JP2011153548A - Injection nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection nozzle achieving high penetration force and also promoting atomization, by suppressing a reduction in kinetic energy of a fuel flow in a suction chamber. <P>SOLUTION: This fuel injection nozzle 10 includes: a nozzle body 20 having a fuel passage 24 and the suction chamber 28 arranged downstream in the fuel flowing direction of the fuel passage 24 and coaxially with the fuel passage, and formed into a recessed shape opened toward the fuel passage 24; and a needle valve 40 advanceably/retractably arranged in the fuel passage 24, and seated/separated on/from the passage wall 24a of the fuel passage 24 so that fuel is injected and is not injected from a nozzle port 30. The end 48 of the needle valve 40 has a second tapered surface 52 entering into the suction chamber 28. Meanwhile, the bottom 28a of the suction chamber 28 is formed with a projection 28d projecting toward the needle valve 40. When the needle valve 40 is separated from a seat surface 24b, the projection 28d always intersects with the extended surface 54 of the second tapered surface 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an injection nozzle, and more particularly to an injection nozzle that injects fuel into a combustion chamber of an internal combustion engine.

  Conventionally, in a fuel injection valve having a space formed by an inner wall of a body between the tip of a needle valve and an injection hole, a protrusion protruding toward the needle valve from a position facing the needle valve in the space There is a known fuel injection valve (see Patent Document 1).

  In this fuel injection valve, an injection hole is formed around the projection at the bottom of the space. In this fuel injection valve, when the needle valve is separated from the valve seat, fuel flows into the space from a fuel passage formed between the outer wall of the needle valve and the inner wall of the body. The fuel that has flowed into the space flows along the side surface of the protrusion and is supplied to the nozzle hole formed in the bottom. According to Patent Document 1, according to such a fuel injection valve, since the fuel that has flowed into the space is guided to the injection hole, the disturbance of the fuel in the space can be suppressed.

JP 7-332201 A

  Here, the tip of the needle valve of the fuel injection valve has a tapered surface inclined toward the central axis of the needle valve. When the needle valve is separated from the valve seat and the fuel flows into the space, the fuel has a property of flowing along the tapered surface. In the needle valve having such a shape, as described above, when the needle valve is separated from the valve seat, the fuel in the fuel passage formed on the outer peripheral side of the needle valve is directed on the extension line of the central axis of the needle valve. Flow into. In Patent Document 1 described above, the fuel can be smoothly guided to the nozzle hole by the protrusion formed at the bottom of the space. However, as described above, the fuel flows along the tapered surface of the needle valve.

  In the fuel injection valve, the extended surface obtained by extending the tapered surface of the needle valve toward the protrusion does not intersect with the side surface of the protrusion when the needle valve is seated on the valve seat. As described above, if the extended surface and the side surface of the protrusion do not intersect, when the needle valve is separated from the valve seat, fuels flowing along the tapered surface collide above the protrusion. Due to this fuel collision, the kinetic energy of the fuel flow is reduced. When this kinetic energy decreases, the penetration force of the fuel injected from the nozzle hole decreases, and the effect of promoting atomization also decreases.

  The present invention has been made in view of the above-described problems, and an object thereof is to suppress a decrease in the kinetic energy of the fuel flow in the sac chamber, achieve a high penetration force and promote atomization. Providing a nozzle.

The invention according to claim 1 is an injection nozzle for injecting fuel from an injection hole.
It is formed in a cylindrical shape, extends in the axial direction, is disposed in a fuel passage through which fuel flows, downstream in the fuel flow direction in the fuel passage, and coaxially with the fuel passage, and has a concave shape that opens toward the fuel passage. A nozzle body having a sac chamber and provided with an injection hole opening in the sac chamber;
A needle valve that moves forward and backward along the axial direction of the fuel passage in the fuel passage so as to be separated from and seated on a passage wall that forms the fuel passage, and communicates and shuts off the fuel passage and the sac chamber;
The tip of the needle valve on the nozzle hole side has at least a part that enters the sac chamber, and has a reduced diameter surface that reduces the diameter of the needle valve toward the nozzle hole. The bottom portion facing the projection has a projection that projects toward the needle valve, and whenever the needle valve is separated from the passage wall, an extension surface and a projection that extend the reduced diameter surface toward the projection It is characterized by the intersection with the club.

