JP2008014216A - Fuel injection valve - Google Patents

Abstract

An injector capable of effectively reducing variations in the spray of fuel injected from each nozzle hole.
SOLUTION: Inner circumferential surface side openings 31 of each nozzle hole 3 are opened at equal intervals on the same circumference of a conical surface 13a at the tip of a nozzle body 13. And the shape of this inner peripheral surface side opening 31 is formed in a perfect circle shape with the same diameter as seen from the sliding shaft n direction of the needle valve. In addition, an expansion portion 33 that extends the opening area of the outer peripheral surface side opening 32 to be larger than the opening area of the inner peripheral surface side opening 31 is provided on the tip side of each nozzle hole 3. 31 is formed in a stepped shape with an expanded width in a stepped manner. Further, the nozzle hole length from the inner peripheral surface side opening 31 of each nozzle hole 3 to the expanded portion 33 is set to the same length for each nozzle hole 3.
[Selection] Figure 3

Description

  The present invention relates to a fuel injection valve having a plurality of injection holes at the tip of a nozzle body, and more particularly, to a measure for reducing variations in the spray of fuel injected from each injection hole.

  In general, the fuel injection valve is provided at the tip of the nozzle body, the needle valve slidably accommodated inside the nozzle body, and penetrates from the inner peripheral surface of the nozzle body to the outer peripheral surface. A plurality of nozzle holes, and when the needle valve is seated on the inner peripheral surface of the nozzle body, fuel spray injected from the nozzle holes is blocked, while the needle valve is disposed inside the nozzle body. By separating from the peripheral surface, spraying of fuel from each nozzle hole is allowed.

  By the way, in some fuel injection valves, the fuel injected from each nozzle hole is sprayed in a specific direction.

  In that case, for ease of processing, the injection hole may be provided at a position that is deviated in a specific direction with respect to the sliding axis of the needle valve (the central axis of the fuel injection valve).

  However, if each nozzle hole is provided at a position deviated in a specific direction with respect to the sliding axis of the needle valve, fuel is injected from a position deviated in the specific direction with respect to the sliding axis of the needle valve. When fuel is injected, fuel flows toward a position deviated in a specific direction with respect to the sliding axis of the needle valve, and the internal pressure near the tip of the nozzle body is specified with respect to the sliding axis of the needle valve. It decreases only in the direction and becomes unbalanced, and the needle valve is biased to the specific direction side (each nozzle hole side). For this reason, in the region where the lift amount of the needle valve is small or the nozzle hole in which the distance from the needle valve among the nozzle holes is small, the inner peripheral surface side opening is blocked by the needle valve and injected from each nozzle hole. The fuel spray will vary greatly.

Therefore, conventionally, by sliding the inner peripheral surface side opening of each nozzle hole opened in the inner peripheral surface of the nozzle body on the substantially same circumference of the inner peripheral surface of the nozzle body, the needle valve slides. The internal pressure against the sliding shaft of the needle valve near the tip of the nozzle body is eliminated by eliminating the fuel injection biased only from a specific direction with respect to the shaft and generating a uniform fuel flow over the entire circumference of the needle valve. Is known to prevent the needle valve from being biased and to suppress large variations in the spray of fuel injected from each nozzle hole (see, for example, Patent Document 1).
JP 2004-76723 A

  However, in the above-mentioned conventional one, the inner peripheral surface side openings of the respective nozzle holes are arranged at equal intervals on substantially the same circumference of the inner peripheral surface of the nozzle body. If the opening on the outer peripheral surface side is provided so as to point in a specific direction from the starting point, the shape of the inner peripheral surface side opening of each nozzle hole will be different, and the fuel flowing into the inner peripheral surface side opening of each nozzle hole Different swirling flows are generated, resulting in variations in the spray of fuel injected from each nozzle hole, which cannot be an effective measure.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel injection valve capable of effectively reducing variations in the spray of fuel injected from each nozzle hole. It is in.

