JP2005155547A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve which can increase an acute angle θ for a fuel to flow in a nozzle even when an inclined angle α of the nozzle provided in a nozzle plate to a valve stem cannot be increased, so that an atomization effect of fuel is greatly enhanced. <P>SOLUTION: A fuel cavity 14d is formed of a valve sheet, the nozzle plate 17, and a valve member inside a fuel path 14c formed of an inclined surface 14a of the valve sheet 14 and the valve member 13 when the valve is opened. A cross-section of the nozzle plate 17 is constituted in a convex shape in a direction from a nozzle plate side to an end side of the valve member. A plurality of injection holes 18 are arranged in an inclined surface 17a constituting the convex shape of the nozzle plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve for injecting fuel into an intake pipe or a combustion chamber of an internal combustion engine, and more particularly to a fuel injection valve having a mechanism for promoting atomization of sprayed fuel to be injected.

An example of a conventional fuel injection valve is disclosed in Japanese Patent Laid-Open No. 9-14090 (hereinafter referred to as Patent Document 1).
In the fuel injection valve shown in this Patent Document 1, in order to promote atomization of fuel injected from a nozzle, a plurality of injection holes are formed in a flat injection hole plate, and a valve member front end surface is an inlet of the injection hole plate. It is formed parallel to the surface, and a fuel flow is made evenly in the flat flow path between the valve member tip flat surface and the nozzle hole plate inlet surface, and the fuel collides directly above the nozzle hole inlet. It is ejected later and atomized.
Further, as shown in the second column, right column, lines 3 to 26 (FIG. 10 in the publication) of JP 2001-263206 A (Patent Document 2), after the fuel flows along the nozzle hole plate, an acute angle is obtained. In order to return to the upstream (0 ° <A <90 ° (page 4, right column, line 33)), the atomized fuel is promoted to be atomized.

Japanese Patent Laid-Open No. 9-14090 (FIG. 1) JP 2001-263206 A (page 2, right column, lines 3 to 26, page 4, right column, line 33, FIG. 10)

  In such a conventional fuel injection valve, the injection angle α (corresponding to A in Patent Document 2) in FIG. 1 of Patent Document 1 is defined as a range of 2 ° to 40 °, and this angle is small. Because the fuel flows smoothly into the nozzle hole, there is little turbulence in the flow in the nozzle hole, and it is difficult for contraction to occur, and the injected fuel is not sufficiently atomized. There was a problem that the performance deteriorated, resulting in a decrease in fuel consumption and an increase in emission of harmful exhaust gas (unburned fuel, etc.).

The present invention has been made to solve the above-described problems, and an object thereof is to obtain a fuel injection valve capable of providing a large atomization effect of fuel to be injected with a simple configuration. .
Further, according to the present invention, even when the inclination angle α of the nozzle hole provided in the nozzle hole plate with respect to the valve shaft cannot be increased, the angle at which the fuel flows into the nozzle hole, that is, the fuel flow direction to the nozzle hole As a result, the angle θ in the direction of returning to the upstream side with respect to the upstream side can be increased, whereby the fuel atomization effect is great, fuel efficiency can be improved, and harmful exhaust emissions can be suppressed. The purpose is to obtain an injection valve.

  (1) A fuel injection valve according to the present invention has a valve seat having an opening at the tip, an inclined surface through which fluid is passed, a valve seat, and a guide on the upstream side of the opening, and the valve A valve member that has a contact portion that can be seated on a valve seat of the seat, is slidably accommodated along the guide portion in the valve seat, and the contact portion separates from and sits on the valve seat; An opening plate provided with a plurality of injection holes disposed at a downstream side of the valve seat so as to close the opening of the valve seat and allowing fluid to flow in a plate thickness direction at a predetermined angle is provided. Sometimes, a fuel cavity is formed by the valve seat, the injection hole plate, and the valve member inside a fuel passage formed by the inclined surface of the valve seat and the valve member. The cross-sectional shape is on the nozzle hole plate side Is configured so as to be convex toward the front end side of the Luo said valve member is obtained by so arranging the injection hole on the inclined surface forming the convex shape of the injection hole plate.