  In the present invention, when the needle valve retracts in the fuel passage along the axial direction of the passage and is separated from the passage wall, fuel flows from the periphery of the needle valve toward the sac chamber. The fuel that has flowed into the sac chamber flows into the nozzle hole and is injected outside. Here, since the tip portion on the nozzle hole side of the needle valve of the present invention has a reduced diameter surface, when the needle valve is separated from the passage wall, the fuel on the reduced diameter side in the fuel passage is It flows along this reduced diameter surface. In the present invention, the bottom of the sac chamber is provided with a protrusion that protrudes toward the needle valve. Further, whenever the needle valve is separated, the extended surface of the reduced diameter surface intersects with the protrusion. Since the sac chamber is configured in this way, the fuel flowing into the sac chamber along the diameter-reduced surface does not collide with each other, and the fuel flows into the outer peripheral side of the protrusion along the side surface of the protrusion. Flowing. Since the fuel that has flowed into the sac chamber flows as described above, the collision of the fuel flowing into the extension line of the central axis of the needle valve above the protrusion is suppressed. Thus, since the collision of the fuels flowing into the sac chamber is suppressed, a decrease in kinetic energy of the fuel flow due to the collision is suppressed. In this way, in the present invention, since the decrease in kinetic energy of the fuel flow due to the collision of fuels is suppressed, a high penetrating force is achieved and atomization is achieved as compared with the conventional technology. An injection nozzle that can be promoted can be provided.

  The diameter-reduced surface in the claims protrudes in a conical tapered surface formed by rotating a straight line inclined toward the central axis of the needle valve around the central axis, or in a direction away from the central axis. A convex curved surface formed by rotating a convex curve around the central axis, or a concave shape formed by rotating a concave curve recessed toward the central axis around the central axis Includes curved surfaces.

  In the invention according to claim 2, the angle formed by the surface located on the outer peripheral side with respect to the respective protrusions of the extended surface and the surface of the portion intersecting the extended surface in the protrusion is an obtuse angle. It is characterized by that.

  In the present invention, the angle formed on the surface located on the outer peripheral side with respect to each protrusion of the surface of the portion intersecting the extension surface of the needle valve and the extension surface of the protrusion is an obtuse angle. The fuel that has flowed into the chamber can be guided to the outer peripheral side of the protrusion. For this reason, it is possible to more reliably avoid the collision between the fuels above the protrusions.

  According to a third aspect of the present invention, the shape of the bottom portion of the sac chamber located between the protrusion and the inner peripheral surface of the sac chamber surrounding the protrusion from the outer peripheral side is a concave curved surface. It is characterized by having.

  In the present invention, the shape of the bottom portion of the sac chamber located between the protrusion and the inner peripheral surface of the sac chamber is a concave curved surface, so that the fuel flowing along the protrusion is smoothly flown inside the sac chamber. It can be guided to the peripheral surface. According to this, a decrease in kinetic energy generated when changing the direction of the fuel flow can be suppressed as much as possible.

  The invention described in claim 4 is characterized in that a recess that opens toward the protrusion and accommodates the top of the protrusion is formed on the inner peripheral side of the reduced diameter surface.

  In order to separate the needle valve from the passage wall, the needle valve must be retracted. That is, the needle valve must be moved away from the protrusion. According to the operation of such a needle valve, when the needle valve moves backward from the passage wall and comes into contact with a stopper or the like and reaches the maximum lift position, which is the position farthest from the protrusion, There is a possibility that a state in which the extended surface of the reduced diameter surface of the needle valve does not intersect with the protruding portion may occur.

  In the present invention, a recess that opens toward the protrusion and accommodates the top of the protrusion is formed on the inner peripheral side of the reduced diameter surface. According to this configuration, in the state where the needle valve is seated on the passage wall, the position where the extended surfaces of the reduced diameter surfaces intersect can be brought as close as possible to the bottom of the sac chamber. Therefore, even when the needle valve reaches the maximum lift position, the extended surface of the reduced diameter surface and the protrusion can be crossed.

  According to a fifth aspect of the present invention, the inner wall surface of the recess serves as a restricting portion that restricts the movement of the needle valve in a direction intersecting the advancing / retreating direction of the needle valve by contacting the protrusion. It is a feature.