  In order to achieve the above object, according to the present invention, a nozzle body, a needle valve slidably accommodated inside the nozzle body, and a tip of the nozzle body are provided. A fuel injection valve including a plurality of injection holes penetrating in a specific direction with respect to the surface is assumed. The openings on the inner peripheral surface side of the nozzle holes that open on the inner peripheral surface of the nozzle body are arranged at equal intervals on substantially the same circumference of the inner peripheral surface of the nozzle body, and the sliding of the needle valve They are all formed in the same shape when viewed from the axial direction.

  With this specific matter, the shape of the inner peripheral surface side opening of each nozzle hole with respect to the inner peripheral surface of the nozzle body is all formed in the same shape when viewed from the sliding axis direction of the needle valve. Different swirling flows do not occur in the fuel flowing into the surface side opening, and the fuel flows into the inner peripheral surface side opening of each nozzle hole by the same swirling flow, and the effect of variations in the spray of fuel injected from each nozzle hole is effective Can be reduced.

  In addition, an extended portion that extends the opening area of the outer peripheral surface side opening to be larger than the opening area of the inner peripheral surface side opening is provided on the tip side of each nozzle hole, and the expanded portion is formed into the inner peripheral surface side opening. On the other hand, if it is formed in a stepped shape with an expanded width in a stepped shape or a tapered shape expanded in a tapered shape with respect to the opening on the inner peripheral surface side, the tip of each nozzle hole is formed by the expanded portion that becomes the stepped shape. It is possible to expand the spread angle of the spray of fuel injected from each nozzle hole by using the negative pressure due to the sudden expansion on the side, and each of the injections using the Coanda effect by the expansion portion having a tapered shape. It becomes possible to increase the spread angle of the spray of fuel injected from the hole. In addition, the spread angle of the fuel spray injected from each nozzle hole can be controlled by controlling the expansion width of the expansion portion that becomes a step shape or the taper angle of the expansion portion that becomes a taper shape. Is possible.

  In addition, due to the expansion portion having a step shape, the thickness around each nozzle hole is reduced, and the temperature around each nozzle hole is cooled by the fuel flowing around the nozzle hole where the thickness is reduced, and the temperature decreases. It is also possible to effectively reduce deposit adhesion around each nozzle hole unique to the internal direct injection fuel injection valve.

  Further, when the nozzle hole length from the inner peripheral surface side opening of each nozzle hole to the expanded portion is set to the same length for each nozzle hole, each nozzle hole is an inner part of the nozzle body. Even if there is a difference in the length from the inner peripheral surface of the nozzle body to the outer peripheral surface between each nozzle hole because it penetrates in a specific direction from the peripheral surface to the outer peripheral surface, the depth of the expansion portion Accordingly, the nozzle hole lengths of the respective nozzle holes are all set to the same length, and it becomes possible to more effectively reduce the variation in the spray of the fuel injected from each nozzle hole.

  In short, by forming the shape of the inner peripheral surface side opening of each nozzle hole with respect to the inner peripheral surface of the nozzle body in the same shape as seen from the sliding axis direction of the needle valve, the fuel is injected by the same swirling flow. The variation in the spray of fuel injected from each nozzle hole can be effectively reduced by flowing into the opening on the inner peripheral surface side of the hole.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of an engine provided with an injector as a fuel injection valve according to a first embodiment of the present invention. The injector 1 is attached to a cylinder head 20 of an engine 2. The injector 1 is a fuel injection valve for a direct injection gasoline engine that directly injects fuel into a combustion chamber 23 formed by an inner peripheral surface of a cylinder block 21, an inner peripheral surface of a cylinder head 20, and an upper end surface of a piston 22. It is. The injection pressure of the injector 1 is 1 MPa to 30 MPa. The fuel spray injected from the injector 1 is a flat fan-shaped spray m1 as indicated by a broken line in FIG. The fan-shaped spray m1 is separated from the axis m0 of the injector 1 along the direction in which the needle valve 11 of the injector 1 is seated on a valve seat 12 (described later), and is inclined with respect to the axis m0. In this case, by setting an optimum angle for inclining the fan-shaped spray m1 with respect to the axis m0 of the injector 1, the fan-shaped spray m1 is formed on the inner wall surface of the spark plug 24 or the piston 22 and the cylinder block 21 forming the combustion chamber 23. It is possible to suppress adhesion and liquefaction.

