JP4782805B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve including a nozzle plate in which an injection hole for injecting fuel is formed.

  Conventionally, various fuel injection valves have been proposed. Patent Document 1 discloses a fuel injection valve as an example.

The fuel injection valve disclosed in Patent Document 1 includes a valve seat, a valve body that can be attached to and detached from the valve seat, a drive unit that drives the valve body, and a nozzle plate that injects fuel. . In this fuel injection valve, when the valve body is opened by being driven by the drive unit, the fuel that has passed between the valve body and the valve seat is injected from the injection hole of the nozzle plate. Thus, in a fuel injection valve equipped with a nozzle plate, fuel can be injected in a predetermined direction through the injection holes of the nozzle plate.
Japanese Patent Laid-Open No. 9-14090

  In a fuel injection valve, atomization of fuel to be injected is required. One means for atomizing the fuel is to promote mixing of the fuel and air.

  However, in the conventional fuel injection valve, the valve body side surface (flow path surface) of the nozzle plate is flat, so that the fuel that has passed between the valve body and the valve seat moves over the nozzle plate on the center of the nozzle plate. And flows into the injection hole in a state where the flow velocity of the fuel is lowered. For this reason, the fuel cannot be sufficiently pressed against the peripheral surface of the injection hole, and a fuel film is not sufficiently formed on the peripheral surface of the injection hole, so that a sufficient contact area between the fuel and the air in the injection hole is obtained. However, there is a problem that mixing of the fuel and air is not easily promoted and atomization of the fuel is not promoted.

  Accordingly, an object of the present invention is to promote atomization of fuel to be injected in a fuel injection valve.

The present invention is directed to a valve seat member in which an annular valve seat is formed, a valve body that can be attached to and detached from the valve seat, a drive unit that causes the valve body to be attached to and detached from the valve seat, and the valve body. A fuel injection valve comprising: a flow path surface; and a nozzle plate disposed on the downstream side of the valve body having an injection hole for injecting fuel between the flow path surface and the valve body. The valve seat is inclined with respect to the axial center line of the valve seat so as to move away from the axial center line of the valve seat as it goes from the upstream portion to the downstream portion of the injection hole. A guide surface that is provided on the side of the injection hole and that guides fuel that has passed between the valve seat and the valve body to the injection hole. The guide surface is tapered. is formed inclined toward the hole edge portion of the injection hole in and extending to the injection hole in the guide surface The peripheral surface of the injection hole is located on a line, said valve body, said bubble generating portion for generating cavitation bubbles in the fuel which is located between the nozzle plate and the valve body is formed, the bubble generating portion A recess facing the guide surface and a recess recessed inward of the valve body, the recess being formed between the guide surface and the facing surface. The cavitation bubbles generated when the fuel flows through are pressed against the peripheral surface of the injection hole by an impact when the cavitation collapses in the recess .

According to the present invention, since the peripheral surface of the injection hole is positioned on the extension line to the injection hole on the guide surface, the fuel guided by the guide surface is strongly collided with the peripheral surface of the injection hole, and the peripheral surface thereof. A fuel film can be formed on the top surface, thereby increasing the contact area between the fuel and the air in the injection hole to promote the mixing of the fuel and the air. Atomization can be promoted.
Further, the valve body has a facing surface facing the guide surface and a concave portion provided in a downstream portion of the facing surface and recessed toward the inside of the valve body, and the nozzle plate and the valve body, A bubble generation part that generates cavitation bubbles is formed in the fuel located between them, and the impact when the cavitation bubbles collapse allows the fuel to be pressed more strongly against the peripheral surface of the injection hole. A wider fuel film can be formed in the hole. Therefore, the contact area between the fuel and air can be further increased, and mixing of the fuel and air can be further promoted, and thus atomization of the injected fuel can be further promoted.