  When the needle valve moves in a direction crossing the advance / retreat direction, the interval between the outer wall of the needle valve and the passage wall of the fuel passage becomes uneven. If the interval is not uniform, the amount of fuel flowing into the periphery of the protrusion will also be non-uniform, and the amount of fuel injected from the nozzle holes will be non-uniform.

  In the present invention, the inner wall surface of the recess formed on the inner peripheral side of the reduced diameter surface serves as a restricting portion that restricts the movement in the direction intersecting the advance / retreat direction of the needle valve. The movement to can be regulated. According to this, it is possible to suppress the interval from becoming non-uniform, and it is possible to suppress non-uniformity in the fuel injection amount injected from the injection hole.

It is sectional drawing which showed the whole structure of the fuel-injection nozzle by position embodiment of this invention. It is sectional drawing to which the principal part of the fuel-injection nozzle was expanded. It is sectional drawing which expanded the front-end | tip part vicinity of the needle valve of a fuel injection nozzle, and is a figure which shows the state which the contact part of the needle valve is seated on the seat surface. It is a figure which shows the state which the contact part of the needle valve has separated from the seat surface, and the needle valve has reached the maximum lift position. It is a figure which shows the state which the needle valve shifted | deviated to radial direction.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the overall configuration of the fuel injection nozzle 10. FIG. 2 is an enlarged cross-sectional view of the main part of the fuel injection nozzle 10. The fuel injection nozzle 10 is mounted corresponding to each cylinder of an internal combustion engine such as a multi-cylinder diesel engine (not shown). The fuel injection nozzle 10 directly supplies high-pressure fuel that has been pressurized and pressurized in a pressurizing chamber of a high-pressure fuel pump (not shown) (a column-type fuel injection pump, a distribution-type fuel injection pump, a high-pressure supply pump, etc.) directly into each cylinder. Injecting into the combustion chamber.

  The fuel injection nozzle 10 includes a nozzle body 20 and a needle valve 40, and is attached to a nozzle holder (not shown) that supplies high-pressure fuel to the nozzle body 20. The nozzle holder has a drive unit (not shown) that drives the needle valve 40.

  The nozzle body 20 is formed in a cylindrical shape from a metal material such as carbon steel. The nozzle body 20 has a guide hole 22, a fuel passage 24, a sac chamber 28, an injection hole 30 and a high-pressure fuel supply passage 32.

  The guide hole 22 is a hole opened along the axial direction of the nozzle body 20 that slidably supports the needle valve 40. The fuel passage 24 is a passage that is arranged coaxially with the guide hole 22 and allows high-pressure fuel to flow toward the sac chamber 28. The fuel passage 24 is formed in a cylindrical hole shape and extends along the axial direction of the nozzle body 20.

  The sac chamber 28 is disposed downstream of the fuel passage 24 in the flow direction of the fuel and coaxially with the fuel passage 24, and is formed in a concave shape opening toward the fuel passage 24. It is a space to accumulate once.

  The injection hole 30 is a hole that communicates the sac chamber 28 with the outside of the nozzle body 20 and injects fuel accumulated in the sac chamber 28 to the outside. In the present embodiment, four nozzle holes 30 are provided. An opening 30 a on the inlet side of the nozzle hole 30 is opened in the inner peripheral surface 28 b of the sack chamber 28. Furthermore, the inlet side opening 30 a of the nozzle hole 30 is opened at the same height in the axial direction of the nozzle body 20.

  Further, the fuel passage 24 is provided with a fuel reservoir chamber 26 in which a passage wall 24a is recessed radially outward at an end portion on the guide hole 22 side. The fuel reservoir chamber 26 is formed in an annular shape so as to surround the central axis of the fuel passage 24. The fuel reservoir chamber 26 and the fuel passage 24 communicate with each other.

  The high-pressure fuel supply path 32 is a passage for supplying high-pressure fuel supplied to the nozzle holder to the fuel reservoir chamber 26. The high pressure fuel in the high pressure fuel supply path 32 flows into the fuel passage 24 through the fuel reservoir chamber 26.