  (2) Further, in the fuel injection valve according to the present invention, in the fuel injection valve according to (1), the diameter D1 of the circumscribed circle of the fuel inlet of each injection hole is an inclined surface of the valve seat constituting the fuel flow path. Is extended to be smaller than the diameter D2 of the circle intersecting the nozzle hole plate.

  (3) In the fuel injection valve according to the present invention, in the fuel injection valve according to (1) or (2), the inclined surface of the injection hole plate provided with the injection holes is perpendicular to the axial direction of the fuel injection valve. Is in a range of 0 ° <β <90 °, and the angle α (the outward direction is positive) of the fuel injection direction with respect to the fuel injection valve shaft direction of the injection hole is − The range is β <α <90 ° −β.

According to the present invention, since the injection hole is disposed on the inclined surface of the convex injection hole plate, the fuel can be supplied at an acute angle (in the direction in which the fuel flows backward) regardless of the fuel injection direction with a simple structure. It is possible to flow into the nozzle hole, so that it is possible to obtain a large atomization effect of the injected fuel, and it is possible to improve fuel efficiency and suppress emission of harmful exhaust gas (unburned fuel etc.) A fuel injection valve can be obtained.
Further, according to the present invention, even when the inclination angle α with respect to the valve shaft of the nozzle hole, which has been impossible in the past, is α ≦ 0 °, the fuel is acute (θ = α + β> 0, the fuel is It can flow into the nozzle hole (in the direction of backflow), and a sufficient atomization effect can be obtained.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a fuel injection valve according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of a vicinity C of an injection hole plate.
1 and 2, the fuel injection valve 1 is formed by integrally molding an electromagnetic coil 3, a fixed iron core 4, and a metal plate 5 constituting a magnetic passage inside a resin housing 2.
The electromagnetic coil 3 includes a resin bobbin 3a, a coil 3b wound around the outer periphery thereof, and a terminal 6 provided for connection to the outside, and is integrally formed with the resin housing 2. ing. An adjuster 8 for adjusting the load of the compression spring 7 is fixed inside the fixed iron core 4. One end of the metal plate 5 constituting the magnetic path is welded to the fixed iron core 4 and the other end is welded to the magnetic pipe 9 constituting the magnetic path.
The nonmagnetic pipe 11 is fixed to the fixed iron core 4 and the magnetic pipe 9 so that the movable iron core 10 disposed inside the magnetic pipe 9 is movable in the axial direction. A needle pipe 12 is welded to one end of the movable iron core 10. The end of the needle pipe 12 on the side of the movable iron core 10 is in contact with the compression spring 7, and the other end is welded with a ball 13 as an example of a valve member.
The valve sheet 14 disposed inside the magnetic pipe 9 has an opening at the tip, and on the upstream side of the opening, an inclined surface 14a serving as a valve seat of the ball 13, a guide portion 14b, A fuel passage 14c is provided.
The outer periphery of the ball 13 is processed into, for example, a pentagon, and is guided by the guide 14b of the valve sheet 14 by the pentagon so as to move back and forth in the axial direction so that it can be seated on the inclined surface 14a. It is placed and accommodated in the valve seat.
The tip of the ball 13 is processed to be flat, and the flat surface 13a, the valve seat 14 and the injection hole plate 17 constitute a fuel cavity 14d.

The injection hole plate 17 has a plurality of injection holes 18 having a cross-sectional shape that is convex upward in the drawing and has inlets at the fuel cavity 14d, and the downstream end of the valve sheet 14 ( The bottom of the valve seat 14 is fixed in a liquid-tight manner so as to close the opening of the valve seat 14.
That is, as shown in FIG. 2, the nozzle hole plate 17 has a cross-sectional shape that is convex toward the nozzle hole inlet side (that is, convex from the nozzle hole plate side toward the tip surface 13a side of the ball 13). The injection hole 18 is formed on a surface 17a inclined at an angle β (0 ° <β <90 °) with respect to a surface perpendicular to the axial direction of the fuel injection valve 1 in the injection hole plate 17 convex toward the injection hole inlet side. The central line is inclined at an angle α (0 ° <α <90 °) with respect to a line parallel to the valve shaft.
Accordingly, each nozzle hole 18 is inclined at an angle θ (= α + β, 0 ° <θ <90 °) with respect to a direction perpendicular to the inclined surface 17a.

