JP5716788B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that injects fuel from an injection hole to an internal combustion engine.

  2. Description of the Related Art Conventionally, a fuel injection valve in which fuel injection from an injection hole is intermittently performed by detaching and seating a valve part of a valve member with respect to a valve seat part provided upstream of the injection hole in a valve body. It has been known.

  As a kind of such fuel injection valve, the one disclosed in Patent Document 1 is provided with a fuel flow path through which fuel is circulated by providing a guide member, which is guided by a valve body, protruding from the fuel upstream side of the valve portion to the outside of the diameter. It is formed between the guide part and the valve body. According to such a configuration, not only the valve seat to and from the valve seat is accurately guided by the guide portion, but also the fuel flows from the upstream side of the guide portion through the fuel flow path at the time of leaving the seat. Since it flows reliably to the downstream side, fuel injection from the injection hole is not hindered by the guide portion.

JP-A-8-128373

  Now, the guide part of the fuel injection valve disclosed in Patent Document 1 is located on the downstream side of the fuel flow path formed between the valve body and the valve part by a step surface that fills the difference in diameter with the valve part. It is in a connected form. For this reason, the fuel flow from the fuel flow path toward the downstream valve portion may be separated from the stepped surface of the guide portion to generate a spiral turbulent flow. However, in the fuel injection valve disclosed in Patent Document 1, the valve portion is formed in a cylindrical shape with a constant diameter toward the contact portion on the downstream side of the fuel that is separated from the valve seat portion. It is not possible to rectify the fuel flow that has become turbulent due to the separation of the fuel. As a result, the flow velocity of the fuel flow in the vicinity of the abutting portion becomes non-uniform depending on the flow location, and there is a risk of causing a variation in the spray state with respect to the fuel injected from the nozzle hole on the downstream side of the abutting portion. there were.

  This invention is made | formed in view of such a problem, The objective is to provide the fuel injection valve which suppresses the dispersion | variation in a spray state about the injection fuel from an injection hole.

According to a first aspect of the present invention, there is provided a valve body having a nozzle hole for injecting fuel to an internal combustion engine, and a valve seat portion provided on the fuel upstream side of the nozzle hole; And a valve member having a guide portion that protrudes radially outward from the fuel upstream side of the valve portion and is guided by the valve body, and the fuel flow path through which the fuel flows The guide portion formed between the fuel flow path and the valve portion is a fuel injection valve connected to the valve portion by a stepped surface that fills the difference in diameter with the valve portion on the fuel downstream side of the fuel flow path. A tapered valve seat surface that is reduced in diameter toward the downstream side is formed, and a contact portion that is reduced in diameter toward the downstream side of the fuel in order to detach from and seat on the valve seat surface, and a cylinder There is at least one reduced diameter surface that decreases in diameter from the planar outer peripheral surface toward the contact portion on the downstream side of the fuel. All of the diameter-reduced surfaces formed in either a tapered surface with a constant diameter reduction toward the fuel downstream side or a convex curved surface with a larger diameter reduction rate toward the fuel downstream side are all valve seats. The axial length of the cylindrical outer peripheral surface surrounded by the cylindrical inner peripheral surface of the valve body on the upstream side of the surface and from the contact portion to the reduced diameter surface on the upstream side of the fuel is than the axial length of the cylindrical surface outer peripheral surface of the reduced diameter surface to reduced diameter surface of the stepped surface or even fuel upstream, long rather, the fuel downstream side of the cylindrical surface shape in the peripheral surface surrounding all of the reduced diameter surface Further, with respect to the outer peripheral edge of the valve seat surface provided on the fuel upstream side from the nozzle hole, from the cylindrical outer peripheral surface from the contact portion to the reduced diameter surface on the upstream side of the fuel, and the reduced diameter surface on the upstream side of the fuel the stepped surface or even cylindrical surface outer peripheral surface to the contraction diameter surface of the fuel upstream, that is positioned radially inwardly And butterflies.

