JP5648539B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device.

  Conventionally, a fuel injection device includes a valve member that is movably accommodated in a valve body (see, for example, Patent Document 1). The valve body has an injection hole for injecting fuel in the sac chamber into which fuel flows from the fuel passage. The valve member includes a seat portion that can contact the valve seat portion of the valve body, and a slope portion that receives a force in a direction in which the seat portion is separated from the valve seat portion. In this fuel injection device, when the seat is separated from the valve seat portion, the fuel flows into the fuel passage between the valve body and the valve member and is injected from the injection hole. At this time, the pressure of the fuel acts to push up the valve member.

By the way, in the conventional fuel injection device, immediately after the valve is opened, the flow rate of the fuel passage becomes relatively fast, and the pressure of the fuel passage becomes relatively small. Accordingly, the force in the separating direction acting on the valve member is small and the valve opening speed is slow, and there is a problem that the responsiveness of the valve opening operation is low.
Patent Document 1 describes that the fuel passage is made relatively long by making the diameter of the opening on the fuel passage side of the sac chamber smaller than the diameter of the bottom portion of the sac chamber, and the force acting on the valve member is increased. ing.

JP 2009-138683 A

  However, since the sac chamber of Patent Document 1 is provided so as to expand toward the bottom side of the valve body, there is a problem that the shape is complicated and the manufacturing cost increases.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection device having a simple configuration and high responsiveness in valve opening operation.

The present invention is a fuel injection device that includes a valve body and a valve member. The valve body includes a fuel passage through which fuel flows, a sac chamber for storing fuel flowing out from the fuel passage, a nozzle hole for injecting fuel in the sac chamber, and a valve seat portion formed on the inner wall of the fuel passage. The valve member is provided in the valve body so as to be movable in the axial direction. The valve member is provided on the sack chamber side of the valve member body so as to face the valve seat portion, and the outer diameter decreases toward the sack chamber. A slope part, a seat part provided on the sack chamber side of the first slope part and capable of contacting and separating from the valve seat part, a second slope part provided on the sack chamber side of the seat part and having a smaller outer diameter toward the sack chamber , Form. Further, the fuel injection device includes a throttle channel portion that is formed in a flow section from the seat portion toward the injection hole and that has a passage area that decreases toward the injection hole.

  In the present invention, when the fuel passage is opened and the fuel flows from the seat portion to the nozzle hole, the throttle channel portion is formed on the downstream side of the seat portion. Since the flow resistance is given to the fuel flowing through the throttle channel portion, the flow speed of the passage (second slope portion passage) between the second slope portion and the valve seat portion located on the upstream side of the throttle passage portion. Is relatively slow. Therefore, the pressure that the second slope portion receives from the fuel increases, and the moving speed of the valve member in the separating direction, that is, the valve opening speed can be increased. Therefore, it is possible to obtain a fuel injection device with a simple configuration and high responsiveness of the valve opening operation.

In the present invention, the throttle channel portion is formed in a minute lift region where the lift amount from the contact position of the valve member to the valve seat portion is a predetermined amount or less. Therefore, the moving speed of the valve member in the minute lift region can be increased. Also, for example, when the minute lift region is exceeded, the passage area of the throttle channel portion is larger than the passage area of the nozzle hole (the total passage area when there are a plurality of nozzle holes), and if the minute lift region is exceeded, the fuel A sufficient injection amount can be secured.

Moreover, in this invention, a valve member forms the projection part which protrudes from a 2nd slope part to the sack chamber side. The throttle channel portion is formed between the outer wall of the protrusion fitted into the sac chamber and the inner wall of the sac chamber. Therefore, the throttle channel portion can be formed at the entrance of the sack chamber located in the minute lift region on the downstream side of the seat portion.

Further, in the present invention, the throttle channel portion has a minute lift when the minimum channel area of the throttle channel unit is Ac and the maximum channel area of the second slope channel from the seat portion to the throttle channel unit is A0. In the area,
Ac ≦ (1/2) ・ A0
It is set so that Therefore, it is possible to sufficiently increase the pressure (hereinafter referred to as “receiving pressure”) received by the second inclined surface portion in the minute lift region.