  An embodiment of the present invention will be described with reference to FIGS. This embodiment is an application example to a fuel injection valve used in an internal combustion engine mounted on a vehicle such as a four-wheeled vehicle or a two-wheeled vehicle. In the following description, for the sake of convenience, the end of the fuel injector that injects fuel is the tip of the fuel injector, and the end of the fuel injector that is supplied with fuel from the fuel pipe is the fuel injector. This will be referred to as the base end portion (the base end portion in the axial direction). In the description, the term “axial direction” refers to the axial direction of the fuel injection valve. 1 is a cross-sectional view showing a fuel injection valve according to the present embodiment together with an internal combustion engine, FIG. 2 is a cross-sectional view (cross-sectional view along the axial direction) showing the fuel injection valve according to the present embodiment, and FIG. It is sectional drawing (sectional drawing along an axial direction) which shows the front-end | tip part of the fuel injection valve concerning this embodiment.

  As shown in FIG. 1, the fuel injection valve 1 has a base end connected to the fuel pipe 103 via a connection pipe 101, and a tip end inserted into the insertion port 105 a of the internal combustion engine 105. Here, in the present embodiment, the insertion port 105 a is formed in the intake pipe 105 b of the internal combustion engine 105. The fuel injected from the fuel injection valve 1 is supplied into the cylinder 105e of the engine block 105d opened by opening the intake valve 105c.

  As shown in FIG. 2, the fuel injection valve 1 includes a substantially cylindrical metal cylinder 5 having a flow path 3 formed therein, and a flow path 3 provided inside the tip of the cylinder 5. The valve part 7 which opens and closes and the drive part 9 which drives this valve part 7 are provided.

  The cylindrical body 5 is formed as a relatively thin metal pipe having a step, for example, by subjecting a metal material such as magnetic stainless steel to press working such as deep drawing. The cylindrical body 5 is formed with a large diameter portion 5a on the base end side and a small diameter portion 5b having a smaller diameter than the large diameter portion 5a on the distal end side. The proximal end portion of the cylindrical body 5 is inserted into the connecting pipe 101, and the outer peripheral surface of the proximal end portion of the cylindrical body 5 closes the gap between the cylindrical body 5 and the connecting pipe 101, and is liquid-tight and airtight between them. An O-ring 11 that secures the above is extrapolated. The cylinder 5 is supplied with fuel that is pumped from a fuel pump (not shown) and flows through the fuel pipe 103 via the connection pipe 101, and the supplied fuel flows along the flow path 3. The cylinder 5 flows from the proximal end portion toward the distal end portion.

  A fuel filter 13 for filtering fuel is attached to the base end portion of the cylindrical body 5. The fuel filter 13 includes a cylindrical metal core 13a press-fitted into the large-diameter portion 5a of the cylinder 5, and a metal core 13a using a resin material softer than the cylinder 5, such as nylon or fluororesin. An integrally formed frame 13b and a mesh-like filter body 13c attached to the frame 13b and filtering fuel are provided.

  As shown in FIGS. 2 and 3, the valve portion 7 is disposed inside the distal end portion of the tubular body 5 and is made of a metal valve seat member 15 fixed to the tubular body 5, and disposed inside the tubular body 5. The metal valve body 17 is provided.

  The valve seat member 15 is formed in a cylindrical shape, and a valve element hole 15a is formed in the axial direction. The valve element 17 is accommodated in the valve element hole 15a so as to be movable in the axial direction. An annular valve seat 15b is formed on the inner peripheral surface of the valve element hole 15a. Specifically, the inner diameter of the valve body hole 15a is formed to be small in a step shape from the base end to the tip, and one of the step surfaces is formed as a valve seat 15b. And the exit part 15c connected to the downstream part of the valve seat 15b is formed in the front-end | tip part (downstream part) of the hole 15a for valve bodies. The valve seat member 15 is fixed to the cylindrical body 5 by all-around laser welding from the outside of the cylindrical body 5. This weld location is indicated by reference numeral 19 in FIG.

  A nozzle plate 21 that closes the valve element hole 15 a is fixed to the tip of the valve seat member 15. As shown in FIG. 3, the nozzle plate 21 has a plurality of injection holes 21a as orifices. The injection holes 21a open into the intake pipe 105b of the internal combustion engine 105, and the valve seat 15b and The fuel that has passed between the valve body 17 is injected. The nozzle plate 21 is made of, for example, a metal such as stainless steel, and is fixed to the valve seat member 15 by annular laser welding surrounding the injection hole 21a. This welding location is indicated by reference numeral 23 in FIG.