  As shown in FIG. 2, the nozzle body 13 of the injector 1 has a conical surface 13a (inner peripheral surface) whose inner peripheral surface is reduced in diameter at the tip (lower end in FIG. 2) which is the downstream end in the fuel flow direction. Yes. A valve seat 12 on which the needle valve 11 slidably accommodated in the nozzle body 13 can be seated is formed on the conical surface 13a. 3, six nozzle holes 3, 3,... Are formed at equal intervals on the same circumference on the tip side of the valve seat 12 of the conical surface 13a. Each nozzle hole 3 is formed by drilling, laser processing or electric discharge machining. When the needle valve 11 is seated on the valve seat 12, fuel injection from each nozzle hole 3 is cut off, and when the needle valve 11 is separated from the valve seat 12, fuel injection from each nozzle hole 3 is allowed and fuel is sprayed. It has come to be.

  Further, as shown in FIG. 2, a cylindrical member 15 is inserted into the inner peripheral wall on the base end side (upper side in FIG. 2) that is the upstream side of the nozzle body 13 in the fuel flow direction. The cylindrical member 15 is fixed to the nozzle body 13 by welding. Further, the cylindrical member 15 includes a first magnetic cylinder portion 15a, a nonmagnetic cylinder portion 15b, and a second magnetic cylinder portion 15c, which are provided in order from the downstream side in the fuel flow direction (lower side in FIG. 2). The non-magnetic cylinder portion 15b prevents a magnetic short circuit between the first magnetic cylinder portion 15a and the second magnetic cylinder portion 15c.

  A movable core 16 is welded and fixed to a base end portion 11a (upper end portion in FIG. 2) of the needle valve 11. The movable core 16 is formed in a cylindrical shape from a magnetic material and reciprocates together with the needle valve 11. The outflow hole 16 a that penetrates the cylindrical wall of the movable core 16 forms a fuel passage that communicates the inside and outside of the cylinder of the movable core 16.

  A fixed core 17 is inserted into the cylindrical member 15 from the upstream side (the upper side in FIG. 2) of the movable core 16 in the fuel flow direction. The fixed core 17 is formed in a cylindrical shape from a magnetic material, and is fixed to the cylindrical member 15 by welding. In this case, the fixed core 17 faces the movable core 16.

  An adjusting pipe 18 is press-fitted into the fixed core 17 to form a fuel passage therein. Further, between the adjusting pipe 18 and the movable core 16, a spring 14 that is locked to both the members 18 and 16 is mounted. The load of the spring 14 applied to the movable core 16 can be changed by adjusting the amount of press-fitting of the adjusting pipe 18. The movable core 16 and the needle valve 11 are biased toward the valve seat 12 by the biasing force of the spring 14.

  A coil 41 is provided on the outer peripheral side of the cylindrical member 15. The coil 41 is wound around the spool 42. The terminal 43 is insert-molded into the connector 44 and is electrically connected to the coil 41. When the coil 41 is energized, a magnetic attractive force acts between the movable core 16 and the fixed core 17, and the movable core 16 is attracted toward the fixed core 17 against the biasing force of the spring 14. Yes. Thereby, the needle valve 11 is separated from the valve seat 12.