Further, in the present invention, when the minimum passage area of the seat portion passage formed between the seat portion and the valve seat portion is As, when the lift amount is smaller than the predetermined amount in the minute lift region,
As <A0
It is set so that Therefore, when pressure loss occurs in the seat portion passage because the minimum passage area of the seat portion passage is smaller than the maximum passage area of the second slope portion passage (As <A0), a throttle passage is formed downstream of the seat portion. Thus, the effect of increasing the pressure receiving pressure of the second slope passage is obtained.

Also, in the present invention, beyond the micro lift region
As> A0
When the above relationship holds, the minimum passage area Ac increases.

Sectional drawing which shows the injector of 1st Embodiment of this invention. Sectional drawing which shows the structure of the front-end | tip part of the injector shown by the arrow A of FIG. The figure which shows the relationship between the lift amount of the needle from the contact position to the valve seat part of the seat part of FIG. 2, and each channel | path area. The figure which showed the change of the lift amount of the needle in the injector of 1st Embodiment, and the change of the lift amount of the needle in the injector of the comparison form shown in FIG. 6 in time series. Sectional drawing which shows the structure of the front-end | tip part of the injector of 2nd Embodiment of this invention. Sectional drawing which shows the structure of the front-end | tip part of the injector of a comparison form.

  Hereinafter, fuel injection devices according to a plurality of embodiments of the present invention will be described with reference to the drawings. Note that, in a plurality of embodiments and comparative embodiments, substantially the same components are denoted by the same reference numerals, and description thereof is omitted.

(First embodiment)
FIG. 1 is a cross-sectional view showing an injector 10 according to a first embodiment of the present invention. The injector 10 is used in a fuel injection system for an internal combustion engine (not shown) and supplies fuel to the internal combustion engine. After being pumped up from the fuel tank by the feed pump, the injector 10 is supplied with the fuel that has been increased in pressure by the high-pressure pump and accumulated in the common rail. In the present embodiment, the injector 10 is a direct injection type that directly injects fuel into a combustion chamber of an internal combustion engine, that is, an in-cylinder injection type.

  The injector 10 includes a housing 13, a valve body 14, a tip packing 15 interposed between the housing 13 and the valve body 14, and a retaining nut 16 that connects these members to each other from the outside. It is equipped with.

  The housing 13 forms an inlet 11 and an outlet 12. The inlet 11 is connected to the discharge port of the common rail. The outlet 12 is connected to a fuel passage (not shown) from the common rail to the fuel tank via a back pressure control valve (not shown). The fuel supplied from the inlet 11 is supplied to the passage 18 and the passage 19 via the passage 17. The fuel supplied to the passage 18 is sent to the valve body 14 side and is mainly used for injection. The fuel supplied to the passage 19 is sent to the control chamber 27.

  The valve body 14 is formed in a bottomed cylindrical shape that opens to the housing 13 side, and has an injection hole 53 for injecting fuel at the bottom. The fuel supplied to the inlet 11 is supplied to the passage 20 inside the valve body 14 via the passage 17, the passage 18, and the passage 21 of the tip packing 15.

  The injector 10 includes a movable shaft 22 that is provided so as to be movable in the axial direction in the housing 13, the tip packing 15, and the valve body 14. The movable shaft 22 includes a needle 23 as a “valve member”, a coupling 24, and a command piston 25. The needle 23 is mainly accommodated in the valve body 14, and the command piston 25 is mainly accommodated in the housing 13. The needle 23 and the command piston 25 are integrally connected by a coupling 24 in the tip packing 15. The movable shaft 22 is urged toward the valve body 14 by a spring 26 interposed between the housing 13 and the coupling 24.

  The injector 10 includes an electromagnetic valve portion 30 on the opposite side of the housing 13 from the valve body 14. The electromagnetic valve unit 30 includes a pair of terminals 32, an armature 33, a body 34, a stopper 35, a coil 36, an electromagnetic control valve member 37, and the like, and is fixed to the housing 13 with a nut 31.

The terminal 32 is for energizing the coil 36. A control valve drive current corresponding to the operating conditions of the internal combustion engine is supplied to the coil 36 via the terminal 32. When the coil 36 is energized, the armature 33 is magnetized.
The armature 33 has a bottomed cylindrical stopper 35 at its axial center. The stopper 35 has a shape that opens to the distal end side, and a spring 38 is disposed therein. The electromagnetic control valve member 37 supported by the body 34 is biased by the spring 38.
When the control valve driving current is supplied to the coil 36 and the armature 33 is magnetized, the electromagnetic control valve member 37 receives an excitation attractive force toward the armature 33 and resists the biasing force of the spring 38, that is, the armature 33. Move to 33 side.