Thus, according to the valve member of the first aspect of the present invention, the fuel in the fuel flow path formed between the guide portion that protrudes radially outward from the fuel upstream side of the valve portion and the valve body that guides the guide portion is provided. On the downstream side, the valve portion is connected to the valve portion by a stepped surface that fills the diameter difference from the valve portion. For this reason, the fuel flow from the fuel flow path toward the downstream valve portion may be separated from the stepped surface of the guide portion to generate a spiral turbulent flow.

  Therefore, according to the valve member of the first aspect of the present invention, the diameter of the valve portion is reduced so that the diameter of the valve portion is reduced toward the contact portion on the downstream side of the fuel that is separated from the valve seat portion of the valve body. A surface is provided. According to this, the fuel that has become a turbulent state due to separation from the stepped surface flows along the reduced diameter surface that decreases in diameter toward the downstream side, and then flows to the downstream side. Is done. As a result of this pressure increase, the fuel in the turbulent state is rectified and reaches the vicinity of the contact portion on the downstream side, so that the fuel flow velocity in the vicinity is unlikely to be uneven depending on the distribution location. In addition, according to the first aspect of the present invention, there is a taper surface with a constant diameter reduction toward the fuel downstream side, or a convex curved diameter reduction surface with a larger diameter reduction rate toward the downstream side. Since the fuel flowing to the downstream side can be surely aligned, the rectifying effect is firmly demonstrated. From the above, it is possible to suppress the variation in the spray state of the fuel injected from the nozzle hole on the downstream side of the contact portion.

  According to the second aspect of the present invention, the stepped surface extends radially inward with respect to the fuel flow path between the valve body and the guide portion. As described above, the fuel flow from the fuel flow path toward the valve portion on the downstream side of the fuel is likely to be peeled off from the step surface that expands radially inward with respect to the fuel flow path between the valve body and the guide portion. However, by providing the reduced diameter surface as described above, it is possible to exert a rectifying action on the fuel that has become a turbulent state due to the separation from the step surface, thereby contributing to suppression of variations in the spray state.

  According to the invention of claim 3, the valve portion is reduced in diameter to a plurality of stages by forming a plurality of reduced diameter surfaces toward the contact portion on the downstream side of the fuel, and the shape of each reduced diameter surface is a tapered surface. Of the curved surface and the convex curved surface. According to this, the fuel in a turbulent state flows along the respective diameter-reduced surfaces formed by reducing the valve portion of the valve member in multiple stages toward the contact portion on the downstream side of the fuel. Rectification may be repeatedly exerted on the fuel until the vicinity of the contact portion is reached. Therefore, the non-uniformity of the fuel flow velocity in the vicinity of the contact portion can be sufficiently eliminated, and the spray state variation can be suppressed.

  According to the fourth aspect of the present invention, the stepped surface that is reduced in diameter toward the valve portion on the downstream side of the fuel is tapered toward the downstream side of the fuel or is tapered toward the downstream side of the fuel. A convex curved surface having a large diameter ratio is formed. As described above, in the guide portion, the diameter reduction rate that is reduced toward the valve portion on the downstream side of the fuel is a constant tapered surface shape toward the downstream side, or a convex curved surface shape in which the diameter reduction rate is larger toward the downstream side. The fuel flow from the fuel flow path on the upstream side of the fuel toward the valve portion is likely to follow the stepped surface of the formation. According to this, generation | occurrence | production of the turbulent flow which causes the nonuniformity of a fuel flow velocity itself can be reduced, and it can contribute to suppression of the dispersion | variation in a spray state.

  The “diameter reduction ratio” means a diameter change amount with respect to a unit distance in a direction toward the downstream side with respect to a diameter that decreases toward the fuel downstream side.