  A filter 45 is installed upstream of the fixed core 17 in the fuel flow direction (upper side in FIG. 2) so that foreign matters in the fuel supplied to the injector 1 are removed. The fuel that has flowed into the fixed core 17 through the filter 45 passes through the fuel passage in the adjusting pipe 18, the fuel passage in the movable core 16, the outflow hole 16 a, the inner peripheral wall of the nozzle body 13, and the outer peripheral wall of the needle valve 11. It passes through between. Further, when the needle valve 11 is separated from the valve seat 12, the fuel passes through an open flow path formed between the needle valve 11 and the valve seat 12 and is guided to each nozzle hole 3.

  Next, the nozzle holes 3, 3,... Formed in the conical surface 13a at the tip of the nozzle body 13 will be described in detail with reference to FIGS.

  As shown in FIG. 3, each nozzle hole 3 has an outer peripheral surface from a conical surface 13a (inner peripheral surface) at the tip of the nozzle body 13 so that the inclination angle of the fan-shaped spray m1 with respect to the axis m0 of the injector 1 becomes an optimum angle. 13b is penetrated in a specific direction. In this case, as shown in FIG. 4, the inner peripheral surface side opening 31 ′ (the inner peripheral surface side opening before performing electric discharge machining described later) of each nozzle hole 3 opening in the conical surface 13 a is a cone of the nozzle body 13. Since each of the nozzle holes 3 is arranged at equal intervals on the same circumference of the surface 13a and provided with the inner peripheral surface side opening 31 'of each nozzle hole 3 as a starting point, the outer peripheral surface side opening 32 is directed in a specific direction. The shape of the inner peripheral surface side opening 31 ′ of the nozzle hole 3 has an elliptical shape different from one to another. For this reason, as shown in FIG. 5, by subjecting the inner peripheral surface side opening 31 ′ of each nozzle hole 3 to electrical discharge machining by a discharge rod H having a circular cross section inserted from the side opposite to the nozzle hole of the nozzle body 13, When viewed from the sliding axis n of the needle valve 11 (the axis m0 of the injector 1), the inner peripheral surface side opening 31 (the inner peripheral surface side opening after electric discharge machining) of each nozzle hole 3 has a perfect circular shape with the same diameter. To be formed. In addition, you may make it the inner peripheral surface side opening 31 of each nozzle hole 3 be formed in the perfect circle shape of the same diameter seeing from the sliding-axis n direction of the needle valve 11 by drill processing or cutter processing.

  Further, as shown in FIG. 6, an expansion portion 33 that extends the opening area of the outer peripheral surface side opening 32 than the opening area of the inner peripheral surface side opening 31 is provided at the tip side of each nozzle hole 3. ing. As shown in FIG. 5, the extended portion 33 is formed in a stepped shape in which the extended width d is increased stepwise with respect to the inner peripheral surface side opening 31. Further, the nozzle hole length f from the inner peripheral surface side opening 31 of each nozzle hole 3 to the expanded portion 33 is set to the same length for each nozzle hole 3.

  Therefore, in the first embodiment, the shape of the inner peripheral surface side opening 31 of each nozzle hole 3 with respect to the conical surface 13a at the tip of the nozzle body 13 is a perfect circle shape with the same diameter as seen from the sliding axis n direction of the needle valve 11. Therefore, different swirl flows do not occur in the fuel flowing into the inner peripheral surface side openings 31 of the respective nozzle holes 3, and the fuel is caused to flow by the same swirl flow, and the inner peripheral surface side openings 31 of the respective nozzle holes 3. It is possible to effectively reduce variations in the spray of fuel injected into each nozzle hole 3.

  Further, an extended portion 33 that extends the opening area of the outer peripheral surface side opening 32 more than the opening area of the inner peripheral surface side opening 31 is provided on the tip side of each nozzle hole 3, and the expanded portion 33 is opened on the inner peripheral surface side opening. 31 is formed in a stepped shape in which the expansion width d is increased stepwise, so that the fuel injected from each nozzle hole 3 using the negative pressure due to abrupt expansion on the tip side of each nozzle hole 3 is formed. The spread angle of the spray can be increased. Moreover, by controlling the expansion width d of the expansion portion 33, the spread angle of the fuel spray injected from each injection hole 3 can be controlled.