  As shown in FIGS. 2 and 3, the valve body 17 is formed in a spherical shape and can be attached to and detached from the valve seat 15 b. The valve body 17 has a seating position (not shown) where the valve seat 17 is seated on the valve seat 15b of the valve seat member 15 by the driving force of the drive unit 9, and a valve opening position where the valve body 17 is separated from the valve seat 15b of the valve seat member 15 (FIG. 3). The position is reciprocated in the axial direction.

  The drive unit 9 is an electromagnetic actuator, and specifically drives the valve body 17 in the valve unit 7. As shown in FIG. 2, the drive unit 9 is disposed inside the cylinder 5 and fixed to the cylinder 5 (core cylinder) 25, and inside the cylinder 5 on the distal end side of the fixed core 25. A movable iron core (anchor) 27 that is arranged and movable in the axial direction, an electromagnetic coil 29 extrapolated to the cylindrical body 5 at a position outside the fixed iron core 25 and the movable iron core 27, and an inner peripheral side of the electromagnetic coil 29 A bobbin 31 arranged and a yoke 33 arranged on the outer peripheral side of the electromagnetic coil 29 are provided. The fixed iron core 25, the movable iron core 27, the electromagnetic coil, and the yoke 33 form a closed magnetic path.

  The fixed iron core 25 is formed in a cylindrical shape extending in the axial direction by a magnetic metal material. The fixed iron core 25 is press-fitted into the small-diameter portion 5b of the cylindrical body 5. The front end surface of the fixed iron core 25 has a relatively small gap δ in the base end surface of the movable iron core 27 when the fuel injection valve 1 is closed. Face each other. An adjuster cylinder 35 extending in the axial direction is fitted into the fixed iron core 25, and the fuel that has flowed into the fixed iron core 25 flows out of the fixed iron core 25 via the inside of the adjuster cylinder 35. It has become. That is, the fixed iron core 25 and the adjuster cylinder 35 form a part of the flow path 3.

  The movable iron core 27 is formed in a stepped cylindrical shape extending in the axial direction by a magnetic metal material, and has a large-diameter portion 27a facing the fixed iron core 25 and a large-diameter portion 27a having a smaller diameter than the large-diameter portion 27a. A small-diameter portion 27b that protrudes from the end portion of the fuel injection valve 1 toward the tip end side of the fuel injection valve 1. The valve body 17 is fixed to the front end portion of the movable iron core 27 by welding. With this structure, the valve body 17 moves integrally with the movable iron core 27. A concave portion 27c that opens toward the fixed iron core 25 is formed in the large diameter portion 27a of the movable iron core 27, and an opening portion 27d that communicates with the concave portion 27c is formed in the side surface in the small diameter portion 27b. A back pressure chamber 37 is formed between the outer peripheral surface of the small diameter portion 27 b of the movable iron core 27 and the inner peripheral surface of the cylindrical body 5. In the movable iron core 27 having such a structure, the fuel that has flowed into the recess 27c from the fixed iron core 25 flows out from the opening 27d into the back pressure chamber 37. That is, the movable iron core 27 forms a part of the flow path 3.

  Between the movable iron core 27 and the fixed iron core 25, a coil spring 39 as an urging member constituting the drive unit 9 is interposed in a compressed state. The coil spring 39 is inserted into the recess 27c of the movable core 27, and one end (base end) thereof is in contact with the tip end surface of the adjuster cylinder 35, while the other end (tip end) is the recess 27c. It is in contact with the bottom surface. This coil spring 39 urges the movable iron core 27 and the valve body 17 in the valve closing direction of the valve body 17 and seats the valve body 17 on the valve seat 15b.

  The yoke 33 is formed in a stepped cylindrical shape, and has a large-diameter portion 33a that covers the outer periphery of the electromagnetic coil 29 and a smaller diameter than the large-diameter portion 33a, and the fuel injection valve 1 from the end of the large-diameter portion 33a. A small-diameter portion 33b that protrudes toward the distal end side. The yoke 33 has a small diameter portion 33b pressed into the small diameter portion 5b of the cylindrical body 5 and is fixed thereto.