  A conical seat surface 24b in which the diameter of the fuel passage 24 decreases as it faces the sac chamber 28 is formed in the passage wall 24a at the end of the fuel passage 24 on the side of the sac chamber 28. The contact portion 52a of the needle valve 40 is seated on the seat surface 24b.

  The needle valve 40 is formed in a cylindrical shape from a metal material such as carbon steel. The needle valve 40 has a sliding part 42, a pressure receiving surface 44, a cylindrical part 46, and a tip part 48. These portions 42, 44, 46, and 48 are arranged coaxially.

  The sliding portion 42 forms a minute gap with the guide hole 22. Thereby, the needle valve 40 can advance and retreat in the fuel passage 24 along the axial direction of the fuel passage 24. The pressure receiving surface 44 is provided at a position where the fuel pressure in the fuel reservoir chamber 26 acts. When the fuel pressure of the high pressure fuel acts on this surface 44, the needle valve 40 moves backward, that is, upward in the drawing. It is formed so as to generate a thrust force. The cylindrical part 46 is a part that connects a tip part 48 provided below the cylindrical part 46. The outer diameter of the cylindrical portion 46 is smaller than the inner diameter of the fuel passage 24 and the outer diameter of the portion of the pressure receiving surface 44 on the injection hole 30 side. A gap is formed between the outer peripheral wall of the cylindrical portion 46 and the passage wall 24 a of the fuel passage 24 so that the high-pressure fuel that has flowed into the fuel reservoir chamber 26 can flow toward the sac chamber 28. This gap is annular.

  The tip 48 has a first tapered surface 50 provided at the end of the cylindrical portion 46 on the nozzle hole 30 side, and a second tapered surface 52 provided further on the nozzle hole 30 side of the first tapered surface 50. The first and second tapered surfaces 50 and 52 are diameter-reduced surfaces such that the diameter of the needle valve 40 is reduced toward the injection hole 30. The first and second tapered surfaces 50 and 52 of the present embodiment are cones formed by rotating a straight line that is inclined toward the central axis of the needle valve 40 toward the injection hole 30 around the central axis. It is the surface of the shape. The inclination angle of the second taper surface 52 with respect to the central axis is larger than the inclination angle of the first taper surface 50. An annular contact portion 52 a that contacts the seat surface 24 b formed in the fuel passage 24 is formed between the first tapered surface 50 and the second tapered surface 52. The end of the second tapered surface 52 on the nozzle hole 30 side is inserted into the sack chamber 28.

  As the needle valve 40 moves forward (moves downward in the figure), the contact portion 52a is seated on the seat surface 24b. As a result, the communication between the fuel passage 24 and the sac chamber 28 is cut off, and the supply of fuel to the sac chamber 28 is cut off. For this reason, the fuel injection from the nozzle hole 30 stops.

  As the needle valve 40 moves backward (moves upward in the figure), the contact portion 52a is separated from the seat surface 24b. As a result, the fuel passage 24 and the sac chamber 28 communicate with each other, so that fuel is supplied to the sac chamber 28. Thereafter, fuel is injected from the injection hole 30.

  The nozzle holder is provided with a stopper (not shown), and the needle valve 40 moves away from the seat surface 24b, moves backward by a predetermined distance, and stops moving in the seating direction when contacting the stopper. The position of the needle valve 40 at this time is the maximum lift position of the needle valve 40.

(Characteristic part)
The configuration and operation of the fuel injection nozzle 10 have been described above. Next, the characteristic part of this embodiment is demonstrated.

  FIG. 3 is an enlarged cross-sectional view of the vicinity of the tip 48 of the needle valve 40 of the fuel injection nozzle 10 and shows a state where the contact portion 52a of the needle valve 40 is seated on the seat surface 24b. FIG. 4 shows a state where the contact portion 52a of the needle valve 40 is separated from the seat surface 24b and the needle valve 40 has reached the maximum lift position.

  A bottom portion 28 a of the sac chamber 28 that faces the tip portion 48 of the needle valve 40 has a projection 28 d that protrudes toward the tip portion 48. The side surface 28f of the projection 28d is a surface whose diameter decreases toward the needle valve 40. The shape of the vertical section of the protrusion 28d is a parabolic shape as shown in FIG. The protrusion 28d is arranged so that the axis of the protrusion 28d and the center axis of the needle valve 40 are arranged coaxially.