  In addition, the thickness around each nozzle hole 3 is reduced by the expanding portion 33 having a stepped shape, and the temperature around each nozzle hole 3 is cooled by the fuel flowing around the nozzle hole 3 having the reduced thickness. The deposit adhesion to the periphery of each injection hole 3 inherent to the fuel injection valve for the direct injection gasoline engine can be effectively reduced.

  Furthermore, since the injection hole length f from the inner peripheral surface side opening 31 of each injection hole 3 to the expansion part 33 is set to the same length for each injection hole 3, each injection hole 3 is connected to the tip of the nozzle body 13. Even if there is a difference in the length from the conical surface 13a of the nozzle body 13 to the outer peripheral surface between the respective nozzle holes 3 because it penetrates in a specific direction from the conical surface 13a to the outer peripheral surface, The injection hole lengths f of the respective injection holes 3 are all set to the same length depending on the depth of the expansion portion 33, which is very advantageous in effectively reducing variation in the spray of fuel injected from each injection hole 3. It will be a thing.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the shape of the inner peripheral surface side opening 31 of each nozzle hole 3 is changed. In addition, the structure other than the inner peripheral surface side opening 31 of each nozzle hole 3 is the same as the case of the said Example 1, The same code | symbol is attached | subjected about the same part and the detailed description is abbreviate | omitted.

  That is, in this embodiment, as shown in FIG. 7, the shape of the inner peripheral surface side opening 51 of each nozzle hole 3 with respect to the conical surface 13a at the tip of the nozzle body 13 is all seen from the sliding shaft n direction of the needle valve 11. It is formed in the same elliptical shape.

  The elliptical shape of the inner peripheral surface side opening 51 of each nozzle hole 3 is inward with respect to orthogonal lines t, t,... Extending orthogonally outward in the radial direction every 60 ° perpendicular to the sliding axis n of the needle valve 11. The major axis of the elliptical shape of the peripheral surface side opening 51 is arranged to be shifted in a predetermined direction (clockwise in the figure) by a predetermined angle α (for example, 30 °).

  Therefore, in the second embodiment, the shape of the inner peripheral surface side opening 51 of each nozzle hole 3 with respect to the conical surface 13a at the tip of the nozzle body 13 is formed in the same elliptical shape when viewed from the sliding axis n direction of the needle valve 11. In addition, the elliptical shape of the inner peripheral surface side opening 51 is on the inner peripheral surface side with respect to orthogonal lines t, t,... Extending orthogonally to the sliding axis n of the needle valve 11 at intervals of 60 °. Since the major axis of the elliptical shape of the opening 51 is arranged to be shifted in a predetermined direction by a predetermined angle α, different swirling flows are not generated in the fuel flowing into the inner peripheral surface side opening 31 of each nozzle hole 3, The fuel flows into the inner peripheral surface side opening 51 of each nozzle hole 3 by the same swirling flow, and variation in the spray of fuel injected from each nozzle hole 3 can be effectively reduced.

  Next, Embodiment 3 of the present invention will be described with reference to FIG.

  In the third embodiment, the expanded portion 33 of each nozzle hole 3 is changed. In addition, the structure of those other than the expansion part 33 of each nozzle hole 3 is the same as the case of the said Example 1, The same code | symbol is attached | subjected about the same part and the detailed description is abbreviate | omitted.

  That is, in the present embodiment, as shown in FIG. 8, an extended portion 53 that extends the opening area of the outer peripheral surface side opening 32 than the opening area of the inner peripheral surface side opening 31 is provided on the tip side of each nozzle hole 3. The extended portion 53 is formed in a tapered shape that is expanded in a tapered shape with respect to the inner peripheral surface side opening 31. And the nozzle hole length from the inner peripheral surface side opening 31 of each said nozzle hole 3 to the expansion part 53 is all set to the same length for every said nozzle hole 3. FIG.