  The control chamber 27 communicates with the outlet 12 through the passage 39 and the like when the electromagnetic control valve member 37 moves toward the armature 33 and is separated from the plate member 41.

  In the injector 10, when the solenoid valve unit 30 is controlled so that the fuel in the control chamber 27 is discharged from the outlet 12 through the passage 39, and the fuel flowing out from the control chamber 27 becomes larger than the fuel flowing into the control chamber 27. And the movable shaft 22 moves in a direction away from the bottom of the valve body 14.

  Hereinafter, the configuration of the tip of the injector 10 indicated by the arrow A in FIG. 1 will be described in detail with reference to FIG. FIG. 2A shows a case where the needle 23 is in contact with the valve body 14. 2B and 2C show a case where the needle 23 is separated from the valve body 14.

The valve body 14 includes a fuel passage 51, a sac chamber 52, a nozzle hole 53, and a valve seat portion 54.
The fuel passage 51 is formed between the valve body 14 and the needle 23, and the fuel supplied from the housing 13 side can flow therethrough. In FIG. 2A, the fuel passage 51 is blocked, and in FIGS. 2B and 2C, the fuel passage 51 is opened. The valve seat portion 54 is formed in a conical surface on the inner wall of the fuel passage 51 so that the inner diameter becomes smaller toward the sack chamber 52.

  The sac chamber 52 is formed in a bottomed cylindrical shape that opens toward the needle 23 in a flow section between the fuel passage 51 and the injection hole 53. A cylindrical portion of the inner wall 55 that forms the sac chamber 52 is formed in a cylindrical surface substantially parallel to the axial direction of the needle 23. The sac chamber 52 temporarily stores the fuel flowing out from the fuel passage 51 and supplies the fuel to the injection hole 53. The nozzle holes 53 are formed in the inner wall 55 of the sack chamber 52 so as to be opened, and for example, a plurality of nozzle holes 53 are provided in the circumferential direction. Each nozzle hole 53 injects fuel in the sac chamber 52.

The needle 23 is movably accommodated in the valve body 14 and includes a needle main body 23a as a “valve member main body”, a first slope portion 23b, a seat portion 23c, a second slope portion 23d, and a projection portion 23e.
The needle body 23a is provided in the valve body 14 so as to be movable in the axial direction. The first inclined surface portion 23 b is provided on the side of the sac chamber 52 of the needle body 23 a so as to face the valve seat portion 54, and is provided so that the outer diameter becomes smaller toward the sack chamber 52.

  The seat portion 23c is provided on the side of the sack chamber 52 of the first slope portion 23b, and can contact and separate from the valve seat portion 54. The second inclined surface portion 23 d is provided on the side of the sack chamber 52 of the seat portion 23 c so as to face the valve seat portion 54, and is provided so that the outer diameter becomes smaller toward the sack chamber 52. The first slope portion 23 b and the second slope portion 23 d form a fuel passage 51 between the valve seat portion 54.

  The seat portion 23 c blocks the fuel passage 51 by contacting the valve seat portion 54. On the other hand, the seat portion 23 c opens the fuel passage 51 by being separated from the valve seat portion 54. The second inclined surface portion 23 d receives the fuel pressure in the fuel passage 51 when the seat portion 23 c is separated from the valve seat portion 54. When the pressure is received, a force in the separation direction of the seat portion 23c acts on the first slope portion 23b and the second slope portion 23d. The direction of the force is indicated by an arrow F in FIG.

  The protruding portion 23e is provided to protrude from the second inclined surface portion 23d to the sack chamber 52 side. The outer wall 56 of the protrusion 23 e is formed in a cylindrical surface shape substantially parallel to the axial direction of the needle 23. As shown in FIG. 2A, the protrusion 23 e is fitted into the suck chamber 52 at a position where the seat portion 23 c is in contact with the valve seat portion 54.