  The bobbin 31 is formed in a cylindrical shape by a resin material and is extrapolated to the cylindrical body 5. The electromagnetic coil 29 is externally inserted into the cylindrical body with the electromagnetic coil 29 wound around the bobbin 31. The electromagnetic coil 29 is supplied with electric power from an external power source (not shown) via a pin 43 and a conductive path 45 provided on the connector 41.

  In the drive unit 9 having such a configuration, when the electromagnetic coil 29 is not energized, the state in which the valve element 17 is seated on the valve seat 15b is maintained by the biasing force of the coil spring 39 (valve closed state). In this case, a gap δ is formed between the fixed iron core 25 and the movable iron core 27 in the axial direction. On the other hand, when the electromagnetic coil 29 is energized, a closed magnetic path is formed by the electromagnetic coil 29, the fixed iron core 25, the movable iron core 27, and the yoke 33, whereby a magnetic force in the direction toward the fixed iron core 25 acts on the movable iron core 27. . Due to this magnetic force, the movable iron core 27 is attracted to the fixed iron core 25 against the urging force of the coil spring 39, and the valve seat member 15 that moves together with the movable iron core 27 separates from the valve seat 15b (valve open state). ).

  An O-ring 46 is externally inserted into the small-diameter portion 33 b of the yoke 33 of the drive unit 9, and this O-ring 46 is formed between the inner peripheral surface of the insertion port 105 a of the internal combustion engine 105 and the outer peripheral surface of the yoke 33. Close the gap to ensure liquid and air tightness between them.

  Further, the fuel injection valve 1 includes a cover 47 that covers an intermediate portion of the cylinder 5 and a protector 49 that covers the tip of the cylinder 5. The cover 47 is made of, for example, resin, and is formed by injection molding in a state where the yoke 33, the electromagnetic coil 29, and the like are assembled on the outer peripheral side of the cylindrical body 5. The cover 47 is integrally formed with the connector 41, and a conductive path 45 is formed in the cover 47. The protector 49 is formed in a cylindrical shape and is sheathed at the distal end portion of the cylindrical body 5 to protect the distal end portion of the cylindrical body 5.

  In the fuel injection valve 1 having such a configuration, when the electromagnetic coil 29 is energized and the valve body 17 is separated and opened, the fuel supplied into the cylinder 5 flows down the flow path 3. That is, the fuel is filtered by the fuel filter 13 and then flows into the back pressure chamber 37 via the fixed iron core 25 and the movable iron core 27, and the valve body 17 and the valve seat member 15 are opened from the back pressure chamber 37. It passes through the gap formed between the valve seat 15b and is injected from the injection hole 21a of the nozzle plate 21 (see FIG. 7).

  Next, the nozzle plate 21 and the valve body 17 constituting the fuel atomization promoting structure in the fuel injection valve 1 will be described in detail with reference to FIGS. Here, FIG. 4 is a plan view showing the nozzle plate according to the present embodiment, FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4, and FIG. 6 is a front end portion of the fuel injection valve according to the present embodiment. FIG. 7 is an enlarged cross-sectional view (a cross-sectional view along the axial direction) showing a part, and FIG. 7 is an explanatory view showing an enlarged part of the tip of the fuel injection valve in the fuel injection state according to the present embodiment. 8 is an explanatory diagram for explaining the flow of fuel in the fuel injection state according to the present embodiment. In addition, the dashed-dotted line in FIG. 7 has shown schematically the fuel injected from the injection hole 21a.

  As shown in FIGS. 3 to 5, the nozzle plate 21 has a circular flow path surface 21 b that is an upstream surface facing the valve element 17 and a plurality of injection holes 21 a.

  A planar circular portion 21c is formed at the center of the flow path surface 21b, and an annular protrusion 21d surrounding the circular portion 21c is formed.

  The circular portion 21c is formed in a circular shape concentric with the valve seat 15b, and a plurality of injection holes 21a are formed in the circular portion 21c.