It is sectional drawing which shows the fuel injection valve by 1st embodiment of this invention. It is sectional drawing which expands and shows the principal part of the fuel injection valve by 1st embodiment of this invention. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is sectional drawing which expands and shows the principal part of FIG. It is a figure which shows the principal part of the fuel injection valve by 2nd embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by 3rd embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by 4th embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by 5th embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by 5th embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by the modification of 5th embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG. It is a figure which shows the principal part of the fuel injection valve by another modification of 5th embodiment of this invention, Comprising: It is sectional drawing corresponding to FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows a fuel injection valve 10 according to a first embodiment of the present invention. The fuel injection valve 10 is installed in a gasoline engine as an internal combustion engine, and injects fuel into a combustion chamber (not shown) of the gasoline engine. In addition to this application form, for example, the fuel injection valve 10 may inject fuel into an intake passage communicating with a combustion chamber of a gasoline engine, or fuel into a combustion chamber of a diesel engine as an internal combustion engine. May be used.

(Basic part)
Hereinafter, the basic part of the fuel injection valve 10 will be described in detail. The fuel injection valve 10 includes a valve body 11, a fixed core 20, a movable core 30, a valve member 40, an elastic member 50, and a drive unit 60.

  The valve body 11 includes a core housing 12, an inlet member 13, a nozzle holder 14, a nozzle body 15, and the like. The core housing 12 is formed in a cylindrical shape, and includes a first magnetic portion 12a, a nonmagnetic portion 12b, and a second magnetic portion 12c in order from one end side in the axial direction toward the other end side. The magnetic portions 12a and 12c made of magnetism and the nonmagnetic portion 12b made of a nonmagnetic material are coupled by laser welding or the like. With such a coupling structure, the nonmagnetic portion 12b prevents the magnetic flux from being short-circuited between the first magnetic portion 12a and the second magnetic portion 12c.

  A cylindrical inlet member 13 is fixed to the axial end of the second magnetic portion 12c opposite to the nonmagnetic portion 12b. The inlet member 13 forms a fuel inlet 13a to which fuel is supplied from a fuel pump (not shown). In this embodiment, a fuel filter 16 is fixed to the inner peripheral side of the inlet member 13 in order to filter the fuel supplied to the fuel inlet 13a and guide it into the core housing 12 on the downstream side.

  A nozzle body 15 is fixed to an axial end of the first magnetic portion 12a opposite to the nonmagnetic portion 12b via a nozzle holder 14 formed in a cylindrical shape by a magnetic material. The nozzle body 15 is formed in a bottomed cylindrical shape and forms a fuel space 17 on the inner peripheral side in cooperation with the core housing 12 and the nozzle holder 14.

  The nozzle body 15 has a nozzle hole 18 and a valve seat portion 19. As shown in FIGS. 2 and 3, a plurality of nozzle holes 18 are provided at equal intervals around the central axis 15 a of the nozzle body 15 and are each formed in a cylindrical hole shape. Each nozzle hole 18 is located on the same virtual circle 15b around the central axis 15a, and is inclined toward the outer peripheral side of the nozzle body 15 toward the fuel outlet side (fuel downstream side). In addition, about the formation form of the nozzle hole 18, for example, the number and shape of formation, an inclination angle, etc., it can set suitably other than what is shown in FIG.

  As shown in FIG. 2, the valve seat 19 is provided on the fuel upstream side with respect to each nozzle hole 18. The valve seat part 19 forms a valve seat surface 19a by an inner peripheral surface having a tapered surface that is reduced in diameter in a certain diameter reduction rate toward the fuel downstream side in the axial direction.

  As shown in FIG. 1, the fixed core 20 is formed in a cylindrical shape by a magnetic material, and is coaxially fixed to the inner peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c in the core housing 12. The fixed core 20 is provided with a through hole 20a penetrating the center portion in the axial direction. The fuel that flows into the through hole 20a from the fuel inlet 13a through the fuel filter 16 flows out of the through hole 20a toward the movable core 30 that is the downstream side.

  The movable core 30 is formed of a magnetic material in a stepped cylindrical shape, is coaxially disposed on the inner peripheral side of the core housing 12, and faces the fixed core 20 on the upstream side of the fuel in the axial direction. The movable core 30 is guided by the inner peripheral wall of the nonmagnetic portion 12b of the core housing 12, so that the movable core 30 can be accurately reciprocated on both sides in the axial direction. The movable core 30 has a first through hole 30a that passes through the central portion thereof in the axial direction, a second through hole 30b that passes through the axial intermediate portion from the radially inner side to the radially outer side and communicates with the first through hole 30a. Is provided. The fuel that has flowed out of the through hole 20a of the fixed core 20 flows into the first through hole 30a of the movable core 30 on the downstream side, and flows out from the second through hole 30b into the fuel space 17 in the core housing 12. .

