valve housing having at one end a valve seat and a valve seat hole connected to the center of the valve seat. A valve body slidably housed in the valve housing and facing the valve seat, a valve spring for urging the valve body in a valve closing direction toward the valve seat, and a valve provided at the other end of the valve housing to be energized at the time of excitation A coil for opening the body, and an injector plate joined to one end surface of the valve housing and having a plurality of fuel injection holes communicating with the valve seat holes. Provided with flat fuel diffusion chambers that communicate with each other.

[0002]

2. Description of the Related Art Such an electromagnetic fuel injection valve is already known, for example, as disclosed in Japanese Utility Model Laid-Open No. 2-7362.

[0003]

In the electromagnetic fuel injection valve having the above structure, when the valve body is opened, high-pressure fuel that has passed through the valve seat is injected from the valve seat hole into the diffusion chamber at a high speed and diffused. This aims to stabilize the direction and angle of spray of the fuel from the fuel injection hole.

However, since the valve seat hole is formed smaller in diameter than the fuel injection hole, the pressure drop when the high-pressure fuel transfers from the valve seat hole to the diffusion chamber when the valve body is opened. Therefore, when the fuel is injected from the fuel injection hole, the atomization effect is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and aims to improve the diffusion of fuel in a diffusion chamber to stabilize the spray angle at the time of fuel injection, and to suppress the fuel pressure drop. It is an object of the present invention to provide the electromagnetic fuel injection valve capable of improving atomization during fuel injection.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a valve housing having at one end a valve seat and a valve seat hole connected to the center of the valve seat, and a valve housing which slides in the valve housing. A valve body that is housed so as to face the valve seat, a valve spring that urges the valve body in a valve closing direction toward the valve seat, and that is provided at the other end of the valve housing to open the valve body when excited. A flat fuel that is connected to one end surface of the valve housing and has an injector plate having a plurality of fuel injection holes communicating with the valve seat holes, the flat fuel communicating between the valve seat holes and the fuel injection holes; In an electromagnetic fuel injection valve with a diffusion chamber, a plurality of fuel injection holes are drilled in the injector plate, and the cross-sectional area of the valve seat hole is set equal to or larger than the total cross-sectional area of these fuel injection holes. Between the valve seat hole and the valve seat. First, a pre-diffusion chamber was defined by forming a concave portion having a conical bottom with a taper angle larger than the taper angle of the valve seat and being coaxial with the valve seat hole of the valve seat, and defining the concave portion and the front end surface of the valve body. Features.

According to this first feature, the high-pressure fuel that has passed through the valve seat collides with the bottom surface of the pre-diffusion chamber where the taper angle is larger than the valve seat and diffuses, and further moves from the valve seat hole to the diffusion chamber. And spread again. Since the diffusion of the high-pressure fuel is performed in two stages in this manner, a high diffusion effect is obtained, and the spray direction and the spray angle when the fuel is injected from each fuel injection hole are adjusted to the direction and shape of each fuel injection hole. It can be made appropriate according to.

In addition, since the cross-sectional area of the valve seat hole is set to be equal to or larger than the total cross-sectional area of the plurality of fuel injection holes, the fuel pressure is not increased until the fuel reaches the diffusion chamber from the valve seat. A large drop does not occur, and the fuel in the diffusion chamber is injected from each fuel injection hole while maintaining a high pressure, so that a good atomization state can be secured.

In addition, the present invention is characterized in that, in addition to the above-described features, the distance from the tip of the valve element in the valve-open state to the bottom surface of the diffusion chamber is set smaller than the inner diameter of the valve seat hole.

According to the second feature, the flatness of the preliminary diffusion chamber and the diffusion chamber can reduce the dead volume as much as possible and enhance the fuel diffusion effect.

Further, in the present invention, in addition to the second feature, a third feature is that a virtual vertex of the conical bottom surface of the pre-diffusion chamber is disposed in the valve seat hole.

According to the third feature, the fuel diffusion effect can be further enhanced by further flattening the preliminary diffusion chamber.

Further, according to the present invention, in addition to any one of the first to third features, the plurality of fuel injection holes of the injector plate are arranged on a pitch circle centered on the axis of the valve seat hole. A fourth feature is that the pitch diameter is set larger than the inner diameter of the valve seat hole.

According to the fourth feature, it is possible to suppress the passage from the valve seat hole to the fuel injection hole, and to make the diffusion function for the fuel in the diffusion chamber accurate.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of an essential part of an internal combustion engine equipped with an electromagnetic fuel injection valve of the present invention, FIG. 2 is a longitudinal sectional view of the electromagnetic fuel injection valve, and FIG. 3 is an enlarged view of the principal part of FIG. 4, FIG. 4 is an enlarged view of a part 4 of FIG. 3, FIG. 5 is a view taken in the direction of arrow 5 of FIG. 4, and FIG. 6 is a view corresponding to FIG.