  A throttle between the valve body 14 and the needle 23, which has a passage area that decreases toward the nozzle hole 53 toward the downstream side of the second inclined surface part 23 d in the flow passage between the seat part 23 c and the nozzle hole 53. A flow path portion 57 is formed. Specifically, in the present embodiment, the throttle channel portion 57 is formed between the outer wall 56 of the protrusion 23 e fitted into the sac chamber 52 and the inner wall 55 of the sack chamber 52. In the present embodiment, the radial clearance Sc between the outer wall 56 and the inner wall 55 is set to 10 μm, for example. As shown in FIG. 2 (a), the throttle flow path portion 57 has a predetermined amount in the axial direction as shown in FIG. 2 (b) from the contact position between the seat portion 23c and the valve seat portion 54. It is formed in a minute lift region Z (see FIG. 3 described later) until the predetermined lift amount Lf moves.

FIG. 3 shows the movement distance in the axial direction of the needle 23 from the contact position between the seat portion 23c and the valve seat portion 54, that is, the lift amount L [mm], the passage areas As, A0, and Ac [mm ² ]. It is a figure which shows the relationship. In FIG. 3, the horizontal axis indicates the lift amount L, and the vertical axis indicates the passage areas As, A0, and Ac. The seat portion passage area As is the minimum passage area of the seat portion passage formed between the seat portion 23c and the valve seat portion 54. The second slope portion passage area A0 is the maximum passage area of the second slope portion passage formed between the second slope portion 23d and the valve seat portion 54. The throttle passage area Ac is the minimum passage area of the throttle channel portion 57. In the present embodiment, the passage areas As, A0, and Ac are in-plane passage areas perpendicular to the fuel flow direction indicated by the arrow f in FIG.

As shown in FIG. 3, the seat portion passage area As is 0 (zero) when the contact position between the seat portion 23c and the valve seat portion 54, that is, the lift amount L is 0 (zero). The seat portion passage area As continuously increases as the seat portion 23c moves away from the valve seat portion 54, that is, as the lift amount L increases.
The second slope passage area A0 is a predetermined value A01 when the lift amount L is 0 (zero). And 2nd slope part channel | path area A0 increases continuously, so that the lift amount L increases.

In the present embodiment, the shape (dimensions) of the valve seat portion 54, the sac chamber 52, the seat portion 23c, the projection portion 23e, and the like (hereinafter referred to as “valve component member”) is such that the lift amount L of the needle 23 is a predetermined lift amount Lf. When it is smaller (when the lift amount L is within the minute lift region Z), the relationship of the following expression (1) is established.
As <A0 (1)
Further, the shape (dimensions) of the valve constituent member is expressed by the following equation (2) when the lift amount L of the needle 23 is the same as the predetermined lift amount Lf (when the lift amount L is the maximum value of the minute lift region Z). Is set as follows.
As = A0 (2)
Further, the shape (dimensions) of the valve component is such that the relationship of the following equation (3) is established when the lift amount L of the needle 23 is larger than the predetermined lift amount Lf (when the lift amount L exceeds the minute lift region Z). Is set.
As> A0 (3)

When the lift amount L of the needle 23 is within the minute lift region Z, the throttle passage area Ac is a constant predetermined value Ac1 because the outer wall 56 and the inner wall 55 are substantially parallel. The throttle passage area Ac increases rapidly when the lift amount L of the needle 23 exceeds the minute lift region Z.
In the present embodiment, the shape (size) of the valve component is set so that the relationship of the following equation (4) is established when the lift amount L of the needle 23 is within the minute lift region Z.
Ac ≦ (1/2) · A0 (4)
The seat portion passage area As matches the throttle passage area Ac at a predetermined value L0 on the side where the lift amount L is relatively close to 0 (zero) in the minute lift region Z.

  Next, the operation of the injector 10 will be described with reference to FIG. FIG. 4 is a diagram showing, in a time series, changes in the lift amount L of the needle 23 of the injector 10 and changes in the lift amount L ′ of the needle 23 of the injector of the comparative embodiment shown in FIG. 6. In FIG. 4, the solid line indicates the lift amount L of the needle 23 of the injector 10 of the present embodiment, and the broken line indicates the lift amount L ′ of the needle 23 of the injector of the comparative embodiment. In the injector 10, the coil 36 is energized from time t0 to time t12 and valve opening control is performed. From time t12 to time t13, the coil 36 is de-energized and valve closing control is performed by the urging force of the spring 26. In the injector of the comparative form, valve opening control is performed from time t0 to time t21, and valve closing control is performed from time t21 to time t22.