  Moreover, the shape of the bottom part 28a located between the protrusion part 28d and the inner peripheral surface 28b surrounding the protrusion part 28d in the sack chamber 28 from the outer peripheral side is a concave curved surface. The surface of the top 28e of the projection 28d that is located on the axis of the projection 28d and furthest away from the bottom 28a is a spherical surface.

  In the present embodiment, the inner peripheral surface 28 b of the sack chamber 28 extends in a direction along the axial direction of the nozzle body 20. For this reason, as shown in FIG. 3, the angle θ2 formed by the inner peripheral surface 28b and the second tapered surface 52 is much larger than the angle θ1 formed by the seat surface 24b and the second tapered surface 52.

  On the other hand, on the inner peripheral side of the second tapered surface 52 of the needle valve 40, a recess 52b that opens toward the top 28e of the projection 28d is formed. The recess 52b is formed so as to accommodate at least a part of the top 28e. The positions of the top portion 28e and the concave portion 52b and the curvatures of the top portion 28e and the concave portion 52b are determined so that a gap is formed in a state where the contact portion 52a is seated on the seat surface 24b as shown in FIG. In addition, it is desirable that the apex of the top portion 28 e and the deepest portion of the recess 52 b be disposed on the central axis of the needle valve 40.

  In the present embodiment, the second tapered surface 52 of the needle valve 40 and the side surface 28f of the projection 28d are in a state where the contact portion 52a of the needle valve 40 is seated on the seat surface 24b, as shown in FIG. Then, the extended surface 54 illustrated by a broken line obtained by extending the second tapered surface 52 toward the protrusion 28d intersects the side surface 28f. Further, among the angles formed by the extended surface 54 and the side surface 28f, the angle α on the outer peripheral side of the projection 28d is an obtuse angle.

  Further, in the present embodiment, as shown in FIG. 4, even when the needle valve 40 has reached the maximum lift position, the extension surface 54 of the second tapered surface 52 is similar to the state shown in FIG. The side surface 28f of the projection 28d intersects. Further, among the angles formed by the extended surface 54 and the side surface 28f, the angle β on the outer peripheral side of the projection 28d is an obtuse angle.

  Next, the flow of fuel in the sac chamber 28 when the fuel injection nozzle 10 is opened will be described with reference to FIG.

  When the contact portion 52a of the needle valve 40 is separated from the seat surface 24b, the fuel in the fuel passage 24 is, as shown in FIG. 4, the annular gap 60 formed by the second tapered surface 52 and the seat surface 24b. And flows into the sac chamber 28 through. As shown in FIG. 4, since the end of the second tapered surface 52 on the nozzle hole 30 side enters the sac chamber 28, the fuel near the second tapered surface 52 is second as shown by the arrow. It flows along the tapered surface 52. Further, the fuel near the seat surface 24b also flows along the seat surface 24b as shown by arrows. Most of the fuel that has passed through the seat surface 24b does not flow along the inner peripheral surface 28b, but flows in the same direction as the fuel that flows along the second tapered surface 52. This is because, as shown in FIG. 3, the angle θ2 formed by the inner peripheral surface 28b and the second tapered surface 52 is much larger than the angle θ1 formed.

  The fuel that has flowed into the sac chamber 28 reaches the side surface 28f of the projection 28d, and the flow direction of the fuel is changed by the side surface 28f. Thereafter, the fuel flows along the side surface 28f and travels toward the bottom portion 28a having an arcuate cross section. The fuel that has reached the bottom portion 28a flows along the shape of the bottom portion 28a, reaches the inner peripheral surface 28b, and proceeds toward the gap 60 along the inner peripheral surface 28b. The fuel that has reached the gap 60 rides on the flow of fuel that flows along the second tapered surface 52 from the gap 60, and again heads toward the protrusion 28d. Thus, since fuel flows in the sac chamber 28, a fuel vortex is generated in the sac chamber 28. This fuel vortex is generated so as to surround the protrusion 28d.