  The valve member 40 is formed in a needle shape having a circular cross section by a nonmagnetic material, and is coaxially disposed in a fuel space 17 in which elements 12, 14, and 15 of the valve body 11 are formed on the inner peripheral side. ing. The axial end of the upstream side of the fuel in the valve member 40 is coaxially fixed to the inner peripheral surface of the first through hole 30 a of the movable core 30.

  The valve member 40 has a valve portion 41 at the end on the fuel downstream side in the axial direction, and a guide portion 44 on the fuel upstream side with respect to the valve portion 41. As shown in FIG. 2, the valve portion 41 forms a contact portion 41a having a diameter that decreases toward the fuel downstream side in the axial direction, and the contact portion 41a can contact the valve seat surface 19a. Is facing. During the valve opening operation in which the valve member 40 separates the contact portion 41a from the valve seat surface 19a, the fuel in the fuel space 17 is injected from each nozzle hole 18 into the combustion chamber. On the other hand, during the valve closing operation in which the valve member 40 seats the contact portion 41a on the valve seat surface 19a, the fuel injection from each nozzle hole 18 to the combustion chamber is blocked.

  As shown in FIGS. 2 and 4, the guide portion 44 protrudes from the axial end portion of the valve portion 41 opposite to the abutting portion 41 a to the outside in the form of a bowl, and an outer peripheral surface forming a protruding edge thereof 44 a is brought into contact with the inner peripheral surface 15 c of the nozzle body 15. With this contact structure, the guide portion 44 can slide and guide the outer peripheral surface 44a by the inner peripheral surface 15c of the nozzle body 15 so that it can accurately reciprocate in the axial direction.

  The guide part 44 forms a fuel hole 45 penetrating in the axial direction. The fuel holes 45 are provided at equal intervals in the circumferential direction of the guide portion 44 and open to the outer peripheral surface 44a and the axial end surfaces 44b and 44c of the guide portion 44, respectively. Due to such an opening form, each fuel hole 45 forms a fuel flow path 46 between the guide portion 44 and the nozzle body 15 for allowing fuel to flow from the upstream side to the downstream side of the guide portion 44 in the fuel space 17. doing. At the same time, the axial end surface 44 b on the side of the guide portion 44 connected to the valve portion 41 forms a step surface 44 b that fills the difference in diameter with the valve portion 41 on the fuel downstream side of each fuel flow path 46. The fuel flow passage 46 extends radially inward.

  As shown in FIG. 1, the elastic member 50 is made of a metal compression coil spring, and is accommodated coaxially on the inner peripheral side of the through hole 20 a provided in the fixed core 20. One end of the elastic member 50 is locked to the axial end of the adjusting pipe 22 fixed to the inner peripheral surface of the through hole 20a. The other end of the elastic member 50 is locked to the inner surface of the first through hole 30 a of the movable core 30. With this locking structure, the elastic member 50 is elastically deformed by being compressed between the elements 22 and 30 sandwiching the elastic member 50. Therefore, the restoring force generated by the elastic deformation of the elastic member 50 becomes an urging force for urging the movable core 30 together with the valve member 40 toward the fuel downstream side. The set load of the elastic member 50 is adjusted according to the amount of press fitting of the adjusting pipe 22 into the through hole 20a.

  The drive unit 60 includes a coil 61, a resin bobbin 62, a magnetic yoke 63, a connector 64, and the like. The coil 61 is formed by winding a metal wire around a resin bobbin 62, and a magnetic yoke 63 is disposed on the outer peripheral side thereof. The coil 61 is coaxially fixed to the outer peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c on the outer peripheral side of the fixed core 20 in the core housing 12 via a resin bobbin 62. The coil 61 is electrically connected to an external control circuit (not shown) via a terminal 64a provided on the connector 64, and energization is controlled by the control circuit.