Referring to FIG. 1, an electromagnetic fuel injection valve I of the present invention is mounted on an intake manifold 31 joined to one side of a cylinder head 30 of an internal combustion engine E. It is directed to the outlet of the intake port 31a.

As shown in FIGS. 2 to 4, the electromagnetic fuel injection valve I has a cylindrical valve housing 1 in which a valve seat member 2 is press-fitted into an inner peripheral surface of a front end portion and integrally connected thereto.
And a stepped cylindrical coil housing 3 having a small diameter portion 3a fitted and welded to the outer peripheral surface of the rear end portion.
These are all made of a magnetic material.

The valve seat member 2 also has a cylindrical shape, and a conical valve seat 2a is formed on the inner surface of the front end wall. A spherical valve portion 4a which can be seated on the valve seat 2a;
The valve body 4 is constituted by a valve rod 4b whose front end is connected by welding, and the valve body 4 is housed in the valve housing 1. A movable core 5 is fixed to the rear end of the valve rod 4b so as to be axially movably fitted to the inner peripheral surface of the rear end of the valve housing 1. Also,
The outer peripheral surface of the movable core 5 is slidably fitted to the inner peripheral surface of the sliding guide cylinder 6 which is welded to the rear end surface of the valve housing 1 all around. A movable core 5 is provided at the rear end of the sliding guide cylinder 6.
The front end of the fixed core 7 disposed with the front end facing the rear end is welded. At this time, a gap corresponding to the opening / closing stroke of the valve element 4 is provided between the front end face of the fixed core 7 and the rear end face of the movable core 5. Therefore, when the rear end face of the movable core 5 abuts on the front end face of the fixed core 7, the valve opening limit of the valve element 4 is defined.

On the outer periphery of the sliding guide cylinder 6 and the fixed core 7,
A coil assembly 8 that surrounds them and is accommodated in the coil housing 3 is provided. The coil assembly 8 includes a bobbin 9 fitted on the outer peripheral surfaces of the sliding guide cylinder 6 and the fixed core 7, and a coil 10 wound around the bobbin 9.

At the rear end of the hollow fixed core 7, a constriction 11
The fuel introduction cylinder 12 is integrally connected to the fuel introduction cylinder 12 via a through hole, and a fuel filter 14 is attached to an inlet at an upper end of the fuel introduction cylinder 12.
A high-pressure fuel conduit connected to a discharge port of a fuel pump (not shown) is connected to the fuel introduction cylinder 12.

A communication pipe 15 that communicates the inside of the fuel introduction cylinder 12 with the hollow portion 7a of the fixed core 7 is fitted and fixed in the narrowed portion 11, and the movable core 5 is provided with a hollow portion 7a of the fixed core 7. A notched passage 5 a communicating with the inside of the housing 1 is formed. Between the movable core 5 and the communication pipe 15, a valve spring 13 for urging the valve body 4 via the movable core 5 in the seating direction of the valve seat 2a, that is, in the valve closing direction, is contracted.

The front end wall of the valve seat member 2 is formed with a valve seat hole 2b coaxial with the valve seat 2a, which penetrates the valve seat member 2 in the axial direction, and a concave portion 2c connecting the valve seat hole 2b and the valve seat 2a. Is done. The recess 2c defines a preliminary diffusion chamber 16 in cooperation with the distal end surface of the valve portion 4a.

An injector plate 17 made of a steel plate is connected to front end surfaces of the valve housing 1 and the valve seat member 2 by two inner and outer annular welds 20 and 21. The injector plate 17 has _one pair and two pairs of fuel injection holes 17 ₁ , arranged on a pitch circle 22 centered on the axis of the conical valve seat 2a.
17 _1, 17 ₁ , 17 ₂ are drilled, and the valve seat holes 2 b are connected to these fuel injection holes 17 ₁ , 17 ₁ ; 17 ₁ , 17 _2.
Is provided between the valve seat member 2 and the injector plate 17. In the illustrated example, the diffusion chamber 23 is provided with a recess 2 d formed on the front end face of the valve seat member 2.
And the upper surface of the injector plate 17.

In the above, as shown in FIGS.
Bottom 16a of the preliminary diffusion chamber 16 is formed in a conical shape having a taper angle theta ₁ is greater than the taper angle theta ₂ of the conical valve seat 2a. Further, the conical bottom surface 16a of the preliminary diffusion chamber 16
Is formed such that its virtual vertex P is arranged in the valve seat hole 2b (see FIG. 4).

The valve seat hole 2b has a cross-sectional area S₁But
Number of fuel injection holes 17₁, 17₁; 17 ₁, 17_TwoThe overall side of
Cross-sectional area S_TwoEqual to or greater than
Formed (see FIG. 5). At this time, the valve body 4 in the open state is
From the tip to the bottom of the diffusion chamber 23, ie, the injector plate
17 is the inner diameter D of the valve seat hole 2b.₁Than
It is set small (see FIG. 6).