  Here, as described above, most of the fuel flowing into the sack chamber 28 from the gap 60 flows along the second tapered surface 52, so that the fuel on the outer peripheral side of the needle valve 40 is an extension of the central axis of the needle valve 40. It flows toward the line. For this reason, the fuel collected in the sac chamber 28 may collide with each other. In the prior art, as described above, since the extended surface of the tapered surface formed at the tip of the needle valve does not intersect the side surface of the protrusion, the fuel flowing into the sac chamber collides above the protrusion. Resulting in. This collision reduces the kinetic energy of the fuel flow in the sac chamber. For this reason, the penetration force of the fuel injected from the nozzle hole is reduced, and the effect of promoting atomization of the fuel is also reduced.

  On the other hand, in this embodiment, as shown in FIG. 4, even if the needle valve 40 reaches the maximum lift position, the extended surface 54 of the second tapered surface 52 and the side surface 28f of the projection 28d intersect. The fuel flowing into the sac chamber 28 can be prevented from colliding with each other. For this reason, since the collision of the fuels above the protrusion part 28d can be suppressed, the reduction | decrease of the kinetic energy which the fuel flow by a collision has can be suppressed. In the present embodiment, when the needle valve 40 is separated from the seat surface 24b, the extended surface 54 of the second taper surface 52 and the protrusion 28d intersect each other. It can suppress the decrease in kinetic energy of the fuel flow due to the collision, and can realize a high penetration power of the fuel and promote atomization of the fuel as compared with the prior art. it can.

  In the present embodiment, the angle α formed between the extension surface 54 and the side surface 28f illustrated in FIG. 3 and the angle β formed between the extension surface 54 and the side surface 28f illustrated in FIG. 4 are both obtuse. The inflowing fuel can be guided to the outer peripheral side of the protrusion 28d. Thereby, it is possible to more reliably avoid the collision of the fuels above the protrusion 28d. Further, it is possible to suppress the decrease in kinetic energy generated when the direction of the fuel flow is changed by the side surface 28f as much as possible.

  Furthermore, since the bottom 28a of the sac chamber 28 between the protrusion 28d and the inner peripheral surface 28b of the sac chamber 28 has an arc shape in cross section, the fuel flowing along the side surface 28f of the protrusion 28d can be smoothly flown. It can be guided to the inner peripheral surface 28b. According to this, a decrease in kinetic energy generated when the direction of fuel flow is changed can be suppressed as much as possible.

  As in the present embodiment, in the fuel injection nozzle having a configuration in which the needle valve 40 is moved backward, that is, the needle valve 40 is moved in a direction away from the protrusion 28d to open the fuel injection nozzle 10, the contact is made. Even when the extended surface 54 of the second tapered surface 52 and the side surface 28f of the projection 28d intersect when the portion 52a is seated on the seat surface 24b, the extended surface is reached when the needle valve 40 reaches the maximum lift position. There is a possibility that a state in which 54 and the side surface 28f do not cross each other may occur. With this, it is impossible to avoid a collision between the fuels flowing into the sac chamber 28.

  On the other hand, in this embodiment, as shown in FIGS. 3 and 4, a recess 52 b that can accommodate the top 28 e of the protrusion 28 d is formed on the inner peripheral side of the second tapered surface 52. According to this configuration, in a state where the contact portion 52a is seated on the seat surface 24b (see FIG. 3), the position where the extended surfaces 54 intersect can be as close as possible to the bottom portion 28a of the sack chamber 28. Therefore, even when the needle valve 40 reaches the maximum lift position, the extended surface 54 and the side surface 28f can be crossed.

  As shown by the solid line in FIG. 5, the needle valve 40 is very long in the axial direction. Therefore, even if the sliding portion 42 of the needle valve 40 is supported by the guide hole 22, the needle valve 40 is in the forward / backward direction. May move in a direction perpendicular to the center axis of the needle valve 40, that is, a direction perpendicular to the central axis of the needle valve 40. The needle valve 40 indicated by a broken line in FIG. 5 shows a state in which the central axis of the needle valve 40 coincides with the central axis of the nozzle body 20.

  As shown in FIG. 5, when the needle valve 40 moves in the radial direction, the gap 60 varies in the circumferential direction. As a result, the amount of fuel flowing into the sac chamber 28 is non-uniform in the circumferential direction, and the amount of fuel injected from the nozzle holes 30 is also non-uniform.