  Here, when the coil 61 is excited by energization, the magnetic yoke 63, the nozzle holder 14, the first magnetic part 12a, the movable core 30, the fixed core 20, and the second magnetic part 12c form a magnetic circuit together. Flows. As a result, a magnetic attractive force that attracts the movable core 30 toward the fixed core 20 on the upstream side of the fuel is generated between the movable core 30 and the fixed core 20. On the other hand, when the coil 61 is demagnetized by stopping energization, the magnetic flux does not flow in the above-described magnetic circuit, so that the magnetic attractive force disappears between the movable core 30 and the fixed core 20.

  In the valve opening operation of the fuel injection valve 10 configured as described above, the magnetic attractive force acts on the movable core 30 by starting energization of the coil 61. Then, the movable core 30 together with the valve member 40 moves to the fixed core 20 side against the restoring force of the elastic member 50, and comes into contact with the fixed core 20 and stops. As a result, since the contact portion 41a is separated from the valve seat surface 19a, fuel is injected from each nozzle hole 18.

  In the valve closing operation of the fuel injection valve 10 after such valve opening operation, the magnetic attraction force acting on the movable core 30 disappears by stopping the energization of the coil 61. Then, the movable core 30 together with the valve member 40 moves to the urging side by the restoring force of the elastic member 50, thereby bringing the valve member 40 into contact with the valve seat portion 19 and stopping. As a result, since the contact portion 41a is seated on the valve seat surface 19a, fuel injection from each nozzle hole 18 is stopped.

(Characteristic part)
Hereinafter, the characteristic part shown in FIG. 2 about the valve part 41 and the guide part 44 of the fuel injection valve 10 is demonstrated.

  As shown in FIGS. 2 and 5, the valve portion 41 is formed by reducing the outer peripheral surface 41 b by one step toward the contact portion 41 a between the contact portion 41 a on the pointed end side and the step surface 44 b of the guide portion 44. The reduced diameter surface 48 is formed at one place in the axial direction. The diameter-reduced surface 48 is formed in a tapered surface shape that is reduced in diameter in the axial direction toward the downstream side of the fuel, which is on the contact portion 41a side, and whose diameter reduction rate is constant toward the downstream side. Further, in the present embodiment, the stepped surface 44b of the guide portion 44 is reduced in diameter in accordance with the reduced diameter surface 48 toward the fuel downstream side on the valve portion 41 side in the axial direction, and the reduced diameter ratio is on the downstream side. It is formed in the shape of a fixed taper surface toward.

  In the opening operation of the fuel injection valve 10 including the valve portion 41 and the guide portion 44, the fuel in the fuel space 17 surrounding the valve member 40 passes through the fuel flow paths 46 from the upstream side of the guide portion 44. Flows downstream. At this time, from the step surface 44b that fills the difference in diameter between the outer peripheral surface 44a of the guide portion 44 and the outer peripheral surface 41b of the valve portion 41 inside the diameter of each fuel flow path 46, the downstream valve from each fuel flow path 46 There is a concern that a vortex-like turbulent flow may occur due to separation of the fuel flow toward the portion 41.

  However, in the guide portion 44 of the present embodiment, the step surface 44b is formed in a tapered surface shape so that the diameter reduction rate of diameter reduction toward the fuel downstream side is constant. The fuel flow from each fuel flow path 46 toward the valve portion 41 is easy to follow. In addition to this, the valve portion 41 of the present embodiment is formed with a tapered diameter-reducing surface 48 that has a constant diameter reduction rate that reduces the diameter toward the fuel downstream side. A fuel flow from the stepped surface 44b side to the abutting portion 41a on the downstream side of the fuel becomes easy to follow along the radial surface 48. At this time, the fuel in a turbulent state due to the separation from the step surface 44b flows along the diameter-reduced surface 48 that is diameter-reduced toward the downstream side and flows to the downstream side. Will be. As a result of such pressure increase, the turbulent fuel is rectified and reaches the vicinity of the downstream abutting portion 41a, so that the flow rate of the fuel flow in the vicinity is unlikely to be uneven depending on the distribution location. Therefore, it is possible to suppress variations in the spray state for the fuel injected from the nozzle hole 18 on the downstream side of the contact portion 41a.