  First, a comparative injector will be described. As shown in FIG. 6, the injector of the comparative form does not include the protruding portion 23 e as in the present embodiment, and the throttle channel portion 57 is not formed. In the injector according to the comparative embodiment, as shown in FIG. 6B, when the lift amount L of the needle 23 is relatively small immediately after the fuel passage 51 is opened, that is, immediately after the valve is opened, the flow velocity of the fuel passage 51 is high. Therefore, no restriction is formed on the downstream side of the seat portion 23c, and the pressure that the second inclined surface portion 23d receives from the fuel is relatively small. Therefore, the moving speed of the needle 23 in the axial direction, that is, the valve opening speed is relatively slow.

  In the injector 10 of the present embodiment, as shown in FIG. 2B, when the fuel passage 51 is opened and fuel flows from the seat portion 23c to the injection hole 53, the throttle passage portion 57 is provided downstream of the seat portion 23c. Is formed. Therefore, a flow resistance is given to the fuel upstream of the throttle channel portion 57, and the flow speed of the second slope portion passage formed between the second slope portion 23 d and the valve seat portion 54 in the fuel passage 51 is increased. Relatively slow. That is, the fuel stays in the second slope passage for a relatively long time. Therefore, the pressure that the second inclined surface portion 23d of the needle 23 receives from the fuel increases as compared with the case of the injector of the comparative form.

  Therefore, as shown in FIG. 4, the injector 10 of this embodiment has a higher moving speed in the axial direction of the needle 23, that is, the valve opening speed, compared to the injector of the comparative embodiment. Here, after the time t11, the lift amount L of the needle 23 exceeds the predetermined value Lf, thereby exceeding the minute lift region Z, and the throttle of the throttle channel portion 57 is opened, that is, the throttle passage area Ac suddenly increases. Become. Therefore, the moving speed of the needle 23 is lower than that of the two-dot chain line a that is virtually shown by extending the inclination of the change in the lift amount L in the minute lift region Z in FIG. However, since the needle 23 continues to move in the separating direction with the inertial force, the amount of decrease in the moving speed of the needle 23 is relatively small.

In the present embodiment, the injector 10 (fuel injection device) includes a valve body 14 and a needle (valve member) 23. The valve body 14 includes a fuel passage 51 through which fuel flows, a sac chamber 52 in which fuel flowing out from the fuel passage 51 is stored, a nozzle hole 53 for injecting fuel in the sac chamber 52, and a valve seat formed on the inner wall of the fuel passage 51. Part 54. The needle 23 is provided in the valve body 14 so as to be movable in the axial direction in the needle body (valve member body) 23a. The needle body 23a is provided on the sack 52 chamber side of the needle body 23a so as to face the valve seat 54. A first slope portion 23b having a smaller outer diameter toward the chamber, a seat portion 23c that is provided on the side of the sac chamber 52 of the first slope portion 23b and can be brought into contact with and separated from the valve seat portion 54, and a sac chamber 52 of the seat portion 23c A second inclined surface portion 23d that is provided on the side and decreases in outer diameter toward the sack chamber 52 is formed. Further, the injector 10 includes a throttle channel portion 57 that is formed in a flow section that extends from the seat portion 23 c to the injection hole 53 and that has a passage area that decreases toward the injection hole 53.
Therefore, when the fuel passage 51 is opened and fuel flows from the seat portion 23c to the injection hole 53, the throttle channel portion 57 is formed on the downstream side of the seat portion 23c. Since flow resistance is imparted to the fuel flowing through the throttle passage portion 57, the second slope passage between the second slope portion 23d and the valve seat portion 54 located upstream of the throttle passage portion 57 is provided. Distribution speed is relatively slow. Therefore, the pressure received by the second inclined surface portion 23d from the fuel increases, and the moving speed of the needle 23 in the separating direction, that is, the valve opening speed can be increased. Therefore, it is possible to obtain the injector 10 having a simple configuration and high responsiveness of the valve opening operation.