  On the other hand, in this embodiment, as shown in FIG. 5, the inner wall surface of the recess 52b of the needle valve 40 becomes a restricting portion 52c that contacts the side surface 28f of the projection 28d when the needle valve 40 moves in the radial direction. ing. According to the restricting portion 52c, it is possible to suppress the needle valve 40 from being excessively displaced in the radial direction, and thus it is possible to reduce the unevenness of the fuel injection amount.

(Other embodiments)
As mentioned above, although several embodiment of this invention was described, this invention is limited to the said embodiment and is not interpreted and can be applied to various embodiment in the range which does not deviate from the summary. .

  For example, the protrusion 28d may have a rectangular cross section. In this case, the shape of the recess 52b formed in the needle valve 40 is also preferably a rectangular cross section.

  Further, at least the second tapered surface 52 portion is replaced with the second tapered surface 52, and a convex curve that protrudes from the central axis of the needle valve 40 is rotated around the central axis. It may be a curved surface, or a concave curved surface formed by rotating a concave curve that is recessed toward the central axis about the central axis. In addition, when the shape of the second tapered surface 52 portion is a convex curved surface or a concave curved surface, the extended surface corresponding to the extended surface 54 of the first embodiment is a tangent at the end of each curved surface on the nozzle hole 30 side. It becomes a surface to include.

  Moreover, although the inlet side opening part 30a of the nozzle hole 30 was demonstrated in the said embodiment in the example provided in the internal peripheral surface 28b of the sack chamber 28, the installation position of the inlet side opening part 30a is not specified to this place. The opening 30a may be provided anywhere as long as the nozzle hole 30 communicates the sac chamber 28 with the outside. For example, the opening 30 a may be provided in the bottom 28 a of the sack chamber 28.

  DESCRIPTION OF SYMBOLS 10 Fuel injection nozzle, 20 Nozzle body, 22 Guide hole, 24 Fuel passage, 24a Passage wall, 24b Seat surface, 26 Fuel reservoir chamber, 28 Suck chamber, 28a Bottom part, 28b Inner peripheral surface, 28d Protrusion part, 28e Top part, 28f Side surface, 30 injection hole, 30a inlet side opening, 32 high pressure fuel supply path, 40 needle valve, 42 sliding portion, 44 pressure receiving surface, 46 cylindrical portion, 48 tip portion, 50 first taper surface, 52 second taper surface , 52a Contact part, 52b Recessed part, 52c Restricting part, 54 Extension surface, 60 Gap

Claims (5)

In the injection nozzle that injects fuel from the injection hole,
It is formed in a cylindrical shape, extends in the axial direction, and is disposed in a fuel passage through which fuel flows, downstream in the fuel flow direction in the fuel passage, and coaxially with the fuel passage, and opens toward the fuel passage. A nozzle body having a formed sac chamber, the nozzle hole being provided to open to the sac chamber;
A needle valve that moves forward and backward along the axial direction of the fuel passage in the fuel passage so as to be separated from and seated on a passage wall forming the fuel passage, and to connect and shut off the fuel passage and the sac chamber; With
At least a part of the tip of the needle valve on the nozzle hole side enters the sac chamber, and has a reduced diameter surface such that the diameter of the needle valve decreases toward the nozzle hole,
The bottom portion of the sac chamber that faces the tip portion of the needle valve has a protrusion protruding toward the needle valve,
Whenever the needle valve is separated from the passage wall, the projecting portion intersects an extended surface obtained by extending the reduced diameter surface toward the projecting portion.   The angle formed by the surface located on the outer peripheral side with respect to each protrusion of the extension surface and the surface of the portion of the protrusion that intersects the extension surface is an obtuse angle. Item 4. The injection nozzle according to Item 1.   The shape of the bottom portion of the sac chamber positioned between the protrusion and the inner peripheral surface of the sac chamber surrounding the protrusion from the outer peripheral side is a concave curved surface. The injection nozzle according to claim 1 or 2.   4. The recess according to claim 1, wherein a recess that opens toward the protrusion and accommodates the top of the protrusion is formed on the inner peripheral side of the reduced diameter surface. 5. The injection nozzle described in 2.   The inner wall surface of the recess serves as a restricting portion that restricts movement of the needle valve in a direction intersecting with the advancing / retreating direction of the needle valve by contacting the protrusion. 4. The injection nozzle according to 4.

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