(Second embodiment)
FIG. 6 shows an enlarged main part of a fuel injection valve 210 of the second embodiment which is a modification of the first embodiment of the present invention. In the valve member 240 of the fuel injection valve 210, the diameter-reduced surface 248 provided on the valve portion 241 is reduced in diameter to a convex curved surface that swells to the outer side (outer peripheral side). Therefore, the diameter reduction rate of the diameter reducing surface 248 is set so as to increase toward the fuel downstream side in the axial direction on the contact portion 41a side.

  Also with the diameter-reduced surface 248 of the second embodiment, in the valve opening operation of the fuel injection valve 210, the fuel flow from the stepped surface 44b side of the guide portion 44 toward the contact portion 41a on the downstream side of the fuel is easy to follow. Become. According to this, even if the fuel flow is in a turbulent state due to separation from the stepped surface 44b, it can be rectified before reaching the vicinity of the contact portion 41a, and therefore downstream of the contact portion 41a. It is possible to suppress variation in the spray state of the fuel injected from the side injection hole 18.

(Third and fourth embodiments)
FIG. 7 shows an enlarged view of the main part of a fuel injection valve 310 of the third embodiment, which is a modification of the first embodiment of the present invention. FIG. 8 shows a modification of the second embodiment of the present invention. About the fuel injection valve 410 of 4th embodiment which is an example, the principal part is expanded and shown. In the valve members 340 and 440 of the fuel injection valves 310 and 410, the step surfaces 344 b and 444 b that fill the difference in diameter between the guide portions 344 and 444 and the valve portions 41 and 241 inside the diameters of the fuel flow paths 46 have diameters. The diameter is reduced to a convex curved surface that swells outward (outer peripheral side). Therefore, the diameter reduction ratios of the step surfaces 344b and 444b are set so as to increase toward the fuel downstream side in the axial direction on the valve portions 41 and 241 side, respectively.

  The step surfaces 344b and 444b of the third and fourth embodiments also serve as fuel flows from the fuel flow paths 46 toward the valve portions 41 and 241 on the fuel downstream side when the fuel injection valves 310 and 410 are opened. Becomes easier to follow. According to this, since the generation of turbulent flow due to fuel separation from the step surfaces 344b and 444b can be reduced, the fuel sprayed from the nozzle hole 18 on the downstream side of the step surfaces 344b and 444b is sprayed. It is possible to suppress the variation in the state.

(Fifth embodiment)
9 and 10 show an enlarged main portion of a fuel injection valve 510 of a fifth embodiment which is a modification of the first embodiment of the present invention. In the fuel injection valve 510, the valve portion 541 of the valve member 540 has a diameter of the outer peripheral surface 541b reduced in a plurality of stages toward the contact portion 41a between the pointed contact portion 41a and the stepped surface 44b of the guide portion 44. As a result, the reduced diameter surfaces 48 having the shape according to the first embodiment are formed at a plurality of axial positions (two positions in FIGS. 9 and 10). Therefore, the diameter of the diameter-reduced surface 48 on the downstream side of the fuel is smaller.

  Thus, in the valve opening operation of the fifth embodiment in which the diameter of the valve portion 541 is reduced to a plurality of stages by forming the plurality of diameter-reduced surfaces 48, the contact of the guide portion 44 from the step surface 44b side to the fuel downstream side is reduced. The fuel flow toward the contact portion 41a flows along the reduced diameter surfaces 48 in order. According to this, even if the fuel flow is in a turbulent state due to separation from the step surface 44b, the rectifying action can be repeatedly exerted before reaching the vicinity of the contact portion 41a. Therefore, it is possible to suppress variation in the spray state of the fuel injected from the nozzle hole 18 on the downstream side of the contact portion 41a.