  The diameter D1 of the circumscribed circle at the inlet of each injection hole 18 is set to be smaller than the diameter D2 of the circle that extends the inclined surface of the valve seat inclined surface 14a and intersects the injection hole plate 17. The central portion of the nozzle hole plate 17 constitutes a flat surface 17b so as not to contact the ball flat surface 13a when the valve is closed.

The fuel injection valve of the present invention is configured as described above. When the electromagnetic coil 3 is energized from the outside via the terminal 6, it is composed of a fixed iron core 4, a metal plate 5, a magnetic pipe 9, and a movable iron core 10. Magnetic flux is generated in the magnetic path, and the movable iron core 10 is attracted to the fixed iron core 4 by electromagnetic attraction. As a result, the needle pipe 12 joined to the movable iron core 10 and the ball 13 welded and fixed to the needle pipe 12 are operated, and the ball 13 is inclined to the valve seat 14. The fuel passage 14c is opened from the seat 14a.
When the fuel passage 14c is in the open state, the fuel supplied from the delivery pipe (not shown) to the fuel injection valve 1 passes through the filter 16, and then the adjuster 8 and the compression spring disposed in the fixed iron core 4. 7. Each of the movable iron core 10, the needle pipe 12, the guide portion 14b of the valve sheet 14 and the outer periphery of the ball 13 is sequentially passed to reach the fuel passage 14c, from which the fuel cavity 14d is further passed. After that, the fuel is injected from the nozzle hole 18 to the outside (inside the intake pipe of the engine).

Here, as shown in FIG. 3, the fuel flows from the fuel passage 14c into the fuel cavity 14d along the valve seat inclined surface 14a. For this reason, in FIG. 3, vortices are formed in the cavity corners 14 e formed by the nozzle hole plate 17 and the valve seat 14. The fuel flowing into the fuel cavity 14d flows in a direction substantially along the valve seat inclined surface 14a, and then along the nozzle hole plate inclined surface 17a. The fuel near the nozzle hole plate inclined surface 17a is the conventional example shown in FIG. As compared with the above, it flows into the nozzle hole 18 at an acute angle with a larger turning angle (θ> α).
Moreover, since the cross-sectional area of the flow path is further reduced toward the nozzle hole as compared with the conventional case, the flow of fuel is accelerated.

  Thus, according to the fuel injection valve according to the first embodiment of the present invention, the injection hole plate whose cross-sectional shape is convex on the fuel inlet side (convex shape from the injection hole plate side toward the tip end side of the valve member). Since a plurality of injection holes are provided on the inclined surface, fuel can flow into the injection holes at an acute angle (in the direction in which the fuel flows backward) regardless of the fuel injection direction. Further, since the cross-sectional area of the flow path becomes smaller toward the nozzle hole, the fuel flow is accelerated as compared with the conventional apparatus, and cavitation is likely to occur near the inlet of the nozzle hole 18 and a large turbulence occurs. Further, when the flow velocity is high, the cavitation grows up to the outlet of the nozzle hole 18, and the fuel is injected as a thin liquid film by the contraction flow at the outlet of the nozzle hole 18. For this reason, a large atomization effect of the injected fuel can be obtained.

  Further, the diameter D1 of the circumscribed circle at the inlet of each nozzle hole 18 is configured to be smaller than the diameter D2 of the circle that extends the inclined surface 14a of the valve seat constituting the fuel passage and intersects the nozzle hole plate 17. Therefore, the fuel that has flowed into the fuel cavity from the flow path constituted by the valve seat and the valve member can be prevented from flowing directly into the injection hole, and a large fine particle effect can be obtained.

Further, as shown in FIG. 5, even if the inclination angle α with respect to the valve axis direction of the nozzle hole, which has been impossible in the past, is α ≦ 0 °, the angle β of the inclined surface of the nozzle hole plate is − By setting α <β, the fuel can flow into the nozzle hole at an acute angle (θ = α + β> 0, in the direction in which the fuel flows backward), and a sufficient atomization effect can be obtained.

Embodiment 2. FIG.
FIG. 6 is a cross-sectional view of the main part of a fuel injection valve according to Embodiment 2 of the present invention.
In the second embodiment, the flat surface 17b of the nozzle hole plate in the first embodiment is not provided, that is, the convex shape of the nozzle hole plate is triangular.
If the ball flat surface 13a does not come into contact with the injection hole plate 17 when the valve is closed, the flat surface 17b may be eliminated in this way, and as in the first embodiment described above, a large atomization effect of the injected fuel is achieved. Can be obtained.