  The injection hole 21a is for injecting fuel between the flow path surface 21b and the valve body 17, and is disposed on the outer edge of the circular portion 21c and penetrates the nozzle plate 21 in the plate thickness direction. The injection hole 21a is inclined with respect to the shaft center line A so as to move away from the shaft center line A of the valve seat 15b from the upstream portion to the downstream portion of the injection hole 21a. The plurality of injection holes 21a are arranged so that the fuel injected from each injection hole 21a does not interfere immediately after injection.

  The protrusion 21 d is located in the outlet portion 15 c in the valve element hole 15 a of the valve seat member 15. The outer diameter of the protruding portion 21d is smaller than the inner diameter of the outlet portion 15c, and a gap 3c as a flow path is formed between the protruding portion 21d and the outlet portion 15c. The protrusion 21d is formed with a guide surface 21e connected to the outer edge of the circular portion 21c.

  The guide surface 21e guides the fuel that has passed between the valve seat 15b and the valve body 17 to the injection hole 21a. The guide surface 21e is located on the valve seat 15b side of the injection hole 21a and is connected to the hole edge 21f of the injection hole 21a. Specifically, the guide surface 21e is formed in an annular shape concentric with the valve seat 15b, surrounds the injection hole group composed of the plurality of injection holes 21a, and approaches the axial center line A of the valve seat 15b as it goes downstream. Tapered surface. The peripheral surface 21g of the injection hole 21a is located on the extension line B to the injection hole 21a in the guide surface 21e.

  As shown in FIGS. 3 and 6, the valve body 17 is formed with a bubble generating portion 17 a that generates cavitation bubbles 55 (see FIG. 7) in the fuel located between the nozzle plate 21 and the valve body 17. ing. The bubble generating portion 17a has a facing surface 17b that faces the guide surface 21e, and a recessed portion 17c that is connected to the downstream portion of the facing surface 17b and that is recessed toward the inside of the valve body 17. The facing surface 17b is formed to face the guide surface 21e substantially in parallel, and is formed in an annular shape around the axis A of the valve seat 15b. This facing surface 17b forms a guide channel 3a between the guide surface 21e of the nozzle plate 21 and the opposing surface 17b. On the other hand, the recessed portion 17 c forms an enlarged flow path 3 b between the flow path surface 21 b of the nozzle plate 21. The enlarged flow path 3b has a larger flow area than the guide flow path 3a, and the cross section of the flow path suddenly expands from the guide flow path 3a to the enlarged flow path 3b. With such a structure, cavitation is generated in the fuel flowing at a relatively high speed in the guide channel 3a and flowing into the expanded channel 3b. That is, when the fuel flows from the guide channel 3a to the enlarged channel 3b, cavitation bubbles 55 are generated in the fuel and disappear in the enlarged channel 3b.

  In such a configuration, as shown in FIG. 7, the fuel that has passed between the valve seat 15b and the valve body 17 is guided by the guide surface 21e, flows into the injection hole 21a, and is injected from the injection hole 21a. .

  At this time, in this embodiment, since the peripheral surface 21g of the injection hole 21a is positioned on the extension line B to the injection hole 21a in the guide surface 21e, the fuel guided in the direction of arrow D by the guide surface 21e is While strongly colliding with the peripheral surface 21g of the injection hole 21a and spreading on the peripheral surface 21g, the fuel film C is formed and flows down the injection hole 21a. The fuel flow direction immediately before the collision at this time is indicated by an arrow E. Thereby, since the contact area of the fuel and air in the injection hole 21a increases, mixing of these fuel and air can be accelerated | stimulated, Therefore, atomization of the fuel injected can be accelerated | stimulated. The fuel flow seen from the upstream side of the nozzle plate 21 at this time is indicated by an arrow F in FIG. 8 shows the VIII-VIII cross section in FIG. 3 with the valve body 17 omitted.

  In the present embodiment, a plurality of injection holes 21a are provided, and the guide surface 21e is formed in an annular shape concentric with the valve seat 15b, so that the fuel can easily flow into the plurality of injection holes 21a.

  Further, in the present embodiment, the valve body 17 is formed with an opposing surface 17b facing substantially parallel to the guide surface 21e, so that the flow of fuel flowing between the guide surface 21e and the opposing surface 17b is reduced. It can guide to the injection hole 21a more stably.