  As shown in FIG. 11 as a modification of the fifth embodiment, the second embodiment is a reduced diameter surface that replaces at least one reduced diameter surface 48 (in FIG. 11, only the reduced diameter surface 48 on the downstream side of the fuel). The diameter-reduced surface 248 having a shape conforming to the above may be determined in advance. Further, as shown in FIG. 12, another modified example of the fifth embodiment may be provided with a step surface 344b having a shape according to the third embodiment as a step surface instead of the step surface 44b.

  Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. It can be done.

10, 210, 310, 410, 510 Fuel injection valve, 11 Valve body, 15 Nozzle body, 15c Inner peripheral surface, 17 Fuel space, 18 Injection hole, 19 Valve seat part, 19a Valve seat surface, 20 Fixed core, 30 Movable Core, 40, 240, 340, 440, 540 Valve member, 41, 241, 541 Valve portion, 41a Contact portion, 41b, 541b Outer peripheral surface, 44, 344, 444 Guide portion, 44a Outer peripheral surface, 44b, 344b, 444b Step surface, 45 Fuel hole, 46 Fuel flow path, 48, 248 Reduced diameter surface, 50 Elastic member, 60 Drive part

Claims (4)

A valve body having a nozzle hole for injecting fuel to the internal combustion engine, and a valve seat provided on the fuel upstream side of the nozzle hole;
A valve member having a valve portion for intermittently injecting fuel from the nozzle hole by being attached to and detached from the valve seat portion, and a guide portion that protrudes radially outward from the fuel upstream side of the valve portion and is guided by the valve body; ,
The guide portion that forms a fuel flow path through which the fuel flows is formed between the valve portion and a stepped surface that fills a difference in diameter with the valve portion on the fuel downstream side of the fuel flow path. A fuel injection valve connected to
The valve seat portion forms a tapered valve seat surface that is reduced in diameter toward the fuel downstream side,
The valve portion includes a contact portion that decreases in diameter toward the downstream side of the fuel so as to be separated from and seated on the valve seat surface, and a contraction toward the contact portion on the downstream side of the fuel from a cylindrical outer peripheral surface. At least one reduced diameter surface is provided,
All of the reduced diameter surfaces formed in either a tapered surface shape with a constant diameter reduction toward the fuel downstream side or a convex curved surface shape with a larger diameter reduction rate toward the fuel downstream side are all the valve seat surfaces. Surrounded by a cylindrical inner peripheral surface of the valve body on the upstream side of the fuel,
Wherein those axial length from the contact portion in the cylindrical surface outer peripheral surface to the reduced diameter surface of the fuel upstream, the diameter of said from reduced diameter surface stepped surface or even fuel upstream of the fuel upstream than the axial length of the cylindrical surface outer peripheral surface to the surface, rather long,
From the abutting portion to the fuel upstream side with respect to the outer peripheral edge of the valve seat surface provided on the fuel downstream side of the cylindrical inner peripheral surface surrounding all the reduced diameter surfaces and on the fuel upstream side of the nozzle holes The cylindrical outer peripheral surface from the reduced diameter surface on the side and the cylindrical outer peripheral surface from the reduced diameter surface on the fuel upstream side to the stepped surface or further to the reduced diameter surface on the fuel upstream side, A fuel injection valve, which is located radially inside .   2. The fuel injection valve according to claim 1, wherein the step surface extends radially inward with respect to the fuel flow path between the valve body and the guide portion. The valve portion is reduced in diameter to a plurality of stages by forming a plurality of the reduced diameter surfaces toward the contact portion on the downstream side of the fuel,
3. The fuel injection valve according to claim 1, wherein a shape of each of the reduced diameter surfaces is one predetermined in each of the tapered surface shape and the convex curved surface shape. 4.   The stepped surface that is reduced in diameter toward the valve portion on the downstream side of the fuel is a tapered surface having a constant diameter reduction toward the downstream side of the fuel, or a convex curved surface having a larger diameter reduction rate toward the downstream side of the fuel. The fuel injection valve according to claim 1, wherein the fuel injection valve is formed as follows.

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