  Therefore, in the said Example 3, since the expansion part 53 is formed in the taper shape, the spreading angle of the fuel injected from each injection hole 3 can be expanded using the Coanda effect. In addition, the spread angle of the fuel injected from each nozzle hole 3 can be controlled by controlling the taper angle of the expanding portion 53 having a tapered shape.

  In addition, this invention is not limited to said each Example, The other various modifications are included. For example, in each of the above embodiments, the injector 1 is used as a fuel injection valve for a direct injection gasoline engine, but it is not only a fuel injection valve for a direct injection diesel engine but also a port injection type that injects fuel into an intake manifold. Of course, it may be applied as a fuel injection valve.

  In each of the above embodiments, six nozzle holes 3, 3,... Are formed at equal intervals on the same circumference of the conical surface 13a of the nozzle body 13. However, the number of nozzle holes is not limited to this. Alternatively, as long as there are a plurality of them, they may be formed at equal intervals on the same circumference of the conical surface.

It is sectional drawing which shows the attachment position of the injector which concerns on Example 1 of this invention, and the spray state to a combustion chamber. It is a sectional view of an injector similarly. It is a figure which similarly shows the nozzle hole after electric discharge machining of the inner peripheral surface side opening which looked at the inside of the nozzle body of an injector from the sliding-axis direction of the needle valve. It is a figure which similarly shows the nozzle hole before electric discharge machining of the inner peripheral surface side opening which looked at the inside of the nozzle body of an injector from the sliding-axis direction of the needle valve. FIG. 6 is an enlarged cross-sectional view of the vicinity of the injection hole showing the expansion width and the injection hole length of the expansion part at the nozzle body tip of the injector. It is sectional drawing which similarly cut | disconnected the nozzle body front end side of the injector in the nozzle hole vicinity. It is a figure which shows the nozzle hole after electric discharge machining of the inner peripheral surface side opening which looked at the inside of the nozzle body of the injector which concerns on Example 2 of this invention from the sliding-axis direction of the needle valve. It is sectional drawing which cut | disconnected the nozzle body front end side of the injector which concerns on Example 3 of this invention in the injection hole vicinity.

Explanation of symbols

1 Injector (fuel injection valve)
11 Needle valve 13 Nozzle body 13a Conical surface (inner peripheral surface)
13b Outer peripheral surface 3 Injection hole 31 Inner peripheral surface side opening 31 'after electric discharge machining Inner peripheral surface side opening 32 before electric discharge machining Outer peripheral surface side opening 33 Expansion portion 51 Inner peripheral surface side opening 53 Expansion portion d Expansion width f Injection hole Long n Needle valve sliding shaft

Claims (3)

A nozzle body, a needle valve that is slidably accommodated inside the nozzle body, and provided at the tip of the nozzle body, penetrates in a specific direction from the inner peripheral surface of the nozzle body to the outer peripheral surface. In a fuel injection valve provided with a plurality of injection holes,
The openings on the inner peripheral surface side of the nozzle holes that open on the inner peripheral surface of the nozzle body are arranged on the substantially same circumference of the inner peripheral surface of the nozzle body at equal intervals, and the needle valve slides. A fuel injection valve characterized by being formed in the same shape as seen from the axial direction. The fuel injection valve according to claim 1, wherein
On the tip side of each nozzle hole, an extended portion that extends the opening area of the outer peripheral surface side opening than the opening area of the inner peripheral surface side opening is provided,
The expansion portion is formed in a stepped shape having an expanded width that is stepped with respect to the inner peripheral surface side opening, or a tapered shape that expands in a tapered shape with respect to the inner peripheral surface side opening. Injection valve. The fuel injection valve according to claim 2,
The fuel injection valve characterized in that the injection hole length from the inner peripheral surface side opening of each injection hole to the expansion portion is set to the same length for each injection hole.

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