The pitch circle 22 is the inner diameter D of the valve seat hole 2b.
₁ larger diameter D ₂ is given.

A cap 24 for covering the outer peripheral portion of the injector plate 17 is mounted on the valve housing 1.

The coil housing 3 and the fuel introduction cylinder 12 exposed from the rear end are fitted with an insulating cover 25 made of synthetic resin.
The insulating cover 25 is integrally formed with a coupler 27 having a connection terminal 26 connected to the coil 10.

Next, the operation of this embodiment will be described.

When the coil 10 is demagnetized, the valve spring 1
3, the movable core 5 and the valve element 4 are pressed forward,
The valve portion 4a is seated on the valve seat 2a. Therefore, the high-pressure fuel supplied from the fuel pump (not shown) into the fuel introduction cylinder 12 through the fuel filter 14 is held in the fixed core 7 and the valve housing 1.

When the coil 10 is energized, the magnetic flux generated by the coil 10 runs sequentially through the fixed core 7, the movable core 5, the valve housing 1 and the coil housing 3, and the movable core 5 moves with the valve body 4 by the magnetic force generated thereby. Since the valve seat 2a is opened by being adsorbed to the fixed core 7, the high-pressure fuel waiting in the valve housing 1 passes through the valve seat 2a, passes through the pre-diffusion chamber 16 and passes through the valve seat hole 2b to the diffusion chamber 23. And from a plurality of fuel injection holes 17 ₁ , 17 ₁ ; 17 ₁ , 17 ₂
The fuel is injected toward the corresponding intake port 30a of the internal combustion engine E.

Incidentally, between the valve seat 2a and the valve seat hole 2b.
Is provided with a preliminary diffusion chamber 16 having a conical bottom surface 16.
a taper angle θ_TwoIs the taper angle of the conical valve seat 2a
θ₁Pre-diffusion from valve seat 2a
The fuel that has entered the chamber 16 collides with the bottom surface 16a and is effective.
Diffuse. Next, the fuel spreads from the valve seat hole 2b.
The fuel is transferred to the dispersion chamber 23 and diffuses again, so that the fuel
Injection hole 17₁, 17₁; 17₁, 17_TwoInjected from
The spray direction and the spray angle at the time ₁, 1
7₁; 17₁, 17_TwoSuitable for the direction and shape of the
It becomes Moreover, the cross-sectional area S of the valve seat hole 2b₁Is plural
Fuel injection hole 17₁, 17₁; 17₁, 17 _TwoComprehensive crossing of
Area S_TwoIs set equal to or greater than
By the time the fuel reaches the diffusion chamber 23 from the valve seat 2a,
There is no significant drop in fuel pressure and therefore its expansion
The fuel in the dispersion chamber 23 is supplied to each fuel injection hole 17 at high pressure.₁, 1
7₁; 17₁, 17_TwoWill be injected from
And the fuel chamber of the internal combustion engine E
Can improve combustion efficiency.

The diffusion chamber 2 extends from the tip of the valve 4 in the open state.
The distance H to the bottom surface 23a of 3 is set smaller than the inner diameter D ₁ of the valve seat hole 2b, preliminary diffusion chamber 16 and the diffusion chamber 2
By the flattening of 3, the dead volume can be reduced as much as possible and the effect of fuel diffusion can be enhanced.

Further, the conical bottom surface 16a of the preliminary diffusion chamber 16
Is arranged in the valve seat hole 2b. Therefore, the flattening of the preliminary diffusion chamber 16 can further enhance the fuel diffusion effect.

The plurality of fuel injection holes 17 ₁ , 17 ₁ ; 17 ₁ , 17 ₂ of the injector plate 17 are provided in the valve seat holes 2b.
Together are arranged on a pitch circle centered on the axis, the diameter D ₂ of the pitch circle is larger than the inner diameter D ₁ of the valve seat hole 2b, the fuel injection holes 17 ₁ from the valve seat hole 2b, 1
7 _1; 17 _1, 17 to suppress the flow-through to _2, the diffusion chamber 2
The diffusion function for fuel No. 3 can be made accurate.

The present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the present invention.

[0038]

As described above, according to the first aspect of the present invention, a plurality of fuel injection holes are formed in the injector plate, and the cross-sectional area of the valve seat hole is reduced by the total cross-sectional area of these fuel injection holes. A recess having a conical bottom with a taper angle larger than the taper angle of the valve seat coaxially with the valve seat hole is formed between the valve seat hole and the valve seat; The high-pressure fuel that has passed through the valve seat can be diffused in the pre-diffusion chamber and the diffusion chamber in two stages, and is injected from each fuel injection hole. The fuel spray direction and spray angle can be stabilized. Moreover, there is no large drop in fuel pressure before the fuel reaches the diffusion chamber from the valve seat.
Since the atomization state of the fuel injected from each fuel injection hole can be improved, the combustion efficiency in the fuel chamber of the internal combustion engine can be improved.