  Further, in the present embodiment, the valve body 17 is provided with a facing surface 17b that faces the guide surface 21e and a recessed portion 17c that is continuous with the downstream portion of the facing surface 17b and is recessed toward the inside of the valve body 17. And the bubble generating part 17a for generating the cavitation bubbles 55 is formed in the fuel located between the nozzle plate 21 and the valve body 17, so that the fuel is moved to the arrow by the impact when the cavitation bubbles 55 collapses. The fuel can be pushed more strongly against the peripheral surface 21g of the injection hole 21a by pushing in the G direction, whereby a wider fuel film C can be formed in the injection hole 21a. Therefore, the contact area between the fuel and air can be further increased, and mixing of the fuel and air can be further promoted, and thus atomization of the injected fuel can be further promoted. In addition, the code | symbol 55a of FIG. 7 has shown typically the cavitation bubble which collapses.

  In this embodiment, since the gap 3c is formed between the protrusion 21d of the nozzle plate 21 and the outlet 15c of the valve seat member 15, the nozzle plate 21 is attached to the valve seat member 15. In addition, the nozzle plate 21 can be easily attached to the valve seat member 15.

  The present invention is not limited to the above-described embodiments, and various other embodiments can be adopted without departing from the gist of the present invention.

It is sectional drawing which shows the fuel injection valve concerning one Embodiment of this invention with an internal combustion engine. It is sectional drawing (sectional drawing along an axial direction) which shows the fuel injection valve concerning one Embodiment of this invention. It is sectional drawing (sectional drawing along an axial direction) which shows the front-end | tip part of the fuel injection valve concerning one Embodiment of this invention. It is a top view which shows the nozzle plate concerning one Embodiment of this invention. It is sectional drawing along the VV line of FIG. It is sectional drawing (sectional drawing along an axial direction) which expands and shows a part of front-end | tip part of the fuel injection valve concerning one Embodiment of this invention. It is explanatory drawing which expands and shows a part of front-end | tip part of the fuel injection valve of the fuel-injection state concerning one Embodiment of this invention. It is explanatory drawing for demonstrating the flow of the fuel of the fuel-injection state concerning one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 9 Drive part 15 Valve seat member 15b Valve seat 17 Valve body 17a Bubble generation part 17b Opposite surface 17c Recessed part 21 Nozzle plate 21a Injection hole 21b Flow path surface 21e Guide surface 21f Hole edge part 21g Circumferential surface 55 Cavitation bubble A Valve Center axis of seat B Extension line

Claims (3)

A valve seat member formed with an annular valve seat;
A valve body that can be attached to and detached from the valve seat;
A drive part for separating and seating the valve body on the valve seat;
A nozzle plate arranged downstream of the valve body, having a flow path surface facing the valve body, and an injection hole for injecting fuel between the flow path surface and the valve body;
In a fuel injection valve comprising:
The injection hole is inclined with respect to the axial center line of the valve seat so as to move away from the axial center line of the valve seat as it goes from the upstream part to the downstream part of the injection hole.
The flow path surface is located on the valve seat side of the injection hole and is connected to the hole edge of the injection hole to guide the fuel that has passed between the valve seat and the valve body to the injection hole. Has a surface,
The guide surface is tapered and inclined toward the hole edge of the injection hole, and the peripheral surface of the injection hole is positioned on an extension line to the injection hole in the guide surface ,
The valve body is formed with a bubble generating portion for generating cavitation bubbles in the fuel located between the nozzle plate and the valve body, and the bubble generating portion is formed between the opposing surface facing the guide surface and the opposing surface. A cavitation bubble generated when fuel flows from the gap between the guide surface and the opposing surface to the recess. The fuel injection valve, wherein the fuel injection valve is pressed against a peripheral surface of the injection hole by an impact when the recess is collapsed . A plurality of the injection holes are provided,
The fuel injection valve according to claim 1, wherein the guide surface is formed in an annular shape concentric with the valve seat.   3. The fuel injection valve according to claim 1, wherein the valve body is formed with an opposing surface that is substantially parallel to the guide surface. 4.

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