Embodiment 3.
FIG. 7 shows the convex shape of the nozzle hole plate 17 formed by a curved surface (curvature R), and a large atomization effect of the injected fuel can be obtained as in the first embodiment. It is.

Embodiment 4.
Further, FIG. 8 shows a case where the convex shape of the nozzle hole plate 17 is constituted by a concave curved surface 17d, and a large atomization effect of the injected fuel can be obtained as in the first embodiment. It is.

Embodiment 5.
Furthermore, in the first embodiment, the case where the end surface of the ball 13 that is a valve member is processed to be flat and has a flat surface 13a is shown. However, the end surface shape of the ball 13 is spherical, curved, tapered, convex, Other shapes such as a concave shape may be used, and a large atomization effect of the injected fuel can be obtained as in the above-described embodiment.

  The present invention is applied as, for example, a fuel injection valve for an internal combustion engine such as a gasoline engine.

It is sectional drawing which shows the whole structure of the fuel injection valve in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the principal part of the fuel injection valve in Embodiment 1 of this invention. It is sectional drawing which shows the flow of the fuel in the fuel channel and nozzle hole in Embodiment 1 of this invention. It is sectional drawing which shows the flow of the fuel in the fuel channel and injection hole of the conventional fuel injection valve. It is sectional drawing which shows the flow of the fuel in a fuel channel and an injection hole in case the inclination-angle (alpha) of the injection hole in Embodiment 1 of this invention is (alpha) <= 0 degree. It is sectional drawing which shows the structure of the principal part of the fuel injection valve in Embodiment 2 of this invention. It is sectional drawing which shows the structure of the principal part of the fuel injection valve in Embodiment 3 of this invention. It is sectional drawing which shows the structure of the principal part of the fuel injection valve in Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve, 13 Valve member (ball), 14 Valve seat, 14a Inclined surface,
14b guide part, 14c fuel passage, 14d fuel cavity,
14e Caby corner, 17 injection hole plate, 17a inclined surface, 17b flat surface,
18 Hole.

Claims (7)

  A valve seat having an opening at the tip, an inclined surface through which fluid passes, a valve seat, and a guide portion upstream of the opening, and a contact portion that can be seated on the valve seat of the valve seat A valve member that is slidably accommodated along the guide portion in the valve seat, and that the contact portion separates from and seats on the valve seat, and the valve so as to close the opening of the valve seat An injection hole plate having a plurality of injection holes arranged at a predetermined position and passing a fluid in a thickness direction at a predetermined angle at a predetermined position, and an inclined surface of the valve seat, the valve member, and A fuel cavity is formed inside the fuel passage formed by the valve seat, the injection hole plate, and the valve member, and the injection hole plate has a sectional shape from the injection hole plate side. Convex shape toward the tip of the member So as constructed, a fuel injection valve, characterized in that so as to dispose the said injection hole to the inclined surface forming the convex shape of the injection hole plate.   The diameter D1 of the circumscribed circle of the fuel inlet of each nozzle hole is configured to be smaller than the diameter D2 of the circle intersecting with the nozzle hole plate by extending the inclined surface of the valve seat constituting the fuel flow path. The fuel injection valve according to claim 1.   The angle β of the inclined surface of the injection hole plate provided with the injection holes with respect to the surface perpendicular to the axial direction of the fuel injection valve is in the range of 0 ° <β <90 °, and the fuel injection shaft of the injection hole The angle α formed by the fuel injection direction with respect to the direction (the outward direction is positive) is in a range of −β <α <90 ° −β. Fuel injection valve.   The fuel injection valve according to any one of claims 1 to 3, wherein the convex shape of the injection hole plate is a trapezoid having an inclined surface and a flat surface.   The fuel injection valve according to any one of claims 1 to 3, wherein a convex shape of the injection hole plate is a triangular shape.   The fuel injection valve according to any one of claims 1 to 3, wherein a convex shape of the injection hole plate is formed by a curved surface.   The fuel injection valve according to any one of claims 1 to 3, wherein the convex shape of the nozzle hole plate is configured by a concave curved surface.

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