  In the present embodiment, the throttle channel portion 57 is formed in the minute lift region Z in which the lift amount L in the axial direction from the seating position of the needle 23 is equal to or less than the predetermined lift amount Lf. Therefore, the moving speed of the needle 23 in the minute lift region Z can be increased.

  In the present embodiment, the needle 23 has a protrusion 23e that protrudes from the second inclined surface portion 23d toward the sack chamber 52 side. The throttle channel portion 57 is formed between the outer wall 56 of the projection 23 e fitted into the sac chamber 52 and the inner wall 55 of the sack chamber 52. Therefore, the throttle channel portion 57 can be formed in the minute lift region Z at the entrance of the sack chamber 52 located on the downstream side of the seat portion 23c.

Further, in the present embodiment, the shape (dimensions) of the valve constituent member forming the throttle channel portion 57 is such that the minimum passage area of the throttle channel portion 57 is Ac, and from the seat portion 23 c to the throttle channel portion 57. Assuming that the maximum passage area of the second slope portion passage is A0, in the minute lift region Z, Ac ≦ (1/2) · A0
It is set so that Therefore, the pressure received by the second inclined surface portion 23d in the minute lift region Z can be sufficiently increased.

Further, in the present embodiment, the throttle channel portion 57 has a minimum passage area of the seat portion passage formed between the seat portion 23c and the valve seat portion 54 as As,
As <A0
It is formed when the above relationship holds. Therefore, when pressure loss occurs in the seat portion passage because the minimum passage area As of the seat portion passage is smaller than the maximum passage area A0 of the second slope portion passage (As <A0), the throttle passage portion is provided downstream of the seat portion 23c. The effect of increasing the pressure-receiving pressure of the second slope passage due to the formation of 57 is obtained.

(Second Embodiment)
FIG. 5 is a cross-sectional view showing an injector according to a second embodiment of the present invention. In this embodiment, the valve body 14 has the recessed part 60 continuously formed in the circumferential direction in the part facing the 2nd slope part 23d among the valve seat parts 54. As shown in FIG. In the present embodiment, the recess 60 includes a cylindrical wall formed parallel to the axial direction of the needle 23 and an annular wall formed in a plane orthogonal to the axial direction of the needle 23. The recessed portion 60 forms an enlarged flow path portion in which the passage area increases toward the nozzle hole 53 in the flow section from the sheet portion 23 c to the nozzle hole 53. Moreover, it has the narrowing flow path part 57 in which a passage area becomes small toward the downstream side in the position adjacent to the downstream side of the said expansion flow path part.

  In the injector of the present embodiment, as shown in FIG. 5B, when the fuel passage 51 is opened and the fuel flows from the seat portion 23c to the injection hole 53, the enlarged flow passage portion and the throttle are arranged on the downstream side of the seat portion 23c. A flow path portion 57 is formed. Therefore, the flow rate of the fuel that has passed through the seat portion 23c decreases in the enlarged flow path portion and the throttle flow path portion 57 (in the recess 60). Therefore, the pressure received by the second slope part 23d of the needle 23 from the fuel in the second slope part passage increases as compared with the case of the injector of the comparative form. The recessed part 60 functions as a volume part for temporarily storing the fuel passing through the seat part 23c and reducing the flow rate of the second slope part passage.

  The structure of the injector of this embodiment is the same as that of 1st Embodiment except the recessed part 60 being formed in the valve seat part 54. FIG. In the present embodiment, when the fuel passage 51 is opened and fuel flows from the seat portion 23 c to the injection hole 53, the throttle passage portion 57 is formed on the downstream side of the seat portion 23 c, so that the upstream side of the throttle passage portion 57. The circulation speed of the second slope portion passage between the second slope portion 23d located on the side and the valve seat portion 54 becomes relatively slow. Therefore, the pressure received by the second inclined surface portion 23d from the fuel increases, and the moving speed of the needle 23 in the separating direction, that is, the valve opening speed can be increased. Therefore, it is possible to obtain an injector with a simple configuration and high responsiveness of the valve opening operation.