According to the second feature of the present invention, the distance from the tip of the valve element in the open state to the bottom surface of the diffusion chamber is set smaller than the inner diameter of the valve seat hole. Flattening can contribute to reducing dead volume and improving the fuel diffusion effect.

According to the third feature of the present invention, since the virtual apex of the conical bottom surface of the pre-diffusion chamber is disposed in the valve seat hole, the flattening of the pre-diffusion chamber further increases the fuel diffusion effect. Can contribute to the improvement.

According to a fourth feature of the present invention,
Since the multiple fuel injection holes of the injector plate were arranged on a pitch circle centered on the axis of the valve seat hole, and the diameter of the pitch circle was set larger than the inner diameter of the valve seat hole,
The diffusion function for the fuel in the diffusion chamber can be made accurate by suppressing the passage from the valve seat hole to the fuel injection hole.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine equipped with an electromagnetic fuel injection valve of the present invention.

FIG. 2 is a longitudinal sectional view of the electromagnetic fuel injection valve.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is an enlarged view of a part of FIG. 3;

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

FIG. 6 is a view corresponding to FIG. 5, showing a valve opening state of the valve body.

[Explanation of symbols]

Crossing D ₁ of the inner diameter D ₂ ... pitch circle of ... valve seat hole diameter I · · · · · electromagnetic fuel injection valve H · · · · · distance S ₁ ... valve seat hole area S ₂ · · · · plurality of taper angle 1 of the taper angle theta ₂ · · · · preliminary diffusion chamber bottom surface of the overall cross-sectional area theta ₁ · · · · valve seat of the fuel injection holes ----- valve housing 2a · ... valve seat 2b ... valve seat hole 4 ... valve element 5 ... movable core 7 ... fixed core 10 ... coil 13 ... valve spring 17 ··· Injector plate 16 ··· Preliminary diffusion chamber 16a ··· Bottom surface of the preliminary diffusion chamber 17 ··· Injector plate 17 ₁ , 17 ₂ ··· Fuel injection hole 22 ··· Pitch circle 23 .... Diffusion chamber 23a ... Bottom of diffusion chamber

Claims (4)

[Claims] 1. A valve seat (2a) and inside the valve seat (2a).
A valve housing having at one end a valve seat hole (2b) connected to a core portion
(1) and slidably housed in this valve housing (1).
A valve body (4) that is accommodated and faces the valve seat (2a);
Valve for urging the body (4) in the valve closing direction toward the valve seat (2a)
Provided at the other end of the spring (13) and the valve housing (1).
A coil (10) for opening the valve body (4) at the time of excitation;
It is joined to one end surface of the valve housing (1) and has a valve seat hole (2).
b) a plurality of fuel injection holes (17)₁, 17_Two)
And a valve seat hole
(2b) and fuel injection holes (17₁, 17_TwoBetween them
A flat fuel diffusion chamber (23) communicating with each other,
In the electromagnetic fuel injection valve, the injector plate (1
7) has a plurality of fuel injection holes (17).₁, 17_Two) When drilling
In both cases, the cross-sectional area of the valve seat hole (2b) (S₁A) these fuels
Nozzle (17₁, 17 _Two) Total cross-sectional area (S_TwoSame as)
Etc. or larger, and set the valve seat hole (2b)
Between the valve seat (2a) and the valve seat hole (2b),
Angle (θ) of the seat (2a)₁) Larger taper angle
(Θ_Two) With a conical bottom surface (16a)
Is formed, and the recess (2c) and the tip end surface of the valve element (4) are
Characterized in that a pre-diffusion chamber (16) is defined,
Type fuel injection valve. 2. The electromagnetic fuel injection valve according to claim 1, wherein a distance (H) from a tip of the valve body (4) in an open state to a bottom surface (23a) of the diffusion chamber (23) is determined by a valve seat hole (H). An electromagnetic fuel injection valve characterized in that it is set smaller than the inner diameter (D ₁ ) of 2b). 3. The method according to claim 2, wherein the virtual vertex (P) of the conical bottom surface (16a) of the diffusion chamber (16) is
An electromagnetic fuel injection valve, which is disposed in a valve seat hole (2b). 4. An electromagnetic fuel injector according to claim 1, wherein said injector plate comprises:
A plurality of fuel injection holes (17 ₁ , 17 ₂ ) are
b) are arranged on a pitch circle centered on the axis of
Characterized by being larger than the inner diameter (D ₁₎ of the diameter (D ₂₎ of the valve seat hole of the pitch circle (2b), the electromagnetic fuel injection valve.