  Further, in the present embodiment, the valve body 14 is continuously formed on the seat portion 23 c side of the throttle passage portion 57 in the circulation section from the seat portion 23 c to the injection hole 53, and the passage area increases toward the injection hole 53. A recess 60 is formed in which becomes larger. Therefore, when the fuel passage 51 is opened and fuel flows from the seat portion 23c to the injection hole 53, an enlarged flow passage portion is formed on the downstream side of the seat portion 23c. Therefore, the flow rate of the fuel that has passed through the seat portion 23c decreases in the enlarged flow path portion, that is, the recess 60, so that the pressure received by the second slope portion passage is further increased.

(Other embodiments)
In the above-described embodiment, the injector 10 is an in-cylinder injection type. On the other hand, in another embodiment of the present invention, the fuel injection device may be a port injection type.

  In the above-described embodiment, the injector 10 is a hydraulic drive type that drives the needle 23 by controlling the hydraulic pressure of the control chamber 27 by the electromagnetic valve unit 30. On the other hand, in another embodiment of the present invention, for example, the needle may be fixed to a movable iron core of a solenoid and directly driven by the solenoid, or the needle is driven by hydraulic control using a piezo element. It is good as well.

  In the above-described embodiment, the throttle channel portion 57 is formed between the inner wall 55 that forms the sac chamber 52 and the outer wall 56 of the protrusion 23e. On the other hand, in another embodiment of the present invention, the throttle channel portion may be formed not between the sac chamber and the protrusion, but between the valve seat portion and the needle, for example.

  In the second embodiment, the enlarged flow path portion is formed by the concave portion 60 provided continuously in the circumferential direction in the valve seat portion 54. On the other hand, in another embodiment of the present invention, the enlarged flow path portion may be formed by a hole or a groove formed in the valve seat portion. The holes and grooves are not necessarily formed continuously in the circumferential direction.

  Thus, the present invention is not limited to the above-described embodiment, and can be applied to various forms without departing from the gist thereof.

10: Injector (fuel injection device)
14 ... Valve body 23 ... Needle (valve member)
23a ... Needle body (valve member body)
23b ... 1st slope part 23c ... Sheet | seat part 23d ... 2nd slope part 23e ... Projection part 51 ... Fuel passage 52 ... Suck chamber 53 ... Injection hole 54 ... Valve seat portion 55 ・ ・ ・ Inner wall 56 ・ ・ ・ Outer wall 57 ・ ・ ・ Throttle channel portion 60 ・ ・ ・ Concavity Ac ・ ・ ・ Throttle channel area (minimum channel area of throttle channel unit)
As ... sheet part passage area (minimum passage area of sheet part passage)
A0 ... second slope section passage area (maximum passage area of the second slope section passage)
L: Lift amount Lf: Predetermined lift amount (predetermined amount)
Z ... Micro lift region

Claims (1)

A valve body having a fuel passage through which fuel flows, a sac chamber for storing fuel flowing out from the fuel passage, a nozzle hole for injecting fuel in the sac chamber, and a valve seat portion formed on the inner wall of the fuel passage;
A valve member main body provided in the valve body so as to be movable in the axial direction, and provided on the side of the sack chamber of the valve member main body so as to face the valve seat portion, and the outer diameter decreases toward the sac chamber. 1 slope part, a seat part provided on the sack chamber side of the first slope part and capable of contacting and separating from the valve seat part, an outer diameter provided on the sack chamber side of the seat part toward the sac chamber And a valve member that forms a second slope portion that decreases, and a projection that projects from the second slope portion toward the sack chamber ;
A distribution section toward the injection hole from the seat portion, said formed between the outer wall of the protrusion to be fitted to suck chamber and the inner wall of the suction chamber, a small passage area as it goes to the injection hole A throttle channel section,
Equipped with a,
The throttle channel portion is formed in a minute lift region in which a lift amount from a contact position of the valve member to the valve seat portion is a predetermined amount or less,
When the minimum passage area of the throttle channel portion is Ac and the maximum passage area of the second slope portion passage from the seat portion to the throttle channel portion is A0, in the minute lift region,
Ac ≦ (1/2) ・ A0
The relationship of
When the minimum passage area of the seat portion passage formed between the seat portion and the valve seat portion is As, when the lift amount is smaller than the predetermined amount in the minute lift region,
As <A0
The relationship of
Beyond the micro lift region
As> A0
When the relationship holds, fuel injection apparatus characterized that you increase the minimum passage area Ac is.

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